Stassen Roderick H M J, van den Akker Guus G H, Caron Marjolein M J, Surtel Don A M, Cremers Andy, van Rhijn Lodewijk W, Welting Tim J M
Laboratory for Experimental Orthopedics, Department of Orthopedic Surgery, Maastricht University, Maastricht, The Netherlands.
Laboratory for Experimental Orthopedics, Department of Orthopedic Surgery, Maastricht University Medical Center +, Maastricht, The Netherlands.
Calcif Tissue Int. 2025 Apr 2;116(1):57. doi: 10.1007/s00223-025-01365-x.
The pathological relevance of articular cartilage calcification in osteoarthritis (OA) is becoming increasingly evident. We are only beginning to understand the pathobiological mechanisms that contribute to articular cartilage calcification in OA. How molecular environmental factors interact with calcification mechanisms is poorly explored. In this study, we developed an in vitro phosphate-driven calcification model for human OA articular chondrocytes, in which these cells are cultured in the presence of calcification medium containing adenosine triphosphate (ATP) and β-glycerophosphate (BGP). We employed this model to investigate the role of transforming growth factor β (TGF-β) in chondrocyte calcification. Chondrocyte culture in calcification medium resulted in mineral nodule formation over a time course of 7 days. The presence of calcium and phosphate deposition in these nodules was validated with von Kossa staining, scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX), and colorimetric calcium and phosphate assays. Supplementation of calcification medium with TGF-β resulted in enhanced nodule formation with a different morphology and changed the expression of extracellular matrix-related genes such as collagen type I and III. In conclusion, we developed a new in vitro model for human OA articular chondrocyte calcification, in which we demonstrated a pro-calcifying role for TGF-β. This in vitro model may be used as a basis to aid the investigation of the influence of environmental factors on chondrocyte calcification and the development of new anti-calcification disease-modifying osteoarthritis drugs.
骨关节炎（OA）中关节软骨钙化的病理相关性日益明显。我们才刚刚开始了解导致OA中关节软骨钙化的病理生物学机制。分子环境因素如何与钙化机制相互作用尚鲜有研究。在本研究中，我们为人OA关节软骨细胞建立了一种体外磷酸盐驱动的钙化模型，其中这些细胞在含有三磷酸腺苷（ATP）和β-甘油磷酸（BGP）的钙化培养基中培养。我们利用该模型研究转化生长因子β（TGF-β）在软骨细胞钙化中的作用。在钙化培养基中培养软骨细胞，在7天的时间进程中会形成矿化结节。通过冯科萨染色、扫描电子显微镜-能量色散X射线光谱法（SEM-EDX）以及比色法钙和磷测定法验证了这些结节中钙和磷的沉积。向钙化培养基中添加TGF-β导致结节形成增强，形态不同，并改变了细胞外基质相关基因如I型和III型胶原的表达。总之，我们为人OA关节软骨细胞钙化建立了一种新的体外模型，其中我们证明了TGF-β具有促钙化作用。这种体外模型可作为基础，有助于研究环境因素对软骨细胞钙化的影响以及开发新的抗钙化疾病修饰性骨关节炎药物。
