Microspheres have been widely applied in osteoarthritis (OA) treatment and tissue engineering because of their favorable biocompatibility and drug delivery capabilities. However, single-component microspheres often fail to provide satisfactory therapeutic outcomes under the complex mechanical environment of the joint, particularly under persistent friction and shear stress. In this study, poly( l -lactic acid) (PLLA)–gelatin grafted with hydroxyphenyl propionic acid (GelHPA) core–shell microspheres were successfully fabricated via an in situ enzymatic cross-linking method. The PLLA core provides structural support and serves as a reservoir for bioactive agents, such as kartogenin (KGN) and nanohydroxyapatite (nHA), while the GelHPA shell offers a hydrated, gelatin-derived interface with improved cytocompatibility and lubrication-related properties. The GelHPA shell supported cell adhesion and spreading on the microsphere surface, while KGN- and nHA-loaded microspheres promoted chondrogenic and osteogenic differentiation of mesenchymal stem cells, respectively. Overall, the PLLA-GelHPA core–shell microsphere system integrates mechanical support with biological functionality, offering a promising injectable platform for OA-related osteochondral repair and tissue engineering applications.
Zhang et al. (Fri,) studied this question.