改造天然生物组织为血管支架材料的预处理方法

Methods for the Pre-treatment of Biological Tissues for Vascular Scaffold

目前 ,临床对血管替代物的需求量越来越大 ,传统的来源已不能满足需要。组织工程化血管的出现使得这一问题有望得到解决。构建组织工程化血管就必然涉及血管支架的预制。生物支架材料是血管支架中的一大类 ,它在细胞黏附及促细胞生长等方面优于人工合成的支架材料。由于生物性材料自活体取出后即开始降解 ,同时不同材料间也存在着种群差异 ,不宜保存和直接应用 ,故需采用一些预处理方法来解决这些问题 ,预处理目的就是在移植生物性材料前 ,降低其抗原性、提高其抗酶降解能力 ,并较长时间地保持其良好的力学性能和组织结构。这些处理方法包括运用戊二醛、多聚环氧化合物、碳化二亚胺、京尼平及原花色素等化学试剂进行交联的化学方法和应用光氧化等进行交联的物理方法。本文详细地叙述了各种预处理方法的机理及相应各种材料处理前后免疫原性、生物稳定性、力学性能、细胞毒性、抗钙化能力等特性的变化 ,并对各种方法的优缺点做一简要的评述。总之 ,生物性材料预处理的发展趋势是继续深入研究和开发细胞毒性小的天然交联剂 。

Today, the blood vessel substitutes are in large demand for coronary and peripheral bypass procedures, and the demand cannot be met by conventional sources. This problem will be solved by applying tissue-engineered blood vessel in clinics. The prefabrication of vascular scaffold will be involved in engineering a blood vessel substitute. Biological tissues are important biomaterials fabricating vascular scaffold which can offer better constructs for adhesion and growth of cells onto synthetic materials. Because of immediate degradation of biological tissues obtained from the abattoir, cadaver or patient and the presence of antigenicity in allogenic or xenogenic tissues, the fresh biological tissues can not directly be preserved and applied. The use and preservation of these natural biomaterials have typically required pre-treatment aimed at (1) reducing the antigenicity of the materials, (2) enhancing the resistance of the materials to enzymatic degradation, (3) stabilizing the structure of the tissues and maintaining their mechanical properties. Physical and chemical methods for the pre-treatment of biological tissues are available. The predominant chemical agents that have been investigated for the pre-treatment of biological tissues for vascular scaffold are glutaraldehyde, polyepoxy compound, carbodiimide, genipin and proanthocyanidin. Typical and particularly promising physical pre-treatment of biological tissues for vascular scaffold is dye-mediated photooxidation. The crosslinking mechanisms of all classes of pre-treatments and the effects of pre-treatments on antigenicity, biostability, mechanical properties, cytoxicity and calcification of treated tissues are described in this article. The advantages and disadvantages of all pre-treatments are also reviewed. The trend of pre-treatment of biological tissues is to investigate and exploit the naturally occurring crosslinking reagent with less cytoxicity. Meanwhile, dye-mediated photooxidation crosslink is also a promising pre-treatment which should be widely applied in vascular scaffold.