Homologous muscle acellular matrix seeded with autologous myoblasts as a tissue-engineering approach to abdominal wall-defect repair

Myoblasts were obtained by culturing in vitro, single muscle fibers, isolated by enzymatic digestion from rat flexor digitorum brevis, and their phenotype was confirmed by myogenic differentiation factor, myogenic factor-5, myogenin and desmin. Cultured myoblasts were harvested and seeded on patches of homologous acellular matrix, obtained by detergent-enzymatic treatment of abdominal muscle fragments. Myoblast-seeded patches were inserted between obliqui abdominis muscles on the right side of 1-month-old rats, while non-seeded patches were implanted on the left side. Thirty days after surgery, non-seeded patches were completely replaced by fibrous tissue, while the structure of myoblast-seeded patches was well preserved until the 2nd month. Seeded patches displayed abundant blood vessels and myoblasts, and electromyography evidenced in them single motor-unit potentials, sometimes grouped into arithmic discharges. Ninty days after implantation, the thickness of myoblast-seeded patches and their electric activity decreased, suggesting a loss of contractile muscle fibers. In conclusion, the present results indicate that autologous myoblast-homologous acellular muscle matrix constructs are a promising tool for body-wall defect repair, and studies are under way to identify strategies able to improve and maintain the structural and functional integrity of implants for longer periods.