Collagen microsphere based 3D culture system for human osteoarthritis chondrocytes (hOACs)

The current study aims to evaluate collagen microencapsulation as an in vitro 3D culture platform for human osteoarthritic chondrocytes (hOACs), and to exemplify its feasibility in screening potential disease modifying factors. We first isolated and expanded hOACs from osteoarthritis (OA) cartilage samples harvested from multiple patients during total knee replacement (TKR) surgery. These cells were microencapsulated into collagen microspheres for subsequent 3D cultures. The change in chondrocyte phenotypes and OA phenotype was evaluated over time, using 2D monolayer culture and traditional 3D pellet culture as controls. The hOACs in the 3D collagen microsphere model resumed their in vivo phenotypes when compared to 2D monolayer. When compared with the 3D pellet model, the 3D hOAC-collagen microsphere model better recapitulated the OA phenotypes. We further demonstrated the responsiveness of the microencapsulated hOACs towards a number of external factors altering the chondrogenic phenotype, corroborating with previous studies. The hOAC encapsulated collagen microspheres better maintained the hOAC phenotype than the traditional 2D monolayer and 3D pellet cultures. The feasibility to use this hOAC-collagen microsphere in vitro model as a screening platform for disease-modifying agents has been demonstrated, contributing to future development of OA therapeutics.