Regrowing a Soldier’s skin no longer the stuff of science fiction

Col. (Dr.) Evan M. Renz prepares a skin sample for the ReCell clinical trial in May 2013. ReCell takes a biopsy from a patient's skin and incubates it in a cocktail of enzymes before it is harvested for keratinocytes, or regenerative cells, that are then suspended in a solution. This solution is sprayed on a wound, where it multiplies and creates new skin tissue. (U.S. Army photo by Steve Galvan)

Col. (Dr.) Evan M. Renz prepares a skin sample for the ReCell clinical trial in May 2013. ReCell takes a biopsy from a patient’s skin and incubates it in a cocktail of enzymes before it is harvested for keratinocytes, or regenerative cells, that are then suspended in a solution. This solution is sprayed on a wound, where it multiplies and creates new skin tissue. (U.S. Army photo by Steve Galvan)

Imagine a Soldier suffered debilitating burns to 60 percent of his body while deployed. After being evacuated to a burn treatment facility and stabilized, surgeons treated his wounds using a

biopsy of his own skin, and re-grew tissue over the injuries. There was little risk of infection, as the wounds were covered quickly, and surgeons did not have to create additional wounds by harvesting large quantities of skin from his body. The Soldier’s body does not reject the new skin, as it was generated from his own cells. He is able to make a full recovery.

This is the future of burn care, according to experts at the U.S. Army Institute of Surgical Research Burn Center, at Joint Base San Antonio in Texas. The primary mission of the center is to evacuate and treat combat causalities with thermal injuries, Col. (Dr.) Booker T. King, director, explained.

“We have a multi-disciplinary staff, including surgeons … nurses of … both critical care as well as … normal bedside — rehabilitation, restorative therapy, you name it. We also have a burn flight team. … the burn flight team’s job is to evacuate severely injured burn casualties, mostly military-related combat, from wherever we can pick them up to back here in San Antonio,” King said. The burn flight team’s proper name is Special MEDCOM Response Capabilities/Burn.

The center performs wound evaluation, physical and occupational therapy, patient education and is continuing to develop a psychosocial care program, King said.  In addition to surgical burn treatment and rehabilitation, the center is participating in several clinical trials to advance skin treatments.

“We’re currently a part of two major regenerative multi-center trials,” King said. “And they are sponsored in part by the Department of Defense. (Another) group is also (involved), they’re called AFRIM, Armed Forces Institute of Regenerative Medicine — that’s a partnership between the Department of Defense and civilian entities.”

The two U.S. Food and Drug Administration trials the ISR is participating in are the ReCell and StrataGraft trials. The ReCell trial takes a piece of skin the size of a stamp and uses it to create a solution of individual cells to cover a wound. The StrataGraft trial grows bioengineered skin from stem cell technology, King explained, adding that these skin substitutes are the “holy grail” of burn surgery.

“The StrataGraft project is the most exciting thing we’ve been a part of; it was a phase-two trial, sort of a pilot study to design the definitive phase three, and it is an off-the-shelf skin substitute that has lots of promise in helping revolutionize burn care,” Lt. Col. (Dr.) Kevin Chung, task area manager of clinical trials in burns and trauma, explained.

“One of the biggest challenges with taking care of burns is getting them to have the burns taken off in a timely fashion, and then having that previously burned skin be covered with what we call definitive coverage. And the only thing that provides definitive coverage and allows patients to heal and get on their way to recovery is their own skin, at the moment,” he added.

Harvested skin requires cell segregation before being suspended in a solution that is sprayed on a wound, where it multiplies and creates new skin tissue. (U.S. Army photo)

Harvested skin requires cell segregation before being suspended in a solution that is sprayed on a wound, where it multiplies and creates new skin tissue. (U.S. Army photo)

For example, if a patient with 40 to 50 percent of their skin burned goes into surgery, all their normal areas of skin will be harvested to cover the wound in an autograft. “So, if you consider that they have a 50 percent burn, by the time they are done with surgery, they are a 90 percent open wound that needs to heal,” Chung said. If the burned area is larger, more like 80 percent, the healthy skin must be spread out over a large area, which impedes wound healing. Areas that can’t be covered with the patient’s own skin are temporarily covered with non-matched donor skin from a cadaver. It functions as a short-term biological dressing, but because it isn’t matched, the patient’s body will reject it and it will eventually fall off. Once that happens, the hope is that donor sites on the patient will have healed and surgeons can harvest more skin for another permanent graft.

“All that time, the patient is at risk for infection and multi-organ failure and death. So this is a … high-intensity problem that has very little solution and thus the bigger burns. Anyone who is 60 percent or … higher still has a greater than 50 percent mortality, even in the best of hands, because of that problem,” Chung added.

StrataGraft will allow surgeons to maintain a patient’s skin and simply apply an off-the-shelf skin substitute like a graft, which will heal normally. “It’s a game changer,” Chung said.

Surgeons will be able to take a very small patch of skin from patients using ReCell, break that sample up and place it in a solution of enzymes, after which it is harvested for keratinocytes, or regenerative cells. Those cells are suspended in a solution and sprayed on a burn wound, where they multiply and form new skin tissue.

“The benefit of that is, the ration of what you can cover is about 80 to one, so you can cover a huge amount of wound based on a small donor site,” King explained. “And that is important for us because in a lot of what we do, we have to cover wounds, and we usually use the patient’s skin …. If we can use less and less of that skin, that’s important for the patient.”

StrataGraft and ReCell wouldn’t have any immediate use downrange, because battlefield treatments are all temporary. Skin substitutes and skin grafts are permanent solutions that require a resource-intensive environment to administer. Currently, burn patients are given initial treatment while downrange, like basic life support, resuscitation, stopping the burning process and basic wound cleaning, Chung explained. Once initial treatments have been administered, the patients are taken to a surgical facility to receive definitive care.

The ISR is also working in parallel with civilian counterparts, developing a potential skin treatment product called a vascularized skin equivalent, which takes amniotic membrane and adds stem

Col. (Dr.) Evan M. Renz holds the spray-syringe with which doctors would administer a ReCell treatment. (U.S. Army photo)

Col. (Dr.) Evan M. Renz holds the spray-syringe with which doctors would administer a ReCell treatment. (U.S. Army photo)

cells into a dermal layer to create a skin substitute, similar to StrataGraft, but able to cover a larger surface area, Chung said.

“Our research task area, one of our major pillars and one of our major efforts, is not only testing out the products that are emerging and on the market in the form of clinical trials, but also identifying gaps and figuring out ways to fill them,” Chung said.

The ISR treats many different kinds of soft tissue wounds, as well, and Chung sees a lot of promise in organ support in the future of regenerative medicine. Several different organ support modalities, such as a bio-engineered spleen from the Vice Institute in Boston, have started to emerge. Chung believes that in the future, these modalities may be combined into one machine, and doctors could support multiple organs at the push of button.

“That’s something that I see happening 10 years down the line, having organ support be more practical and more expansive and being able to support multiple organs at the same time,” Chung said.

Participating in the ReCell and StrataGraft clinical trials is a prestigious achievement for a Department of Defense facility, because only the best of the best are able to join FDA trials. Chung said he is very proud of the work the ISR has done.

“Between industry and our own research products within the ISR, we will have a solution in the next five to 10 years.”