In a pre-clinical trial among five men with 50% to 90% of leg-muscle loss due to injury, researchers found that implanted cells from pig bladders formed a biologically active scaffold that recruited native stem cells to help rebuild skeletal muscle. The authors of the study, in Science Translational Medicine, said the peptides released as the pig cells degraded mobilized the patients’ own stem cells to the site of injury. Three of the five patients showed marked improvement in standing, walking, and stair climbing. All five had undergone unsuccessful prior surgeries and physical therapy (PT). Speaking of PT, all five patients received a specialized 12- to 16-week course of PT prior to the implantation and postoperative PT that lasted from 5 to 23 weeks. The authors also stressed that the implanted scaffold works only in a scar tissue-free area adjacent to healthy tissue that has nerve and blood supplies.