Engineered EVs from 3D-Cultured MSCs for Synergistic Modulation of Inflammatory Microenvironment and Cartilage Regeneration in Osteoarthritis.

Osteoarthritis (OA) is a common and serious joint disease characterized by synovitis and articular cartilage degeneration. Effective nonsurgical treatments for OA are still lacking. In this study, we designed an injectable temperature-sensitive hydrogel system delivering engineered extracellular vesicles for the treatment of OA. We increased the yield and efficacy of extracellular vesicles by three-dimensional(3D) culture of adipose mesenchymal stem cells. The anti-inflammatory drug celecoxib was then loaded into the extracellular vesicles via electroporation, resulting in the construction of engineered extracellular vesicles (CEVs) with both anti-inflammatory and cartilage regeneration functions. An injectable thermosensitive hydrogel was prepared with Pluronic F127 (F127) and hyaluronic acid (HA) for the delivery of CEVs, thereby forming a composite treatment system (CEVs@F127-HA). CEVs@F127-HA could inhibit M1-type macrophage polarization, protect the metabolic homeostasis of chondrocytes, and promote the differentiation of bone marrow mesenchymal stem cells (BMSCs) into chondrocytes in vitro. CEVs@F127-HA also prolonged the retention time of CEVs in the joint cavity and provided long-term synergistic therapeutic benefits. In vivo experiments utilizing a sodium iodoacetate-induced OA mouse model also demonstrated that CEVs@F127-HA could effectively reduce joint inflammation and promote cartilage repair and regeneration, thereby inhibiting OA progression. Thus, the two-in-one synergistic therapy of CEVs@F127-HA centrally addresses both pathological features of OA and is a potential and effective strategy for OA treatment.