Cell-Free Osteoarthritis Treatment with Sustained-Release of Chondrocyte-Targeting Exosomes from Umbilical Cord-Derived Mesenchymal Stem Cells to Rejuvenate Aging Chondrocytes.

As chondrocytes from osteoarthritic cartilage usually exhibit aging and senescent characteristics, targeting aging chondrocytes could be a potential therapeutic strategy. In this study, exosomes derived from umbilical cord-derived mesenchymal stem cells (UCMSC-EXOs) combined with the chondrocyte-targeting capacity and controlled-release system were proposed for osteoarthritis (OA) treatment via rejuvenating aging chondrocytes. The essential functional miRNAs within UCMSC-EXOs were investigated, with the p53 signaling pathway identified as the key factor. To improve the therapeutic efficiency and retention time of UCMSC-EXOs in vivo , the exosomes (EXOs) were engineered on membranes with a designed chondrocyte-targeting polymers, and encapsulated within thiolated hyaluronic acid microgels to form a "two-phase" releasing system, which synergistically facilitated the repair of OA cartilage in a rat model. Together, this study highlighted the rejuvenating effects of UCMSC-EXOs on OA chondrocytes and the potential to combine with chondrocyte-targeting and sustained-release strategies toward a future cell-free OA treatment.