Excessive mechanical stress induced temporomandibular joint osteoarthritis via osteoclasts-mediated osteogenic differentiation of BMSCs

Role and Mechanism of Mechanical Load in the Homeostasis of the Subchondral Bone in Knee Osteoarthritis: A Comprehensive Review

Osteoarthritis (OA) is one of the most prevalent degenerative joint diseases, and the knee joint is particularly susceptible to it. It typically affects the entire joint and is marked by the erosion of cartilage integrity, chondrocytopenia, subchondral bone sclerosis and the mild synovial inflammation. Pathological changes in the subchondral bone often serve as initiating factors for joint degeneration. Various predisposing factors, including metabolic disorders, oxidative stress, and abnormal mechanical loading, regulate OA pathogenesis. Of them, mechanical loading is closely associated with the maintenance of the subchondral bone. Disrupted mechanical loading, leading to subchondral bone remodeling, can potentially trigger OA, whereas appropriate loading might ameliorate its progression. Therefore, this narrative review aimed to discuss existing knowledge and explore how mechanical loading mediates changes in the subchondral bone, influencing the development of knee osteoarthritis. Special emphasis is placed on its role and underlying mechanisms in maintaining joint homeostasis.

The dynamic progression of temporomandibular joint osteoarthritis-like lesions elicited by mandibular shift in a rat model

BACKGROUND

Temporomandibular joint osteoarthritis (TMJ-OA) presents significant challenges due to its complex etiology, often insidious onset, high incidence, and progressive structural deterioration. While research has explored genetic and molecular factors, treatment outcomes remain suboptimal, emphasizing the need for a deeper understanding of disease progression.

OBJECTIVE

This study employs a specific mandibular shift rat model to explore the dynamic progression of TMJ-OA-like lesions and evaluate the potential for self-repair at different stages, aiming to inform early diagnosis and preventative strategies.

METHODS

Seventy-two female Sprague-Dawley rats were randomized into three groups: a control group (n=24; average weight: 157.23±1.63 g) receiving sham surgery. an experimental group (n=24; average weight: 157.78±1.88 g) subjected to mandibular shift induction, and a removal group (n=24; average weight: 158.11±2.20 g) experiencing mandibular shift for one, two, or four weeks followed by a one-month recovery period (designated as 1w Removal, 2w Removal and 4w Removal, respectively). Histomorphological and molecular analyses were conducted at designated time points.

RESULTS

Rats in the 1-week removal group exhibited substantial recovery in condylar morphology, cartilage thickness, extracellular matrix composition, and expression of OA-related genes. Conversely, the 4-week removal group mirrored the experimental group, indicating limited self-repair capacity at later stages. The 2-week removal group presented with variable outcomes, with some animals showing signs of recovery and others resembling the experimental group, indicating a potential transitional phase in the disease process.

CONCLUSION

Recovery from early-stage TMJ-OA involves eliminating provoking factors such as occlusal interference or reducing joint loading. However, advanced stages exhibit diminished self-repair capabilities, necessitating additional therapeutic interventions. These findings emphasize the importance of early diagnosis and intervention in TMJ-OA management.

Research progress on the regulatory mechanism of integrin-mediated mechanical stress in cells involved in bone metabolism

Mechanical stress is an internal force between various parts of an object that resists external factors and effects that cause an object to deform, and mechanical stress is essential for various tissues that are constantly subjected to mechanical loads to function normally. Integrins are a class of transmembrane heterodimeric glycoprotein receptors that are important target proteins for the action of mechanical stress stimuli on cells and can convert extracellular physical and mechanical signals into intracellular bioelectrical signals, thereby regulating osteogenesis and osteolysis. Integrins play a bidirectional regulatory role in bone metabolism. In this paper, relevant literature published in recent years is reviewed and summarized. The characteristics of integrins and mechanical stress are introduced, as well as the mechanisms underlying responses of integrin to mechanical stress stimulation. The paper focuses on integrin-mediated mechanical stress in different cells involved in bone metabolism and its associated signalling mechanisms. The purpose of this review is to provide a theoretical basis for the application of integrin-mediated mechanical stress to the field of bone tissue repair and regeneration.