Functionally heterogeneous human satellite cells identified by single cell RNA sequencing

Abstract

Although heterogeneity is recognized within the murine satellite cell pool, a comprehensive understanding of distinct subpopulations and their functional relevance in human satellite cells is lacking. We used a combination of single cell RNA sequencing and flow cytometry to identify, distinguish, and physically separate novel subpopulations of human PAX7+ satellite cells (Hu-MuSCs) from normal muscles. We found that, although relatively homogeneous compared to activated satellite cells and committed progenitors, the Hu-MuSC pool contains clusters of transcriptionally distinct cells with consistency across human individuals. New surface marker combinations were enriched in transcriptional subclusters, including a subpopulation of Hu-MuSCs marked by CXCR4/CD29/CD56/CAV1 (CAV1+). In vitro, CAV1+ Hu-MuSCs are morphologically distinct, and characterized by resistance to activation compared to CAV1- Hu-MuSCs. In vivo, CAV1+ Hu-MuSCs demonstrated increased engraftment after transplantation. Our findings provide a comprehensive transcriptional view of normal Hu-MuSCs and describe new heterogeneity, enabling separation of functionally distinct human satellite cell subpopulations.

Human skeletal muscle organoids model fetal myogenesis and sustain uncommitted PAX7 myogenic progenitors

“…While the few described three-dimensional (3D) differentiation approaches have provided cohorts of terminally differentiated myofibers, focus on potential interactions with the vasculature and nervous system has neglected assessment of the developmental identity or sustainability of myogenic progenitors (Faustino Martins et al, 2020, Maffioletti et al, 2018, Rao et al, 2018. Single cell technologies increasingly provide databases for deciphering myogenic trajectories and expression profiles of myogenic stem and progenitor cells (Xi et al, 2020, Barruet et al, 2020, enabling full evaluation of the ability of PSC differentiation protocols to mimic human development. Translation to model muscular dystrophies and investigate potential interventions in vitro necessitates methods that provide expandable populations of muscle progenitors while promoting self-renewal and preserving a quiescent, non-dividing, state (Quarta et al, 2016, Montarras et al,2005.…”

Derivation and Characterization of Immortalized Human Muscle Satellite Cell Clones from Muscular Dystrophy Patients and Healthy Individuals

“…In all six clones tested, 100% of iHMuSCs expressed both desmin and Pax7 protein, confirming that they were myogenic cells. Moreover, all 38 clones stemmed from CD56 expressing cells and then were further tested after expansion for their expression of CD56, which is a canonical marker of MuSCs in human, where cells that express CD56 invariably express Pax7 [ 31 , 32 ]. Additionally, we investigated the expression of dystrophin in differentiated iHMuSC clones, since in mouse, dystrophin expression is reported to be specific of satellite cells and differentiated myoblasts, but absent from growing myoblasts [ 33 ].…”

Tetraspanin CD82 is necessary for muscle stem cell activation and supports dystrophic muscle function

“…Our previous study reported expression of CD82 in both quiescent and activated human satellite cells, with cells positive for CD82 exhibiting strong myogenic activity both in vitro and in vivo. Recent single cell RNA seq studies have also confirmed robust CD82 expression in mouse satellite cells [18,19]. In hematopoietic stem cells, CD82 expression is typically indicative of quiescence; thus, CD82 loss of function leads to over-proliferation of cells [20,21].…”