Study tests senescence propagation thresholds

This proposed study asks whether ageing-like senescence can spread through human connective-tissue cells only after enough senescent cells accumulate. Researchers would mix senescent and healthy IMR-90 fibroblasts, cells that help build connective tissue, across donor proportions of 5-80% and culture them for 96 hours. The key test is the curve. A gradual rise in recipient p16INK4a, a marker of cellular senescence, would fit signalling by secreted factors. A sharp S-shaped rise near 20-30% senescent donors would support a connectivity threshold, where direct cell contacts form a spreading network. The design would then alter cell contact, membrane voltage and extracellular vesicles, tiny cargo-carrying particles, to decide whether direct Cx43 junctions or vesicle transfer best explains any threshold.