High fluid shear stress induces Hippo/YAP pathway in articular cartilage superficial layer cells: a potential mechanistic link to 0steoarthritis

Abnormal mechanical loading, which can lead to articular cartilage damage, is a significant contributor to the onset of osteoarthritis (OA). Articular cartilage superficial layer cells are among the first cells to respond to changes in the mechanical environment and are highly sensitive to mechanical stimuli. This study aimed to investigate the effects of high fluid shear stress on the articular cartilage superficial layer cells and the underlying mechanisms. We found that high fluid shear stress of 20 dyne/cm² induces inflammation and promotes catabolic processes in these cells. Short-term high fluid shear stress has a protective effect, but its efficacy varies with time. YAP plays a crucial role in mediating the effects of high fluid shear stress and may represent a potential therapeutic target for early-stage osteoarthritis. The study also established osteoarthritis models using anterior cruciate ligament transection (ACLT) or injection of sodium iodoacetate (MIA) to further confirm the findings. The Primary articular cartilage superficial layer cells were treated with or without 20 dyne/cm² fluid shear stress