Scientists are hailing the “foundations for exciting new therapies” after hair follicle transplants were found to help mend scars by altering their architecture and genetic makeup.
A study by a team at Imperial College London, UK, found skin scars behaved like uninjured skin after they were treated with hair follicle transplants, with scarred skin harbouring new cells and blood vessels, remodelled collagen to restore healthy patterns.
Writing in today’s edition of *Nature Regenerative Medicine*, the team found scarred skin also expressed genes found in healthy unscarred skin.
Lead author Dr Claire Higgins, of Imperial’s Department of Bioengineering, said the results from the study of three volunteers could lead to better treatments for scarring both on the skin and inside the body, leading to hope for patients with extensive scarring, which can impair organ function and cause disability.
“After scarring, the skin never truly regains its pre-wound functions, and until now all efforts to remodel scars have yielded poor results,” she said.
“Our findings lay the foundation for exciting new therapies that can rejuvenate even mature scars and restore the function of healthy skin.”
Healthy skin undergoes constant remodelling by the hair follicle and hairy skin heals faster and scars less than non-hairy skin. Hair transplants have also been shown to help wound healing.
The research team thought transplanting growing hair follicles into scar tissue might induce scars to remodel themselves and they worked with Dr Francisco Jiménez, lead hair transplant surgeon at the Mediteknia Clinic and associate research professor at University Fernando Pessoa Canarias, in Gran Canaria, Spain, to test the hypothesis.
In 2017, they transplanted hair follicles into the mature scars on the scalp of three participants, selecting normotrophic scars, the most common type of scar that usually forms following surgery.
They microscope imaged 3mm-thick biopsies of the scars just before transplantation, and followed up at two, four, and six months, finding the follicles inspired profound architectural and genetic shifts in the scars towards a profile of healthy, uninjured skin.
Dr Jiménez said: “Around 100 million people per year acquire scars in high-income countries alone, primarily as a result of surgeries. The global incidence of scars is much higher and includes extensive scarring formed after burn and traumatic injuries. Our work opens new avenues for treating scars and could even change our approach to preventing them.”
The team also found that after transplantation, the scars expressed 719 genes differently from before. Genes that promote cell and blood vessel growth were expressed more, while genes that promote scar-forming processes were expressed less.
The researchers are unsure precisely how the transplants facilitated such a change and are now working to uncover the underlying mechanisms so they can develop therapies that remodel scar tissue towards healthy skin, without requiring transplantation of a hair follicle and growth of a hair fibre.
Dr Higgins said: "This work has obvious applications in restoring people’s confidence, but our approach goes beyond the cosmetic as scar tissue can cause problems in all our organs.
“While current treatments for scars like growth factors focus on single contributors to scarring, our new approach tackles multiple aspects, as the hair follicle likely delivers multiple growth factors all at once that remodel scar tissue. This lends further support to the use of treatments like hair transplantation that alter the very architecture and genetic expression of scars to restore function.”
Plotczyk M, Jiménez F, Limbu S et al. Anagen hair follicles transplanted into mature human scars remodel fibrotic tissue. * Nature Regenerative Medicine* 6 January 2023
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