Dorheim M A, Sullivan M, Dandapani V, Wu X, Hudson J, Segarini P R, Rosen D M, Aulthouse A L, Gimble J M
Immunobiology and Cancer Program, Oklahoma Medical Research Foundation, Oklahoma City 73104.
J Cell Physiol. 1993 Feb;154(2):317-28. doi: 10.1002/jcp.1041540215.
A growing body of data suggests that the bone marrow stroma contains a population of pluripotent cells capable of differentiating into adipocytes, osteoblasts, and lymphohematopoietic supporting cells. In this work, the murine stromal cell lines BMS2 and +/+ 2.4 have been examined as preadipocytes and adipocytes for evidence of osteoblastic gene expression. Adipocyte differentiation has been quantitated using fluorescence activated cell sorting. Within 7-10 days of adipocyte induction by treatment with glucocorticoids, indomethacin, and methylisobutylxanthine, between 40% to 50% of the cells contain lipid vacuoles and exhibit a characteristic adipocyte morphology. Based on immunocytochemistry, both the adipocytes and preadipocytes express a number of osteoblastic markers; these include alkaline phosphatase, osteopontin, collagen (I, III), bone sialoprotein II, and fibronectin. Based on biochemical assays, the level of alkaline phosphatase expression is not significantly different between preadipocyte and adipocyte cells. However, unlike rat cell lines, dexamethasone exposure causes a dose-dependent decrease in enzyme activity. The steady-state mRNA levels of the osteoblast associated genes varies during the process of adiopogenesis. The relative level of collagen I and collagen III mRNA is lower in adipocyte-induced cells when compared to the uninduced controls. Osteocalcin mRNA is detected in preadipocytes but absent in adipocytes. These data indicate that osteoblastic gene expression is detected in cells capable of undergoing adipocyte differentiation, consistent with the hypothesis that these cell lineages are interrelated.
越来越多的数据表明，骨髓基质含有一群多能细胞，能够分化为脂肪细胞、成骨细胞和淋巴细胞造血支持细胞。在这项研究中，已将小鼠基质细胞系BMS2和+/+ 2.4作为前脂肪细胞和脂肪细胞进行检测，以寻找成骨细胞基因表达的证据。使用荧光激活细胞分选法定量脂肪细胞分化。在用糖皮质激素、消炎痛和甲基异丁基黄嘌呤诱导脂肪细胞后的7 - 10天内，40%至50%的细胞含有脂质空泡，并呈现出典型的脂肪细胞形态。基于免疫细胞化学，脂肪细胞和前脂肪细胞均表达多种成骨细胞标志物；这些标志物包括碱性磷酸酶、骨桥蛋白、胶原蛋白（I、III）、骨唾液蛋白II和纤连蛋白。基于生化分析，前脂肪细胞和脂肪细胞中碱性磷酸酶的表达水平无显著差异。然而，与大鼠细胞系不同，地塞米松暴露会导致酶活性呈剂量依赖性下降。在脂肪生成过程中，成骨细胞相关基因的稳态mRNA水平会发生变化。与未诱导的对照相比，脂肪细胞诱导细胞中胶原蛋白I和胶原蛋白III mRNA的相对水平较低。在前脂肪细胞中可检测到骨钙素mRNA，但在脂肪细胞中不存在。这些数据表明，在能够进行脂肪细胞分化的细胞中检测到了成骨细胞基因表达，这与这些细胞谱系相互关联的假设一致。
