Scientists surgically implanted extracellular matrix (ECM) derived from pig bladder into several men with leg muscle loss - and say three out of five experienced signs of regeneration.
When a severe amount of muscle tissue is lost, typically the result of trauma, the body can't replace it and it forms inefficient scar tissue instead.
Pig bladder ECM is the scaffold left behind after cells have been removed. It is commonly used in hernia repair and treatment of skin ulcers. So, senior investigator Stephen F. Badylak and his team suggested that ECM could also be used to regenerate lost leg muscle by placing it at the injury site. Once in place, the scaffolding-like material would signal the body to recruit stem and other progenitor cells to restore healthy tissue.
"This new study is the first to show replacement of new functional muscle tissue in humans, and we're very excited by its potential," Badylak said. "These are patients who can't walk anymore, can't get out of a car, can't get up and down from a chair, can't take steps without falling. Now we might have a way of helping them get better."
In the study - named the Muscle Tendon Tissue Unit Repair and Reinforcement Reconstructive Surgery Research Study and sponsored by the US Department of Defense - participants were five men who had at least six months earlier lost 25 percent or more leg muscle volume and function compared to their normal, uninjured limb.
Before experimenting with the pig bladder ECM, they underwent physical therapy for 12 to 26 weeks until their function and strength remained consistent.
Then, study lead surgeon Dr. J. Peter Rubin surgically implanted a "quilt" of compressed ECM sheets designed to fill into their injury sites.
Three of the participants, two of whom had thigh injuries and one a calf injury, were stronger by 20 percent or more six months after the surgery. Biopsies and scans all showed their muscle had regenerated.
Findings are published in the journal Science Translational Medicine.