Myogenic and adipogenic potential of porcine muscle satellite cells isolated by flow cytometry

Skeletal muscle mesenchymal stromal cells (MSCs) are resident cells in the stromal, interstitial or perivascular areas, with satellite cells (SCs) acting as essential precursors for muscle growth and regeneration. This study firstly aimed to phenotype freshly isolated SCs using cell surface markers and gene expression and to assess their ability to differentiate in myogenic or adipogenic conditions. Then, refined SCs populations sorted according to the myogenic CD56 cell surface marker were characterized. SCs were isolated from the longissimus muscle of 5-7-day-old piglets and analyzed using flow cytometry. The hematopoietic CD45 + cells represented 20 % of the total isolated cell population. The myogenic CD29 and CD56 positive cell populations were the most abundant (80 % and 50 % respectively). Mesenchymal CD90 positive cells were also highly present (34 %) while the proportions of fibro-adipogenic CD140a and CD34-positive cells were low (<3 %). In this study, we showed that total isolated muscle-derived SCs were able to differentiate into myotubes in both myogenic and adipogenic media. Transcriptional profiles were similar, except for PPARγ, PGC1α, and Myosin Heavy Chain 2B witch present a higher induction during differentiation in the adipogenic medium. Interestingly, non-hematopoietic CD45^-sorted cells further separated in CD45-/CD56+ and also CD45-/CD56-sub-populations mostly formed myotubes under both conditions, with CD56^-cells showing potential and gene expression profile of myoblasts. Mature adipocytes were found in the CD45-/CD56+ group after differentiation in adipogenic medium. This study increases knowledge on myogenic cell surface marker and underscores the complexity and heterogeneity of muscle SCs.