Systemic recalibration and epigenetic resetting as complementary strategies in ageing biology

Two principal strategies have gained prominence among currently recognised approaches to anti-ageing: systemic interventions that modulate the circulatory environment and cellular interventions that reset epigenetic information. Systemic approaches, beginning with experimental heterochronic parabiosis models that are not applicable to humans and extending to clinically applicable therapeutic plasma exchange, test the hypothesis that ageing is promoted by the accumulation of inhibitory blood-borne factors. Cellular reprogramming, particularly partial reprogramming through transient expression of Yamanaka factors, tests the alternative hypothesis that ageing is primarily a cell-intrinsic process associated with loss of epigenetic information. This perspective critically evaluates these two modalities. The dilution hypothesis is examined together with its limitations and the unresolved complexities of systemic interventions. The challenge of cell-autonomous ageing is also considered, particularly the persistence of cell populations that remain refractory to systemic rejuvenation. A conceptual framework integrating these two axes of ageing is then presented. This framework suggests that combined systemic recalibration and targeted partial reprogramming warrant further investigation as a multimodal approach to ageing intervention. Future research priorities include mechanistic clarification of this systemic-cellular interaction and development of robust biomarkers to evaluate multimodal interventions.