He is testing implants of ‘‘extracellular matrix’’ — connective tissue that holds cells together — to boost muscle mass. The matrix is thought to release chemical signals that promote regrowth of healthy tissue instead of scar tissue.
‘‘It changes the body from thinking, ‘I need to respond to injured tissue,’ to ‘I need to rebuild this tissue,'’’ Badylak said.
The material is supplied by a private company — ACell Inc. of Columbia, Md. — and comes from pigs. The immune system tolerates it because it doesn’t contain cells. It comes in multi-layered sheets like slightly stiff gauze and can be cut or molded to fit the needed shape.
Strang, who lost half of a thigh muscle, is among the five patients treated so far in an 80-patient study. Doctors wait at least six months after an injury to make sure all natural healing has occurred, and put patients through intensive physical therapy before implanting the matrix.
‘‘We want to be able to say after the surgery that they were as good as they could be’’ and that the matrix accounted for any improvement, Badylak explained.
In early testing, ‘‘They've shown up to 10 to 20 percent improvement’’ in strength of the muscle after treatment, said Irgens, the director of AFIRM, which funded some of the early work. The Department of Defense is sponsoring the study under way now, which includes non-military patients as well as former troops. The new study is measuring changes in strength and muscle volume, and doctors are aiming for the kind of quality-of-life improvement Strang has enjoyed.
In other efforts, Pittsburgh and Rice University scientists are working on growing bone to fix jawbone and other facial defects. Researchers at Massachusetts General and Rutgers University are trying to grow eyelid muscles. Blindness can result from not being able to close an eyelid.
Doctors also are testing various ways to make skin. In one method, doctors take a postage stamp-sized piece of a patient’s skin, process it in the lab and spray these cells onto a burn or other wound. The sprayer device that is used for this treatment is already licensed in seven countries, and AFIRM is sponsoring a study aimed at winning U.S. approval so the treatment can be offered here.
The second approach uses sheets of skin developed from cells in the lab that originally came from foreskin after circumcisions.
‘‘That’s in clinical trials now and they’re having tremendous results,’’ Irgens said.
Beyond ‘‘bionic arms’’ to transplants
For all the advances that have been made in modern prosthetics, the arms and hands are not as effective as the legs and feet. Dozens of wounded troops would rather try a transplant.
The government also estimates that up to 200 troops might need face transplants, although Dr. Bohdan Pomahac, a Boston surgeon who has done four face transplants on non-military patients, thinks only 50 to 100 ultimately will get one.
One reason is the lifelong drugs needed to prevent rejection. They have side effects and raise the risk of cancer.
Dr. W.P. Andrew Lee, plastic surgery chairman at Johns Hopkins University, has been working to minimize those risks. Previously, at the University of Pittsburgh, he led hand transplants on five patients with minimal immune suppression, giving them bone marrow taken from their donors along with the hands to help them better tolerate the new tissue. All five patients have done well and four now take just one anti-rejection drug.
‘‘There’s really no reason to think faces will be any different,’’ he said.
He also showed that rejection can often be stopped by rubbing on a cream containing immune-suppressing medicine.
‘‘Skin is the primary target of the rejection,’’ he explained, so with a hand transplant, ‘‘we can detect rejection much earlier than we can for organ transplants. The patient literally calls us. They notice a rash on the skin first thing in the morning. We just tell them to put the cream on.’’
With military funding, a host of doctors are evaluating troops as potential face transplant candidates. Pomahac told of one man who lost much of his face, jaw and lips in a bomb blast. Despite 25 operations, he still can’t move one side of his face or lips and drools all the time.
‘‘He walks around with a towel on his shoulder. It’s a major quality-of-life issue,’’ Pomahac said.
Advancing reconstructive surgery
Many troops remain disfigured or impaired despite multiple reconstructive operations. Tackling the toughest cases is the goal of Operation Mend, a program of the UCLA Medical Center, Brooke Army Medical Center in San Antonio and the Veterans Affairs-Greater Los Angeles Healthcare System.Continued...