In the current study, we compared gene therapy and a coacervate sustained delivery system to deliver BMP2 to test whether using coacervate-delivered BMP2 could enhance hMDSC-mediated cartilage repair using an MIA-induced osteoarthritis model, and the results were compared to lenti-BMP2/GFP-transduced hMDSC-mediated gene therapy. Here, BMP2 is linked to osteoarthritis.