Recent reports have documented the differentiation of human pluripotent stem cells toward the skeletal myogenic lineage using transgene- and cell purification-free approaches. Although these protocols generate myocytes, they have not demonstrated scalability, safety, and in vivo engraftment, which are key aspects for their future clinical application. Here we recapitulate one prominent protocol, and show that it gives rise to a heterogeneous cell population containing myocytes and other cell types. Upon transplantation, the majority of human donor cells could not contribute to myofiber formation. As a proof-of-principle, we incorporated the inducible PAX7 lentiviral system into this protocol, which then enabled scalable expansion of a homogeneous population of skeletal myogenic progenitors capable of forming myofibers in vivo. Our findings demonstrate the methods for scalable expansion of PAX7+ myogenic progenitors and their purification are critical for practical application to cell replacement treatment of muscle degenerative diseases.
Bibliographical noteFunding Information:
This project was supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the NIH under Award Number R01 AR055299 and the Parent Project Muscular Dystrophy (PPMD grant no. 00031645). We thank the generous support from MyDirectives. The monoclonal antibody to MHC was obtained from the Developmental Studies Hybridoma Bank developed under the auspices of the NICHD and maintained by the University of Iowa. We thank Cynthia Dekay for assistance in graphic design.
- MHC myocytes
- PAX7 myogenic progenitors
- pluripotent stem cells
- skeletal muscle
- stem cell therapy