Pitt makes strides in muscle regeneration

Luis Fábregas
| Wednesday, April 30, 2014, 2:46 p.m.

In the months after he broke his left leg while skiing, Nick Clark thought he'd never walk again.

His leg twisted as he turned sharply, and Clark lost nearly all the nerves and muscle tissue on one side of his leg.

“It was pretty brutal. I was bed-ridden for a while. I couldn't even roll over in bed,” Clark, 34, said of the 2005 accident at Seven Springs Mountain Resort.

In 2012, Clark enrolled in a clinical trial at the University of Pittsburgh to test an unheard-of approach to regenerate muscle. Doctors implanted in his leg a biological scaffold made from pig bladders to try to stimulate his stem cells to grow into strong, healthy tissue.

It worked.

“It's been a pretty dramatic change. I don't have to use a cane to walk anymore. It's been a big improvement,” said Clark of Greensburg, an applications engineer at Powerex Inc. in Youngwood.

Researchers at Pitt and the McGowan Institute for Regenerative Medicine on Wednesday published preliminary results from the trial involving five patients, including Clark. Doctors said the approach, using a so-called extracellular matrix, dramatically restored function for patients who lost nearly all muscle in parts of their legs.

“The things that you and I take for granted — getting out of a chair, taking steps, stepping off a curb, getting out of a car — these are the types of deficits that these individuals had,” said senior investigator Stephen Badylak, professor of surgery at Pitt and deputy director of the McGowan Institute.

“It's nice to conduct a study where we can show nice, pretty pictures of stem cells, but if it doesn't make a difference for the patients at the end of the day, it's nothing really other than a study. ... These patients got better.”

Three of the five who received the biological scaffold experienced dramatic improvement, growing stronger by 20 percent or more six months later. The two other patients had some improvement and felt better, the researchers report in the journal Science Translational Medicine.

The researchers said the extracellular matrix is not a medical device and cautioned that using it involves a complex process that includes removing scar tissue and placing the material adjacent to healthy tissue so that it can recruit the patient's stem and progenitor cells.

Patients in the study underwent often grueling post-surgery rehabilitation that required them to start physical therapy on the day after the procedure. Doctors designed it that way so that the stem cells would begin to adapt immediately, Badylak said. The therapy lasted up to six months.

Clark, who experienced the most muscle loss among participants, showed remarkable improvement in two tests conducted in the months after the procedure, said Dr. Elke Brown, a clinical researcher in Pitt's department of physical medicine and rehabilitation.

He was able to jump 34.5 inches on his injured leg six months after surgery, compared with 3 inches before the procedure. In addition, he was able to stand on his leg with his eyes closed for 18.5 seconds six months after the surgery, compared with 10 seconds on the day before surgery, Brown said.

“I had extensive nerve damage, so I still have issues,” said Clark, who cannot run and won't ski again.

Doctors for years have used the pig-derived material to repair hernias and help reconstruct breasts after cancer removal. To ensure patient safety, researchers selected patients whose tissue healed to avoid the potential for infection. They purposely picked people who tried and failed at other treatments.

Researchers say the technique could be beneficial not only for thousands of soldiers injured in combat, but for people with severe trauma from car or motorcycle accidents. Three patients in the study had lower leg injuries; two had injuries in the upper leg. All lost between 60 percent and 90 percent of their injured muscle.

People who experience such severe injuries have limited treatment options, said Dr. Peter Rubin, the study's co-investigator and chair of plastic surgery at Pitt. In the past, doctors tried to reroute tendons or move muscle from another part of the body, but those techniques were not always successful, he said.

“While the number of patients was small, we are very encouraged by the data,” Rubin said.

Researchers are recruiting more patients for the trial, which is partly funded with $3 million from the Department of Defense. Other grants came from the Department of the Interior and National Institutes of Health.

Luis Fábregas is Trib Total Media's medical editor. Reach him at 412-320-7998 or lfabregas@tribweb.com.

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