Pig Bladder Cells Help Build Muscle

Cells taken from pig bladders and implanted in severely injured legs recruited native stem cells to help build muscle. Sarah Wickline, staff writer for Med Page Today, reported that three out of five patients with lower limb volumetric muscle loss gained measurable improvement in their ability to walk and climb stairs six months following placement of the porcine extracellular matrix scaffolding in their legs. The two patients who were identified as failures obtained more than 25% improvement in all of their tasks except one. The research was carried out by Stephen F. Badylak, M.D. of the University of Pittsburgh and his colleagues. The pig cells boosted the ability of native stem cells to form dense muscle tissue, he said.

Wickline quoted Badylak as saying, “When you lose so much muscle that the gap is too large for the normal restorative processes to occur, the end result is typically filling that gap with scar tissue. [We found] an effective method for restoring…new functional enervated and vascularized muscle tissue, using an approach that does not involve the delivery of any cells.”

What happens, he said, is that as the pig cells degrade they release peptides, which serve as a homing device to recruit the body’s endogenous stem cells to the injury site. Wickline reported that all five of the patients in the study were male and had experienced anywhere from 58% to 90% of leg muscle loss from a serious injury at least six months prior to the experimental procedure.

Badylak explained that when the stem cells arrive at the injury site they depend on cues from the environment to direct them what to do. “If that does not happen, ” he said, “and they [the stem cells] don’t get those signals, they can turn into anything else, fat tissue, cartilage, bone.” The cells need a scar tissue-free area. “It’s got to have a blood supply; [it’s] got to be enervated, ” Badylak said. “If you put this material in the middle of a scar, all it’s going to do is turn into more scar.”