Manufacturing autologous myoblast for regenerative medicine applications

Background: Autologous myoblasts have been tested in the treatment of muscle-related diseases. However, the standardization of manufacturing myoblasts is still not established. Here we report a flask and animal-free medium-based method of manufacturing clinical-grade myoblast together with establishing releasing criteria for myoblast products under Good Manufacturing Practice (GMP). Methods: Quadriceps muscle biopsy samples were donated from three patients with myogenic ptosis. After biopsy samples were digested through enzymatic dissociation, the cells were grown in T175 flasks (passage 0) and hyperflasks (passage 1) in the animal-free SkGM(TM)-2 skeletal muscle cell growth medium containing 5% human platelet lysate for 15-17 days. The harvested cells were released based on cell morphology, cell dose, viability, sterility, endotoxin, mycoplasma and immunophenotype. Myotube differentiation was also evaluated. Results: 400 to 500 million myoblast cells were manufactured within 15 to 17 days by the end of passage 1, which met pre-determined releasing criteria. The manufactured myoblast cells could differentiate and fuse into myotubes in vitro, with the possible trend that the donor age may impact the differentiation ability of myoblasts. Conclusions: The present study establishes a flask-based method of manufacturing myoblast in the animal-free medium together with releasing criteria, which is simple, robust, inexpensive and easily reproducible. This study will serve as the validation for a planned phase 1 clinical trial to assess the use of autologous myoblast transplants for the treatment of myogenic ptosis and other myogenic diseases.