Single-cell RNA-Seq reveals changes in immune landscape in post-traumatic osteoarthritis

Osteoarthritis (OA) is the most common joint disease, affecting over 300 million people world-wide. Accumulating evidence attests to the important roles of immune system in OA pathogenesis. Understanding the role of various immune cells in joint degeneration or joint repair after injury is helpful for improving therapeutic strategies for treating OA. Post-traumatic osteoarthritis (PTOA) develops in ~50% of individuals who have experienced an articular trauma like an anterior cruciate ligament (ACL) rupture. Here, using highly sensitive single-cell RNA sequencing technology, we delineated the temporal dynamics of immune cell accumulation in the mouse knee joint after ACL rupture. Overall design: Right knee joints of 10-week-old C57Bl/6J mice were injured using a tibial compression injury model. Uninjured joints and injured joints from 1-, 3-, 7-, 15- and 30 days post-injury (n=5/group) were collected and immune (Cd45+) cells were analyzed using scRNA-seq. Non-immune (Cd45-) cells from D0 were also profiled using scRNA-seq to determine immune stromal interactions.