Assay tests stiffness–age thresholds

This proposed experiment asks whether collagen stiffness can make cultured human lung fibroblasts change biological age in sudden steps or along a smooth slope. Researchers will grow IMR-90 cells, a human lung fibroblast line, for 14 days on eight collagen gels spanning 0.2 to 40 kilopascals, a measure of stiffness. They will verify each gel before and after culture, then use EPIC arrays, chips that read DNA methylation, chemical marks linked to cell state, to estimate epigenetic age. Six biological replicates per condition will set the test. A three-year age shift between neighbouring gels plus a Davies breakpoint test below 0.01 would support a discrete boundary. A gradual curve would favour progressive coupling and guide whether stiffness should be changed abruptly or incrementally.