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Differentiation of the human PAX7-positive myogenic precursors/satellite cell lineage in vitro.

Satellite cells (SC) are muscle stem cells which can regenerate adult muscles upon injury. Most SC originate from PAX7-positive myogenic precursors set aside during development. While myogenesis has been studied in mouse and chicken embryos, little is known about human muscle development. Here, we report the generation of human induced Pluripotent Stem (iPS) cell reporter lines in which fluorescent proteins have been introduced into the PAX7 and MYOG loci. We use single cell RNA sequencing to analyze the developmental trajectory of the iPS-derived PAX7-positive myogenic precursors. We show that the PAX7-positive cells generated in culture can produce myofibers and self-renew in vitro and in vivo. Together, we demonstrate that cells exhibiting characteristics of human fetal satellite cells can be produced in vitro from iPS cells, opening interesting avenues for muscular dystrophy cell therapy. This work provides significant insights into the development of the human myogenic lineage.