Geiger Florian, Bertram Helge, Berger Irina, Lorenz Helga, Wall Olga, Eckhardt Christina, Simank Hans-Georg, Richter Wiltrud
Department of Orthopaedic Surgery, University of Heidelberg, Heidelberg, Germany.
J Bone Miner Res. 2005 Nov;20(11):2028-35. doi: 10.1359/JBMR.050701. Epub 2005 Jul 5.
Healing of fractures is dependent on vascularization of bone, which is in turn promoted by VEGF. It was shown that 0.1 and 1 mg of pVEGF165-GAM led to a significant increase in vascularization and bone regeneration in defects that would otherwise have led to atrophic nonunions.
One reason for lack of bone healing in nonunions is the absence of vascularization. In skeletogenesis, which is tightly linked to angiogenesis, vascular endothelial growth factor (VEGF) promotes the vascularization of the growth plate and transformation of cartilage to bone. We postulate that a gene-activated matrix (GAM), created with a plasmid coding for human VEGF165, coated on a collagen sponge could efficiently accelerate bone healing in large segmental defects.
Sixty New Zealand white rabbits received a 15-mm critical size defect on one radius, which was filled with either 0.1 or 1 mg plasmid-DNA as GAM. Radiographs were obtained every 3 weeks. After 6 or 12 weeks, animals were killed. New bone was measured by microCT scans. Vascularity was measured using anti-CD31 staining of endothelial cells in 18 regions of interest per implant.
Scaffold and control plasmid showed no defect healing, whereas most of the animals in the VEGF groups showed partial or total bone regeneration. Significantly more bone was found in the VEGF groups, with no significant differences between the 0.1- and 1-mg groups. Immunohistochemical staining of endothelial cells revealed that the VEGF groups showed two to three times the number of vessels and a significantly larger endothelial area after 6 weeks. Twelve weeks after surgery, the amount of vascularization decreased, whereas more new bone was detectable.
The rabbit critical size defect was appropriate in size to produce atrophic nonunions. We showed that angiogenesis and osteogenesis can be promoted by a VEGF165-GAM that is an appropriate tool to induce bone healing in atrophic nonunions.
骨折愈合依赖于骨的血管化，而血管内皮生长因子（VEGF）反过来又能促进骨的血管化。研究表明，0.1毫克和1毫克的质粒编码血管内皮生长因子165-基因激活基质（pVEGF165-GAM）可显著增加缺损部位的血管化和骨再生，否则这些缺损会导致萎缩性骨不连。
骨不连中骨愈合缺乏的一个原因是缺乏血管化。在与血管生成紧密相关的骨骼发生过程中，血管内皮生长因子（VEGF）促进生长板的血管化以及软骨向骨的转化。我们推测，用编码人VEGF165的质粒构建并包被在胶原海绵上的基因激活基质（GAM）能够有效加速大段骨缺损的愈合。
60只新西兰白兔的一侧桡骨制造一个15毫米的临界尺寸缺损，缺损处分别填充0.1毫克或1毫克作为GAM的质粒DNA。每3周拍摄X线片。6周或12周后处死动物。通过显微CT扫描测量新生骨。使用抗CD31抗体对每个植入物的18个感兴趣区域的内皮细胞进行染色来测量血管化程度。
支架和对照质粒组未见缺损愈合，而VEGF组的大多数动物出现部分或完全骨再生。VEGF组的新生骨明显更多，0.1毫克组和1毫克组之间无显著差异。内皮细胞的免疫组化染色显示，6周后VEGF组的血管数量增加了两到三倍，内皮面积显著增大。术后12周，血管化程度降低，但可检测到更多新生骨。
兔临界尺寸缺损的大小适合产生萎缩性骨不连。我们表明，VEGF165-GAM可促进血管生成和成骨，是诱导萎缩性骨不连愈合的合适工具。
