Pluripotent stem cell-derived myogenic progenitors remodel their molecular signature upon in vivo engraftment [Microarray]

Optimal cell-based therapies for the treatment of muscle degenerative disorders should not only regenerate fibers, but provide a quiescent satellite cell pool ensuring long-term maintenance and regeneration. Conditional expression of Pax3/Pax7 in differentiating pluripotent stem cells (PSC) allows the generation of myogenic progenitors endowed with satellite cell-like abilities. To identify the molecular determinants underlying their regenerative potential, we performed transcriptome analyses of these cells along with primary myogenic cells from several developmental stages. Here we show that in vitro generated PSC-derived myogenic progenitors possess a molecular signature similar to embryonic/fetal myoblasts. However, compared to fetal myoblasts, following transplantation they show superior myofiber engraftment and ability to seed the satellite cell niche, respond to multiple re-injuries and contribute to long-term regeneration. Upon engraftment, the transcriptome of Pax3/Pax7-induced PSC-derived myogenic progenitors changes dramatically, acquiring similarity to that of satellite cells, particularly in genes involved in extracellular matrix remodeling. Single cell profiling reveals that these changes are induced, not selected, by the in vivo environment. These findings demonstrate that Pax3/Pax7-induced PSC-derived myogenic progenitors possess proliferative and migratory abilities characteristic of earlier developmental stages, and an intrinsic ability to respond to environmental cues upon skeletal muscle regeneration. Three replicates of each sample (iPax3 and iPax7 mononucleated cells) were analyzed and compared to reference developmental samples adult satellite cells (three rep each). Transcriptome profiling of iPax3/7 cells injected in vivo and re-isolated was then compared to adult satellite cells (3 reps each).