By agitating the interference between the skin cells that make up the roots of the hair, the researchers report that strands of hair have once again grown on damaged skin. The findings better explain why hair does not normally grow on injured skin and may help in the search for better medications to restore hair growth, say the study's authors.
Directed by researchers from the NYU School of Medicine and published in November in the journal Communications of nature, the study examined the effect of different signaling pathways on the damaged skin of laboratory mice. The experiments focused on cells called fibroblasts that secrete collagen, the structural protein most responsible for maintaining the shape and strength of skin and hair.
As part of their research, the researchers activated the signaling pathway of sonic hedgehog used by cells to communicate with each other. It is known that the pathway is very active during the early stages of human growth in the uterus, when hair follicles form, but otherwise stops in the injured skin in healthy adults. The researchers say that this possibly explains why hair follicles do not grow on the replaced skin after an injury or surgery.
"Our results show that the stimulation of fibroblasts through the pathway of the sonic hedgehog can trigger hair growth not previously seen in wound healing," says lead researcher and cell biologist Mayumi Ito, PhD, associate professor of the Department of Dermatology Ronald O. Perelman at the University of New York. Langone Health.
Re-growing hair on damaged skin is an unmet need in medicine, says Ito, due to the disfigurement suffered by thousands of traumas, burns and other injuries. However, his most immediate goal, he adds, is to signal mature skin to return to its embryonic state so that new hair follicles can grow, not only on injured skin, but also in people who have become bald from aging.
Ito says that scientists have so far assumed that, as part of the healing process, scars and the accumulation of collagen on damaged skin were behind their inability to regrow hair. "Now we know that it's a signaling problem in cells that are very active as we develop in utero, but less in mature skin cells as we get older," he adds.
The key among the findings of the study was that no signs of hair growth were seen in the untreated skin, but were observed in the treated skin, which provides evidence that the signaling of the sonic hedgehog was behind the hair growth. .
To avoid the risk of tumors reported in other experiments that activated the pathway of the sonic hedgehog, the team of NYU Langone activated only the fibroblasts located just below the surface of the skin where the roots of the hair follicles (dermal papillae) appear. The researchers also focused on fibroblasts because it is known that cells help direct some of the biological processes involved in healing.
Hair regrowth was observed within four weeks after the skin wound in all treated mice, and structures of the root and hair shaft began to appear after nine weeks.
Ito says his team plans additional research on how the chemical and genetic stimulants of fibroblasts could activate the sonic hedgehog pathway in wounded human skin. Its objective is to identify possible pharmacological objectives for hair growth.