兔动静脉短路环法诱导组织工程骨支架材料血管生成的初步研究

Inducing angiogenesis at tissue engineered bone scaffold by an arteriovenous loop in rabbits

目的通过比较动静脉短路环（AV环）和动静脉束（AV束）植入珊瑚后诱导血管新生的程度，探讨构建带血管蒂的组织工程骨支架材料动物模型的可行性。方法新西兰兔36只，解剖分离出左侧股静脉和股动脉及胭动脉分支。AV环组（A组）将胭动脉和股静脉末端切断，近心端行血管端端吻合，形成动静脉短路环，环绕套入天然珊瑚块的侧槽中。AV束组（B组）股动静脉血管束保持血流通畅，不切断，动静脉分开套入珊瑚块的两边侧槽中。植入体外加ePTFE膜包裹隔绝，固定于大腿皮下。2、4、6周行标本的墨汁灌注和血管铸型，墨汁灌注后珊瑚脱钙、HE染色、组织学观察，分析珊瑚孔隙中组织结构和血管新生情况，计数每份标本的平均血管密度，血管密度做计量统计学分析；血管铸型标本行大体解剖和腐蚀后血管分布等观察，了解血管与珊瑚的关系，以及新生血管程度和来源。结果珊瑚植入体内后表面和深部有大量纤维血管样组织生长。墨汁灌注显示血管广泛分布在珊瑚表层和间隙内，结构成熟，4周已贯穿珊瑚块的全层。2、4、6周血管密度逐渐加大，A组（2周276．6±4．67；4周517．20±10．66，6周707．00±11．87）较B组（2周153．60±7．16，4周269．40±6．80，6周279．20±6．53）血管生成密度更大，差异有统计学意义（P〈0．01）。血管铸型显示A组血管环周边和珊瑚表层充满小血管，B组血管明屈稀疏。腐蚀铸型显示A组血管环动静脉段芽生和伴行有丰富的小血管，在入口处形成网状结构，并相互吻合；B组主干动脉血管无发芽新生血管，仅有周边伴行的部分小血管长入。结论AV环方法和AV束方法均可以促进珊瑚的血管化，前者诱导血管新生的能力更强。

Objective To compare the effects of 2 vascular carriers, arteriovenous loop and arteriovenous bundle, on inducing angiogenesis in coral scaffold of vaseularized tissue-engineered bone in animal models. Methods Thirty-six adult male New Zealand rabbits were randomized into 2 even groups. In group A, an arteriovenous loop （AVL） was formed by microsurgical anastomosis at the proximal ends between the femoral popliteal artery and vein, and placed in the circular side groove of the coral block （6 mm × 8 mm × 10 mm） . In group B, flow-through vessels bundles of both femoral artery and vein were placed in the side grooves of the coral block. All the implants in 2 groups were wrapped by a micro-porous expanded-polytetrafluoroethylene （ePTFE） membrane, and fixed subcutaneously by suturing. Evaluation methods included gross morphological observations, histological examinations, India ink perfusion and vascular casting after 2, 4, 6 weeks. The density of blood vessels was analyzed by the statistical software SPSS 10.0. Results All the corals were encased by newly formed fibrovascular tissues in 2 groups. Ink-stained vessels distributed the surfaces and side grooves, and invaded the interspaces of corals. The degree of vascularization increased over the course of experiment. Blood vessel density demonstrated a significant continuous increase between 2 and 6 weeks after implantation in group A. The mean value of blood vessel density in group A （2 weeks 276.60 ±4.67, 4 weeks 517.20 ±10. 66, 6 weeks 707.00 ±11.87） was significantly higher than in groupB （2 weeks 153.60 ±7.16, 4weeks269.40±6.80, 6 weeks 279.20±6.53） （P 〈0.01）. Vascular casting showed that in group A, significant blood vessels sprouted from all areas of the loop, especially at the entrance of the arteriovenous pedicle where the small tubes were densely interconnected. In group B, however, no blood vessels sprouted from the arteriovenous bundles and only some small vessels grew from the entrance and exit. Conclusions A vascularized coral model can be constructed by inserting an arteriovenous loop or an arteriovenous bundle, useful in vascular bone tissue engineering. The former, however, have stronger abilities to induce angiogenesis than the latter.