Dr. Longaker’s obsession with scars began in 1987 with an experiment as a new postdoctoral fellow in Dr. Michael R. Harrison at the University of California at San Francisco. Dr. Harrison, who studied fetal surgery, suggested that Dr. Longaker operated on a fetal lamb for two-thirds of the pregnancy and then returned the fetus to the womb for further development.
Dr. Longaker gasped as he later gave birth to the baby lamb. The skin was intact. There were no scars to be seen.
“I will never forget this moment,” he said.
He later became a pediatric plastic surgeon and saw firsthand the scars on children after they underwent surgery for cleft lips or palates. And he ran a lab dedicated to preventing scars.
He learned that for the first two trimesters of fetal life, the skin is gelatinous, “like a bowl of Jell-O,” said Dr. Longaker. As the fetus develops to live outside of the sterile liquid world of the uterus, the skin forms a barrier to prevent water loss and block the entry of microorganisms. At this point, breaking the skin barrier can be fatal, so the body turns on a system to quickly seal it off.
But there’s a tradeoff in the speed of healing a wound, noted Dr. Longaker. “The cost is loss of form and function.” And scarring.
Dr. Tomic-Canic described the process: When there is a wound, the strong muscle under the skin contracts, bringing the edges of the wound together. A clot forms over the wound as a temporary barrier, and beneath it, the body forms thick coils of collagen that form a bridge to allow skin cells to migrate across the gap and fill the opening. These ropes of collagen remain – they are the scar.
As molecular biology and genetics progressed, Dr. Longaker’s new tools to study the molecular pathways required for scar formation. The main starting point for scarring is the mechanical tension when a wound tears the skin, which should be taut. (Older people with loose skin are less prone to scarring because their skin is less under tension.) The crack in the layers of the skin causes a type of skin cell – fibroblasts – to form ropes of collagen and trigger a chain reaction of molecular events within the skin, skin cells. The reactions culminate in the activation of a protein called YAP for Yes-associated protein. YAP then binds to DNA and scarring begins.
