Studies on mechanisms of proliferation, differentiation and calcification of chondrocytes using established clonal cell lines.

1)从小鼠肋骨生长软骨（GC）中建立了3个克隆细胞系，它们在培养3年多的时间内对甲状旁腺激素（PTH）的反应性、碱性磷酸酶活性和产生内皮细胞生长抑制剂的能力存在差异。MGC/T1.17细胞具有高活性的碱性磷酸酶、钙化能力和表皮生长因子（EGF）受体，并且对表皮生长因子、转化生长因子β反应良好。MGC/T1.18细胞对甲状旁腺激素反应良好，并产生硫酸化因子。MGC/T1.4细胞产生内皮细胞生长因子和硫酸化因子。糖胺聚糖（GAG）的合成在三个克隆系远远低于原代培养的GC细胞。3个克隆株主要合成I型胶原。由于这些细胞系具有不同的特性，它们将有助于软骨内骨化、PTH对骨骼细胞的作用以及抗血管生成因子的研究。2）从人软骨肉瘤中建立了一个培养3年以上的具有软骨表型的克隆细胞系。该克隆系命名为HCS-2/8，形成了合成的软骨型蛋白多糖和II型和Xi型胶原，这是典型的软骨表型。与原代培养的兔肋软骨细胞一样，它们也对胰岛素样生长因子I和II、转化生长因子β和视黄酸反应良好。HCS-2/8细胞具有低碱性磷酸酶活性，并且在不存在抗坏血酸的情况下不钙化，但在维生素存在下酶活性显著增加。这些细胞产生碱性磷酸酶和钙化的抑制剂。由于这些特性，该细胞系应该是有用的研究内软骨骨化。

1) Three clonal cell lines with differences in responsiveness to parathyroid hormone (PTH), alkaline phosphatase activity and ability to produce an endothelial cell growth inhibitor(s) during more than 3 years in culture were established from growth cartilage (GC) of mouse ribs. MGC/Tl.17 cells had high activity of alkaline phosphatase, an ability to calcify and epidermal growth factor (EGF) receptors and responded well to epidermal growth factor, transforming growth factor beta. MGC/Tl.18 cells responded well to parathyroid hormone and produced sulfation factor. MGC/Tl.4 cells produced endothelial cell growth factor and sulfation factor. Glycosaminoglycan (GAG) syntheses in the three clonal lines were much lower than that of primary cultures of GC cells. The three clonal lines mainly synthesized type I collagen. Because of their different properties, these cell lines should be useful for studies on endochondral ossification, the actions of PTH on skeletal cells and anti-angiogenesis factors.2) A clonal cell line with cartilage phenotypes during more than 3 years in culture was established from a human chondrosarcoma. The clonal line, named HCS-2/8, formed synthesized cartilage-type proteoglycans and collagen types II and XI which are typical cartilage phenotypes. Like rabbit costal chondrocytes in primary culture, they also responded well to insulin-like growth factors I and II, transforming growth factor beta and retinoic acid. HCS-2/8 cells had low alkaline phosphatase activity and did not calcify in the absence of ascorbic acid but the enzyme activity increased markedly in the presence of the vitamin. The cells produced inhibitors of alkaline phosphatase and calcification. Because of these properties, the cell line should be useful for studies on endochondral ossification.