Oreffo R O, Virdi A S, Triffitt J T
MRC Bone Research Laboratory, Nuffield Department of Orthopaedic Surgery, University of Oxford, England.
Eur J Cell Biol. 1997 Nov;74(3):251-61.
Knowledge of the controlling mechanisms of human osteoprogenitor cell differentiation has important implications for understanding bone turnover. The in vitro differentiation of human bone marrow fibroblasts into adipogenic and osteogenic cells and the interaction of 1,25 dihydroxyvitamin D3 (1,25(OH)2D3) and dexamethasone in this process has been investigated together with the effects of human serum. Marrow fibroblasts cultured in human serum and dexamethasone for 28 days, generated lipid containing cells as confirmed by morphology, Oil red O staining and immunocytochemistry using antiserum to the adipocyte-specific protein, adipocyte P2 (aP2). In cultures containing 1,25(OH)2D3 and dexamethasone, adipogenesis was stimulated within 21 days. Osteocalcin expression, as assessed by in situ hybridization, was dependent on the presence of 1,25(OH)2D3 and was decreased in cultures treated with dexamethasone. Northern analysis confirmed the decrease in osteocalcin expression and increase in lipoprotein lipase expression with the appearance of the adipogenic phenotype in these cultures. Marrow cultures maintained for 14 days in human serum and osteotropic agents before switching to fetal calf serum indicated the continuous requirement of human serum in these cultures for adipogenesis. These results demonstrate that human serum contains factors that exert dramatic effects on human bone marrow cell differentiation to augment the osteogenic and adipogenic activity of 1,25(OH)2D3 and dexamethasone.
了解人类骨祖细胞分化的调控机制对于理解骨转换具有重要意义。研究了人骨髓成纤维细胞在体外向脂肪细胞和成骨细胞的分化，以及1,25 - 二羟基维生素D3（1,25(OH)2D3）和地塞米松在此过程中的相互作用，同时也研究了人血清的作用。在人血清和地塞米松中培养28天的骨髓成纤维细胞产生了含脂质的细胞，通过形态学、油红O染色以及使用抗脂肪细胞特异性蛋白脂肪细胞P2（aP2）的抗血清进行免疫细胞化学鉴定得以证实。在含有1,25(OH)2D3和地塞米松的培养物中，21天内脂肪生成受到刺激。通过原位杂交评估的骨钙素表达依赖于1,25(OH)2D3的存在，并且在地塞米松处理的培养物中降低。Northern分析证实了这些培养物中随着脂肪生成表型的出现，骨钙素表达降低而脂蛋白脂肪酶表达增加。在切换到胎牛血清之前，在人血清和促骨生成剂中维持14天的骨髓培养物表明这些培养物中脂肪生成持续需要人血清。这些结果表明，人血清中含有对人骨髓细胞分化产生显著影响的因子，可增强1,25(OH)2D3和地塞米松的成骨和成脂活性。
