基于多肽修饰和孔结构设计的新型小口径人工血管研究
发布时间：2018-11-13 13:35
【摘要】：心血管疾病已经成为世界上致死率和发病率最高的疾病之一,目前全球有超过30%的患者因心血管疾病而死亡。人工血管介入治疗和血管搭桥手术是如今临床上普遍使用的治疗手段。由于血管狭窄严重或血管病变,在许多情况下不适合支架植入,血管搭桥手术常常受到自体血管来源不足的限制。随着组织工程的发展,人工血管已经成为研究的热点。目前,已经有商品化的大口径人工血管应用于临床治疗,且移植后长期通畅率较高；但是由于容易堵塞或内膜增生,还没有理想的小口径人工血管(6mm)可应用于临床治疗。本论文采用原位诱导人工血管在体内快速内皮化的思路,以期解决小口径人工血管长期通畅性问题,并结合血管材料的结构设计,促进血管体内重构过程,为构建理想的小口径人工血管奠定基础。 研究证明,聚己内酯(PCL)由于生物惰性和较慢的降解速度限制了其作为人工血管材料的应用,而含有精氨酸-甘氨酸-天冬氨酸(RGD)的多肽的修饰可以促进内皮细胞(EC)的迁移、粘附和增殖。因此,本文发明了多种方法在PCL支架表面修饰RGD多肽。首先,通过引入2-氰基苯并噻唑(CBT)和D-半胱氨酸的缩合反应成功地在PCL支架表面共价修饰了RGD多肽衍生物,这是一种新的化学选择性连接作用,反应条件温和、收率高、无需催化剂,具有良好的生物相容性。研究结果证明这种方法是安全而便捷的,可有效改善PCL支架表面的亲水性和细胞相容性。 再则,创新性地发展了一种可以在生理条件下进行的温和的表面涂覆技术,利用“表面诱导自组装”在PCL支架材料表面修饰Nap-FFGRGD多肽,该两亲性多肽分子可在疏水纤维表面自组装,形成稳定的生物活性涂层。修饰后的PCL支架在体外可抑制血小板聚集,促进EC的粘附、铺展和增殖。在植入兔颈动脉后,该多肽的修饰改善了PCL人工血管的通畅性,抑制了血栓基质的沉积,同时显著促进了内皮化进程和平滑肌再生。此外,通过对Nap-FFGRGD分子抑制血小板聚集机理的研究,作者证明了Nap-FFG可能是通过某种未知的配体-受体相互作用与血小板结合,并在血小板周围自组装形成纳米纤维,通过静电排斥作用抑制血小板聚集。因此,凝胶分子Nap-FFGRGD在PCL支架表面的修饰能够同时实现原位诱导人工血管在体内的抗凝血功能和快速内皮化。 但是修饰后的支架材料由于电纺纤维间较小的孔径限制了细胞浸润和微血管新生,不利于人工血管的长期重构。为此,本文结合电喷聚氧化乙烯(PEO)和电纺PCL技术制备了三层复合人工血管,中层为致孔层,孔径大约40-50μm。兔颈动脉移植结果表明三层PCL支架这种微米级孔和纳米纤维结合的结构显著促进了细胞浸润和微血管新生,有效改善了支架材料的降解、内皮化进程和平滑肌再生。此外,单核/巨噬细胞在人工血管重构过程中也发挥了重要的旁分泌作用。结果证明这是一种可应用于构建小口径人工血管的良好结构。 将构建的RGD修饰的人工血管应用于2型糖尿病大鼠体内移植研究。虽然该血管材料在正常大鼠体内再生效果良好,但是在2型糖尿病大鼠体内的重构明显变差,表现在血小板粘附增多,内皮化进程变缓,并伴有早期钙化和慢性炎症反应等方面。因此发展一种更好的小口径人工血管以改善其在糖尿病患者体内的再生是十分必要的,作者认为动物疾病模型是可以用于后续评价小口径人工血管体内表现的一种重要模型。 此外,本文创新性地合成了一氧化氮(NO)小分子水凝胶,具有酶控缓释NO的性质。NO的释放速率是恒定的,并且可以通过改变p-半乳糖苷酶的浓度进行调节。利用这种水凝胶对小鼠急性皮肤损伤治疗7天后显著促进了血管新生和伤口愈合。这种具有酶控缓释NO功能的新型小分子水凝胶在再生医学和组织工程领域将拥有巨大的应用前景。 综上所述,本论文从多肽修饰和结构设计两方面对小口径人工血管的构建进行了深入研究,构建了原位诱导体内重构的小口径人工血管,为制备理想的可临床应用的人工血管奠定了一定的基础。
[Abstract]:Cardiovascular disease has become one of the world's highest morbidity and morbidity, and more than 30% of the world's patients now die due to cardiovascular disease. Artificial blood vessel interventional therapy and vascular bypass surgery are currently widely used in clinical practice. Because of the severe or vascular stenosis of the vessel, in many cases it is not suitable for stent implantation, and the vascular bypass surgery is often limited by the insufficient source of the autologous blood vessel. With the development of the tissue engineering, the artificial blood vessel has become the hot spot of the research. At present, the commercial large-caliber artificial blood vessel has been applied to the clinical treatment, and the long-term patency rate after the transplantation is high; however, the small-caliber artificial blood vessel (6 mm), which is not ideal because of being easy to block or hyperplasia, can be used for clinical treatment. In order to solve the problem of long-term patency of the small-caliber artificial blood vessel, and to combine the structural design of the vascular material and promote the in-vivo reconstruction of the artificial blood vessel, the paper lays the foundation for the construction of the ideal small-caliber artificial blood vessel. Studies have shown that polycaprolactone (PCL) has limited its application as an artificial blood vessel material due to the biological inertia and the slower degradation, and the modification of the polypeptide containing arginine-glycine-aspartic acid (RGD) can promote the migration, adhesion and adhesion of the endothelial cells (EC), Thus, a variety of methods have been invented to modify the RGD on the surface of the PCL scaffold, Firstly, the RGD polypeptide derivative is successfully modified on the surface of the PCL scaffold by the condensation reaction of 2-cyanogen-based benzo-cyanophenyl (CBT) and D-cysteine, which is a new chemical selective connection effect, the reaction conditions are mild, the yield is high, The agent has a good biological phase. The results of the study show that the method is safe and convenient, and can effectively improve the hydrophilic and cellular phase of the surface of the PCL scaffold. In addition, a mild surface coating technique which can be carried out under physiological conditions is creatively developed, the Nap-FFGRGD polypeptide can be modified on the surface of the PCL support material by using the 鈥淪urface-induced self-assembly鈥，
本文编号：2329265
[Abstract]:Cardiovascular disease has become one of the world's highest morbidity and morbidity, and more than 30% of the world's patients now die due to cardiovascular disease. Artificial blood vessel interventional therapy and vascular bypass surgery are currently widely used in clinical practice. Because of the severe or vascular stenosis of the vessel, in many cases it is not suitable for stent implantation, and the vascular bypass surgery is often limited by the insufficient source of the autologous blood vessel. With the development of the tissue engineering, the artificial blood vessel has become the hot spot of the research. At present, the commercial large-caliber artificial blood vessel has been applied to the clinical treatment, and the long-term patency rate after the transplantation is high; however, the small-caliber artificial blood vessel (6 mm), which is not ideal because of being easy to block or hyperplasia, can be used for clinical treatment. In order to solve the problem of long-term patency of the small-caliber artificial blood vessel, and to combine the structural design of the vascular material and promote the in-vivo reconstruction of the artificial blood vessel, the paper lays the foundation for the construction of the ideal small-caliber artificial blood vessel. Studies have shown that polycaprolactone (PCL) has limited its application as an artificial blood vessel material due to the biological inertia and the slower degradation, and the modification of the polypeptide containing arginine-glycine-aspartic acid (RGD) can promote the migration, adhesion and adhesion of the endothelial cells (EC), Thus, a variety of methods have been invented to modify the RGD on the surface of the PCL scaffold, Firstly, the RGD polypeptide derivative is successfully modified on the surface of the PCL scaffold by the condensation reaction of 2-cyanogen-based benzo-cyanophenyl (CBT) and D-cysteine, which is a new chemical selective connection effect, the reaction conditions are mild, the yield is high, The agent has a good biological phase. The results of the study show that the method is safe and convenient, and can effectively improve the hydrophilic and cellular phase of the surface of the PCL scaffold. In addition, a mild surface coating technique which can be carried out under physiological conditions is creatively developed, the Nap-FFGRGD polypeptide can be modified on the surface of the PCL support material by using the 鈥淪urface-induced self-assembly鈥，
本文编号：2329265
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