Pig bladder material can improve muscle strength and function in leg injuries

Damaged leg muscles grew stronger and showed signs of regeneration in three out of five men whose old injuries were surgically implanted with extracellular matrix derived from pig bladder, according to a study in Science Translational Medicine.
Pig bladder extracellular matrix has been used for many years as the basis for medical products for hernia repair and treatment of skin ulcers. But this is thought to be the first study that has used it to replace functional muscle tissue in humans.
The extracellular matrix regenerates lost muscle by placing the material in the injury site where it stimulates the body to rebuild healthy tissue.
“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,” explains Prof Stephen F Badylak, who led the work. “Now we might have a way of helping them get better. This new study is the first to show replacement of new functional muscle tissue in humans, and we’re very excited by its potential.”
Five men who had lost at least 25% of leg muscle volume and function over six months earlier were given physical therapy for 12–26 weeks, until improvement had plateaued. A surgeon then implanted a “quilt” of compressed extracellular matrix sheets into their injury sites. The volunteers continued physical therapy for another 26 weeks.
Biopsies and scans showed that muscle growth had occurred.
Three of the men were stronger by 20% or more six months after the surgery. One improved on the “single hop test” by 1,820% Another had a 352% improvement in a chair lift test and a 417% improvement in the single-leg squat test.
Two participants with calf injuries did not have such dramatic results, but both improved on at least one functional measure and said they felt better.
“This work represents an important step forward in our ability to repair tissues and improve function with materials derived from natural proteins,” explains the surgeon involved in the study. “There will be more options to help our patients.”