Mirroring some of the work taking place in the tissue engineering field with decellularized donor tissue, in which the donor's cells are removed and then the structure left behind repopulated with the recipients cells, researchers here are using extracellular matrix (ECM) material from pig tissue as the basis for scaffolds to spur regrowth in large muscle injuries:
When a large volume of muscle is lost, typically due to trauma, the body cannot sufficiently respond to replace it. Instead, scar tissue can form that significantly impairs strength and function. Pig bladder ECM has been used for many years as the basis for medical products for hernia repair and treatment of skin ulcers. It is the biologic scaffold that remains left behind after cells have been removed. [Previous research] suggested that ECM also could be used to regenerate lost muscle by placing the material in the injury site where it signals the body to recruit stem and other progenitor cells to rebuild healthy tissue.
For the Muscle Tendon Tissue Unit Repair and Reinforcement Reconstructive Surgery Research Study, five men who had at least six months earlier lost at least 25 percent of leg muscle volume and function compared to the uninjured limb underwent a customized regimen of physical therapy for 12 to 26 weeks until their function and strength plateaued for a minimum of two weeks. Then [researchers] surgically implanted a "quilt" of compressed ECM sheets designed to fill into their injury sites. Within 48 hours of the operation, the participants resumed physical therapy for up to 26 additional weeks.
The researchers found that 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 indicated that muscle growth had occurred. Two other participants with calf injuries did not have such dramatic results, but both improved on at least one functional measure and said they felt better.