Ageing and excessive mechanical strain on the articular cartilage have both been associated with the development of knee osteoarthritis (OA). Cartilage degeneration in OA involves a senescent phenotype of chondrocytes, as well as modifications of the extracellular matrix (ECM). Research published in Bone Research investigates how mechanical signals in the form of altered ECM stiffness might lead to chondrocyte senescence in knee OA.

“While reviewing articles related to the mechanical response of chondrocytes in knee OA, we noticed that most studies focused on the effects of actively applied stresses on cartilage, such as shear, compression and tensile forces. However, as arthritis symptoms in patients with OA do not seem to be substantially relieved after bed rest, we hypothesized that mechanical signals in the resting state also have a crucial impact on cartilage,” notes Wenhua Huang, co-corresponding author of the study. Liu, Huang and colleagues thus set out to investigate how ECM stiffness is altered in a mouse model of knee OA induced by destabilization of the medial meniscus, as well as in cartilage samples from patients with OA, and how these changes affect chondrocyte phenotypes.

衰老和关节软骨过度机械应变都与膝骨关节炎（OA）的发生有关。 OA 中的软骨退变涉及软骨细胞的衰老表型以及细胞外基质 (ECM) 的改变。发表在《Bone Research》上的研究调查了 ECM 硬度改变形式的机械信号如何导致膝关节 OA 中的软骨细胞衰老。

“在回顾与膝骨关节炎中软骨细胞机械反应相关的文章时，我们注意到大多数研究都集中在主动施加的应力对软骨的影响上，例如剪切力、压缩力和拉力。然而，由于 OA 患者的关节炎症状在卧床休息后似乎并未得到实质性缓解，因此我们推测静息状态下的机械信号对软骨也有至关重要的影响，”该研究的共同通讯作者黄文华指出。因此，Liu、Huang 及其同事开始研究在由内侧半月板不稳定引起的膝关节 OA 小鼠模型以及 OA 患者的软骨样本中 ECM 硬度如何发生变化，以及这些变化如何影响软骨细胞表型。