血管内皮生长因子对珊瑚人工骨材料成骨作用的影响*☆○

背景：人工骨材料在大块骨缺损中常常无法发挥成骨作用，研究表明如果存在血供不足，骨缺损难以愈合。 目的：了解血管内皮生长因子（vascular endothelial growth factor，VEGF）质粒转染细胞对珊瑚人工骨材料成骨作用的影响。设计、时间及地点：随机对照动物实验，于2004-08/2007-06在德国海德堡大学附属骨科医院实验室完成。材料：应用6~9月龄雌性新西兰白兔24只制备桡骨骨缺损模型，并随机分为4组；自兔的骨髓分离培养骨髓基质干细胞，传代培养扩增；通过EndoFree Plasmid Giga 试剂盒扩增pVEGF165和pCR3.1的质粒。方法：将pVEGF165或pCR3.1质粒转染骨髓基质干细胞，将含有VEGF基因的质粒和VEGF基因重组的骨髓基质干细胞分别载入珊瑚人工骨材料，然后植入2组模型兔桡骨干中段15 mm的骨缺损内，另外2组植入载空白质粒或空白质粒转染的骨髓基质干细胞的珊瑚人工骨材料。主要观察指标：实验动物桡骨骨缺损内人工骨材料吸收速度，血管数目以及新形成的骨量。结果：VEGF重组的骨髓基质干细胞分泌足量VEGF超过1周；血管计数发现VEGF质粒和骨髓基质干细胞能促进血管生成，但体外转染VEGF的细胞疗效更显著；VEGF质粒或其转染的骨髓基质干细胞对珊瑚人工骨材料的吸收具有促进作用。结论：VEGF基因重组的细胞能够持续表达高于正常水平的VEGF，并且能够在一定程度上促进人工骨材料的吸收。

Influence of vascular endothelial growth factor on osteogenesis of coral bone substitute

BACKGROUND: Critical sized bone defects will not be healed only by filling bone graft substitutes, studies indicates that insufficient blood supply impedes bone healing. OBJECTIVE: To evaluate the influence of vascular endothelial growth factor (VEGF) plasmid transfected cells on the osteogenesis of coral bone substitute.DESIGN, TIME AND SETTING: A randomized controlled animal experiment was carried out in the laboratory centre of Orthopaedic Hospital Affiliated to Heidelberg University (Germany) from August 2004 to June 2007. MATERIALS: A total of 24 female New Zealand white rabbits, aged 6-9 months old, were created into animal model of radial bone defect, which was divided into four groups at random. Bone marrow derived stromal stem cells (BMSCs) were separated from bone marrow of the rabbits and cultured. EndoFree Plasmid Giga kit was used to produce plasmid DNA of pVEGF165 and pCR3.1. METHODS: BMSCs were transfected by phVEGF165 or pCR3.1 according to grouping. The coral bone substitute was taken as the scaffold, which was either coated with a control-plasmid DNA, coated with VEGF-plasmid DNA, loaded with BMSCs transfected with control plasmid or with both BMSCs and the VEGF plasmid. Scaffolds were implanted into in a rabbit radius critical size defect.MAIN OUTCOME MEASURES: Resorption rate of artificial bone in radial bone defects, number of vessels and new formed bone in the bone defects were all measured.RESULTS: The recombinant BMSCs secreted a sufficient quantity of VEGF for more than one week; VEGF plasmid and BMSCs could promote the vascularization, whereas the cells transfected with VEGF in vitro showed a significantly better effect; The resorption of natural coral bone substitute could be improved by VEGF plasmid or the transfected BMSCs.CONCLUSION: VEGF-recombinant cells may express VEGF in a continuous and highly productive manner, it also enhances the resorption of the coralline bone substitute.