Induction of experimental OA
We used two different models of experimental OA, CIOA and DMM, because they differ in synovial inflammation. Experimental CIOA (which has relatively high synovial inflammation) was induced as previously described. Briefly, right knee joints of mice were injected with 1 U collagenase type VII from Clostridium histolyticum (SigmaeAldrich) at day 0 and day 2, causing disruption of the ligaments and local instability of the knee joint. To achieve a CIOA with less synovial activation, only one time 1 U collagenase was injected. Experimental DMM OA (destabilized medial meniscus, a model where synovial activation is scant) was induced by transection of the medial anterior meniscotibial ligament.