Temporal and Spatial Vascularization Patterns of Unions and Nonunions: Role of Vascular Endothelial Growth Factor and Bone Morphogenetic Proteins
Temporal and Spatial Vascularization Patterns of Unions and Nonunions: Role of Vascular Endothelial Growth Factor and Bone Morphogenetic Proteins
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DOI：
10.2106/jbjs.j.00795
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发表时间：
2012-01-04
影响因子：
5.3
通讯作者：
Menger, M. D.
中科院分区：
文献类型：
--
作者：
Garcia, P.;Pieruschka, A.;Menger, M. D.
背景：骨折愈合失败合并骨不连是一个主要的临床问题。血管生成与骨再生密切相关，但血管生成在骨不连形成中的作用尚不清楚。由于已建立的骨不连有良好的血管化，我们假设骨折愈合早期缺乏血管内皮生长因子(VEGF)的表达和血管形成决定了骨不连的形成。方法：在72只CD-1小鼠上，建立了间隙为1.80 mm(骨不连组)和间隙为0.25 mm(愈合组)的股骨截骨术，并用针夹技术进行固定。分别于术后3、7、14、21、28和70天通过显微计算机断层扫描和组织形态计量学分析愈合情况。用免疫组织化学方法检测不同愈合区的血管生成情况。术后7天、14天、21天取材，用Western印迹分析血管内皮生长因子、骨形态发生蛋白-2和骨形态发生蛋白-4的表达。结果：显微计算机断层扫描和组织形态计量学显示骨折愈合组动物完全骨桥接，而骨不连组动物出现萎缩性骨不连形成。两组血管形成从第3天到第7天增加，14天后减少。然而，在工会和非工会之间，加班后的整体血管形成并无差异。有趣的是，14天后骨内膜愈合区的血管形成在骨不连中甚至比愈合中更高。结论：骨不连愈合失败后，骨折愈合早期的血管生成并未受到损害，骨不连形成骨不连不是由于血管生成的失败所致。骨折愈合失败与BMP-2和BMP-4表达减少以及血管生成和成骨生长因子的比例失调有关，这可能是导致骨不连的原因。
Background: Failure of fracture-healing with nonunion is a major clinical problem. Angiogenesis is closely linked to bone regeneration, but the role of angiogenesis in nonunion formation remains unclear. Because established nonunions are well vascularized, we hypothesized that lack of vascular endothelial growth factor (VEGF) expression and vascularization during the early time course of fracture-healing determine nonunion formation.Methods: In seventy-two CD-1 mice, a femoral osteotomy with a gap size of 1.80 mm (nonunion group) or a gap size of 0.25 mm (union group) was created and stabilized by a pin-clip technique. Healing was analyzed after three, seven, fourteen, twenty-one, twenty-eight, and seventy days by micro-computed tomography and histomorphometry. Vascularization was determined in different healing zones by immunohistochemical staining of PECAM-1 (platelet-endothelial cell adhesion molecule). Additional animals were analyzed after seven, fourteen, and twenty-one days with Western blot analysis of VEGF, bone morphogenetic protein (BMP)-2, and BMP-4 expression.Results: Micro-computed tomography and histomorphometry showed complete bone-bridging in the union group, whereas animals in the nonunion group showed atrophic nonunion formation. Vascularization increased from day 3 to day 7 in both groups, with a subsequent decrease after fourteen days. However, overall vascularization did not differ between unions and nonunions overtime. It is of interest that vascularization within the endosteal healing zone was even higher in nonunions than in unions after fourteen days. Expression of VEGF was significantly higher in nonunions, while expression of BMP-2 and 4 and proliferating cell nuclear antigen were found significantly reduced compared with unions.Conclusions: Because vascularization during the early time course of fracture-healing was not impaired despite the failure of bone-healing in nonunions, we rejected our hypothesis and accepted the null hypothesis that nonunion formation is not due to failure of VEGF-mediated angiogenesis. Failure of fracture-healing was associated with a decreased expression of BMP-2 and 4 and a disturbed ratio of angiogenic to osteogenic growth factors, which may be responsible for nonunion.