BMP-9 and TGF-β3 Synergistically Regulate Chondrogenic Pathways in Bovine Synovial FluidDerived Mesenchymal Stem Cells (BSF-MSCs) in Transwell Co-Culture with Chondrocytes

The prevalence of osteoarthritis (OA), a degenerative condition affecting joints, has significantly risen in recent years. The primary pathogenic characteristic of OA encompasses the destruction of articular cartilage. Synovial fluid-derived mesenchymal stem cells (SF-MSCs) are considered a promising stem cell resource for healing cartilage defects due to their inherent multilineage differentiation capacity. Our study aimed to assess the chondrogenic differentiation potential of BSF-MSCs in a transwell co-culture system with chondrocytes. SF-MSCs were isolated, cultured, and characterized for multilineage differentiation potential. SF-MSCs were cultured with varying combinations of chondrogenic growth factors, including BMP-9 (10ng/mL) and TGF-β3 (10ng/mL), over 21 days in a transwell co-culture system along with chondrocytes. At the end of the experiment, the cells were analyzed for morphological assessments, immunofluorescence staining for COL-II, Alcian blue staining for glycosaminoglycan deposition, and real-time PCR for chondrogenic marker-specific markers including COL2A1, SOX9, ACAN, and for hypertrophic markers COL10A1. The results of real-time PCR revealed significant upregulation of COL2A1 (P<0.001), SOX9 (P<0.05), and ACAN (P<0.05) in experimental groups. These findings highlight the role of BMP-9 and TGF-β3 in enhancing chondrogenesis through BSF-MSCs and chondrocyte interactions.