US researchers have regrown hair strands on damaged skin by stirring crosstalk among skin cells that form the roots of hair, an advance that may help search for better drugs to restore hair growth.The team from the New York University (NYU) examined the effect of distinct signalling pathways in damaged skin of laboratory mice as well as focused on cells called fibroblasts that secrete collagen -- the structural protein responsible for maintaining the shape and strength of skin and hair.The researchers then activated the sonic hedgehog signalling pathway that is used by cells to communicate with each other. The pathway is also known to be very active during the early stages of human growth in the womb, when hair follicles are formed, but is otherwise stalled in wounded skin in healthy adults.Hair regrowth was observed within four weeks after skin wounding in all treated mice, with hair root and shaft structures starting to appear after nine weeks, the researchers said.
"Our results show that stimulating fibroblasts through the sonic hedgehog pathway can trigger hair growth not previously seen in wound healing," said Mayumi Ito, Associate Professor and cell biologist at NYU Langone Health.Until now it was assumed that, as part of the healing process, scarring and collagen buildup in damaged skin were behind its inability to regrow hair. "Now we know that it's a signalling issue in cells that are very active as we develop in the womb, but less so in mature skin cells as we age," Ito noted.The study was published in the journal Nature Communications. Regrowing hair on damaged skin is an unmet need in medicine, Ito said, because of the disfigurement suffered by thousands from trauma, burns, and other injuries.However, her more immediate goal, she adds, is to signal mature skin to revert to its embryonic state so that it can grow new hair follicles, not just on wounded skin, but also on people who have gone bald from ageing.