After my recent knee surgery, I acquired at least three small pink scars. Two from the key hole surgery, and one inch long line where they took a bit of my hamstring; each a reminder to be more careful next time! However, it got me thinking: why do we scar, is there a need for it, and is there any research underway in this area?
A scar is a mark left on the skin after a wound or injury. You may have one from scratching at chickenpox, or when you tripped up on the patio in your garden, or even from putting your hand on a hot pan. The majority of people have scars in one form or another, and they are just a natural part of the healing process which we don’t really think about day-to-day. Over time, scars tend to fade and become paler, but will never completely disappear. Why do we get scars in the first place?
After injury we bleed and then form a blood clot, protecting the wounds from more harm. Chemical messengers set off the repair process. Granulation tissue replaces the clotted blood and restores blood flow to the site. Scars form when there is damage to the deep, thicker layer of skin (the dermis). Our body reacts quickly and wants to repair the damage, so we produce more collagen fibres (a naturally occurring protein) in the damaged area. Collagen builds up where the tissue is damaged, helping to heal and strengthen the wound, and continue to do so for several months. Collagen fibres are orientated in one direction, resulting in scar tissue which can be thick, and will appear and feel different to the skin around it as these normal fibres are randomly oriented. There are 5 types of scar: scar contractures (which usually occur after a burn and the skin appears to shrink), pitted/sunken, keloid and hypertrophic (resulting from an excess of collagen), and finally, normal fine-line scars (usually occur after a wound or surgery, fading over time as the collagen breaks down).
While most scars go untreated, are small, and do not require any adjustment, some can be large and painful as movement is restricted and nerve endings wake up. Current treatment for such cases according to NHS UK are silicone gels, pressure dressings, steroids, and in extreme cases, surgery, whilst other sites boast dermabrasion (the removal of the surface layer of skin), microneedling and laser resurfacing (same as dermabrasion but using lasers) to name a few. Treatments haven’t progressed very far; is there new research which could change how we treat the body’s largest organ (skin)?
In the 1980’s work began to identify why foetuses don’t scar when operated on in the womb (in utero). Michael Harrison, from the University of California, operated on foetuses and realised they did not have scars from surgery. The research which followed taught the field lots about why we scar, but didn’t gain much in the way of new treatments. One avenue of investigation is exploring unlocking regenerative properties (see Deadpool: Regeneration Reality) we naturally have when we’re a foetus. In 2017 one research team found that by manipulating wound healing to incorporate hair follicle production, they could promote normal, regenerative skin growth. Scar tissue not only looks different because of the collagen build up, but also due to the lack of hair follicles and fat cells (adipocytes). The group suspect hair follicles assist the growth of adipocytes for normal skin regeneration. The group induced hair follicle growth in newly forming scar tissue (of mice and human skin samples) and the resultant skin was indistinguishable from pre-existing skin!! Increasing the number of fat cells could have applications in HIV cures, other dermatological conditions, and even help battle ageing. Although this is VERY promising, such a process would have to be a very precise procedure, making it difficult to become a reality soon and human trials still need to be undertaken.
Although scar treatments are currently limited, research into why we scar in the first place has uncovered some fascinating results. Developments are underway: Spray on skin by ReCell was approved by the FDA for burns victims. A traditional skin graft can cover 3x the area it was taken from, whereas spray on skin can cover 80x that taken and scarring is much less. The Scar Free Foundation opened in 2018 too, as the first military and civilian wound research centre, so whilst new treatments have been slow to reach us, there is a lot of buzz in this field now. Such work could completely change some people’s lives.