Identification Of Distinct Cellular Populations In The Synovium Of Early- And Late-Stage Radiographic Knee OA Using Single Nucleus RNA Sequencing

Purpose: Osteoarthritis (OA) is a complex, multifactorial and heterogeneous joint disease of unknown etiology. OA can affect one or more joints, with the knee being the commonly affected site. Knee OA is characterized by irreversible degradation of cartilage, remodeling of subchondral bone tissue, and inflammation of the synovium. The synovium lines the joint capsule and under homeostatic conditions produces synovial fluid for joint lubrication. During OA, the synovium exhibits increased vascularization, inflammation, cellular proliferation and hyperplasia. Currently, there is a limited understanding of the synovium’s role in OA pathophysiology. To help delineate the contribution of the synovium to OA pathogenesis we sought to identify if distinct cell subtypes exist in the synovium of early (KL1) versus late stages (KL3/4) of radiographic knee OA and in a mouse model of osteoarthritis.