Effect of VEGF's on osteockast formation and activation

血管内皮生长因子(VEGF)是生理性血管生成的关键介质。这种细胞因子与两个细胞表面受体结合，这两个受体由同样属于酪氨酸激酶受体家族的Flt-1或Flk-1/KDR编码。巨噬细胞单核细胞系仅表达Flt-1。本研究旨在探讨血管内皮生长因子对体外培养破骨细胞分化的影响。骨髓细胞和脾细胞取自5~8周龄雄性ddy小鼠OP/OP。未贴壁的G10传代细胞在含有15%胎牛血清、100 ng/mlRANKL、20 ng/mlGSF-1或100 ng/mlVEGF的α-MEM中培养。培养7d后，加入RANKL和血管内皮生长因子的骨髓细胞和脾细胞(Wt&OP)的TRAP阳性多核细胞(Wt&OP)明显小于RANKL和CSF-1组(P<0.05)，并出现吸收陷窝。Flt-1/Fc嵌合体和抗VEGF抗体可抑制RANKL和VEGF诱导的破骨细胞分化，但中和抗CSF-1受体抗体不能抑制其诱导的破骨细胞分化。用抗Flt-1抗体免疫细胞化学方法检测破骨细胞及其前体细胞中Flt-1的表达，但不检测Flk-1的表达。这些结果提示，在破骨细胞分化和骨吸收系统中，血管内皮生长因子和脑脊液-1具有重要作用。

Vascular endothelial growth factor (VEGF) is a key mediator of physiological angiogenesis. This cytokine binds to two cell surface receptors which are encoded by flt-1 or flk-1/KDR that also belong to the tyrosine kinase receptor family. Only the Flt-1 is expressed on macrophage monocyte lineage. In the present study, we investigated that whether the effect of VEGF treatment on the osteoclast differentiation in vitro. Bone marrow cells and spleen cells were obtained from 5-to 8-week-old male ddy miceor op/op mice. Non adherent G10-passed cells were cultured in & alpha-MEM with 15% FBS, 100 ng/ml RANKL, 20 ng/ml GSF-1 or 100 ng/ml VEGF. After culture for 7 days, smaller size of TRAP positive multinucleated cells were observed in the presence of RANKL and VEGF from bone marrow cells and spleen cells(Wt & op), as well as resorption pits were found than that of in the presence of RANKL and CSF-1. Treatment with Flt-1/Fc chimera, and anti VEGF antibody inhibit the RANKL and VEGF-induced osteoclast differentiation but neutralizing anti-CSF-1 Receptor antibody did not. In addition, Flt-1 was detected by immunocytochemical study with anti-Flt-1 antibody but not Flk-1 on osteoclast and its precursors. These results suggest that VEGF has important role in osteoclast differentiation and bone resorption system as well as CSF-1.