Salamanders Grow New Limbs, Why Not Soldiers?

‘We’re not quite there yet …’

Regrowing limbs could be the future for military medicine

(Military Health) Military researchers are studying how some animals, such as salamanders, are able to regrow limbs.

U.S. Army veteran Wesley Leon-Barrientos stands in front of an AC-130W Stinger II on the flightline at Cannon Air Force Base, N.M., March 22, 2012. Leon-Barrientos is a double-amputee and three time Purple Heart recipient from his service during Operation Iraqi Freedom. (U.S. Air Force photo by Airman 1st Class Eboni Reece)

The work is designed to help those with amputations regrow their own arms and legs. 

For some animals, such as salamanders, regrowing a missing limb is a common healing process. But what if people could do the same? Could the future of treating amputations include warfighters regrowing their own muscle, bone, and nerve tissues?

“We’re not quite there yet,” said Army Lt. Col. David Saunders, extremity repair product manager for the U.S. Army Medical Materiel Development Activity, Fort Detrick, Maryland.

Their goal: ‘to improve long-term outcomes in function and form of injured extremities’

“What we’re trying to do is develop a toolkit for our trauma and reconstructive surgeons out of various regenerative medicine products as they emerge to improve long-term outcomes in function and form of injured extremities.”

Saunders was part of a session focusing on the research being done on extremity regeneration, part of a larger theme of regenerative medicine at the Military Health System Research Symposium.

Saunders said while there’s been amazing progress in the areas of using synthetic grafts to start the regrowth of muscle, nerve, vascular, and connective tissues, it’s still not the same as the real thing.

A juvenile California tiger Salamander migrates across the Travis Air Force Base, California, airfield in search of a suitable burrow. Department of Defense photo

“We would like it to be as restorative as possible, resist infection … and be durable,” he said.

“This is going to be implanted in young people who may go on to live another 60 to 70 years.”

One researcher is using fillers to bridge the gap in damaged bones, hoping to figuratively bridge the gap between current regenerative techniques and the ideal: people regrowing lost limbs.

Stephanie Shiels with the U.S. Army Institute of Surgical Research, Fort Sam Houston, Texas, talked about her research to develop a synthetic bone gap filler that heals bones and reduces infection by infusing those grafts with a variety of anti-microbials.

“We know that it reduces infection,” said Shiels.

“Other things to consider include adding a bulking agent … to help regenerate bone.”

Regrowing muscle lost in traumatic injuries

Other research focuses on regrowing muscle lost in traumatic injuries, as well as recovering nerves, or at least preserving them, for future use. But besides treating those deep tissue wounds, there’s something a bit more on the surface that can impact warfighters: skin.

The skin is known for its regenerative properties. Research is being conducted to help it do that job better and recover scar tissue.

Jason Brant with the University of Florida has turned to a mouse to help the military reduce scarring of injured warfighters. He said the African spiny mouse has evolved a capability to lose large parts of its skin when a predator tries to grab it, allowing the mouse to escape and live to recover.

The mouse is able to recover scar-free in a relatively short amount of time, which is remarkable considering the amount and depth of tissue lost. Brant wants to know how the mouse is able to do that.

Army Lt. Col. David Saunders talks about extremity regeneration at the Military Health System Research Symposium. Photo courtesy of Military Health

‘A scaffold to start regenerative growth’

“Warfighters and civilians alike suffer large surface [cuts] and burns, and these result in medically and cosmetically problematic scars,” said Brant.

“The impacts of these scars … are really staggering. The ability to develop effective therapies will have an enormous impact not only on the health care system but on the individuals as well.”

He believes a certain protein in the mouse could be the key, but he’s still trying to figure out how it could apply to humans.

Another way to reduce scarring involves the initial treating of wounds. Army Maj. Samuel Tahk, a research fellow with the Uniformed Services Health Consortium, passed around to attendees samples of biocompatible sponges he’s investigating for their ability to promote skin healing, and thus, reduce scarring.

“It provides a scaffold to start regenerative growth,” said Tahk. “This could simplify patient care and also reduce costs.”

While the field of regenerating body parts is still new, Saunders believes it will be the future of wounded warrior care.

“Extremity wounds are increasingly survivable due to the implementation of body armor and damage control surgeries,” he said. “[There are] many wonderful things emerging in the field of regenerative medicine to restore form and function to our wounded warfighters.” SOURCE: Military Health, Department of Defense 

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