Unlike normal skin, scar tissue doesn't contain any hair follicles. New research now indicates that when such follicles are transplanted into scar tissue, that tissue changes to become much more like uninjured skin.
Previous studies have already shown that skin with lots of hair follicles heals faster and scars less than non-hairy skin. It has additionally been found that follicles boost the healing process when transplanted into relatively fresh wound sites.
Scientists at Imperial College London set out to take things further, by seeing if hair follicle transplants could reduce or eliminate existing scars.
Working with Dr. Francisco Jiménez from Spain's Universidad Fernando Pessoa Canarias, they transplanted follicles into mature scars on the scalps of three human test subjects. The scars were normotrophic, which is the most common type.
Three-millimeter-thick samples of the scar tissue were taken and analyzed immediately before transplantation, and then again after two, four and six months had elapsed. It was found that not only did the follicles continue to produce hair, but they also "inspired profound architectural and genetic shifts in the scars towards a profile of healthy, uninjured skin."
More specifically, genes in the scar tissue that promoted the growth of blood vessels and normal skin cells were expressed more than before, whereas genes that promoted scar formation were expressed less. As a result, after four months, the number of blood vessels in the tissue nearly matched that of healthy skin.
Additionally, after six months, the scar's epidermis (which is the outermost layer of skin) had doubled in thickness, making it approximately as thick as the tougher epidermis of uninjured skin. At the same time, though, the density of collagen fibers within the scar tissue was reduced, making it softer and more pliable. These are important considerations, as scar tissue is typically thinner than normal skin – leaving it more susceptible to injury – and also less flexible, potentially impeding movement.
Of course, new hair growth might not be desirable when treating scars in areas other than the scalp. With that fact in mind, the scientists are now trying to get a better understanding of what mechanism is at work, in hopes of being able to replicate the scar-reducing effect without the need for actual hair follicle transplants.
"After scarring, the skin never truly regains its pre-wound functions, and until now all efforts to remodel scars have yielded poor results," said the lead scientist, Dr. Claire Higgins. "Our findings lay the foundation for exciting new therapies that can rejuvenate scars and restore the function of healthy skin."
A paper on the research was recently published in the journal npj Regenerative Medicine.
Source: Imperial College London
