653 Substance P ameliorates epidermal thickness, basal cell density, and asymmetric stem cell self-renewal in skin with decreased sensory innervation

This study investigated the impact of decreased sensory innervation and substance P (SP) on stem cell (SC) and committed progenitor (CP) proliferation in the skin. Decreased innervation, induced by capsaicin, led to an 80% reduction in asymmetric SC self-renewal and a near-complete loss of the suprabasal layer. SP treatment increased epidermal stratification in both normal and innervation-decreased skin and restored basal cell density and asymmetric SC division in the latter to normal levels. In normal skin, Lapatinib inhibited SP-induced increases in asymmetric SC divisions and stratification, indicating the necessity of asymmetric SC divisions for stratification. The study suggests that SP could be used to rebalance SC fate, with potential applications in conditions like diabetes and aging.