Pig Bladders Could Be the Secret to Healing Severe Muscle Injuries

When large chunks of muscle are lost in severe injuries, they don't grow back. But now, scientists have discovered a way to regenerate some lost muscle with material from pig bladders—a technique actually quite common in medicine.

The five men in this study published today (April 30) in Science Translational Medicine all suffered leg injuries so severe that 60 to 90 percent of a muscle was destroyed—three while in the military and two others in skiing accidents. They had all been through multiple surgeries and long bouts of physical therapy, but their progress hit a wall. When so much muscle is missing, scar tissue, rather than skeletal muscle, grows to fill in the gap.

So they decided to try one more surgery using this experimental technique. Scar tissue was scraped away, and a thin sheet of biological scaffolding was placed at the injury site to coax the growth of new muscle. This scaffolding is made from the extracellular matrix of pig bladder. Essentially, it's pig bladder stripped of all cells, leaving only collagen, sugars, and proteins. The extracellular matrix from pig bladders is commercially available and commonly used in reconstructive surgeries in more passive parts of the body, such herniated abdominal walls and breast reconstructions.

As the matrix breaks down, it releases chemicals that attract stem cells to the area. At the same time, patients are getting intense physical therapy, and the flexing of muscles coaxes the stem cells into muscle cells. Some muscle actually regrew for all the patients.

Three of the patients passed the cutoff of 25 percent improvement that the researchers set for success, though all five reported more ease in their their day-to-day activities like walking and standing. The researchers are now testing the same technique on upper-body injuries, and the results are promising, they say.

The current study is small, but the technique, if it works broadly, could start to heal injuries we thought could never be healed. [Science Translational Medicine via Tech Review, The Scientist]

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