Intercellular communication breakdown in aging—not hormones, but local paracrine signaling

We focus on circulating hormones in aging. But most cell-cell communication is local—growth factors, cytokines, extracellular vesicles acting within microns, not systemically.

Old tissues lose local coordination. Cells still make hormones, but neighbors don't respond. The tissue becomes a collection of individuals, not a community.

Restoring paracrine signaling (not just hormones) may be the key to tissue rejuvenation.