Intravenous Administration of Stromal Vascular Fraction Attenuates Early Busulfan-Induced Testicular Injury in Rats: An Alternative Cell-Based Approach for Spermatogenic Impairment.

Osteoarthritis (OA) is a comprehensive joint disorder characterized by structural alterations in hyaline articular cartilage, subchondral bone, ligaments, joint capsule, synovium and periarticular muscles (). The pathogenesis of OA involves complex interactions among mechanical, inflammatory, and metabolic factors that ultimately lead to progressive structural damage and functional failure of synovial joints. Rather than a passive “wear-and-tear” condition, OA is now recognized as an active and dynamic process resulting from an imbalance between tissue repair and degradation within the joint (,). As one of the most prevalent musculoskeletal disorders worldwide, OA affects more than 300 million individuals and represents a major cause of pain, disability, and reduced quality of life in aging populations (). Epidemiological studies consistently demonstrate a pronounced sex difference in OA prevalence and progression. For example, the prevalence of symptomatic knee OA in China is approximately 8.1%, with a substantially higher rate in women (10.3%) than in men (5.7%) (). This sex disparity has long attracted attention and is widely believed to be associated with hormonal changes, particularly the sharp decline in estrogen levels after menopause (). Accumulating experimental and clinical evidence suggests that estrogen plays an important role in maintaining cartilage homeostasis, regulating subchondral bone remodeling, and modulating joint inflammation. Consequently, estrogen deficiency has been proposed as a key endocrine factor contributing to the increased susceptibility to OA in women (). In addition to estrogen, other sex hormones, including androgens and progesterone, have also been implicated in the regulation of joint homeostasis. Increasing evidence indicates that these hormones influence joint tissues through their respective receptors and downstream signaling pathways. Therefore, elucidating the roles of sex hormones and their receptor-mediated signaling in joint tissues is essential for understanding sex-specific differences in OA and its underlying mechanisms. Such insights may provide a theoretical basis for improved risk assessment and the development of targeted therapeutic strategies for OA.