Effect of reduced oxygen tension on chondrogenesis and osteogenesis in adipose-derived mesenchymal cells

TLDR

Adipose‑derived mesenchymal cells are promising for cell‑based therapies because they can differentiate into bone, cartilage, and fat. This study aimed to determine how oxygen tension affects AMC differentiation into bone and cartilage. Chondrogenesis was induced in 3‑D micromass cultures with TGF‑β1 and evaluated by collagen II immunostaining and Alcian blue proteoglycan staining, while osteogenesis was promoted with osteogenic medium containing retinoic acid or vitamin D and assessed by alkaline phosphatase activity and mineralization. Cultures exposed to 2 % O₂ showed markedly reduced chondrogenesis and severely diminished osteogenesis, demonstrating that hypoxia strongly inhibits both differentiation pathways in AMCs.

Abstract

Recent studies have demonstrated that adipose-derived mesenchymal cells (AMCs) offer great promise for cell-based therapies because of their ability to differentiate toward bone, cartilage, and fat. Given that cartilage is an avascular tissue and that mesenchymal cells experience hypoxia during prechondrogenic condensation in endochondral ossification, the goal of this study was to understand the influence of oxygen tension on AMC differentiation into bone and cartilage. In vitro chondrogenesis was induced using a three-dimensional micromass culture model supplemented with TGF-β1. Collagen II production and extracellular matrix proteoglycans were assessed with immunohistochemistry and Alcian blue staining, respectively. Strikingly, micromasses differentiated in reduced oxygen tension (2% O 2 ) showed markedly decreased chondrogenesis. Osteogenesis was induced using osteogenic medium supplemented with retinoic acid or vitamin D and was assessed with alkaline phosphatase activity and mineralization. AMCs differentiated in both 21 and 2% O 2 environments. However, osteogenesis was severely diminished in a low-oxygen environment. These data demonstrated that hypoxia strongly inhibits in vitro chondrogenesis and osteogenesis in AMCs.