Researchers Work Toward Regenerating Lost Extremities

By Elaine Wilson
Special to American Forces Press Service

Aug. 28, 2008 - A powder that regrows fingers and toes sounds like the stuff of fairy tales, but medical experts here are hoping they can use it to make magic happen for wounded warriors. Doctors from the U.S. Army Institute of Surgical Research are trying a regenerative medicine powder that's already approved by the Food and Drug Administration in hopes of stimulating tissue growth in soldiers with missing extremities.

"The powder is FDA approved and is already being used for hernia repairs and other applications," said Dr. Steven Wolf, chief and task area manager of clinical trials at ISR. "But it has never been used for this reason in people."

ISR researchers are working with Steve Badylak at the Pittsburgh Tissue Engineering Initiative, whom they found while seeking medical innovations that could benefit wounded warriors. They were particularly interested in medical advances that could aid in combating the loss of extremities, which is a "common problem" on today's battlefield, Wolf said.

"This is a topic the Army and Department of Defense are interested in, because when injuries happen in war, most of them are extremity injuries," the doctor said. "With burns in particular, we commonly end up with loss of digits."

Based on studies, ISR doctors were intrigued by what they nicknamed "pixie dust," and the idea of a new application for an existing innovation.

"Since the powder was FDA approved and safe for use, we figured we would try it," Wolf said. "The idea was out there that it might work for this application, but it had never been tried on humans."

The "pixie dust" is far from magic. It is derived from pig bladder. To create what Wolf refers to as extracellular matrix, scientists take a mix of protein and connective tissue, "spin" it to remove the cells, and then mash the remaining material into a powder.

"When put onto open wound, it seems the body starts to regrow normal tissue," Wolf said.

The theory is that when the powder is applied, circulating stem cells see the matrix, stop and differentiate into whatever they are near, Wolf said. For instance, if by a bone, then the cells become bone; if by a blood vessel, then they become a blood vessel; or if by a nerve, they become a nerve.

In other words, the regenerative medicine powder acts as a stop sign for stem cells, which are undifferentiated cells everyone has circulating throughout their blood stream.

Wolf likens the concept to regrowth of a severed tail in a salamander.

"You pull a tail off a salamander, and it regrows," Wolf said. "The end of the tail forms what is called a blastema, and that blastema elongates. We think that's what happens when we put this powder on.

"This process of growing your fingers has happened to you before, in your mother's womb," Wolf said. "The code is there, the DNA is there. What we're trying to do is trick your body into doing that again."

Application of the powder involves surgery to open the wound and apply it, a procedure that can be done in conjunction with an already scheduled surgery. Other than the normal risks of surgery, Wolf said, trials of the powder are practically harmless.

"If it doesn't work, there is no downside," Wolf said. "That's why we're testing it on fingers vs. legs. If we apply it to a leg amputee, the downside is the soldier won't be able to walk for several months, and it may not work."

So far, doctors have applied the powder to two soldiers with missing fingers.

"The first time, we saw an increase in length of the finger, but the wound closed before further growth could occur," Wolf said. "The other case is too soon to tell."

Wolf emphasized the concept is referred to as an innovative surgical technique. "It's not a sure thing," he said. "It's a possibility."

However, "We're hoping for increased length with bone support," Wolf said. "But we're not sure how long it will take or if it will even work."

The odds may be high, but Wolf is hoping to take a complex scientific innovation and yield magical results for improvised explosive device victims and other wounded warriors.

"If we have a soldier who was blown up by an IED and missing fingers, and we have a chance to give him his fingers back, increase his function, how can we not try?" he said.

(Elaine Wilson works in the Fort Sam Houston Public Affairs Office.)