A Regenerative Medicine Breakthrough for Burn Patients

Steven Kahn, M.D.

By Kat Hendrix

The South Carolina Burn Center at MUSC Health made an important leap forward as the first US center reported to successfully use a novel combination of two revolutionary products in a minimally invasive skin graft procedure.

Nexobrid® is an enzymatic burn debridement product that uses bromelain, which is an enzyme extracted from pineapple stems, to remove burns instead of traditional surgery with a knife.

Steven Kahn, M.D., Director of the Center and Chief of Burn Surgery in the MUSC Department of Surgery explains, "This enzyme eats away damaged and dead tissue at a cellular level without damaging the living tissue that's left. It's very precise; much more precise than surgery using human eyes and hands and preserves as much living tissue as possible. The difference of a few thousandths of an inch can determine whether a wound will heal without a graft."

The second product, Recell®, is a point-of-care regenerative skin-grafting therapy that allows surgeons to harvest a sample of autologous skin and reduce it to a solution that can be sprayed over the burned area to grow new cells. "We take a small biopsy of skin from the patient and put it in a special device with a solution that breaks down the extracellular matrix. We then manually disaggregate the skin sample into individual skin cells that we can spray. The sprayed cells can cover 80-times the size of the original biopsy and distribute very evenly over the wound," said Kahn.

Because Nexobrid® is only available in the US through research studies, and Recell® just received FDA-approval in September 2018, U.S. surgeons could not use the two in combination until recently. However, having participated in studies of both products, Kahn was well aware of the potential advantages.

"The enzyme allows us to clean the wound at a cellular level,” Kahn said. “So it preserves the most amount of healthy dermis possible, which helps with healing and reduces grafting. Overall, burn patients who get this treatment are three times less likely to need a graft. If they do, it's about a third the size it would have been with standard surgery. Furthermore, the skin spray forms a better scar and doesn't leave gaps that contract during healing like a graft can. We can use the spray alone for deep second-degree burns, or we can use a meshed graft and overspray the holes for third degree burns. With third-degree burns, we can still decrease donor site size by using a more widely meshed graft and over spraying."

Although Recell® is often called "spray-on-skin," there must be some dermal tissue left for it to adhere and grow new cells. "One limitation is that the spray won't work if there's not enough dermis left,” explained Kahn. “You can't spray it over subcutaneous fat or connective tissue.”

This means the burn characteristics are critical for regenerative skin spray to be effective. Recell® can be used on burns without a conventional skin graft up to a deep second-degree level but not on third-degree burns. Up to half of the patients seen at the Burn Center have this type of burn, including a young man admitted in late July after gasoline exploded near a fire he was using to clear some trees.

"He had 17% burns and half of that area needed grafts," said Kahn. "After we used the enzyme and saw there was a minute amount of dermis left, I decided to use the spray. There was still enough dermal tissue–a thin layer–that I thought the spray would work." Although this young man's burns did not have enough dermis left to heal on his own, the enzyme allowed preservation of just enough dermis to activate the spray and replace the missing cells. He was able to heal without a skin graft–a result that would have been unlikely with traditional surgery.

Katie Hollowed, RN, MSN, and program manager, has 40 years of experience treating burn patients and was excited to see this new technology. "I'd heard of both of these products, but I'd never seen them used together until I came to MUSC,” she said. “We didn't have to take a big donor site on this patient–that's huge. There's less pain and less opportunity for a wound infection. Plus, it's another scar they'll have to deal with forever. Not creating a large donor site can reduce complications, and the patient went home sooner with less pain and scarring."

Kahn estimates that a conventional graft would have required using almost all of the skin from this patient's anterior thighs. "We were able to treat all of his burns–which amounted to about 2,000 square centimeters–with only 24 square centimeters of donor skin. That's less than a third of the size of his hand," Kahn said.

Burn teams have waited decades for a major new development in burn surgery. With no significant advances since excision and grafting began in the 1970s, the field has struggled to attract staff. It is hoped that recent treatment advances will encourage more people choose burn care. Hollowed explains, "For a long time, burn care was just the same standard treatments. In the past few years, several long-time burn physicians retired but they had mentored a younger generation in the field. Now, there's a new crop of energetic, enthusiastic physicians, and it's inspiring. This new generation is really driven to improve burn care."

Minimally invasive grafting for deep partial thickness burns has been discussed at burn meetings in the U.S. for several years but using Nexobrid® and Recell® together was hampered by the fact that both were previously only available through studies. This meant surgeons could not use them on the same patient, since patients can only participate in one study at a time. "We've talked about combining them for a while to treat deep second degree burns without a traditional meshed graft, and several major U.S. centers have been gearing up to do it," said Kahn. "As far as I know after reviewing the literature, this is the first report of a successful minimally invasive skin graft in the United States.”

“I’m just glad we were able to help this patient, decrease his pain and speed up his recovery,” said Kahn.