In vitro-generated human muscle reserve cells are heterogeneous for Pax7 with distinct molecular states and metabolic profiles

Axelle Bouche; Benoit Borner; Chloé Richard; Ysaline Grand; Didier Hannouche; Thomas Laumonier

doi:10.1186/s13287-023-03483-5

In vitro-generated human muscle reserve cells are heterogeneous for Pax7 with distinct molecular states and metabolic profiles

Stem Cell Res Ther. 2023 Sep 8;14(1):243. doi: 10.1186/s13287-023-03483-5.

Authors

Axelle Bouche^#^{1

2}, Benoit Borner^#¹, Chloé Richard^{1

2}, Ysaline Grand^{1

2}, Didier Hannouche^{1

2}, Thomas Laumonier^{3

4}

Affiliations

¹ Cell Therapy and Musculoskeletal Disorders Laboratory, Department of Orthopedic Surgery, Geneva University Hospitals and Faculty of Medicine, University Medical Center, 1 rue Michel Servet, 1211, Geneva, Switzerland.
² Department of Cell Physiology and Metabolism, Faculty of Medicine, Geneva, Switzerland.
³ Cell Therapy and Musculoskeletal Disorders Laboratory, Department of Orthopedic Surgery, Geneva University Hospitals and Faculty of Medicine, University Medical Center, 1 rue Michel Servet, 1211, Geneva, Switzerland. thomas.laumonier@unige.ch.
⁴ Department of Cell Physiology and Metabolism, Faculty of Medicine, Geneva, Switzerland. thomas.laumonier@unige.ch.

^# Contributed equally.

Abstract

Background: The capacity of skeletal muscles to regenerate relies on Pax7⁺ muscle stem cells (MuSC). While in vitro-amplified MuSC are activated and lose part of their regenerative capacity, in vitro-generated human muscle reserve cells (MuRC) are very similar to quiescent MuSC with properties required for their use in cell-based therapies.

Methods: In the present study, we investigated the heterogeneity of human MuRC and characterized their molecular signature and metabolic profile.

Results: We observed that Notch signaling is active and essential for the generation of quiescent human Pax7⁺ MuRC in vitro. We also revealed, by immunofluorescence and flow cytometry, two distinct subpopulations of MuRC distinguished by their relative Pax7 expression. After 48 h in differentiation medium (DM), the Pax7^High subpopulation represented 35% of the total MuRC pool and this percentage increased to 61% after 96 h in DM. Transcriptomic analysis revealed that Pax7^High MuRC were less primed for myogenic differentiation as compared to Pax7^Low MuRC and displayed a metabolic shift from glycolysis toward fatty acid oxidation. The bioenergetic profile of human MuRC displayed a 1.5-fold decrease in glycolysis, basal respiration and ATP-linked respiration as compared to myoblasts. We also observed that AMPKα1 expression was significantly upregulated in human MuRC that correlated with an increased phosphorylation of acetyl-CoA carboxylase (ACC). Finally, we showed that fatty acid uptake was increased in MuRC as compared to myoblasts, whereas no changes were observed for glucose uptake.

Conclusions: Overall, these data reveal that the quiescent MuRC pool is heterogeneous for Pax7 with a Pax7^High subpopulation being in a deeper quiescent state, less committed to differentiation and displaying a reduced metabolic activity. Altogether, our data suggest that human Pax7^High MuRC may constitute an appropriate stem cell source for potential therapeutic applications in skeletal muscle diseases.

Keywords: AMPK; Fatty acid oxidation; Human muscle reserve cell; Metabolism; Pax7 heterogeneity; Quiescence.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Fatty Acids
Humans
Metabolome
Muscle Cells*
Muscle, Skeletal
Satellite Cells, Skeletal Muscle*

Substances

Fatty Acids
PAX7 protein, human