Mechanistic study comparing cartilage formation from human mesenchymal stromal cells and iPSC-derived multipotent cells [scRNA-seq]

ABSTRACT: Multipotent progenitor cells (iMPCs) created from induced pluripotent stem cells (iPSCs) is a promising cell source for cartilage regeneration. In most studies, bone morphogenetic proteins (BMPs) were shown to significantly enhance transforming growth factor-b (TGFb)-induced iMPC chondrogenesis. In contrast, TGFb alone is sufficient to induce robust chondrogenesis of human primary mesenchymal stromal cells (MSCs). Currently, the mechanism underlying this difference between iMPCs and MSCs has not been fully understood. In this study, we first generated iMPCs from human iPSCs and examined their differentiation capacity at different passages. We then optimized the conditions for chondrogenesis and determined that medium supplemented with TGFb and BMP6 led to robust cartilage formation from iMPCs with minimal hypertrophy. Moreover, the cartilage generated from this new method was resistant to osteogenic transition upon subcutaneous implantation and led to a hyaline cartilage-like regeneration in osteochondral defects in rats. Interestingly, TGFb alone induced phosphorylation of Smad2/3 in iMPCs but not Smad1/5, which led to poor chondrogenesis. In contrast, TGFb resulted in the phosphorylation of both Smad2/3 and Smad1/5 and robust chondrogenesis in human MSCs. We further discovered that the remarkably low level of Activin receptor-like kinase 1 (ACVRL1/ALK1) in iMPCs, when compared to MSCs, partially accounts for this difference. For instance, overexpression of ALK1 in iMPCs activated both Smad1/5 and Smad2/3 upon TGFb only treatment and resulted in a high level of chondrogenesis, which was not observed in control iMPCs. In summary, this study describes a robust method to generate chondrocytes with low hypertrophy for hyaline cartilage repair and elucidates the difference between MSCs and iMPCs in response to TGFb.

ORGANISM(S): Homo sapiens

PROVIDER: GSE197170 | GEO | 2022/12/20

REPOSITORIES: GEO