Nerve-derived Schwann cell precursors, acting in a paracrine fashion, are essential for mammalian digit tip regeneration [RAT]

Multi-tissue regenerative capacity is lost in adult mammals with the exception of the distal digit, which regenerates via largely-uncharacterized mechanisms. Here, we demonstrate that following adult mouse distal digit removal, nerve-associated Schwann cell precursors (N-SCPs) dedifferentiate and secrete growth factors that promote expansion of the blastema and digit regeneration. Specifically, when N-SCPs were dysregulated or ablated, mesenchymal precursor proliferation in the blastema was decreased, nail and bone regeneration were impaired, and regeneration could be rescued by transplantation of exogenous N-SCPs. We show that N-SCPs secreted factors that promoted self-renewal of mesenchymal precursors, and we used transcriptomic and proteomic analysis to define candidate factors. Two of these, oncostatin M (OSM) and PDGF-AA, were made by N-SCPs in the regenerating digit, and rescued the deficits in regeneration caused by loss of N-SCPs due to denervation. Since nerves innervate every peripheral tissue, these results have broad implications for mammalian tissue repair and regeneration. We obtained three independent isolates of back skin SKPs and sciatic nerve NSCPs from newborn Sprague-Dawley rat pups