Checking a set of hypotheses

Mechanism. First increase measurable mitophagic flux with urolithin A, then activate THRB with resmetirom; the proposed mechanism depends on ATG7.

Prediction. A factorial experiment testing both treatment orders in aged liver microtissues will assess viable functional mass after repeated lipid challenge as the primary outcome, with measurements of respiration and autophagic flux. Temporary ATG7 reduction will test the proposed mechanism. Support requires the specified effect and dependence on reserve and ATG7 at measured free urolithin A exposure achievable according to human pharmacokinetics. The thresholds are proposed development criteria, not experimental findings; a negative conclusion requires target engagement and a 95% confidence interval excluding the minimum effect, while a wide interval indicates uncertainty.

Mechanism. Late attenuation of SLC7A5–mTORC1 signaling supports Tfh memory, with a larger relative benefit for a new antigen with rare precursors than for a familiar antigen with an expanded memory-cell pool.

Prediction. Attenuate late SLC7A5–mTORC1 signaling after primary or repeat noninfectious immunization, and compare the responses separately while standardizing the antigen and late intervention window. Measure initial antigen-specific precursor frequency, functional B-cell help and late avidity, and test the interaction between intervention and immunization history; the relative benefit should be greater for the primary response after accounting for initial cell frequency.

Mechanism. ITGA11 has a specialized role in restoring old dermal matrix that ITGA2 cannot replace through equivalent overall attachment to collagen.

Prediction. Compare separate increases in ITGA11 and ITGA2 with control across several old donor fibroblast lines in the same 3D scaffold, matching overall collagen attachment and comparing cell density, adhesion and collagen quantity. The ultimate strength of newly synthesized matrix should be at least 20% greater with ITGA11 than with ITGA2. Refutation requires confirmed target engagement and a 95% confidence interval excluding the proposed minimum effect; a wide interval indicates uncertainty. The unit of analysis is the donor or animal.

Mechanism. Temporarily increasing ITGA11 in old dermal fibroblasts and then returning it to baseline limits persistent myofibroblast activation compared with continuous elevation at comparable cumulative exposure.

Prediction. Compare a pulse, continuous elevation and control in old donor skin equivalents. After identical stretching cycles, the pulse should reduce residual deformation by at least 15% relative to continuous elevation, with strength no more than 10% worse; also assess ACTA2 and fiber architecture. Refutation requires confirmed target engagement and a 95% confidence interval excluding the proposed minimum effect; a wide interval indicates uncertainty. The unit of analysis is the donor or animal.

Mechanism. Brief inhibition of MLKL interrupts the ongoing activity that maintains mitochondrial damage in aged hematopoietic stem cells, allowing sustained functional recovery.

Prediction. Compare aged cells after brief MLKL inhibition, continuous inhibition and control treatment, using young cells as a physiological reference. After withdrawal, transplant equal numbers of viable cells under comparable conditions and measure long-term production of different blood cells, self-renewal and individual clone contributions. Support requires sustained hematopoietic recovery after withdrawal and restoration of clonal diversity, rather than expansion of a few clones; confirm target inhibition, recovery of its activity after withdrawal and mitochondrial damage dynamics, accounting for differences in total exposure between regimens.

Mechanism. Partially reduce SIRT1 deacetylase activity only in dividing T cells with insufficient histone synthesis. Target activated naive T cells from older donors with replication stress during the first S phases after antigen activation, restoring activity when expansion ends.

Prediction. Compare S-phase suppression, early suppression before division and continuous suppression with the same initial response. Measure histone synthesis, replication fork speed, DNA damage, chromosomal abnormalities and survival of individual clones, then test a repeat specific response after complete withdrawal of the intervention. Faster division without reduced DNA damage and improved diverse functional memory would not indicate correction of the proposed age-related defect.

Mechanism. In old hematopoietic stem cells with low SIRT7 and elevated mitochondrial protein stress, temporarily restore SIRT7 expression to the young range during quiescence before a neutral hematopoietic stimulus. Through SIRT7, limit excessive activation of the NRF1 mitochondrial translation program without permanently switching off NRF1, and return regulation to baseline after stress is reduced.

Prediction. Compare preparatory and continuous regimens, catalytically inactive SIRT7 and control. Measure protein stress rather than mitochondrial mass alone, clonal lymphoid output and responses to two different noninfectious antigens; separately restore the elevated NRF1 program to test mediation. If stress decreases but the diversity of new lymphocytes and functional responses do not improve, this metabolic barrier is not a sufficient limiting factor.

Mechanism. First activate THRB in hepatocytes, then use D+Q to act on persistent senescent cells, placing metabolic unloading before liver senolysis.

Prediction. Compare both treatment orders, monotherapies and simultaneous treatment in multicellular liver microtissues from older donors. The primary outcome is albumin synthesis after withdrawal of all treatments; measure lipotoxicity, cell death and new matrix. The resmetirom→D+Q sequence should retain a 20% advantage after withdrawal that is not attributable to unequal residual drug.

Mechanism. Achieve the same inhibition of epidermal JAK1/JAK2 while reducing exposure of dermal cells and the vascular compartment.

Prediction. In perfused skin explants from elderly donors with the same superficial defect, the retained formulation will meet the stated strength, perfusate-release and barrier criteria. Measure the spatial distribution of free drug and vascular viability, and verify equivalent epidermal target suppression. These thresholds are proposed development criteria, not experimentally observed results.

Mechanism. The proposed metabolic condition is the initial capacity to oxidize long-chain fatty acids. SIRT3 mitochondrial deacetylase activity is raised to the young range, and ACADL/LCAD expression is restored to the young range only when a deficiency is detected, before neurogenic activation; the intervention is then returned to baseline during differentiation.

Prediction. Measure fatty acid oxidation flux and the activity of both proteins beforehand, then compare SIRT3, ACADL, their combination and control factorially in the two initial states. Assess mitochondrial protein acetylation, oxidative stress, return to quiescence and mature progeny of the second wave. The combination should overcome resistance to SIRT3 in ACADL-deficient cells but provide no additional benefit with normal ACADL. If initial ACADL does not predict response, or the combination does not overcome resistance despite confirmed restoration of flux, the proposed metabolic condition is incorrect.

Mechanism. The functional response to restoring ITGA11/integrin α11β1 to the range found in young donors depends on the continuity of the collagen scaffold.

Prediction. Use a paired 3D factorial experiment with old donor fibroblasts: ITGA11/control × intact/fragmented matrix, keeping collagen mass equal. Measure the ultimate strength of newly formed matrix after removing cells, along with initial mechanics, viability and receptor occupancy. The functional gain on the intact scaffold should exceed that on the fragmented scaffold by at least 20%. Refutation requires confirmed target engagement and a 95% confidence interval excluding the proposed minimum effect; a wide interval indicates uncertainty. The unit of analysis is the donor or animal.

Mechanism. Restoring SUOX to the young physiological range in aged endothelium with low LATS1/2 will provide a catalytic-activity-dependent functional benefit associated with reduced reverse operation of ATP synthase.

Prediction. In paired chips made from aged donor cells under identical disturbed flow, compare SUOX restoration, CD38 suppression, and their combination using the same untreated blood. SUOX restoration is expected to reduce platelet coverage by at least 25% despite persistently high CD38, whereas catalytically inactive SUOX will not reproduce the effect; measure ATP, ROS, SUOX, and the direction of complex V operation while controlling for monolayer integrity.

Mechanism. Exercise activates mitochondrial turnover in muscle. Slowed mitophagy in aged muscle allows damaged mitochondria to accumulate, sustaining oxidative stress and inflammation and weakening strength recovery; уралицин A, a gut microbiota metabolite, induces mitophagy.

Prediction. In a randomized, blinded, placebo-controlled study of people aged 65-80 years, compare a course of уралицин A within 24-72 hours after exercise with the same course after 7 days and with placebo, using equal total doses. The primary outcome is the change in maximal strength after 2 weeks, with a prespecified window-by-treatment interaction analysis; the gain should be statistically significantly greater within the window. Secondary outcomes include endurance, mitochondrial respiration, and biopsy markers of mitophagy, including PINK1/Parkin and LC3-II/p62. Equal strength gains in both windows would reject the window hypothesis; no strength gain despite confirmed mitophagy activation would reject mitophagy as the limiting step in human recovery.

Mechanism. Restoration of membrane COL17A1 in basal keratinocytes restores epidermal regenerative reserve, with the benefit revealed by repeated injury.

Prediction. Use long-lived organotypic equivalents with elderly primary keratinocytes and two identical injuries separated by complete recovery. Measure the proportion of cultures with a restored barrier at a prespecified time after the second injury and track the clonal contribution of basal cells. The expected advantage is at least 20 percentage points; an advantage below 20 percentage points refutes the hypothesis only with confirmed target engagement and a 95% confidence interval excluding the proposed minimum effect. A wide confidence interval indicates uncertainty. The unit of analysis is the donor or animal.

Mechanism. Temporarily reduce the fraction of GTP-bound CDC42 in old hematopoietic stem cells to the young range and reversibly attenuate chronic IL-1 signaling in bone marrow stroma through IL1R1. Apply the correction in naturally old mice with high CDC42 activity and an inflamed niche before an immune challenge, followed by withdrawal.

Prediction. Use a 2×2 comparison of control, CDC42 intervention alone, IL1R1 intervention alone and the combination, with equal levels of each intervention in the single and combined groups. Track polarity and individual clone fate, distinguishing changes in clonal composition from rejuvenation of each cell, and check preservation of existing immune memory. The primary outcome is the number of distinct new lymphoid clones participating in the response to a new protein antigen after withdrawal. The hypothesis is rejected if the combination does not outperform the best single intervention after withdrawal or if its effect is explained by loss of stem-cell clonal diversity.

Mechanism. Increase local CCL21 presentation on the T-zone stromal network to the young range when deficiency is confirmed, targeting fibroblastic reticular cells of an old lymph node before antigen arrival and during the early search for specific T-clones.

Prediction. Compare network presentation with soluble delivery at comparable total exposure, expecting greater repertoire coverage with network presentation. Measure movement directionality, productive encounter frequency, time to first division, and the number of independent memory TCR-clones. Monitor excessive cell retention and total lymph node cellularity. If contacts increase but the number of specific memory clones does not, the proposed search barrier does not explain immune aging.

Mechanism. In old hematopoietic stem cells with low autophagic flux and a limiting ATG12 deficiency, increase ATG12 expression when protein deficiency is confirmed and restore formation of the functional ATG12–ATG5 conjugate to the young level before returning to productive hematopoiesis. Do not stimulate cells that already have high flux.

Prediction. First distinguish deficient autophagosome formation from blocked lysosomal degradation. Compare targeted and uniform increases, a nonfunctional conjugation control and the initial state, measuring flux, long-term clonal output, the balance of myeloid and lymphoid cells, and the immune response after withdrawal of the intervention. If the conjugate and flux are restored but functional lymphoid clones do not increase, the selected component does not explain immune aging in this subgroup.

Mechanism. Inhibit mTORC1 and assess whether the response depends on ATG7-dependent autophagic flux. Functional autophagic reserve determines the response in age-related dermal fibroblast dysfunction.

Prediction. Test 3D skin from older donors prospectively stratified by measured flux, using tensile strength as the primary outcome and paired temporary ATG7 reduction to test causality. Account for degradation, collagen synthesis and cell number. Absence of a functional benefit or the predicted interaction with flux constitutes refutation or a stopping criterion; LC3 accumulation alone is insufficient. The thresholds are proposed for a development decision, not obtained results; a negative conclusion requires target engagement and a 95% confidence interval excluding the minimum effect, while a wide confidence interval indicates uncertainty. Use measured free exposure achievable under human pharmacokinetics and separately check tissue and systemic exposure for a topical formulation; an effect only at unachievable exposure stops this development path.

Mechanism. Raise ST8SIA2/ST8SiaII polysialyltransferase activity to the young range in immature granule neurons of the aged dentate gyrus with insufficient PSA-NCAM, increasing polysialylation of existing NCAM1 without increasing its total expression. Apply this during early positioning and growth, then return ST8SIA2 to baseline before connections stabilize.

Prediction. Compare transient ST8SIA2 elevation, continuous elevation, increased NCAM1 and a control, with catalytically inactive ST8SIA2 as a control. Measure NCAM1 and its associated polysialic acid separately, and assess soma location, dendrites, mature synapses and survival of the traced cohort. Restoring the modification should improve integration more than increasing NCAM1; restoration of PSA-NCAM without improved positioning and functional integration would show that this modification's deficiency is not a sufficient limiting factor.

Mechanism. The response to reduced PTGER2/EP2 signaling in tissue macrophages depends on baseline lysosomal reserve, assessed through lysosomal acidification and the ability to digest engulfed material.

Prediction. Compare EP2 blockade with control in paired human tissue samples, measuring uptake and subsequent digestion of standardized cellular material separately. Test the interaction between baseline lysosomal reserve and the intervention effect at the donor level: preserved reserve should predict stronger restoration of clearance beyond baseline EP2 expression. With confirmed EP2 suppression, an effect independent of baseline reserve or no added predictive value beyond EP2 levels would refute the prediction.

Mechanism. Temporarily restore E47 levels in aged B cells with reduced expression and restore the local CXCL13 gradient in the follicle while preserving normal B-zone boundaries. The proposed setting is aged lymph nodes with both a weak B-cell program and a blurred follicular chemokine distribution.

Prediction. A 2×2 comparison of control, A alone, B alone and A+B, with matched levels of each intervention in the single and combined groups, will track B-clone positions, contacts with follicular dendritic cells and clone fates. Compare a local gradient with uniform delivery of the same quantity of CXCL13. The expected result is improved affinity of specific antibodies with preserved B-memory diversity; an effect due only to B-cell numbers, no improvement in selection quality or deterioration of follicular structure would refute the hypothesis.

Mechanism. Restoring C1GALT1 in old endothelium restores O-glycans that shield VCAM1-mediated leukocyte interactions without reducing surface VCAM1 abundance.

Prediction. In a factorial C1GALT1 × VCAM1-blockade experiment in endothelial channels from old donors, stable monocyte adhesion per area under equal flow should decrease by at least 25% with unchanged VCAM1 abundance, and VCAM1 blockade should eliminate at least half of the glycan advantage. Measure VCAM1 accessibility, abundance, and permeability to distinguish shielding from transcriptional suppression.

Mechanism. Restore functional DISC1 protein expression to the level of young new neurons when a deficiency is detected in postmitotic granule neurons born in the old hippocampus, at the onset of dendritic growth and formation of the first synapses. This is proposed to restore coordination between growth and correct network integration.

Prediction. Compare DISC1 restoration, moderate reduction of AKT/mTOR signaling with comparable early growth and control. Measure dendritic length, soma position, dendrite orientation, projections to CA3, excitability and long-term integration, tracing the original cohort to exclude increased divisions as an explanation. DISC1 correction should improve positioning, mature function and survival; merely slowing growth without these improvements would not support the proposed benefit of restoring the pace of integration.

Mechanism. Urolithin A enhances removal of damaged mitochondria; its functional effect requires ATG7-dependent mitophagic flux and intact lysosomal completion.

Prediction. Test muscle microtissues from elderly donors with measured flux. The primary outcome is fatigability at equal initial force, controlling for ATP, lysosomal completion and fiber number; transient ATG7 reduction tests the necessity of the process. Intact completion should permit the at least 25% improvement, whereas impaired completion should yield less than half the effect. These thresholds are proposed development criteria, not experimental findings.

Mechanism. More precise arrival will reduce collateral damage, but inflammation will continue without clearance of spent cells. PI3Kδ modulation is restricted to navigation toward the site and stops before full neutrophil effector activity; surface MERTK is restored in macrophages during the subsequent clearance phase.

Prediction. A 2×2 comparison of control, A alone, B alone and A+B, with equal levels of each intervention in the single and combined groups, should show reduced integrated tissue damage with preserved effectiveness of two consecutive innate responses. Neutrophil trajectories, protease localization, uptake of nonpathogenic particles and removal of spent cells are tracked, with a separate test of the response to a second stimulus. Reduced damage through suppression of effector function, or failure of MERTK correction to improve completion of the response, would refute the hypothesis.

Mechanism. Restore membrane expression of IL22RA1 to the young range when deficiency is confirmed, using a limited local IL22 signal without increasing it systemically. Target aged thymic epithelial cells that respond poorly to IL-22 during the early epithelial recovery window, stopping enhancement after regeneration.

Prediction. Compare receptor restoration, ligand increase, their combination and a control. Measure IL22RA1, IL10RB and receptor responsiveness; assess thymic structure, negative selection, diversity of new T-cell clones and the response to a new protein antigen. Receptor restoration is expected to enable functional recovery with a smaller local signal; if selection and functional output do not improve despite restored receptor responsiveness, receptor insufficiency is not a sufficient limiting factor.

Mechanism. Raise FOXN1 expression in epithelial cells of the old thymus to the young range and reversibly reduce excessive basal NLRP3 activity in thymic myeloid cells. Limit both interventions to the recovery period in an old thymus with epithelial deficiency and chronic inflammasome activity.

Prediction. A 2×2 comparison of control, FOXN1 alone, NLRP3 reduction alone and the combination, with matched intervention levels in single and combined groups, tests output of diverse new naive T-cells with normal self-tolerance after both interventions are withdrawn. Measure epithelial structure, inflammation and negative-selection quality separately, and check preservation of a brief innate response after inhibition is withdrawn. The hypothesis is refuted if the combination increases only thymic mass, does not exceed FOXN1 alone in functional output, or impairs the protective response.

Mechanism. Reducing nuclear IL33 only in aged lymphatic endothelial cells before enhancing VEGFC–FLT4 will allow growth to begin after cellular vulnerability has decreased.

Prediction. Compare the sequential, reverse, and simultaneous regimens and individual interventions in aged cardiac lymphatic models with equal total exposures and equal observation times after withdrawal. The time to remove half of the interstitial tracer is expected to be at least 25% shorter with IL33↓→VEGFC↑ than with the reverse sequence, with the advantage retained at equal network density and residual exposure; measure lymphatic endothelial viability, the network, and tissue edema.

Mechanism. First enhance mitophagic flux with urolithin A, then suppress MSTN/myostatin activation with apitegromab.

Prediction. Compare both treatment orders, monotherapies and a control in innervated muscle models from elderly donors. The primary outcome is force per fiber area; measure fatigability, mitophagy and active myostatin while excluding differences in hydration and fiber number. Urolithin A followed by apitegromab should produce the at least 20% specific-force advantage over apitegromab alone, with a smaller effect from the reverse order. The threshold is a proposed development criterion, not an experimental finding.

Mechanism. Vascular TNAP accounts for the barrier effect of GPLD1 independently of serum alkaline phosphatase. Reduce ALPL/TNAP only in old brain endothelium; separately increase GPLD1 while retaining catalytically active TNAP on the endothelial membrane that is resistant to this method of removal.

Prediction. Use a paired old barrier-on-chip model to compare GPLD1, ALPL suppression, each with restoration of membrane TNAP, and a control. Measure albumin permeability as the primary outcome, confirm the localization and activity of the restored enzyme, and ensure identical other medium components and viability. Local ALPL suppression is expected to reduce permeability by at least 25%, and preservation of active membrane TNAP is expected to eliminate at least half of the GPLD1 effect. These are proposed thresholds, not observed results. Refutation requires confirmed target engagement and a 95% confidence interval excluding the specified minimum effect; a wide confidence interval indicates uncertainty. The independent unit is the donor or animal.

Mechanism. Reduce AP2A1 only in fibroblasts, compared with simultaneous reduction in fibroblasts and keratinocytes, while keeping dermal suppression identical.

Prediction. Construct two-layer equivalents from independently treated primary cells of elderly donors. Measure integrated excess permeability after injury and monitor viability in each layer. Dermis-restricted intervention should reduce the barrier defect by at least 20%, while dermal strength should be no more than 10% inferior. Failure to reduce the barrier defect by at least 20% or loss of more than 10% of the dermal functional benefit refutes the hypothesis. Refutation requires confirmed target engagement and a 95% confidence interval excluding the proposed minimum effect; a wide confidence interval indicates uncertainty. The unit of analysis is the donor or animal.

Mechanism. Briefly neutralize CXCL12 after restoration of continuous endothelial coverage, preserving early migration while suppressing subsequent chronic CXCL12 signaling.

Prediction. Compare late, continuous and control regimens with identical late neutralization in an old-donor vascular chip with a standardized endothelial defect. Measure the integral of platelet coverage during brief standardized perfusions as the primary outcome, alongside defect closure, barrier function and residual CXCL12. The late regimen is expected to reduce platelet coverage by at least 25% relative to the continuous early regimen while preserving early migration. This threshold is a proposed criterion, not an observed result.

Mechanism. Partially reduce DUSP4 expression in activated CD4 T cells and restore TFEB activity and lysosomal flux in the same donor's B cells, correcting both the delivery of T-cell help and the B cell's capacity to use it.

Prediction. Use a 2×2 comparison of control, DUSP4 intervention alone, TFEB intervention alone, and both, with identical levels of each intervention in the single and combined groups and the same antigen in all groups. Cross-combine treated and untreated T and B cells from the same donor, comparing help per T cell and antibody response per initial B-cell clone. The primary outcome is the number of functional antigen-specific memory B-cell clones after removal of the interventions. The hypothesis is refuted if the combination increases only total immunoglobulin secretion, does not increase specific memory, or causes autoreactivity.

Mechanism. In neuroblasts of the rostral migratory stream of old mice with a confirmed deficit, increase membrane expression of functional ERBB4 to the young range during migration from the subventricular zone, stopping the increase upon arrival at the olfactory bulb. Restoring the receptor restores sensitivity to existing route signals.

Prediction. Compare ERBB4 restoration in neuroblasts, increased NRG1 in surrounding tissue, and control, with kinase-inactive ERBB4 as a control. Measure receptor activation, individual cell trajectories and speed, aggregation, and the proportion of arriving cells, followed by descendant maturity and function with equal starting numbers of neuroblasts. Restored ERBB4 and receptor responses without changes in migration directionality or the number of integrated descendants would refute receptor deficiency as an explanation for lost neuronal output.

Mechanism. LASN01 blocks IL11RA; the IL11-induced ERK response of tissue fibroblasts measures the proposed tissue response.

Prediction. Paired lung slices from elderly donors will be stratified in advance using a functional IL11RA test, with compliance after identical exposure as the primary outcome. Restoring signaling downstream of the receptor will test the causal chain, and epithelial viability will serve as a constraint. Support requires a difference in functional response that does not merely reflect fibroblast abundance, at measured free exposure achievable according to human pharmacokinetics. The thresholds are proposed development criteria, not experimental findings; a negative conclusion requires target engagement and a 95% confidence interval excluding the minimum effect, while a wide interval indicates uncertainty.

Mechanism. Suppress pathological VDAC1 oligomerization without disabling normal exchange through the channel to stop mtDNA release and restore vascular energetics more effectively than TMEM173/STING suppression alone at an equal reduction in the inflammatory program.

Prediction. A paired experiment in aged barrier chips with independent genetic confirmation of the targets will measure permeability as the primary functional outcome and cellular ATP as a joint mechanistic criterion. Measure cytosolic mtDNA, respiration, and viability to exclude nonspecific mitochondrial shutdown. The hypothesis is refuted if either 20% threshold is not reached or the advantage is explained by unequal inflammatory suppression, cell death, or disruption of basal VDAC1 exchange. These are proposed thresholds, not observed results; refutation requires confirmed target engagement and a 95% confidence interval excluding the specified minimum effect, while a wide interval indicates uncertainty. The independent unit is a donor or animal.

Mechanism. NR3C2 blockade in fibroblasts and other responsive cardiac cells is proposed to provide greater benefit during active matrix turnover than in a static scar.

Prediction. Paired living cardiac slices from older donors with measured baseline collagen turnover will be tested for passive mechanics at fixed pressure and tone, with separate assessments of matrix degradation, viability, and contractility. No interaction with matrix turnover, or a reduction in biomarkers without mechanical benefit, would refute the hypothesis.

Mechanism. Restore deficient LTβR expression on fibroblastic reticular cells of the old lymph node, targeting LTBR, and temporarily restore surface CCR7 in antigen-loaded dendritic cells with insufficient chemokine responsiveness. In old lymphoid models with impaired stroma and DC navigation, preserve endogenous lymphotoxin signaling without continuous LTβR agonism.

Prediction. A 2×2 comparison of control, LTBR restoration alone, CCR7 restoration alone, and their combination, with identical levels of each intervention in the single and combined groups, will separately count DC arrival in the node and contacts in the T-zone. Assess preservation of the natural chemokine field, the response to whole protein, and memory formation. The primary outcome is specific T-cell memory diversity for the same number of antigen-loaded DC. Failure of LTBR to restore the network, CCR7 no longer limiting navigation, or an effect consisting only of DC accumulation without memory would refute the hypothesis.

Mechanism. Matrix stiffness alters mechanical signaling in the human iTEC model, with mechanosensitive YAP1 assessed in relation to the functional effect.

Prediction. Compare matrices with identical chemistry and different stiffness, with and without control of mechanical signaling. Increased stiffness should reduce TCR diversity at equal live-cell output, and normalization of mechanical signaling should partially reverse the effect; separately measure PSMB11, AIRE and nuclear YAP1. No stiffness effect after controlling matrix chemistry and cell number, or no association between YAP1 changes and the functional effect, would refute the prediction.

Mechanism. GLP1R activation is proposed to be linked to the reserve of endothelial NOS3 signaling and capillary oxygen delivery, with preservation of muscle oxygenation determining the functional benefit of semaglutide.

Prediction. A prospectively stratified mechanistic study in older patients will measure change in power adjusted for baseline, alongside muscle oxygenation, strength, hydration, and body composition, and confirm the direction of the effect in perfused donor muscle models. No interaction with vascular reserve, or disappearance of that interaction after accounting for strength and weight loss, would refute the hypothesis.

Mechanism. Briefly reduce PTGDR/DP1 expression or block the receptor response to prostaglandin D2 in a selected cohort of dendritic cells in aged respiratory mucosa that have already taken up a noninfectious protein antigen. Restrict the intervention to the window of tissue exit and migration to the draining lymph node, then restore the DP1 response.

Prediction. Compare targeted and tissue-wide suppression with equal antigen input. Track migration, the number of antigen-positive cells in the lymph node, TCR-repertoire coverage, and long-term memory. Monitor barrier damage and the repeat response after withdrawal; the number of migrated cells is not the final measure of success. Improved delivery to the lymph node without increased specific memory, or accompanied by persistent mucosal inflammation, would mean that the proposed regimen does not provide useful rejuvenation.

Mechanism. Restore spatially restricted CXCL13 presentation within the B-cell follicle and immobilized CCL21 presentation on the T-zone network. Keep the quantity of each chemokine fixed while primarily changing its distribution.

Prediction. A 2×2 comparison of control, CXCL13 restoration alone, CCL21 restoration alone, and their combination, with identical levels of each intervention in the single and combined groups, will compare localized and uniform delivery at equal quantities and measure boundary contacts, clone movement, and antibody-response quality. The primary outcome is the number of productive T–B interactions culminating in affinity-based B-cell memory. An effect fully explained by total chemokine or cell quantity, with no additional outcome from restored spatial organization, would refute the hypothesis.

Mechanism. Partially and reversibly reduce BCL6 expression only in FOXP3-positive follicular regulatory T cells, Tfr, in aged lymph nodes with an elevated Tfr/Tfh ratio. Preserve BCL6 in T-helper cells and B cells, intervene during the early germinal-center response, and restore regulatory participation during quality selection.

Prediction. Compare brief partial, prolonged, and complete suppression with control at initially high and normal Tfr/Tfh. Measure regulator location, help, affinity, memory diversity, and autoantibodies; confirm intervention specificity and preservation of peripheral regulatory function. An increased titer accompanied by reduced affinity or increased autoreactivity would mean that the regimen does not rejuvenate humoral immunity.

Mechanism. Suppress NLRP3 in monocytes and tissue macrophages, using ASC assemblies and caspase-1 as a functional test.

Prediction. Paired cardiac–macrophage co-cultures from elderly donors, stratified before randomization, will test relaxation under equal load as the primary outcome, with IL1B/IL18 and preservation of phagocytosis as additional outcomes. Failure of the functional test to distinguish responses, or cytokine reduction without improved relaxation, would refute the hypothesis. The numerical threshold is a proposed development criterion, not an experimental finding.

Mechanism. Partially and reversibly reduce CDKN1C/p57 expression in viable radial stem cells of the aged dentate gyrus without substantial DNA damage, from cell-cycle entry through the first productive division, then restore expression to reestablish quiescence.

Prediction. Compare partial reversible reduction, continuous reduction and a control, matching early activation between the reduction conditions. Measure p57 protein, cell-cycle duration, DNA damage and clonal fates while preserving responses of other control pathways; after several months, assess the second wave and functionally mature progeny from both waves. Restoring p57 should preserve a productive reserve, and two waves should produce a greater total mature output than continuous suppression.

Mechanism. When a CDK5 activity deficit is confirmed, restore its kinase activity to the physiological range of young new neurons in new postmitotic granule neurons of the aged dentate gyrus, before a stable primary dendrite direction is selected.

Prediction. Compare early restoration with restoration after the primary dendrite direction has formed, kinase-inactive CDK5 and a control, without seeking supraphysiological activity. Measure dendritic direction, soma position, incoming and outgoing connections, excitability and behavior, using reversible silencing of the labeled cohort to test its contribution. Early restoration should improve geometry and the contribution of new neurons more than late restoration at equal survival, with a greater functional benefit at similar synapse numbers.

Mechanism. Partially and reversibly reduce DUSP6 phosphatase activity to the young range in naive CD4-positive T cells from elderly donors with elevated DUSP6, during a short window of contact with an antigen-presenting cell when both antigen and costimulatory signals are present.

Prediction. Compare brief and continuous suppression in cultures with autologous antigen-presenting cells. Measure the ERK response, the number of unique responding TCR, memory formation and the response after withdrawal. Controls include self-antigens, absence of costimulation and restoration of suppression-resistant DUSP6. The hypothesis is rejected if the increased response results from nonspecific activation or autoreactivity and specific memory diversity does not increase.

Mechanism. Briefly increase SATB1 expression in the activating fraction of old hematopoietic progenitors and restore local CXCL12 production to the young range in deficient CAR cells of the bone marrow stroma. Apply this in old bone marrow with both weak lymphoid priming and a disrupted CXCL12 niche, with spatial targeting confirmed beforehand.

Prediction. Use a 2×2 comparison of control, SATB1 intervention alone, CXCL12 intervention alone and the combination, with equal levels of each intervention in the single and combined groups. Track cell location and progeny, measuring bone marrow retention, release into blood and functional maturation separately. The primary outcome is the diversity of new antigen-specific memory B cells after protein immunization. The hypothesis is rejected if the combination only retains cells in the bone marrow or does not increase completed lymphoid output relative to SATB1.

Mechanism. Equal suppression of mTORC1 in the dermis while reducing exposure of basal keratinocytes.

Prediction. Compare the two formulations in perfused skin from older donors at equal dermal free exposure. Joint outcomes are epidermal recovery and transdermal passage, with substance mapping distinguishing delivery from changes in intrinsic activity. The retained formulation should meet both the 25% closure-rate threshold and the twofold reduction in passage into the perfusate while preserving the beneficial dermal effect.

Mechanism. Partially reduce the proportion of functionally confirmed myeloid-biased CD150-high stem cells while preserving balanced clones, targeting SLAMF1/CD150, and restore FOXN1 expression in the epithelium of the old thymus. In old mice, begin epithelial restoration before the expected influx of new lymphoid progenitors. CD150 serves as a targeting marker, not proof of myeloid bias.

Prediction. Use a 2×2 comparison of control, SLAMF1/CD150 intervention alone, FOXN1 intervention alone and the combination, with equal levels of each intervention in the single and combined groups. Measure the stem-cell reserve, thymic emigrants and new TCR; check negative selection and autoreactivity, since an increase in total T-cell number is insufficient. The primary outcome is the number of new functional TCR clones responding to an unfamiliar protein antigen. The hypothesis is rejected if the increase comes from old peripheral clones, tolerance is disrupted or the effect does not exceed FOXN1 alone.

Mechanism. Temporarily increase TFEB expression and nuclear activity to the range of young cells in memory T cells from older donors with low lysosomal reserve and reduced autophagic flux. Apply this before repeat antigen stimulation and stop the additional activation before peak expansion.

Prediction. Compare preparatory and continuous regimens with a control. Measure completed autophagic flux, lysosomal pH and cargo degradation rather than lysosome number alone; assess the repeat specific response, survival and composition of the original TCR clones, using disruption of TFEB DNA binding as a mechanistic control. Preparatory restoration is expected to improve recall function with less interference in division metabolism; if degradative reserve is restored without improved recall function and clone preservation, this reserve is not a sufficient limiting factor for immune memory.

Mechanism. Restore DHPS activity and eIF5A hypusination in B cells with a demonstrated enzymatic limitation, and briefly increase local IL-21 signaling during full antigen-specific T–B-cell contact. DHPS correction supplies the B cell with the capacity to use the help signal.

Prediction. Before study inclusion, measure the level of the substrate spermidine, DOHH activity, and the receptor response. Use a 2×2 comparison of control, DHPS intervention alone, IL21 intervention alone, and both, with identical levels of each intervention in the single and combined groups and identical BCR and CD40 conditions throughout. Measure hypusination, lysosomal flux, death, and memory, accounting for the context-dependent ability of IL-21 to induce apoptosis. The primary outcome is the yield of functional antigen-specific memory cells after withdrawal and antigen rechallenge. The hypothesis is refuted if DHPS is not limiting, IL-21 increases death, or the combination provides no additional memory beyond a single correction.

Mechanism. Endothelial-targeted IDO1 permits vascular recovery without excess AHR activation in neighboring immune cells, separating endothelial NAD effects from intercellular effects of IDO1 metabolites.

Prediction. In an aged endothelial–macrophage vascular model, compare endothelial-targeted IDO1 elevation with elevation throughout the co-culture, matching the increase in endothelial NAD, with and without macrophage-specific AHR reduction. The primary outcome is the recovered perfused fraction after a second identical challenge; measure kynurenines, the AHR response and removal of damaged cells. Targeted elevation should yield the proposed 20% recovery advantage, and macrophage AHR reduction should narrow the gap by at least half. These thresholds are proposed criteria, not observed results. Refutation requires confirmed target engagement and a 95% confidence interval excluding the specified minimum effect; a wide confidence interval indicates uncertainty. The independent unit is a donor or animal.

Mechanism. Retain admilparant in the stroma to block LPAR1 in fibroblasts with less exposure of the epithelial compartment.

Prediction. Compare the free and experimentally stromally retained forms in a multilayer lung chip made from elderly donor cells, jointly measuring barrier function and mechanics and quantitatively mapping free compound. Separate reduction of LPAR1 in the epithelium and stroma tests the cause of the difference; the retained form should meet both stated thresholds at equal suppression of the fibroblast response.

Mechanism. Reversibly reduce excessive CD39 ectonucleotidase activity only in conventional activated CD4-T cells, after first restoring their TFEB-dependent lysosomal program. The proposed setting is elderly donors with high inducible CD39 expression and insufficient clearance; regulatory T cells and endothelium are not intervention targets.

Prediction. A 2×2 comparison of control, A alone, B alone and A+B, with matched levels of each intervention in the single and combined groups, will measure ATP, AMP and adenosine together with autophagic flux and track response termination and reactivation after withdrawal. The expected result is increased diversity of viable specific CD4 memory after normal completion of the response. Only transiently increased survival, persistent inflammatory activation or autoreactivity would refute the hypothesis.

Mechanism. Dasatinib + quercetin suppress survival-supporting SRC/ABL-dependent and other D+Q-sensitive pathways, with the response depending on the senescent cell type.

Prediction. Compare D+Q and control in paired liver slices from older donors with MASH, determining cell fractions in advance. The primary outcome is mechanical stiffness with simultaneous preservation of albumin synthesis; selective removal of the sensitive fraction tests the mechanism. Stellate-cell-predominant samples should show at least 25% greater reduction in excess stiffness; no response difference or loss of more than 10% of functional hepatocytes accompanying reduced stiffness is a stopping condition.

Mechanism. CXCR4 mediates a reversible component of the vascular effect of old plasma that depends on CXCL12. Partially reduce CXCR4 only in endothelium exposed to old plasma, leaving ACKR3 and the remaining plasma components unchanged.

Prediction. Compare original old plasma, plasma after selective CXCL12 removal, and plasma after CXCL12 add-back, each with CXCR4 intervention and a control. Flow-induced dilation of a perfused arterial segment should recover by at least 30% of the lost dilation with CXCR4 suppression, and CXCL12 removal should reduce its additional effect by at least half; verify equal smooth muscle responses to external NO.

Mechanism. Raise MEIS2 expression to the young range in PAX6/DLX2-positive neuroblasts of the old subventricular zone during subtype selection, before final incorporation into the olfactory bulb. Preserve baseline PAX6 and DLX2 levels rather than increasing them throughout the lineage, restoring the missing cofactor required for complex assembly.

Prediction. First confirm the MEIS2 protein deficit and factor interactions, then compare MEIS2 restoration, PAX6 elevation and control. Track mature subtypes, their locations and odor responses, and assess total neuronal output and diversity to distinguish subtype redistribution from increased neurogenesis. MEIS2 restoration should improve functional output of the relevant lineage more than PAX6 elevation; restoration of the complex without increased mature functional output would mean cofactor deficiency is not a sufficient explanation of the age-related loss.

Mechanism. Briefly suppress HDAC1, GSK3, and TGFBR1 in mature arterial cells from elderly donors, then restore physiological KLF2 signaling under laminar flow to provide a maturation phase after reprogramming.

Prediction. Paired arterial networks will compare the pulse, flow, their sequence, and a control, with an additional arm targeting KLF2 for reduction. The primary outcome is permeability after withdrawal of chemical treatment; monitor thromboresistance, VE-cadherin, cell identity, and the contribution of proliferation by individual clones. The hypothesis is refuted if the advantage is less than 25%, does not depend on KLF2, or accompanies loss of endothelial identity or greater platelet adhesion. These are proposed thresholds, not observed results; refutation requires confirmed target engagement and a 95% confidence interval excluding the specified minimum effect, while a wide interval indicates uncertainty. The independent unit is a donor or animal.

Mechanism. Increase surface amounts of the complement receptors CR2/CD21 and CR1/CD35 on FDC to the young range; in the mouse, both forms are encoded by Cr2. Target follicular dendritic cells in old lymph nodes with insufficient antigen retention for a limited period of the germinal center response to a noninfectious protein antigen.

Prediction. Compare FDC-targeted and B-cell restoration at the same antigen dose and complement coating, expecting greater qualitative benefit from FDC-targeted restoration. Measure capture, return of antigen to the surface, selection duration, affinity, and memory. Monitor termination of the response and appearance of autoantibodies; antigen retention must not become indefinite. If retention time is restored but affinity and long-term memory do not improve, or autoreactivity increases, the proposed correction is not beneficial.

Mechanism. Endothelial B3GNT3 restoration restores the glycocalyx and vascular reactivity through NOS3-dependent endothelial NO signaling.

Prediction. Compare endothelial restoration of B3GNT3, C1GALT1 and control treatment in aged animals, using regimens with comparable leakage reduction selected in an independent pilot and fixed before the main experiment. Measure cerebral blood flow increases during identical neuronal activation while recording neuronal responses and systemic pressure. B3GNT3 should improve the vascular response through endothelial NOS3; test this dependence while controlling baseline blood flow and preserved vascular responses to an NO donor.

Mechanism. Reduce MAPK14/p38α in smooth muscle cells of already old arteries with low or high baseline calcification. Accumulated load-bearing mineral deposits limit the functional benefit of late MAPK14 blockade.

Prediction. Stratify old arterial segments by baseline mineral imaging before allocation to intervention and control. Measure the passive pressure–diameter curve at the same geometry, and separately measure new mineral formation and persistence of old mineral. The expected improvement is at least 15% in the low-mineral group, with the high-mineral group retaining no more than half that functional gain. These are proposed thresholds, not observed results. Refutation requires confirmed target engagement and a 95% confidence interval excluding the specified minimum effect; a wide confidence interval indicates uncertainty. The independent unit is the donor or animal.

Mechanism. Suppress C3/C3b and enhance ATG7-dependent removal of damaged mitochondria in the pigment epithelium.

Prediction. Paired human retinal and pigment epithelial models will undergo a factorial experiment with stratification by reserve and an ATG7 control, using light response as the primary outcome. The combination is expected to provide at least 20% better preservation at low reserve and less than half that additional effect at preserved reserve; the test must confirm achievable urolithin exposure in the target tissue and no increase in vascular leakage. No additional functional effect, no dependence on mitophagy or unattainable required tissue exposure would refute or stop this approach.

Mechanism. Inhibit SLC5A2 in the proximal tubule while preserving the energetic capacity of distal segments for transport.

Prediction. Use a linked proximal–distal model made from elderly donor cells under equal filtration load. High distal respiratory reserve should yield at least 25% less total nephron injury than low reserve. The primary outcome is preservation of transport function across the whole system after repeated loading; measure oxygen, ATP and injury in each segment. Absence of the predicted interaction with reserve, or failure of overall transport function to improve with preserved reserve, would refute the hypothesis.

Mechanism. Restore local CCL25 signaling at precursor entry sites when deficient recruitment is confirmed, and restore DLL4 membrane density on cortical epithelial cells to the young range. The combination coordinates thymic colonization with T-cell fate choice.

Prediction. A 2×2 comparison of control, CCL25 alone, DLL4 alone and the combination, with matched intervention levels in single and combined groups, tests the number of distinct new TCR clones completing maturation and normal selection. Assess entering-cell numbers and the fraction completing T-cell differentiation separately, accounting for recruitment already being sufficient in many old thymuses. The hypothesis is refuted if recruitment does not limit the process or the combination does not increase output relative to DLL4 alone without impairing selection.

Mechanism. Delivering more antigen will not eliminate the intrinsic weakness of responding T cells. The combination targets PTGDR/DP1 only in antigen-loaded dendritic cells and restores LAMP2A-dependent CMA in naive CD4 T cells beforehand. A noninfectious protein antigen is used, and DP1 signaling returns after the migration window.

Prediction. A 2×2 comparison of control, A alone, B alone and A+B, with equal levels of each intervention in the single and combined groups, separately tracks DC migration and the response to one contact. The primary outcome is the diversity of durable CD4 memory at a fixed antigen load; mucosal barrier integrity, completion of activation and a repeat response after withdrawal are also checked. Only a larger brief response, sustained mucosal inflammation or no increase in memory would refute the hypothesis.

Mechanism. The two molecular profiles distinguish sensitivity to correction of survival through BIRC6 suppression from sensitivity to correction of the differentiation program through disruption of the H3K23ac–TRIM24 interaction.

Prediction. Compare BIRC6 suppression, disruption of the H3K23ac–TRIM24 interaction, and a control in the same donor panel of previously characterized HSC. The initial molecular profile should interact with the intervention in determining restoration of absolute lymphoid output; simultaneously measure cell death to distinguish selection from a change in fate.

Prediction. Measure the GATA3/Th2 program within memory CD4 cells, keeping cell proportions as separate variables. Train a model on one season of the public atlas and freeze it before analyzing another, splitting data by people rather than cells. Adding the signature should improve calibration and prediction error for late HAI in the held-out season; failure to improve the prespecified metric or an effect explained by baseline titers would refute the prediction.

Prediction. Combine epigenetic measurement with functional differentiation in independent donor samples. The combined measure should outperform MEG3 in predicting the ratio of absolute outputs after accounting for initial cell proportions, with model transfer evaluated across separate donors rather than separate cells.

Mechanism. Rejuvenation of the microcirculation requires simultaneous restoration of blood inflow and lymphatic outflow through targeted IDO1 elevation in blood vascular endothelium and enhancement of VEGFC–FLT4 in the lymphatic compartment.

Prediction. A factorial IDO1 × VEGFC–FLT4 experiment in an established ischemia model in aged animals will measure tissue oxygenation and water content after the same recovery period, with separate measurements of perfusion, lymphatic clearance, pressure and leakage. Loss of the functional lymphatic response should eliminate the combination's additional effect. Absence of either specified functional improvement, a benefit explained solely by capillary number or independence from lymphatic outflow would refute the hypothesis. The thresholds are proposed criteria, not obtained results; refutation requires confirmed target engagement and a 95% confidence interval excluding the specified minimum effect, while a wide confidence interval indicates uncertainty. The independent unit is a donor or animal.

Mechanism. Dasatinib + quercetin remove sensitive senescent cells while preserving the RUNX2/SP7-positive osteogenic reserve.

Prediction. Test paired living bone explants from older donors, stratified in advance by mineralization capacity. The primary outcome is microdamage accumulation under equal loading, with separate monitoring of resorption, matrix formation and baseline density. Mechanical improvement should depend on osteoblast reserve and meet the stated thresholds; absence of an interaction with reserve or improved markers without improved mechanics is a stopping condition.

Mechanism. Block NR3C2 and SLC5A2, testing the role of distal sodium delivery and KCNJ1/ROMK-dependent potassium transport in the aged distal nephron.

Prediction. A factorial experiment with both drugs in a coupled human nephron–fibroblast model, with independent reduction of KCNJ1, will test the predicted reserve-dependent difference using potassium transport and matrix mechanics as joint primary outcomes, controlling flow, sodium and viability. Absence of the predicted difference, or an advantage unrelated to KCNJ1 at matched flows, would refute the hypothesis. The numerical thresholds are proposed development criteria, not experimental findings.

Mechanism. Periodically inhibit FKBP12–mTORC1 and allow pS6 to recover before the active repair phase.

Prediction. Compare pulsed treatment, continuous treatment and vehicle in paired skin explants from older donors. The primary outcome is time to permeability recovery, with monitoring of pS6, pAKT-S473, proliferation and epidermal integrity. Absence of a 20% benefit, an advantage explained by lower exposure or epidermal thinning constitutes refutation or a stopping criterion. The threshold is proposed for a development decision, not an obtained result; a negative conclusion requires target engagement and a 95% confidence interval excluding the minimum effect, while a wide confidence interval indicates uncertainty. Use measured free exposure achievable under human pharmacokinetics and separately check tissue and systemic exposure for the topical formulation; an effect only at unachievable exposure stops this development path.

Mechanism. Temporary reduction of AP2A1 in elderly dermal fibroblasts, followed by complete cessation of the intervention, leaves a functional memory that persists after AP2A1 returns to baseline.

Prediction. Compare a pulse, continuous suppression and a control. After confirming the return of AP2A1, transfer equal numbers of live cells into fresh, identical 3D matrices, excluding carryover of old matrix and residual reagent. The primary outcome is the strength of newly produced material, with an expected advantage of at least 20% over control during the subsequent culture cycle. An advantage below 20% after AP2A1 returns or disappearance of the advantage after transfer to fresh matrix refutes the hypothesis. Refutation requires confirmed target engagement and a 95% confidence interval excluding the proposed minimum effect; a wide confidence interval indicates uncertainty. The unit of analysis is the donor or animal.

Mechanism. Temporarily inhibit JAK1/JAK2, then allow the physiological STAT response to recover so that the aged epidermis can restore its own defenses.

Prediction. In paired immunocompetent skin models from elderly donors with equal integrated exposure, pulsed treatment will meet both thresholds for barrier durability after repeated sterile challenge and recovery of the signaling response. Cell death and residual drug must be controlled. These thresholds are proposed development criteria, not experimentally observed results.

Mechanism. Raise FOXN1 expression in thymic epithelium to the young range; restore AIRE expression in medullary epithelium only if a deficit persists after FOXN1 correction. First restore the epithelial program in cortical and medullary epithelial cells of the old thymus, then assess increased T-cell output after checking negative selection.

Prediction. Compare FOXN1, AIRE, their combination, and a control, identifying thymuses with residual AIRE deficiency in advance. Measure the diversity of presented self-antigens, removal of model autoreactive clones, new thymic emigrants, and the response to a foreign protein antigen; organ size and cell counts are insufficient. The expected benefit requires AIRE to improve selection in thymuses with a residual defect after FOXN1 correction.

Mechanism. Free urolithin A exposure in muscle, conversion of circulating conjugates and the ATG7-dependent mitophagic response link the metabolite profile to the functional effect.

Prediction. Expose muscle microtissues from elderly donors to realistic metabolite mixtures and measure force preservation during repeated contractions. Use mass spectrometry to distinguish the parent molecule from metabolites and assess local conversion. Only profiles producing free tissue exposure should yield the at least 25% improvement, and equalizing the intracellular active form should eliminate profile differences. The threshold is a proposed development criterion, not an experimental finding.

Prediction. Compare changes in CD4 help programs and B-cell activation between baseline and day 7. Define a discordance measure before analyzing outcomes and compare it with the two individual amplitudes and their sum, analyzing donors and accounting for baseline titer and season. The measure should improve prediction in an independent group or held-out season; no improvement in external prediction or full explanation by differences in cell numbers would refute the prediction.

Mechanism. Partially reduce CRYAB in the senescent endothelial fraction alone or in the senescent fractions of both the endothelial and smooth muscle layers; the targeting of CRYAB senolysis determines the strength of the old vascular wall.

Prediction. Assemble vascular equivalents from separately characterized old-donor fractions. Compare the restricted and two-layer regimens using the number of standardized pulse cycles before irreversible deformation as the primary outcome, with separate measurements of dilation, viable contractile cells and multimarker senescence. At equal removal of senescent endothelium, the restricted regimen is expected to preserve at least 20% greater fatigue strength without losing more than 10% of the vasodilatory gain. These thresholds are proposed criteria, not observed results.

Mechanism. Exercise-induced mitophagy supports muscle stem cell regenerative competence, but the response in aged muscle occurs within a narrow window. Inducing mitophagy outside this window does not restore the stem cells; chronic administration may act by accumulating effects across exercise windows.

Prediction. In people aged 65-80 years, measure muscle-biopsy markers of mitophagy and stem cell state at 0, 24, 48, 72 hours after standardized exercise to establish or reject the window. Compare уралицин A within the identified window, the same course outside it, chronic administration at the same cumulative dose, and placebo. At equal cumulative doses, administration within the window should yield a greater increase in specific contractile force than either administration outside it or chronic administration, assessed at 72 hours and after repeated exercise, with confirmed induction of mitophagy in biopsies. Measure mitochondrial respiration, stratify by microbiota metabotype and use plasma metabolite levels as a covariate; parallel preclinical ATG5/PINK1 controls should test dependence on mitophagy in muscle stem cells. An effect that persists after eliminating stem cell mitophagy, or is entirely explained by microbiota metabotype or plasma metabolite levels without association with mitophagy markers, would not support the hypothesis.

Mechanism. Removal of uPAR-positive cells using an existing senolytic CAR-T platform restores the intestinal niche, leading to an improved sustained antigen-specific secretory IgA response.

Prediction. Compare anti-uPAR CAR-T with control T-cells under identical immunization, measuring late antigen-specific IgA, mucosal plasma cells, and epithelial recovery while accounting for intestinal permeability and the volume of secreted fluid. The sustained specific IgA response should improve after these adjustments, and early epithelial regeneration should predict the gain better than the total number of T-cells.

Mechanism. Increase SATB1 expression to the young range only in the activated fraction of old HSC with low SATB1 selected to transition toward lymphoid progenitors. Apply this during the early transition to the lymphoid program and stop additional expression after commitment.

Prediction. Compare increasing SATB1 in the activated fraction with increasing it throughout the pool at comparable early lymphocyte production. Track clones, the reserve and the second wave of lymphopoiesis, and assess B- and T-receptor diversity, response to a new antigen and preservation of the response to a previously encountered antigen. An increased first wave accompanied by loss of clones and deterioration of the second wave would refute sustained restoration through a restricted SATB1 pulse.

Mechanism. The response to CD38 suppression in naturally aged brain endothelium without added amyloid depends on cytosolic mtDNA signaling. Causally reduce cytosolic mtDNA available to cGAS in a separate experimental arm.

Prediction. Prospectively stratify aged donor barriers by mtDNA while maintaining comparable baseline permeability and cell numbers, and confirm the stratification in independent donors. Use albumin flux as the primary outcome and assess cGAS–STING, NAD, and the absence of amyloid exposure. The hypothesis is refuted if the high-mtDNA group lacks the 25% effect, the predicted group difference is absent, or causal elimination of the mtDNA signal does not weaken the additional effect of CD38 suppression. These are proposed thresholds, not observed results; refutation requires confirmed target engagement and a 95% confidence interval excluding the specified minimum effect, while a wide interval indicates uncertainty. The independent unit is a donor or animal.

Mechanism. Insufficient MFSD2A transport activity limits restoration of the aged barrier after TNAP suppression. Suppress ALPL/TNAP and restore MFSD2A in aged brain endothelium with low baseline MFSD2A transport activity.

Prediction. A factorial ALPL × MFSD2A experiment in paired barriers from elderly donors with measured baseline lipid transport will test the stated differences, using vesicular albumin flux as the primary outcome, assessing intercellular junctions separately, and using transport-inactive MFSD2A as a mechanistic control. The hypothesis is refuted if the additional effect in initially deficient cells is less than 30%, does not depend on MFSD2A transport function, or does not differ from the preserved group. These are proposed thresholds, not observed results; refutation requires confirmed target engagement and a 95% confidence interval excluding the specified minimum effect, while a wide interval indicates uncertainty. The independent unit is a donor or animal.

Mechanism. DT2216 reduces BCL2L1 through VHL-dependent degradation in sensitive senescent fibroblasts.

Prediction. Test paired lung slices from older donors and platelets from the same donors at comparable free exposure, with pathological contractility as the primary outcome. The joint functional test should predict an independent functional response meeting the stated selectivity thresholds, and VHL suppression should abolish degradation and the tissue effect.

Mechanism. Restore SIRT7 expression in old hematopoietic stem cells and enhance formation of the ATG12–ATG5 complex only when ATG12 deficiency is confirmed and lysosomal degradation is intact. Prepare old stem cells with mitochondrial protein stress and low autophagic flux before division.

Prediction. Use a 2×2 comparison of control, SIRT7 intervention alone, ATG12 intervention alone and the combination, with equal levels of each intervention in the single and combined groups. Distinguish increased flux from autophagosome accumulation, and measure protein stress, quiescence and each clone's lymphoid progeny at equal initial viability. The primary outcome is sustained output of diverse functional B and T cells without depletion of the stem-cell reserve. The hypothesis is rejected if one variable fully removes both constraints or if the combination only increases the number of surviving cells without improving their progeny.

Mechanism. Preserving NAD precursors will not remove accumulated cellular debris, while enhancing lysosomes may be limited by the metabolic environment. The proposed combination partially reduces extracellular CD38 NADase activity without removing cells and restores nuclear TFEB activity when lysosomal degradation is insufficient, after confirming both limitations.

Prediction. A 2×2 comparison of control, A alone, B alone and A+B, with equal levels of each intervention in the single and combined groups, should show preserved repeated clearance function and specific T-cell memory after withdrawal. Extracellular metabolites, intracellular NAD and completed digestion are measured separately, and support for autologous T-cell memory is tested at equal macrophage numbers. Changes confined to metabolic markers, lysosome accumulation without degradation or worsened lymphocyte support would refute the hypothesis.

Mechanism. Temporarily degrade BCL2L1 and time the next pulse to recovery of the efferocytic function of MERTK-positive macrophages.

Prediction. Compare two regimens and a control in a lung co-culture from elderly donors containing macrophages. Leakage after the second phase should be at least 25% lower with recovery-guided dosing at equal senolysis; track cellular debris. Temporary reduction of MERTK tests whether the advantage depends on clearance. Absence of the 25% advantage or independence from efferocytosis would refute the hypothesis.

Mechanism. Enhance VEGFC until a predefined restoration of the lymphatic network is reached, then stop the intervention to preserve drainage while reducing excess blood-vessel leakage associated with continued stimulation.

Prediction. In paired aged tissue models with separate blood and lymphatic circuits, compare stopping VEGFC at a prespecified restoration threshold with continuing VEGFC after the same initial phase. After equal washout, the limited regimen is expected to retain at least 90% of the prolonged regimen's clearance improvement while reducing blood-vessel albumin leakage by at least 25% and reducing residual edema; control for the density of both networks and water content. No initial excess blood-vessel leakage would refute the proposed advantage of stopping in that model.

Mechanism. QPRT determines whether stimulation of IDO1 is converted into vascular NAD synthesis; the proposed benefit depends on QPRT catalysis and NAD flux.

Prediction. Perform a factorial IDO1 × QPRT experiment in aged vascular networks with a metabolic limitation measured in advance. The primary outcome is the perfused fraction after hypoxic injury; isotope analysis distinguishes NAD synthesis from kynurenine accumulation, and catalytically inactive QPRT serves as a control. The combination should produce the proposed 25% benefit in the deficient group, increased labeled tryptophan flux into NAD and an additional functional benefit less than half as large in the group with intact QPRT. These thresholds are proposed criteria, not observed results. Refutation requires confirmed target engagement and a 95% confidence interval excluding the specified minimum effect; a wide confidence interval indicates uncertainty. The independent unit is a donor or animal.

Mechanism. Restore expression of the mitochondrial deacetylase SIRT3 in old hematopoietic stem cells and partially suppress extracellular NADase activity of CD38 in bone marrow macrophages without removing them. The proposed joint limitation involves low SIRT3 and high niche CD38 activity; baseline NAD precursor availability is measured separately.

Prediction. A 2×2 comparison of control, SIRT3 restoration alone, partial CD38 suppression alone and the combination, with matched intervention levels in single and combined groups, tests sustained functional lymphoid output per original stem cell clone. Measure cellular and mitochondrial NAD separately, SIRT3 substrate acetylation and clonal lymphoid output; do not infer intracellular NAD from plasma measurements. The hypothesis is refuted if CD38 correction does not change NAD in the required compartment or SIRT3 provides no additional functional benefit.

Mechanism. Restoring COL17A1 only in basal keratinocytes of an aged skin equivalent before a brief experimental reduction of GPX4 preserves the epidermal barrier during GPX4-dependent senolysis.

Prediction. Use a factorial experiment comparing COL17A1/control × brief GPX4 intervention/vehicle, with the integrated increase in permeability after senolysis as the primary outcome. Assess removal using several independent signs of senescence rather than p16 alone, and check preservation of nonsenescent basal cells. The expected barrier benefit is at least 25% at comparable senolysis; a benefit below 25% or one explained solely by reduced cell removal refutes the hypothesis. Refutation requires confirmed target engagement and a 95% confidence interval excluding the proposed minimum effect; a wide confidence interval indicates uncertainty. The unit of analysis is the donor or animal.

Mechanism. Restoring LATS1 and LATS2 to the physiological range in aged endothelium is proposed to preserve repair better than continuous YAP1 suppression when reductions in the senescence program are matched.

Prediction. Compare LATS1/2 restoration, YAP1 suppression, and a control in paired aged vascular chips. Following identical local cell loss, the time to restore baseline albumin permeability is expected to be at least 25% shorter with LATS1/2 restoration than with continuous YAP1 suppression, with no more than a 10% increase in baseline leakage; control for proliferation, baseline permeability, and viable cell number.

Mechanism. Restore C1GALT1-dependent O-glycans in aged arterial endothelium before restoring KCNJ2/Kir2.1. Glycocalyx restoration must precede the return of Kir2.1 mechanosensitivity; transfer of the result from blood–brain barrier endothelium to arterial endothelium is part of the hypothesis.

Prediction. Compare the sequence with each intervention alone and the reverse sequence in paired aged arterial segments or vascular equivalents, with equal final expression and washout time. Measure dilation under standardized flow, O-glycans, Kir2.1 current, NO and smooth-muscle responses to external NO. Suppressing KCNJ2 after restoration should remove the additional mechanical response. Failure to reach either dilation threshold, exceeding the leakage limit or independence from Kir2.1 would refute the hypothesis. The thresholds are proposed criteria, not obtained results; refutation requires confirmed target engagement and a 95% confidence interval excluding the specified minimum effect, while a wide confidence interval indicates uncertainty. The independent unit is a donor or animal.

Mechanism. Transiently reduce excessive DUSP6 phosphatase activity, limiting the reduction to antigen contact and costimulation, after restoring the lysosomal isoform LAMP2A and chaperone-mediated autophagy. Threshold correction recruits additional specific clones, and restored clearance supports their survival and memory formation.

Prediction. Use a 2×2 comparison of control, DUSP6 intervention alone, LAMP2A intervention alone, and both, with identical levels of each intervention in the single and combined groups. Measure the number of responding TCR before division, CMA-substrate removal, and memory after withdrawal, with mandatory self-antigen controls. The primary outcome is the number of distinct functional memory clones per equal starting number of naive cells. The hypothesis is refuted if the combination merely increases nonspecific activation or adds no memory beyond the better single intervention.

Mechanism. Temporarily increase BMP4 secretion from thymic endothelial cells in old mice with an insufficient BMP4 response to the range of a productive regenerative response. Apply this during a preparatory phase of epithelial restoration, ending the increase before prolonged lymphocyte expansion.

Prediction. Compare local endothelial, systemic, and continuous local delivery. Assess epithelial FOXN1 and DLL4, vascular preservation, corticomedullary structure, and negative selection, and measure new T-cell clones and responses after signal withdrawal. Reducing the epithelial BMP-receptor response should abolish the effect; epithelial growth without increased diverse, self-tolerant T-cell output would not constitute immune rejuvenation.

Mechanism. Reversibly reduce TMEM173/STING expression in microglia of the aged neurogenic niche with confirmed cGAS–STING activation during a preparatory window before a new cohort is born, then restore baseline expression. This is proposed to reset the niche's inflammatory state.

Prediction. Compare preliminary, late and continuous TMEM173 reduction with control, verifying actual STING restoration after the preparatory window and measuring signaling markers and cytokines. Track productive clones, mature descendants and the reserve; reactivating STING before activation tests whether the benefit persists. Benefit that exists only during ongoing suppression and disappears after STING restoration would refute the proposed preliminary reset of the niche.

Mechanism. Inhibit renal SLC5A2, with a proposed contribution from β-hydroxybutyrate and its utilization through OXCT1 in the heart.

Prediction. Test paired plasma samples from a controlled study on aged human cardiac microtissues, measuring relaxation rate under equal load while controlling glucose, osmolarity and residual drug. Expect at least a 20% improvement, loss of at least half the effect when β-hydroxybutyrate is adjusted to baseline, and restoration upon adding it back. Reduction of OXCT1 tests metabolic dependence. Absence of the 20% effect or independence from ketone metabolism after controlling plasma composition would refute the hypothesis.

Mechanism. Partially reduce NLRP3 expression only in the pathologically active microglial subgroup of the aged dentate gyrus with persistent inflammasome activity confirmed by ASC aggregates and caspase-1. Apply suppression during early neuroblast survival and stop after normalization, preserving basal pathway function.

Prediction. Validate selection of the active subgroup, since high RNA abundance alone is insufficient, then compare targeted and uniform suppression at the same average IL-1β. Assess basal microglial functions, survival of traced neuroblasts and descendant maturity without mixing the aging model with diabetes or stroke. Failure to improve neuronal yield at matched IL-1β, or unstable subgroup selection, would leave the proposed advantage of cellular selectivity unsupported.

Mechanism. Briefly increase local BMP4 production by thymic endothelium and provide a limited increase in local IL-22 signaling to thymic epithelium with intact receptors, combining a regenerative signal with epithelial survival. Apply this in aged thymic models with defective epithelial recovery after checking responsiveness to both signals and excluding baseline excess.

Prediction. A 2×2 comparison of control, BMP4 alone, IL-22 signaling alone and the combination, with matched intervention levels in single and combined groups, tests sustained output of new tolerant T-cells per unit of epithelial tissue. Track epithelial survival and spatial differentiation, negative selection, cessation of growth and effects after withdrawal. The hypothesis is refuted if the combination produces only edema or proliferation, one signal fully replaces the other, or selection deteriorates.

Mechanism. Compare removal of ALPL/TNAP from the surface of old endothelium with reversible suppression of its catalytic activity, matching initial residual TNAP activity. The difference in persistence depends on restoration of membrane TNAP.

Prediction. In old barrier chips, establish the same initial TNAP activity and degree of improvement. After washout, measure the time until half of the gain in albumin permeability is lost, while measuring recovery of membrane protein and residual inhibitor. The duration ratio is expected to be at least two, and the difference should depend on restoration of membrane TNAP rather than residual drug. These are proposed criteria, not observed results. Refutation requires confirmed target engagement and a 95% confidence interval excluding the specified minimum effect; a wide confidence interval indicates uncertainty. The independent unit is the donor or animal.

Mechanism. The composition of the restored glycocalyx determines barrier benefit: C1GALT1-dependent O-glycan restoration is more effective than heparan sulfate accumulation through HPSE suppression at comparable thickness.

Prediction. Compare increased C1GALT1, HPSE suppression, and a control in donor-derived barrier chips. Albumin permeability should be at least 25% lower with C1GALT1-dependent restoration within a predefined overlapping thickness range; separately measure thickness, O-glycans, heparan sulfate, and transport pathways.

Mechanism. Temporarily raising PROX1 expression to the level of young granule cell precursors in neuronally committed precursors of the old dentate gyrus with confirmed low PROX1, after departure from the radial stem cell state, is proposed to complete granule cell differentiation. The increase is stopped after granule cell identity stabilizes.

Prediction. Compare late and early pulses, sustained elevation and control, tracing cell origins and state transitions and assessing correct granule cell identity, location and synaptic function. Exclude the subventricular zone from delivery. Late correction should increase correctly positioned functional granule neurons without prematurely depleting the reserve; changes in markers alone would not show that the proposed commitment barrier has been removed.

Mechanism. Suppress NLRP3 predominantly in synovial macrophages while limiting chondrocyte exposure.

Prediction. Human synovial–cartilage co-cultures from elderly donors with sensory neurons will test neuronal excitation and recovery of mechanical properties as joint outcomes. Medium after IL1B neutralization will test the mediator component, and drug distribution will test targeting. Absence of a functional window, or reduction of only an inflammatory marker without an effect on neuronal response and mechanics, would refute the hypothesis. The numerical thresholds are proposed development criteria, not experimental findings.

Mechanism. Reducing UBE3A preserves ABCA1, restoring cholesterol efflux in myelin-overloaded microglia and macrophages and their capacity to support another repair cycle.

Prediction. Apply two successive myelin loads in a cellular model, then test aged animals, comparing controls with phagocyte-restricted UBE3A reduction and separately testing ABCA1 dependence. After repeated injury, nerve impulse conduction and fully formed myelin should recover better after withdrawal. Persistence of the effect despite functionally confirmed ABCA1 inactivation would refute the proposed ABCA1-dependent mechanism; verify preservation of neuronal UBE3A and control phagocyte viability, initial lipid load and extracellular cholesterol acceptor availability.

Mechanism. First reduce LPAR1-dependent stromal contractility, then maintain PDE4B-dependent limitation of reactivation.

Prediction. Test both sequences, simultaneous treatment, monotherapies, and a control in paired aged lung microtissues. Measure the mechanical response after withdrawal of all treatments and repeated challenge as the primary outcome, separately measuring epithelial restoration and residual compound; admilparant→nerandomilast should produce at least 20% less loss of compliance than the reverse sequence, with the advantage persisting after residual exposure is equalized.

Mechanism. Compare selective suppression of MSTN activation with blockade of ACVR2A/ACVR2B at the same increase in fiber area.

Prediction. Test paired muscle–vascular models from elderly donors under simulated equal energy deficits. The primary outcome is force per fiber area; assess fatigue, recovery, vascular support and residual activin signaling. Selective inhibition should yield at least 20% greater specific force and less deterioration in recovery at comparable growth, without the advantage being explained by unequal growth, exposure or energy deficit. The threshold is a proposed development criterion, not an experimental finding.

Mechanism. The benefit of reducing lipid load for repeated clearance depends on preserved lysosomal degradation; improved uptake without degradation does not constitute restored function.

Prediction. Compare partial FIT2 reduction with control in microglia from old mice under intact and moderately restricted lysosomal flux, using two sequential pulses of labeled cellular debris with washing between them. Measure uptake, degradation and residual cargo separately, match initial uptake and viability, and monitor free fatty acids and peroxidative damage. The benefit of FIT2 reduction in the second cycle should disappear when degradation is restricted; preserved repeated clearance regardless of flux would refute the hypothesis.

Mechanism. Suppress C3/C3b in the damaged region, preserving living photoreceptors at the lesion border.

Prediction. Retinal–pigment epithelial models using material from older donors and predefined injury, with confirmation in available controlled clinical data, will assess local light response or border-zone microperimetry as the primary outcome and analyze lesion area separately. Preserved baseline reserve is expected to predict at least 25% greater functional preservation; failure of reserve to predict functional response, or preservation of tissue area without activity, would refute the hypothesis.

Mechanism. In memory B cells from older donors with insufficient eIF5A hypusination, increase DHPS activity to the young range when its limitation is confirmed, and restore the fraction of functionally hypusinated EIF5A while maintaining its total amount. Apply this before repeat antigen stimulation and stop the enhancement after TFEB translation is restored.

Prediction. Measure spermidine, DHPS, DOHH, and eIF5A hypusination, establishing the limiting step beforehand. Compare DHPS enhancement, spermidine replenishment, their combination, and a control; assess TFEB, autophagic flux, antigen-specific antibody affinity, and memory survival separately from a general increase in protein synthesis. If DHPS activity does not predict nonresponse to spermidine replenishment, or correcting it does not restore the functional response, the proposed enzymatic limitation is incorrect.

Mechanism. Increase C1GALT1 and then B3GNT3 in old brain endothelial cells, restoring the O-glycan core before elongation.

Prediction. In a paired microfluidic blood–brain barrier model using cells from elderly donors, compare both sequences, each enzyme alone, and a control. Albumin flux after an identical maturation phase should meet both proposed reduction thresholds, with confirmed O-glycan structures, viability, equal shear flow, and equal final enzyme expression.

Mechanism. Increase local IL-7 availability for early thymocytes when signaling insufficiency is confirmed, and restore FOXN1 expression in the epithelium of the old thymus. Limited local IL-7 action supports early thymocytes while restoration of the epithelial program addresses the subsequent maturation limitation.

Prediction. A 2×2 comparison of control, IL-7 alone, FOXN1 alone and the combination, with matched intervention levels in single and combined groups, tests an increase in new tolerant T-cell clones beyond the effect of FOXN1 alone. Track maturation-stage transitions, thymic emigrants and TCR diversity, distinguishing systemic expansion of old T-cell clones from thymopoiesis; early precursor numbers alone do not establish success. The hypothesis is refuted if additional IL-7 increases only the early pool, adds no mature clones, or impairs cessation of proliferation.

Mechanism. Activate THRB in hepatocytes and inhibit IL11RA in active stroma; residual IL11RA activity explains the gap between fat reduction and liver recovery.

Prediction. A factorial experiment in perfused liver models from elderly donors will use prespecified stratification and IL11RA suppression as a specificity control. The primary outcome is the proportion of patent sinusoids, with separate measurements of matrix, albumin and endothelial injury. Support requires the predicted interaction and improved perfusion, rather than reduced fibrosis markers alone, at measured free exposure achievable according to human pharmacokinetics. The thresholds are proposed development criteria, not experimental findings; a negative conclusion requires target engagement and a 95% confidence interval excluding the minimum effect, while a wide interval indicates uncertainty.

Mechanism. Suppress CXCL12 secretion by old endothelial cells while maintaining its measured concentration in the incoming perfusion medium; local endothelial CXCL12 is more important for permeability than its plasma concentration.

Prediction. Independently vary the cellular source and incoming medium composition in a flow-through vascular chip, using CXCL12 add-back and controls for other SASP factors. Measure albumin permeability as the primary outcome and the concentration profile near the wall. Local suppression is expected to reduce permeability by at least 25%, with an effect at least twice that of reducing circulating CXCL12 alone. These thresholds are proposed criteria, not observed results.

Mechanism. Moderately increasing ATP5IF1 in aged endothelium with confirmed reverse operation of complex V will limit reverse ATP synthase operation and reduce cytosolic ATP consumption while preserving mitochondrial potential and respiration.

Prediction. Stratify aged donor chips in advance by the direction of ATP synthase operation and separately compare ATP5IF1 elevation with CD38 suppression. Under identical flow using the same untreated blood, platelet coverage is expected to decrease by at least 25% in cells with reverse complex V operation, with an effect less than half as large in cells without it; jointly measure ATP, membrane potential, respiration, monolayer integrity, and viability. Increased ATP alone is insufficient.

Prediction. Jointly measure the absolute or consistently normalized naive CD4 reserve and the intracellular Th2 program in memory cells. Prespecify a comparison between an additive model and a model with one specified interaction, controlling for baseline titer, age, sex, and CMV, without selecting multiple thresholds after the fact. The interaction should reproduce and improve prediction in held-out donors and a held-out season.

Prediction. Measure late pS6 in antigen-reactive CD4-cells from older vaccinated people in an independent vaccine cohort with suitable stored cells, prespecifying time points and the model. pS6 dynamics should add predictive value for late titer in held-out participants beyond age and baseline and peak titers, with the association persisting after accounting for baseline immune history; technical replicates must not be treated as separate people.

Mechanism. Suppress MAPK14 or RUNX2 separately in old smooth muscle cells while matching the reduction in new mineral formation. MAPK14 suppression affects additional inflammatory programs.

Prediction. Compare paired constructs made from elderly donor smooth muscle cells under the two interventions and a control. Measure contraction force per equal number of starting cells under a standard stimulus, while controlling new mineral quantity, MYH11, survival, and wall thickness. At the same reduction in calcification, MAPK14 suppression is expected to produce at least 20% greater contractile force than RUNX2 suppression alone. This is a proposed threshold, not an observed result. Refutation requires confirmed target engagement and a 95% confidence interval excluding the specified minimum effect; a wide confidence interval indicates uncertainty. The independent unit is the donor or animal.

Mechanism. Reduce MAPK14 in old smooth muscle cells and separately increase local ENPP1 activity, which increases extracellular pyrophosphate formation. ENPP1 complements MAPK14 suppression by stopping extracellular propagation of mineralization.

Prediction. Use old vascular equivalents with identical baseline mineral foci in a MAPK14 × ENPP1 factorial experiment. Measure the number of pulse cycles until irreversible deformation as the primary functional outcome, image the new mineral front, and measure pyrophosphate while ruling out differences in cell death. The combination is expected to achieve both at least 30% slower front propagation and at least 20% greater fatigue resistance. These are proposed thresholds, not observed results. Refutation requires confirmed target engagement and a 95% confidence interval excluding the specified minimum effect; a wide confidence interval indicates uncertainty. The independent unit is the donor or animal.

Mechanism. Inhibit JAK1/JAK2, comparing a STAT1-dominant background with a predominantly TNF/NFκB-dominant background.

Prediction. Paired skin explants from older donors, stratified before treatment by functional signaling profile, will be assessed for barrier permeability as the primary outcome, while monitoring pSTAT1, pSTAT3, proliferation and epidermal restoration. STAT1-dominant skin is expected to show at least 25% greater restoration of permeability without slowing small-defect closure by more than 10%; no interaction with signaling profile, or barrier improvement accompanied by impaired repair, would refute the hypothesis.

Mechanism. Restore the TFEB lysosomal program in old B cells before antigen contact, then provide limited additional CD40 signaling only to antigen-bound B cells with insufficient costimulation. In an organ model of lymphoid tissue, terminate CD40 signaling after the early window while keeping other cytokines fixed.

Prediction. A 2×2 comparison of control, TFEB restoration alone, additional CD40 signaling alone, and their combination, with identical levels of each intervention in the single and combined groups, will assess actual degradation flux, antigen presentation, and memory after withdrawal. Hold antigen quantity constant and verify normal termination of activation. The primary outcome is functional B-cell memory per unit duration of CD40 stimulation with preserved specificity. A combination that only increases early plasmablasts, depletes memory, or sustains chronic activation would refute the hypothesis.

Mechanism. Endothelial APP maintains defective clearance of damaged cells through macrophage CD74.

Prediction. Use a factorial flow co-culture of aged endothelium and donor macrophages, independently reducing endothelial APP and macrophage CD74 while preserving the number and state of both cell types. Measure permeability after the same standardized damaging challenge and track damaged and living cells separately. Restoring APP and CD74 tests specificity; control MIF and baseline phagocytic activity. The proposed functional thresholds should be met, and reducing CD74 should eliminate at least half of the additional APP effect. Predominant engulfment of living cells or an APP effect independent of CD74 refutes the hypothesis; a change in IL10 alone is insufficient. These thresholds are proposed criteria, not observed results. Refutation requires confirmed target engagement and a 95% confidence interval excluding the specified minimum effect; a wide confidence interval indicates uncertainty. The independent unit is a donor or animal.

Mechanism. Temporarily increase KLF9 expression to the level of young cells at the corresponding stage in traced new granule neurons of the aged dentate gyrus, after the main dendritic branches have formed and during late synaptic maturation.

Prediction. Compare early, late, and continuous expression with comparable additional expression, defining stages by morphology and electrophysiology rather than cell age alone. Measure synaptic currents, excitability, ensemble participation, and survival, analyzing early growth separately. The late pulse should improve functional maturity relative to the early pulse and control; no such improvement, or changes in markers alone, would refute the proposed timing restriction.

Mechanism. GLP1R activation and NR3C2 blockade complement each other when a mineralocorticoid response and profibrotic signaling persist.

Prediction. Cardiac tissues from older donors exposed to plasma from a controlled study will undergo factorial addition of finerenone. Passive stiffness will be measured at identical cellular composition, NR3C2 suppression will test specificity, and contractile force will serve as a constraint. Absence of a 20% advantage, absence of NR3C2 dependence, or a decrease in contractile force of more than 10% would refute the hypothesis or stop development.

Mechanism. Locally increase SEMA3A availability in the dendritic growth zone of traced new granule neurons in the aged hippocampus after cell-cycle exit, during dendritic branching, while preserving functional semaphorin binding by NRP1 in the new neurons.

Prediction. Compare local and spatially uniform SEMA3A with a control, using selective disruption of semaphorin binding by NRP1 as a control after verifying methods for separating its semaphorin and VEGF binding. Measure CDK5/FAK responses, dendritic direction, synaptic currents, vascular density and mature survival of the cohort. Persistence of the effect after confirmed loss of the NRP1 semaphorin response, or an effect explained solely by vascular changes, would refute the proposed direct dendritic mechanism.

Mechanism. Temporarily suppress NLRP3 while allowing macrophage clearance of cellular debris to recover between pulses.

Prediction. Paired aged joint co-cultures exposed to identical repeated sterile challenges will compare pulsed and continuous treatment using integrated neuronal activity after withdrawal as the primary outcome, accounting for exposure, damaged-cell debris and NLRP3 activity. Absence of the 25% advantage, an advantage explained by residual drug, or impaired clearance would refute the hypothesis. The numerical thresholds are proposed development criteria, not experimental findings.

Mechanism. Inhibit PDE4B after epithelial closure of the defect has begun, separating suppression of fibrosis from interference with initial repair.

Prediction. Test paired alveolar–stromal models from elderly donors with identical defects, measuring residual leakage and pathological contractility jointly. Prespecify treatment initiation using an independent epithelial criterion; delayed initiation should meet both stated thresholds at equal exposure.

Mechanism. Predominantly inhibit PDE4B in the renal stroma while preserving epithelial transport.

Prediction. Test paired kidney models from elderly donors at human free exposure, with controls for active and inactive fibrosis, jointly measuring transport and mechanics and measuring tissue accumulation and epithelial injury. Both functional improvements should reach at least 20% and weaken after independent suppression of PDE4B.

Mechanism. Restore FLT4/VEGFR3 to the physiological range in aged lymphatic endothelium with low receptor levels, then provide the same VEGFC signal. Restoring FLT4 removes the limit on the response of aged lymphatic vessels to VEGFC, with the benefit requiring FLT4 activity.

Prediction. In prospectively stratified aged lymphatic models, a factorial FLT4 × VEGFC experiment will measure the volume of tracer removed over the same time interval while controlling pressure, junction integrity, cell death and vessel density. Kinase-inactive FLT4 will test the mechanism. Support requires the proposed clearance benefit and the predicted difference between receptor-level groups; a benefit below 30% in the low-receptor group, independence from FLT4 activity or absence of the predicted group difference would refute the hypothesis. Refutation requires confirmed target engagement and a 95% confidence interval excluding the specified minimum effect; a wide confidence interval indicates uncertainty. The independent unit is a donor or animal.

Mechanism. Increase MEF2C expression to the young microglial range where an age-related decline is confirmed, in microglia immediately surrounding the aged hippocampal neurogenic niche, before precursor activation and during early neuroblast survival. The proposed benefit depends on preserving useful microglial functions.

Prediction. Compare MEF2C restoration, IFNAR1 reduction and control at comparable baseline cytokine levels. MEF2C restoration should improve neuronal yield while preserving the brief IFN response and phagocytosis of cellular debris; assess labeled neuroblast survival, mature neurons and their synaptic function after 12 weeks, and monitor spread of the intervention to neurons. If neuronal yield does not improve or the advantage disappears entirely after inflammation is matched, preservation of useful microglial functions provides no separate effect.

Mechanism. Block IL11RA with LASN01 and preferentially inhibit PDE4B with nerandomilast, addressing different limiting processes when each pathway responds incompletely.

Prediction. A factorial experiment in paired aged lung slices with independent stratification will assess compliance and epithelial repair as joint outcomes. The combination will be compared with the mathematical expectation for independent effects, without calling simple addition synergy. Support requires the additional 20% benefit while preserving epithelial repair at measured free exposure achievable according to human pharmacokinetics. The thresholds are proposed development criteria, not experimental findings; a negative conclusion requires target engagement and a 95% confidence interval excluding the minimum effect, while a wide interval indicates uncertainty.

Mechanism. Partial reduction of AP2A1 in aged dermal fibroblasts removes excess adhesions, but its functional benefit depends on mechanical support, compared between spread and compressed states with identical 3D-matrix chemistry.

Prediction. Use a paired factorial experiment with a geometrically controlled matrix and independent elderly donors. The primary outcome is the change in strength of newly formed matrix relative to the corresponding control; also measure adhesion, DNA damage and viability. The functional response should be at least 20% greater in the spread state. A difference below 20% or a better response in compressed cells refutes the hypothesis only with confirmed target engagement and a 95% confidence interval excluding the proposed minimum effect; a wide confidence interval indicates uncertainty. The unit of analysis is the donor or animal.

Mechanism. Briefly enhance TNFRSF11A/RANK receptor activation only in the thymic epithelial lineage with an insufficient response, targeting medullary epithelial cell progenitors in the old thymus. Use a short window to restore the AIRE-positive compartment, then return to baseline activity.

Prediction. Compare pulsed and continuous regimens at comparable total exposure and a control. Track epithelial clones, AIRE, self-antigens, selection of model autoreactive T cells, and output of functional emigrants; assess persistence of the effect after a repeated immune stimulus and exclude systemic activation of bone remodeling through targeting. The proposed temporal advantage requires the pulse to preserve the epithelial reserve and increased AIRE to improve actual selection.

Mechanism. High BIRC6 expression alone does not guarantee a response without functional dependence on the antiapoptotic pathway; the BH3 profile measures baseline readiness for apoptosis.

Prediction. Suppress BIRC6 in donor HSC and compare the baseline BH3 profile with the BIRC6 level. Conduct paired treatment and control experiments on an independent panel of donor HSC, followed by a differentiation assay, with lymphoid output per initial number of live HSC as the primary outcome. A predictive model evaluated on donors not used for tuning should show added predictive value from the BH3 profile beyond BIRC6; prediction of cell death alone without improved functional output would refute the prediction.

Mechanism. In aged mice with low thymic output and disorganized lymph nodes, restore FOXN1 expression in thymic epithelium and the immobilized spatial presentation of CCL21 in peripheral lymph-node T zones. Prepare the receiving network before new thymic emigrants arrive so that new clones can encounter antigen-presenting cells.

Prediction. A 2×2 comparison of control, FOXN1 intervention alone, CCL21 intervention alone, and the combination, with matching intervention levels in the single and combined groups, should increase the fraction of distinct new TCR clones forming durable specific memory. Clonally label thymic emigrants and track their peripheral encounters and response to a new protein antigen; assess preservation of existing memory and self-tolerance separately. Benefit explained by expansion of old clones, mere accumulation of new cells in nodes, or impaired tolerance would refute the hypothesis.

Mechanism. Vascular growth following IDO1 requires a subsequent ANGPT1–TIE2 maturation phase: a limited phase of endothelial IDO1 elevation is followed by enhanced ANGPT1–TEK/TIE2 signaling.

Prediction. In aged pericyte-containing networks after identical hypoxic injury, compare both treatment orders, simultaneous treatment, individual treatments and a control. The primary outcome is the perfused fraction; the required second outcome is albumin leakage after withdrawal. Confirm TIE2 dependence through separate targeted blockade. The IDO1→TIE2 sequence should meet both proposed thresholds at an equal number of segments, and its benefit should depend on TIE2. These thresholds are proposed criteria, not observed results. Refutation requires confirmed target engagement and a 95% confidence interval excluding the specified minimum effect; a wide confidence interval indicates uncertainty. The independent unit is a donor or animal.

Mechanism. Retention in fibrotic tissue reduces NR3C2 signaling in fibroblasts while reducing exposure of the collecting tubules, separating the antifibrotic effect from loss of potassium reserve.

Prediction. A coupled system of fibrotic tissue and a human collecting duct will compare finerenone with a prototype formulation retained in fibrotic tissue, using tissue compliance and vectorial potassium transport as joint outcomes. Free drug will be mapped separately and NR3C2 dependence tested. Failure to separate beneficial and renal exposure, or tissue retention requiring a toxic concentration, would refute the hypothesis or stop development.

Mechanism. Suppress C3/C3b predominantly at the boundary of damage by retaining the C3 inhibitor there, limiting exposure in the rest of the choroidal compartment.

Prediction. A human retinal–choroidal model under complement stress will jointly assess light response and vascular permeability, map the drug, C3 activation and vessel growth, and separately exclude a mechanical carrier effect. The retained formulation is expected to reduce pathological vascular leakage by at least 30% at equal preservation of the photoreceptor response, without increased inflammatory damage; failure to achieve this separation, loss of neuronal function or carrier toxicity would refute the hypothesis.

Mechanism. Restore PINK1 protein abundance and kinase activity to the young range in committed neuronal precursors of the aged hippocampus with reduced PINK1 activity as they transition to postmitotic growth, without continuous elevation in the quiescent reserve. Preserve PRKN/Parkin function, using temporary reduction only to test whether the effect depends on it.

Prediction. Compare late and continuous restoration, kinase-inactive PINK1 and control. Measure mitochondrial disposal flux, respiration and death rather than organelle abundance alone; separately test dependence on PRKN while accounting for its own effects, and assess mature labeled neurons after 12 weeks. If kinase activity is restored but respiration and mature neuronal yield do not improve, PINK1 is not a limiting target in this aged subgroup.

Mechanism. Temporarily stabilize mRNA for the E47 isoform of TCF3 to the young range by selectively reducing its degradation in activated B cells of an old organism with accelerated E47 mRNA decay. Preserve overall ZFP36/TTP expression and its action on inflammatory transcripts, restrict stabilization to the short antibody class-switching window, and then restore normal RNA degradation.

Prediction. Compare E47 mRNA protection, general TTP reduction, and a control, first mapping the functional regulatory region without assuming that a ready-made targeted construct exists. Assess E47, AID, class switching, affinity, genomic instability, and continued suppression of TNF transcripts. An increase only in AID and DNA damage, without an improved specific response under preserved inflammatory control, would not support the approach.

Mechanism. Degrade BCL2L1 in lung fibroblasts while limiting passage of DT2216 into the bloodstream.

Prediction. In an alveolar–endothelial barrier model with fibroblasts from elderly donors, local delivery should preserve at least 90% of the compliance improvement while reducing drug passage into the vascular circuit at least threefold. Joint outcomes are compliance and drug passage into the vascular circuit; assess alveolar toxicity, platelets and the distribution of free drug. Failure to achieve both outcomes, or epithelial damage from the local concentration, would refute the hypothesis or stop development.

Mechanism. Restore physiological contact presentation of IL-15 by supporting cells without changing the total cytokine dose, and partially reduce excessive loss of surface CD16A from mature NK cells while preserving their ability to detach from target cells. Targeted correction is not replaced by global ADAM17 suppression.

Prediction. A 2×2 comparison of control, A alone, B alone and A+B, with equal levels of each intervention in the single and combined groups, should increase the number of completed antibody-dependent cytotoxic cycles per NK cell. Surface CD16A, contact and detachment times, repeated killing events and effects on healthy cells are measured. Enhancement of only the first strike, slower detachment or failure to improve the series of responses would refute the hypothesis.

Mechanism. Partially reduce SESN2 expression in a selected subgroup of dysfunctional aged CD4 T cells with an active sestrin–MAPK complex for a limited period of antigen-specific response recovery, leaving innate-like CD8 cells without intervention.

Prediction. Compare SESN2 reduction restricted to CD4 cells with reduction in all T cells and a control. Assess complex assembly, TCR-dependent function and memory; separately measure NKG2D/DAP12-dependent responses of the untouched CD8 subgroup to standard cellular targets and nonspecific damage to healthy cells. The targeted intervention should restore specific memory while preserving additional useful function; failure to achieve either would refute the proposed advantage of separating the populations.

Mechanism. Systemic GLP1R activation changes circulating factors early, without assuming GLP1R expression in the endothelium.

Prediction. A prespecified early plasma analysis from a controlled study with comparable glycemia and weight change will test flow-mediated dilation ex vivo. Drug-removal and add-back controls will distinguish direct drug action from changes in the circulating environment. No early functional effect, or an effect fully explained by residual drug, glycemia, or weight loss that has already occurred, would refute the hypothesis.

Mechanism. Reduce excessive TNF production by aged B cells only before immunization, then restore normal regulation. Restore deficient surface CD21 on follicular dendritic cells without changing the receptor on B cells, in aged lymphoid models with chronic B-cell TNF and weak immune-complex storage, while preserving the normal contribution of TNF to follicular maintenance.

Prediction. A 2×2 comparison of control, A alone, B alone and A+B, with matched levels of each intervention in the single and combined groups, will distinguish capture, retention and repeated presentation of protein antigen, account for human and mouse CR1/CR2 differences and exclude indefinite antigen retention. The expected result is long-term B-cell memory with antigen affinity after finite antigen exposure. Destruction of the network by TNF suppression, failure to improve antigen storage or persistent autoreactive stimulation caused by the combination would refute the hypothesis.

Mechanism. Suppress IL11RA-dependent stromal activation while preserving SFTPC-positive type II alveolar cells; preserved alveolar reserve determines whether IL11RA blockade produces lung recovery.

Prediction. Human alveolar–stromal models from elderly donors with clonogenic reserve measured in advance will be tested. The primary outcome is functional gas-transport area at identical geometry, with assessments of barrier function, differentiation and cell death. Support requires the predicted interaction with reserve and increased functional area, rather than collagen reduction alone, at measured free exposure achievable according to human pharmacokinetics. The thresholds are proposed development criteria, not experimental findings; a negative conclusion requires target engagement and a 95% confidence interval excluding the minimum effect, while a wide interval indicates uncertainty.

Mechanism. Selectively reduce PTGER2/EP2 in tissue macrophages before noninfectious immunization of old mice to restore macrophage clearance of old neutrophils.

Prediction. Using an existing macrophage model, an untreated control and identical immunization, compare clearance, germinal centers and late avidity while accounting for titer, separating tissue effects from direct drug effects on lymphocytes. Restored clearance is expected to improve late avidity and B-cell memory quality; restoration without these improvements at a prespecified late time point would refute the prediction.

Mechanism. Increase membrane DLL4 expression on cortical epithelial cells of the old thymus with a confirmed deficit, at sites of contact with early lymphoid progenitors during T-lineage commitment. Preserve the normal transient NOTCH1 response in progenitors without constitutive activation, and do not extend the enhanced signal into later selection.

Prediction. Compare contact-localized and uniform increases at the same total amount of DLL4. Measure NOTCH1-response duration, commitment, receptor diversity, passage through selection, and long-term naive T-cell output, while monitoring abnormal proliferation and ectopic cell fates. If DLL4 distribution does not affect functional output at the same protein amount, the proposed spatial restriction is not supported.

Mechanism. Returning endothelial TGFBR1 to its baseline physiological range after brief suppression of HDAC1/GSK3/TGFBR1 is needed for a stable association between the endothelium and supporting cells.

Prediction. In aged endothelial–pericyte networks receiving the same initial pulse, compare restoration of baseline TGFBR1 only in the endothelium with continued suppression. The primary outcome is the fraction of continuously perfused segments after washout; assess pericyte coverage, leakage and fibrotic matrix. Restoration should meet the proposed 25% perfusion and 10% collagen-deposition criteria. These thresholds are proposed criteria, not observed results. Refutation requires confirmed target engagement and a 95% confidence interval excluding the specified minimum effect; a wide confidence interval indicates uncertainty. The independent unit is a donor or animal.

Mechanism. Suppress MSTN activation during GIPR/GLP1R agonism, beginning alongside weight loss rather than after its early phase.

Prediction. A controlled mechanistic study in older adults, with authorized access to the candidate, will compare changes from baseline in knee extensor power while controlling nutrition, activity, hydration and body composition. Early initiation is expected to preserve at least 20% greater muscle power under matched conditions; no functional advantage, or a difference entirely explained by final mass, would refute the hypothesis.

Mechanism. Overlap in surface uPAR density between normal endothelium and senescent targets limits the selective window of uPAR×CD3-mediated senolysis.

Prediction. Compare viability of human liver endothelium and senescent cells in co-culture across a range of exposures, with quantitatively measured uPAR density, controlling endothelial senescence status and T-cell activity. Substantial overlap should limit the range permitting selective removal; a broad selective window at equal surface uPAR density and comparable target accessibility would refute the prediction.

Mechanism. The vascular effect of 25-hydroxycholesterol depends on CRYAB reduction.

Prediction. In a perfused vascular construct containing old-donor endothelial and smooth muscle cells, compare 25HC, direct CRYAB reduction, 25HC with restored CRYAB, and a control. Measure compliance at identical pressure and tone, accounting for cell death, matrix mass and cholesterol metabolism. Direct CRYAB reduction is expected to reproduce at least half of the effect of 25HC, while maintaining CRYAB at its baseline level is expected to eliminate at least half of that effect. These thresholds are proposed criteria, not observed results.

Mechanism. Briefly raising NEUROD1 expression to the young postmitotic range in genetically traced neuroblasts of the old dentate gyrus, after confirmed cell-cycle exit and during the early postmitotic survival window, is proposed to improve survival of the existing cohort. Additional expression is switched off before late integration.

Prediction. Compare brief and sustained elevation, late elevation after the window of losses and control. Verify absence of delivery to astrocytes, measure the initial cohort size, apoptosis, dendrites and synaptic responses, and normalize new neuron numbers to the number of neuroblasts before intervention. Brief correction should improve survival and functional integration of the original cohort; restoration of transcriptional markers without those improvements would refute the proposed limitation.

Mechanism. Partially or almost completely block LPAR1, measuring receptor response rather than external concentration alone; intermediate blockade preserves epithelial migration while maximal blockade more strongly suppresses fibroblasts.

Prediction. Test paired aged lung models across a gradient of measured free exposure, with compliance after standardized injury as the primary outcome and monitoring of epithelial migration, stromal contractility, and off-target toxicity. Intermediate blockade should yield at least 20% better final compliance than maximal blockade; a monotonic functional effect within the tolerated range or deterioration explained solely by toxicity outside LPAR1 would refute the hypothesis.

Mechanism. Reduce SLC5A2-dependent renal workload and separately inhibit NLRP3.

Prediction. Test a factorial renal–vascular co-culture from elderly donors with monocytes, using albumin permeability as the primary outcome and prespecified stratification by ASC assemblies. Adding dapansutrile should provide at least a 25% barrier benefit with persistently high NLRP3 activity, with less than half that benefit at low activity. Genetic suppression of NLRP3 should eliminate the additional drug effect. Absence of the 25% benefit or lack of association with residual NLRP3 at equal renal exposure would refute the hypothesis.

Mechanism. Matrix glycation limits the mechanical benefit of CRYAB senolysis. Reduce CRYAB in old vascular cells while comparing matrices with high and low amounts of AGE crosslinks at identical initial stiffness.

Prediction. Compare intervention and control conditions in paired vascular constructs with premeasured crosslinks for each matrix. Measure the gain in passive compliance after complete smooth muscle relaxation, confirming comparable loss of senescent cells and baseline mechanics. Improvement on the minimally glycated matrix is expected to be at least 20%, while improvement on the highly glycated matrix is expected to be no more than half that gain. These thresholds are proposed criteria, not observed results.

Mechanism. Partially reduce DUSP4 in activated CD4 T cells from elderly donors and transiently restore expression of the E47 isoform in B cells with a confirmed deficiency, targeting TCF3/E47. Apply the interventions in paired T–B-cell cultures from the same elderly donor, limiting them to the beginning of the antigen-specific response.

Prediction. Use a 2×2 comparison of control, DUSP4 intervention alone, TCF3/E47 intervention alone, and both, with identical levels of each intervention in the single and combined groups. Cross-combine the four cell variants and monitor class switching, specificity, and DNA damage; increased activity of the mutation program alone does not constitute success. The primary outcome is the yield of diverse memory B-cell clones with functional antigen-specific antibodies. The hypothesis is refuted if the combination increases only titer, expands autoreactive clones, or increases genomic instability.

Mechanism. Restore SIRT2 activity in old macrophages with excessive NLRP3 acetylation and preserve functional MERTK on the macrophage membrane when its proteolytic shedding is excessive. Apply this combination to macrophages from elderly donors and old mice with background inflammation and poor apoptotic-cell clearance, without suppressing global protease activity.

Prediction. A 2×2 comparison of control, SIRT2 restoration alone, MERTK preservation alone, and their combination, with identical levels of each intervention in the single and combined groups, will distinguish dead-cell uptake from completed digestion. After withdrawal, measure the return of basal inflammation and the ability to mount a new limited response. The primary outcome is maintenance of low background inflammation with a normal inducible response after several clearance cycles. A requirement for continuous suppression, persistence of cell remnants, or loss of a new protective response would refute the hypothesis.

Mechanism. In aged lymph nodes with an elevated Tfr/Tfh ratio and disrupted follicular geography, briefly and partially reduce BCL6 only in excess Tfr, then restore regulation, while restoring the spatial organization of CXCL13. BCL6 in B cells and Tfh is preserved.

Prediction. A 2×2 comparison of control, BCL6 intervention alone, CXCL13 intervention alone, and the combination, with matching intervention levels in the single and combined groups, should yield diverse, high-affinity B-cell memory without increased autoantibodies. Distinguish early expansion from late affinity selection and check restoration of Tfr function, autoreactivity, and normal germinal-center termination. An increase only in titre, impaired affinity, loss of tolerance, or no effect of CXCL13 correction would refute the hypothesis.

Mechanism. Briefly increase GADD45B expression in activated mature granule neurons of the aged dentate gyrus responding to a novel environment, synchronizing the pulse with physiological ensemble activation without continuous expression. The proposed link connects the GADD45B response to trophic support for neurogenesis.

Prediction. Compare synchronized and time-shifted pulses with control under equal behavior and network activity. Measure DNA modifications in regulatory regions of Bdnf and Fgf1, local protein production, neuronal output, and reserve; separately reduce these trophic signals to test mediation while accounting for their independent effects. Synchronization should produce additional mature neuronal output and restore the trophic response; failure of either would refute the lost temporal coupling hypothesis.

Mechanism. First reduce endothelial CD38 activity, then provide the NAD precursor nicotinamide riboside to interrupt self-sustaining NAD consumption; compare with the reverse sequence at equal total exposure.

Prediction. Paired barrier chips from naturally aged donor cells will compare both sequences, simultaneous treatment, each treatment alone, and a control. The primary outcome is the area under the albumin permeability curve after a common washout; measure CD38, NAD, cytosolic mtDNA, and the duration of residual activity. The hypothesis is refuted if the sequence advantage is less than 25% or disappears after matching total exposure and residual CD38 suppression. These are proposed thresholds, not observed results; refutation requires confirmed target engagement and a 95% confidence interval excluding the specified minimum effect, while a wide interval indicates uncertainty. The independent unit is a donor or animal.

Mechanism. The surface profile comprising CD150, CD24, CD201, CD9 and CD63 in mouse HSC is associated with functional sensitivity to disruption of H3K23ac–TRIM24.

Prediction. Train a simple, prespecified constrained model on a subset of animals and test it in an independent batch. The panel should improve prediction of the treatment/control difference in functional differentiation relative to CD150 alone and chronological age, with robustness to technical batch and sex.

Prediction. Stop urolithin A exposure after a cellular response has been achieved and separately follow metabolism and the naive-like CD8 phenotype. In an agreed withdrawal study with a control group and serial samples, compare the return times of two prespecified measures; the metabolic measure is expected to return to baseline first. Ex vivo washout can provide a preliminary test but cannot replace testing withdrawal in participants.

Mechanism. Use jointly high expression of SLAMF1/CD150 and SELP/CD62P as a dual address for a single, partial depletion of a functionally verified myeloid-biased HSC subgroup in old mice, without systemic suppression of these proteins' functions, followed by observation of hematopoietic recovery.

Prediction. First validate the selective depletion system separately and determine how well the marker combination predicts clonal fate. Then compare dual-marker and single-marker selection at the same extent of depletion, measuring loss of useful clones, new lymphocytes, responses to new and familiar antigens, platelets, and preservation of other cells bearing these markers. The proposed advantage requires improved specificity without narrowing the repertoire or impairing memory.

Mechanism. Prolonged exposure to the old stromal environment leaves functional memory in iTEC. Chromatin accessibility and CDKN2A are possible explanations to be examined.

Prediction. Compare brief and prolonged exposure in the same iPSC lines, matching cumulative inflammatory load and using an identical recovery phase after complete medium replacement. Prolonged exposure should leave a persistent deficit in functional mature T-cell output per live iTEC after washout, whereas brief exposure should permit recovery. Track RELA/NF-κB, CDKN2A and iTEC chromatin accessibility without substituting these measurements for function. Equal recovery, or a residual deficit entirely explained by cell death or continuing exposure, would refute the prediction.

Mechanism. Restore GPX4 activity in aged activated CD4 T cells with excessive membrane lipid peroxidation, and partially reduce mTORC1 signaling through RPTOR only after early productive expansion. Use T cells from elderly donors with both defects measured; verify sufficient glutathione and active GPX4, since overexpression without activity does not count as correction.

Prediction. A 2×2 comparison of control, GPX4 intervention alone, RPTOR intervention alone, and the combination, with matching intervention levels in the single and combined groups, should increase functional specific memory while preserving the early response and genomic stability. Measure lipid peroxides, the type of cell death, late mTORC1, and repeat function, and check normal early signaling and response termination. Merely preserving dysfunctional cells, weakening the primary response, or failing to outperform a single correction would refute the hypothesis.

Mechanism. The effect of EP2 blockade on neutrophil clearance depends on the daily phase of neutrophil arrival for removal.

Prediction. Reduce PTGER2/EP2 at comparable exposure during different phases of the daily cycle in an existing model, with identical feeding and lighting conditions. Measure neutrophil turnover, macrophage uptake and drug exposure; CXCR4 or CD62L alone is not sufficient evidence of senescence. The blockade effect is expected to interact with cycle phase after accounting for exposure and the available amount of cellular material.