TGFβ1 determines the fate of human adipose-derived stromal cells by restraining their immaturity and white/beige adipocyte potentials

Human adipose-derived stem/stromal cells (hASCs) can differentiate into a large broad of specialized cell types to ensure homeostasis of tissues. Thus, they are drawing increasing attention in cell therapy and regenerative medicine. However, culture conditions are still critical to ensure their regenerative capabilities. Here we compared Standard conditions (αMEM containing 10% fetal bovine serum) and Endothelial cell Growth Medium 2 (EGM2) containing few serum (2% v/v) for expansion of hASCs. Both types of hASCs were exhaustively characterized by high throughput studies, Gene Set Enrichment Analyses (GSEA) and differentiation potentials experiments. EGM2-hASCs showed enhanced multipotency and their phenotype was more immature than Standard-hASCs. The adipogenic potential of EGM2-hASCs was clearly more extented, including toward the thermogenic beige adipocyte fate. Data from microarray and GSEA highlighted Transforming Growth Factor β1 (TGFβ1) as upstream factor influencing the becoming of Standard-hASCs which is consistent with higher TGFβ1 content in Standard medium. This was associated with nuclear SMAD3 localization and higher expression of its active form in Standard-hASCs. Moreover, these cells were primed into osteoblast, chondroblast and Vascular Smooth Muscle (VSM) lineages at the expense of their adipogenic potential. Their treatment with TGFβ1 receptor inhibitors resulted in a cytoplasmic re-localization of SMAD3 and a decrease of VSM and osteoblastic lineages markers, increasing in turn their beige adipogenic potential. Therefore, TGFβ1 is a key factor committing hASCs toward osteo-chondroblastic and VSM lineages at the expanse of their beige adipogenic potential. Thanks to low TGFβ1 content, EGM2 medium improves the maintenance of uncommitted hASCs with strong beige adipocyte potential.

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