Divergent effects of distinct perivascular cell subsets for intra-articular cell therapy in posttraumatic osteoarthritis

Intra-articular injection of mesenchymal stem cells has shown benefit for the treatment of osteoarthritis (OA). However, mesenchymal stem/stromal cells at the origin of these clinical results are heterogenous cell populations with limited cellular characterization. Here, two transgenic reporter mice were used to examine the differential effects of two precisely defined perivascular cell populations (Pdgfrα⁺ and Pdgfrβ⁺ cells) from white adipose tissue for alleviation of OA. Perivascular mesenchymal cells were isolated from transgenic Pdgfrα-and Pdgfrβ-CreER^T2 reporter animals and delivered as a one-time intra-articular dose to C57BL/6J mice after destabilization of the medial meniscus (DMM). Both Pdgfrα⁺ and Pdgfrβ⁺ cell preparations improved metrics of cartilage degradation and reduced markers of chondrocyte hypertrophy. While some similarities in cell distribution were identified within the synovial and perivascular spaces, injected Pdgfrα⁺ cells remained in the superficial layers of articular cartilage, while Pdgfrβ⁺ cells were more widely dispersed. Pdgfrβ⁺ cell therapy prevented subchondral sclerosis induced by DMM, while Pdgfrα⁺ cell therapy had no effect. In summary, while both cell therapies showed beneficial effects in the DMM model, important differences in cell incorporation, persistence, and subchondral sclerosis were identified.