Single cell level characterization of injury-induced immune changes in 10-week-old and 95-week-old C57BL/6 knee joints

Post-traumatic Osteoarthritis (PTOA) occurs in about half of individuals who sustained articular injuries including tibial plateau fracture, meniscus tear, or an anterior cruciate ligament (ACL) rupture. Damage-associated molecular pattern (DAMP) proteins are typically secreted from injured or dying cells of the synovial joint into the surrounding environment immediately following injury which in turn recruit leukocytes to mediate debris clean-up and repair. Prior bulk RNA-seq experiments exploring organismal age-related differences following ACL rupture found an increased expression of inflammatory-response related genes in 95-week-old mice relative to 10-week-old mice. Using single-cell RNA sequencing technology we temporally explored differences in immune cell infiltration in the synovial joint in 10-week-old and 95-week-old C57BL/6 mice. Right knee joints of 10-week-old and 95-week-old C57BL/6 mice were injured using a tibial compression injury model. Uninjured joints and injured joints from 7-post-injury were collected and immune (Cd45+) cells were analyzed using scRNA-seq.