UC San Diego

Skeletal muscle is the most abundant tissue in the body, comprising up to 40% of the total mass. In addition to its most salient role in locomotion, it also plays a central role in metabolic homeostasis. Therefore, injury-, age- and disease-related compromise of skeletal muscle can be extremely detrimental to overall health and quality of life. As such, the development of regenerative therapies for skeletal muscle that contribute to in vivo repair, as well as in vitro strategies that can hasten the development of personalized drug treatment, could be of vital importance. Human induced pluripotent stem cells (hiPSCs) are a powerful tool that can meet both these challenges; they are patient-specific, can give rise to derivatives of all three germ layers, including myogenic progenitors, and are scalable since pluripotent cells readily self-renew in vitro. However, the robust, transgene free myogenic differentiation of hiPSCs remains a hurdle.

In this dissertation, I address these challenges by identifying key time-varying signaling, transcriptional, and epigenetic-related mechanisms that lead to enhanced in vitro myogenesis by comparing the longitudinal transcriptomic profiles of multiple hiPSC lines. Furthermore, I show that targeted genetic perturbation at the outset of differentiation may bias lineage specification to the paraxial mesoderm fate. Finally, through the selective expansion and terminal differentiation of hiPSC-derived myogenic progenitor cell populations, we show that they form functional 3D microtissues in an in vitro skeletal muscle-on-a-chip platform, as well as give rise to dystophin positive fibers in vivo in a murine model of muscular dystrophy.