The role of mechanical stress and transforming growth factor beta 1 (TGF-β1) is important in the initiation and progression of osteoarthritis (OA). However, the underlying molecular mechanisms are not clearly known. In this study, TGF-β1 from osteoclasts and knee joints were analyzed using a co-cultured cell model and an OA rat model, respectively. Five patients with a femoral neck fracture (four female and one male, mean 73.4 years (68 to 79)) were recruited between January 2015 and December 2015. Results showed that TGF-β1 was significantly upregulated in osteoclasts by cyclic loading in a time- and dose-dependent mode. The osteoclasts were subjected to cyclic loading before being co-cultured with chondrocytes for 24 hours.Objectives
Methods
Excessive mechanical stress on synovial joints causes osteoarthritis
(OA) and results in the production of prostaglandin E2 (PGE2), a
key molecule in arthritis, by synovial fibroblasts. However, the
relationship between arthritis-related molecules and mechanical
stress is still unclear. The purpose of this study was to examine
the synovial fibroblast response to cyclic mechanical stress using
an Human synovial fibroblasts were cultured on collagen scaffolds
to produce three-dimensional constructs. A cyclic compressive loading
of 40 kPa at 0.5 Hz was applied to the constructs, with or without
the administration of a cyclooxygenase-2 (COX-2) selective inhibitor
or dexamethasone, and then the concentrations of PGE2, interleukin-1β (IL-1β),
tumour necrosis factor-α (TNF-α), IL-6, IL-8 and COX-2 were measured.Objective
Method
An understanding of the remodelling of tendon is crucial for the development of scientific methods of treatment and rehabilitation. This study tested the hypothesis that tendon adapts structurally in response to changes in functional loading. A novel model allowed manipulation of the mechanical environment of the patellar tendon in the presence of normal joint movement via the application of an adjustable external fixator mechanism between the patella and the tibia in sheep, while avoiding exposure of the patellar tendon itself. Stress shielding caused a significant reduction in the structural and material properties of stiffness (79%), ultimate load (69%), energy absorbed (61%), elastic modulus (76%) and ultimate stress (72%) of the tendon compared with controls. Compared with the material properties the structural properties exhibited better recovery after re-stressing with stiffness 97%, ultimate load 92%, energy absorbed 96%, elastic modulus 79% and ultimate stress 80%. The cross-sectional area of the re-stressed tendons was significantly greater than that of stress-shielded tendons. The remodelling phenomena exhibited in this study are consistent with a putative feedback mechanism under strain control. This study provides a basis from which to explore the interactions of tendon remodelling and mechanical environment.
