Contribution of Donor Muscle Progenitor Cells to Bioengineered Skeletal Muscle in a Rodent Muscle Injury Model

The ultimate goal of these studies is to develop bioengineered skeletal muscle that can be used for functional restoration of injured muscle in vivo. A critical aspect of determining the mechanistic basis for the utility of our technology is to understand the contribution of the donor versus host cells to the functional recovery achieved following implantation of tissue engineered skeletal muscle. Towards this objective we developed methods to analyze the contribution of donor cells to host tissue formation. 5 days after isolation rat MPCs were transduced (MOI of 10) with lentiviruses expressing fluorescent or LacZ reporter, and seeded on BAM scaffolds on day 8 and 9. Seeded scaffolds were differentiated in vitro for 7 days and subjected to bioreactor preconditioning for 7 days prior to implantation in a surgically created 50% defect of the lattisimus dorsi (LD) muscle in nude mice. Tissues retrieved 1 or 2 months post implantation revealed evidence for the presence of myofibers formed from fusion of labeled donor cells with host myofibers. In short, donor MPCs were characterized by muscle specific marker expression from isolation to implantation. The impact of donor MPCs on host tissue formation is being further evaluated by immunofluorescence and immunohistochemistry to more precisely determine the nature and duration of the contribution of donor cells to muscle regeneration. Funding by NIAMS (R01AR057325‐01).