Implanted Hair Follicle Cells Produce Remodeling of Scar Tissue

Researchers here report on an interesting approach to treating scar tissue in skin. Noting that hair follicles appear to promote regeneration in healthy skin, they implant follicles into scar tissue. The result is some degree of beneficial remodeling of the scar. While the next logical step is to better understand the signaling involved in this effect, it is worth noting that researchers have been attempting to understand the mechanisms of skin regeneration for some time now. It is a very complex situation involving many different cell types, structures, and phases of activity that change over time. There is unlikely to be a simple solution that recapitulates the influence of follicle tissue on skin structure and maintenance.

Compared to scar tissue, healthy skin undergoes constant remodelling by the hair follicle. Hairy skin heals faster and scars less than non-hairy skin - and hair transplants had previously been shown to aid wound healing. Inspired by this, the researchers hypothesised that transplanting growing hair follicles into scar tissue might induce scars to remodel themselves. In a new study involving three volunteers, skin scars began to behave more like uninjured skin after they were treated with hair follicle transplants. The scarred skin harboured new cells and blood vessels, remodelled collagen to restore healthy patterns, and even expressed genes found in healthy unscarred skin.  

After transplantation, the follicles continued to produce hair and induced restoration across skin layers. Scarring causes the outermost layer of skin - the epidermis - to thin out, leaving it vulnerable to tears. At six months post-transplant, the epidermis had doubled in thickness alongside increased cell growth, bringing it to around the same thickness as uninjured skin. Scar maturation leaves the dermis with fewer cells and blood vessels, but after transplantation the number of cells had doubled at six months, and the number of vessels had reached nearly healthy-skin levels by four months. Scarring also increases the density of collagen fibres which causes them to align such that scar tissue is stiffer than healthy tissue. The hair transplants reduced the density of the fibres, which allowed them to form a healthier, 'basket weave' pattern, which reduced stiffness.

The researchers are unsure precisely how the transplants facilitated such a change. In their study, the presence of a hair follicle in the scar was cosmetically acceptable as the scars were on the scalp. They 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. They can then test their findings on non-hairy skin, or on organs like the heart, which can suffer scarring after heart attacks, and the liver, which can suffer scarring through fatty liver disease and cirrhosis