Since multiple sources report that IL-6 is partly responsible for OA progression by inducing angiogenesis, and therapeutics that block IL-6 mediated signaling inhibit angiogenesis in arthritis, MSCs’ therapeutic potential in treating OA needs to be clarified: whether and how secreted IL-6 interacts with vessel formation in OA when MSCs are implanted [123,124]. Here, IL6 is linked to arthritic joint disease.