小口径生物型人工血管移植后的血管壁重构

背景：人工血管相对人体血管最大的优势就是来源丰富，经过生物化改造的人工血管，其特性更接近人体血管，移植后自体化程度也较高。 目的：观察新型小口径生物型人造血管移植后1.5年内不同时期实验犬的生存、生活状况，移植材料的组织相容性、移植血管壁重构的组织病理学变化。 方法：以猪血管为基材，经交联固定，多方位去抗原，共价结合肝素，以及偶联可黏附、富集生长因子的特定多肽等系列生化处理而制成的一种高抗凝的人造血管，管径3.5~4.5 mm。建立犬颈总动脉-人造血管端端连续缝合的动物模型，1.5年内不同时期切取标本，做病理组织学检查。 结果与结论：切取标本发现，移植血管与周围组织粘连少、疏松。病理组织学检查：移植后8周，镜下开始发现宿主组织通过人造血管孔隙长入血管腔内参与移植血管新内膜的形成，移植后12周，镜下于吻合口处，可见新内膜表面有不连续的内皮细胞生长，移植后6个月，通畅的人造血管整段管腔内面均可见内皮细胞生长。移植后12个月，移植血管管壁VG染色尚可见支架层内有大量胶原纤维和毛细血管生长，原先的支架结构已部分被宿主血管壁组织取代。移植后18个月，原先的支架结构已大部分被宿主血管壁组织取代。说明新型小口径生物型人造血管新内膜形成早且完整，自然内皮化相对满意，血管壁重构和血管支架的再生能力强，生物相容和稳定性好。

Experiment study of vessel wall reconstruction after a novel biological small-diameter vascular graft

BACKGROUND:Compared with human vessels, vascular prosthesis has the greastest advantage for its rich source. Besides, its characteristics are similar to the human vessel, and vascular prosthesis has high histocompatibility after graft. OBJECTIVE: To observe the survival and life status, graft histocompatibility and histopathological changes of the reconstructed vascular wall in experimental dogs within eighteen months following the implantation of biological small-diameter vascular graft. METHODS:By crosslinking fixation, removing antigen, covalent bonding with heparin and coupling with specific polypetide capable of sticking and enriching growth factors, a kind of highly anticoagulant biological artificial vessel with the diameter of 3.5 to 4.5 mm was prepared. Artificial vascular grafts were implanted end-to-end by a continuous suture in the common carotid artery of the experimental dogs. Sample procedure was performed at different time for postoperative eighteen months, for histopathological examination. RESULTS AND CONCLUSION:Only a little adhesion between the artificial artery and the surounding tissue was found during sampling procedure. Eight weeks after grafting, the host tissue penetrated the poros of grafts and protruded into the lumen, forming the neointima of the graft vessel. Twelve weeks after grafting, endothelial cells were sparsely distributed throughout the neointima near the stoma. Six months after grafting, endothelial cells were present on the whole surface of the patent graft lumen. Twelve months after grafting, VG staining of the graft wall revealed that the graft stent had been replaced by a large amount of newly grown collagen fibers and blood capillaries. The previous graft stent was partly replaced by the host vascular tissue. Eighteen months after grafting, the previous graft stent was mostly replaced by the host vascular tissue. All of the above proves that the novel biological small-diameter vascular graft has early and intact formation of the neointima with strong capacity of vessel wall reconstruction and intravascular stent regeneration, taken together with the good biocompatibility and stability.