Chondrocyte-Targeted MicroRNA Delivery by Engineered Exosomes toward a Cell-Free Osteoarthritis Therapy

Targeted delivery to the diseased cell or tissue is the key to the successful clinical use of nucleic acid drugs. In particular, delivery of microRNA-140 (miRNA-140, miR-140) into chondrocytes across the dense, nonvascular extracellular matrix of cartilage remains a major challenge. Here, we report the chondrocyte-targeting exosomes as vehicles for the delivery of miR-140 into chondrocytes as a new treatment for osteoarthritis (OA). By fusing a chondrocyte-affinity peptide (CAP) with the lysosome-associated membrane glycoprotein 2b protein on the surface of exosomes, we acquire CAP-exosomes that can efficiently encapsulate miR-140, specifically enter, and deliver the cargo into chondrocytes in vitro. CAP-exosomes, in contrast to nontagged exosome vesicles, are retained in the joints after intra-articular injection with minimal diffusion in vivo. CAP-exosomes also deliver miR-140 to deep cartilage regions through the dense mesochondrium, inhibit cartilage-degrading proteases, and alleviate OA progression in a rat model, pointing toward a potential organelle-based, cell-free therapy of OA.