Ex Vivo Expansion and In Vivo Self-Renewal of Human Muscle Stem Cells

Summary

Adult skeletal muscle stem cells, or satellite cells (SCs), regenerate functional muscle following transplantation into injured or diseased tissue. To gain insight into human SC (huSC) biology, we analyzed transcriptome dynamics by RNA sequencing of prospectively isolated quiescent and activated huSCs. This analysis indicated that huSCs differentiate and lose proliferative potential when maintained in high-mitogen conditions ex vivo. Further analysis of gene expression revealed that p38 MAPK acts in a transcriptional network underlying huSC self-renewal. Activation of p38 signaling correlated with huSC differentiation, while inhibition of p38 reversibly prevented differentiation, enabling expansion of huSCs. When transplanted, expanded huSCs differentiated to generate chimeric muscle and engrafted as SCs in the sublaminar niche with a greater frequency than freshly isolated cells or cells cultured without p38 inhibition. These studies indicate characteristics of the huSC transcriptome that promote expansion ex vivo to allow enhanced functional engraftment of a defined population of self-renewing huSCs.

Graphical Abstract

Highlights

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  Prospective isolation of highly pure huSCs from diverse muscles

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  RNA sequencing resource for studying the huSC transcriptome

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  Core transcription factor regulatory network of huSC differentiation

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  Expanded huSCs that are genetically manipulable and self-renew in vivo

Abstract

In this article, Rando and colleagues purify and study human skeletal muscle stem cells using RNA sequencing and cell transplantation. They show that p38 MAPK signaling is important for human muscle stem cell differentiation and that pharmacologic inhibition of p38 enables expansion of muscle stem cells capable of self-renewing after transplantation.