Effect of CFS-1 on osteoclast and its precursor cells

集落刺激因子-1 (Colony-stimulating factor-1, CSF-1)，又称巨噬细胞集落刺激因子，是单核吞噬系统细胞生长、分化激活和存活所必需的。这种细胞因子已被证明对破骨细胞的发育以及诱导破骨细胞祖细胞的增殖和分化至关重要。它还能维持成熟破骨细胞的存活，并刺激这些细胞的扩散和迁移。在本体外实验中，从大鼠长骨分离的破骨细胞与CSF-1孵育后，观察到形成具有大量细胞核的大型trap阳性细胞。这些在塑料上培养的大细胞结合降钙素，沿着细胞边缘形成f -肌动蛋白。在有CSF-1存在的情况下，在牙本质切片上也观察到这种大的trap阳性多核细胞的融合和凹坑的形成。从塑料培养中获得的定量数据表明，在250 pM CSF-1存在的情况下，破骨细胞的数量在72小时内略有增加，而在缺乏CSF-1的情况下，破骨细胞的数量在24小时后迅速下降，这证实了该细胞因子是破骨细胞存活所必需的。每个破骨细胞的细胞核数量在与CSF-1孵育16小时后达到最大值，是不含CSF-1时的两倍。在250 pM-500pM的浓度下，细胞因子对融合过程的影响最大。计算每个破骨细胞平均细胞核分布频率的中位数，结果显示，在没有CSF-1的情况下，每个破骨细胞有4个细胞核，在有CSF-1的情况下，每个破骨细胞有6个细胞核。酪氨酸激酶抑制剂染料木素和herbimycin A抑制CSF-1诱导的融合。这些数据表明，CSF-1诱导破骨细胞融合，酪氨酸激酶参与了这一过程。这种融合过程可能贯穿破骨细胞的整个生命周期。

Colony-stimulating factor-1 (CSF-1), Also called macrophage colony-stimulating factor, is required for growth, differentiation activation, and survival of cells of the mononuclear phagocytic system. This cytokine has been shown to be essential foe osteoclast development as well as for inducing both proliferation and differentiation of osteoclast progenitors. It also sustains survival of mature osteoclasts and stimulates spreading and migration of these cells. In the present in vitro study, the formation of large TRAP-positive cells with a high number of nuclei was observed when osteoclasts isolated from rat long bones were incubated with CSF-1. These large cells, cultured on plastic, bind calcitonin and form F-actin along the edges of the cells. Fusion to such large TRAP-positive multinucleated cells in the presence of CSF-1 and the formation of pits were also observed on dentine slices. Quantitative data obtained from cultures on plastic demonstrated that the number of osteoclasts slightly increased in the course of 72 hrs in the presence of 250 pM CSF-1, whereas it decreased rapidly after 24 hrs in the absence of CSF-1, which confirms that this cytokine is required for the survivai of osteoclasts. The number of nuclei per osteoclast was maximal after 16 hrs incubation with CSF-1, namely twice the value found in the absence of CSF-1. The maximal effect of the cytokine on the fusion process was observed at a concentration of 250 pM-500pM.A calculation of the medians of the average frequency of nuclei distribution per osteoclast resulted in 4 nuclei per osteoclast in the absence, and 6 in the presence of CSF-1. Genistein and herbimycin A,inhibitors of tyrosine kinases, inhibited the fusion induced by CSF-1. The data suggest that CSF-1 induces osteoclast fusion, and that tyrosine kinase (s) are involved in this process. The fusion process may continue throughout the entire life on an osteoclast.