DMOG Negatively Impacts Tissue Engineered Cartilage Development

Objective: Articular cartilage exists in a hypoxic environment, which motivates the use of hypoxia-simulating chemical agents to improve matrix production in cartilage tissue engineering. The aim of this study was to investigate whether dimethyloxalylglycine (DMOG), a HIF-1α stabilizer, would improve matrix production in 3-dimensional (3D) porcine synovial-derived mesenchymal stem cell (SYN-MSC) co-culture with chondrocytes. Design: Pellet cultures and scaffold-based engineered cartilage were grown in vitro to determine the impact of chemically simulated hypoxia on 2 types of 3D cell culture. DMOG-treated groups were exposed to DMOG from day 14 to day 21 and grown up to 6 weeks with n = 3 per condition and time point. Results: The addition of DMOG resulted in HIF-1α stabilization in the exterior of the engineered constructs, which resulted in increased regional type II collagen deposition, but the stabilization did not translate to overall increased extracellular matrix deposition. There was no increase in HIF-1α stabilization in the pellet cultures. DMOG treatment also negatively affected the mechanical competency of the engineered cartilage. Conclusions: Despite previous studies that demonstrated the efficacy of DMOG, here, short-term treatment with DMOG did not have a uniformly positive impact on the chondrogenic capacity of SYN-MSCs in either pellet culture or in scaffold-based engineered cartilage, as evidenced by reduced matrix production. Such 3D constructs generally have a naturally occurring hypoxic center, which allows for the stabilization of HIF-1α in the interior tissue. Thus, short-term addition of DMOG may not further improve this in cartilage tissue engineered constructs.