Bone morphogenetic proteins stimulate angiogenesis through osteoblast-derived vascular endothelial growth factor A
Bone morphogenetic proteins stimulate angiogenesis through osteoblast-derived vascular endothelial growth factor A
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DOI：
10.1210/en.143.4.1545
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发表时间：
2002-04-01
期刊：
影响因子：
4.8
通讯作者：
Löwik, CWGM
中科院分区：
文献类型：
--
作者：
Deckers, MML;van Bezooijen, RL;Löwik, CWGM
在骨形成和骨折愈合过程中，内皮细胞和成骨细胞之间存在串扰。我们之前表明，血管内皮生长因子 A (VEGF-A) 可能是这种串扰中的一个重要因素，因为成骨细胞样细胞以分化依赖性方式产生这种血管生成因子。此外，外源添加的 VEGF-A 可增强成骨细胞分化。在本研究中，我们研究了血管生成和骨形成之间的耦合，骨形态发生蛋白（BMP）是否通过产生 VEGF-A 来刺激成骨细胞生成和血管生成。为此，我们使用了在体外形成矿化结节的小鼠前成骨细胞样细胞系 KS483，以及包含能够在体外形成管状结构的 17 日龄胎鼠骨外植体的血管生成测定。用 BMP-2、-4 和 -6 处理 KS4S3 细胞增强了结节形成、骨钙素 mRNA 表达以及培养 18 天后的矿化。在整个培养期间，伴随着 VEGF-A 蛋白水平的剂量依赖性增加。然而，BMP 诱导的成骨细胞分化独立于 VEGF-A，因为通过 VEGF-A 抗体或 VEGF 受体 2 酪氨酸激酶抑制剂阻断 VEGF-A 活性并不影响 BMP 诱导的矿化。 为了研究 BMP 是否通过 VEGF-A 刺激血管生成，测定了 BMP 的血管生成活性。用 BMP 处理骨外植体可增强血管生成。这是可溶性 BMP 受体 1A 或 noggin 抑制的。在 VEGF-A 抗体存在的情况下，未刺激的和 BMP 刺激的血管生成均被抑制。用 BMP 处理的 KS483 细胞的条件培养基也诱导了强烈的血管生成反应，该反应被抗小鼠 VEGF-A 阻断，但不被 noggin 阻断。这些作用是 BMP 特有的，因为 TGFbeta 抑制成骨细胞分化和血管生成，同时刺激 VEGF-A 产生。这些发现表明，BMP 通过成骨细胞产生 VEGF-A 来刺激血管生成。总之，成骨细胞响应 BMP 产生的 VEGF-A 不参与成骨细胞分化，但将血管生成与骨形成耦合。
During bone formation and fracture healing there is a crosstalk between endothelial cells and osteoblasts. We previously showed that vascular endothelial growth factor A (VEGF-A) might be an important factor in this cross-talk, as osteoblastlike cells produce this angiogenic factor in a differentiation-dependent manner. Moreover, exogenously added VEGF-A enhances osteoblast differentiation. In the present study we investigated, given the coupling between angiogenesis and bone formation, whether bone morphogenetic proteins (BMPs) stimulate osteoblastogenesis and angiogenesis through the production of VEGF-A. For this we used the murine preosteoblast-like cell line KS483, which forms mineralized nodules in vitro, and an angiogenesis assay comprising 17-d-old fetal mouse bone explants that have the ability to form tube-like structures in vitro.Treatment of KS4S3 cells with BMP-2, -4, and -6 enhanced nodule formation, osteocalcin mRNA expression, and subsequent mineralization after 18 d of culture. This was accompanied by a dose-dependent increase in VEGF-A protein levels throughout the culture period. BMP-induced osteoblast differentiation, however, was independent of VEGF-A, as blocking VEGF-A activity by a VEGF-A antibody or a VEGF receptor 2 tyrosine kinase inhibitor did not affect BMP-induced mineralization.To investigate whether BMPs stimulate angiogenesis through VEGF-A, BMPs were assayed for their angiogenic activity. Treatment of bone explants with BMPs enhanced angiogenesis. This was inhibited by soluble BMP receptor 1A or noggin. In the presence of a VEGF-A antibody, both unstimulated and BMP-stimulated angiogenesis were arrested. Conditioned media of KS483 cells treated with BMPs also induced a strong angiogenic response, which was blocked by antimouse VEGF-A but not by noggin. These effects were specific for BMPs, as TGFbeta inhibited osteoblast differentiation and angiogenesis while stimulating VEGF-A production.These findings indicate that BMPs stimulate angiogenesis through the production of VEGF-A by osteoblasts. In conclusion, VEGF-A produced by osteoblasts in response to BMPs is not involved in osteoblast differentiation, but couples angiogenesis to bone formation.