Keratin-mediated hair growth and its underlying biological mechanism

Injecting human hair-derived keratin into mice skin accelerates hair growth & formation, as TGF beta 2 secretion during hair destruction stimulates epithelial cell death and keratin release, leading to dermal cell condensation & hair growth. Here we show that intradermal injection of keratin promotes hair growth in mice, which results from extracellular interaction of keratin with hair forming cells. Extracellular application of keratin induces condensation of dermal papilla cells and the generation of a P-cadherin-expressing cell population (hair germ) from outer root sheath cells via keratin-mediated microenvironmental changes. Exogenous keratin-mediated hair growth is reflected by the finding that keratin exposure from transforming growth factor beta 2 (TGF beta 2)-induced apoptotic outer root sheath cells appears to be critical for dermal papilla cell condensation and P-cadherin-expressing hair germ formation. Immunodepletion or downregulation of keratin released from or expressed in TGF beta 2-induced apoptotic outer root sheath cells negatively influences dermal papilla cell condensation and hair germ formation. Our pilot study provides an evidence on initiating hair regeneration and insight into the biological function of keratin exposed from apoptotic epithelial cells in tissue regeneration and development.

Automated summary

Injecting human hair-derived keratin into mice skin promotes hair growth and formation, due to the extracellular interaction of keratin with hair forming cells. Keratin induces condensation of dermal papilla cells and the formation of hair germ. Keratin plays a critical role in hair growth.