New device could reduce surgical scarring

Posted by Chris Nova

Scientists at Stanford University have developed an extraordinary wound dressing capable of greatly reducing scar tissue from incisions.

The results of animal tests and of an early medical trial of the dressing were "stunning," said Michael Longaker, MD, MBA, the Deane P. and Louise Mitchell Professor at the School of Medicine and senior author of a study that details the findings.

"It was a surprisingly effective treatment," he said.

The study will be published online today in the Annals of Surgery.

After sutures are removed, the edges of a healing cut are pulled in different directions by the stiff, surrounding skin, this causes scar tissue to thicken and spread. The new dressing, which the authors call a "stress-shielding device," gets rid of this tension and therefore a substantial amount of scarring.

"This work actually started 20 years ago when I was an intern at Massachusetts General Hospital," said lead author Geoffrey Gurtner, MD, professor and associate chair of surgery. "I realized early on that we were not going to solve the problem of scarring with current surgical tools and techniques."

Co-author Reinhold Dauskardt, PhD, professor of materials science and engineering in the School of Engineering, remembered a meeting he had with Gurtner that began the effort to make a stress-shielding device.

"We were talking about our respective research," Dauskardt said. "Geoff had a lot of experience in wound healing and was thinking about factors that led to scarring. He said, 'If only we could keep in check the mechanical forces acting on the wound.' I had multiple programs on skin biomechanics and transdermal-drug delivery. I said, 'I think I can do that.'"

Dauskardt and his coworkers made the dressing in his lab. It is made from a thin and elastic silicone plastic that is stretched over the incision after sutures have been taken out. The dressing sticks to the skin with the help of an adhesive. As it contracts, it provides even compression across the wound.

Scar tissue, is less flexible than regular skin, it can cause functional problems, such as limiting motion. Hair will not grow in a scar, and they do not have sweat glands. Also, scars do not have an appearance like regular skin does: They are often raised and have a pinkish hue. Many people find them unattractive. However they are an unavoidable side effect of surgery. Each year in the United States, over 50 million incisions are made during operations. Presently, hundreds of millions of people already have scars that they would like to eliminate. Current scar-removal practices, including surgical excision, steroid injections and laser therapy, are generally costly, painful or they simply do not work, the authors say.

The researchers think that the dressing will be used not only to reduce scarring from incisions, but also to make the surgical modification of current scars a more attractive option; the second scar would be much less visible, if it’s even visible at all.

Pigs were used in the research because they have skin similar to humans. In the pig skin that was used, the area of scars caused by roughly 1-inch incisions was reduced six-fold by the stress-shielding device, compared to pigs in a control group with the same-sized incisions, the study said. The stress-shielded wounds "demonstrated nearly scarless closure" eight weeks after sutures had been removed.

The researchers also tested the device on approximately 1-by-1.5-inch excisions — a wound representing the kind caused by scar removal — and found that "stress shielding dramatically decreased scar area" compared to unfortified wounds of the same size. "The device seemed to promote regenerative-like repair rather than scar formation," the authors wrote.

The researchers then tested the device on nine female patients who had undergone abdominoplasties (tummy tucks). Taking into consideration the quantity of tissue removed during this optional surgery, an incredible amount of tension occurred across the wound after closure. (Scars from these procedures are typically wide and thick.) Longaker said he and his colleagues purposely chose to test the dressing on incisions closed with high tension: If the dressing could diminish scarring in such cases, it would have to work on any other kind of incision.

One side of the abdomen-wide incision on each patient was treated with the stress-shielding dressing; the other half was not. A board of three plastic surgeons not linked to the research, as well as a panel of three people not in the medical profession, acted as judges. On a 100-point scale, the nonprofessional panel scored the appearance of stress-shielded wounds an average of 13.2 points higher than the control wounds. The expert panel rated the scar appearance of the treated incisions 39.2 points higher. In both of these studies, the difference between the treated side and the control side were very noticeable, the researchers said.

Nonetheless they noted that some of the wounds showed more dramatic improvement than others. They think that this may have been due to differences in the amount of tension present in the dressings when they were put on the wounds. The researchers made sure to note that this was a preliminary clinical study designed only to show "proof of principle in humans."

"Larger clinical trials are being planned to include greater ethnic diversity within the patient population and to determine the optimal range of stress-shielding forces for anatomic region- and dimension-specific wounds," the authors wrote.