Hepatic DFI restores thymic output

Age-related immune decline leaves the thymus, the organ that makes new T cells, producing too few fresh defenders. Researchers tested whether the liver could briefly become a support niche for thymic renewal in 72-week-old mice. Lipid nanoparticles delivered three messenger RNAs that made liver cells present a contact signal and hold interleukin-7, an immune-growth signal, in the surrounding tissue matrix. After twice-weekly dosing for 28 days, mice had more circulating naïve T cells, a better naïve-to-memory balance, and partially restored thymic size and cell numbers. Each factor alone failed to reproduce the effect. In a separate tumour experiment with checkpoint treatment, 3 of 8 aged mice had no measurable B16-OVA tumours.