Male Sprague Dawley rats weighing 250–300 g (Harlan Laboratories, Frederick, MD) were euthanized using CO . Gastrocnemius muscles were isolated bilaterally (Figure 1A), frozen at −80°C, and shipped to the Musculoskeletal Transplant Foundation (MTF, Edison, NJ) to be decellularized. Decellularization was performed by a proprietary method using multiple saline, detergent, and disinfection soaks developed by MTF. The rat tissue was processed aseptically and without any terminal sterilization.
