小口径人造血管的研究

本文概述了人造血管材料的发展历程,指出目前的组织工程学研究为小口径人造血管材料提供了极好的发展机会,天然可降解高分子材料是用于小口径血管材料组织工程学研究的重点。     

组织工程血管种子细胞研究现状

随着开始步入老年化社会，心血管疾病的发病率逐年增高，严重威胁到人们的生活质量。而心血管外科需要各种直径的血管移植修复物作为修补材料。目前，临床上常用的组织修复途径大致有3种：即自体组织移植，异体组织移植或人工合成材料。这3种方法都存在不足，如供体不足，免疫排斥反应，管腔易狭窄，血栓易形成及不适合替代小口径血管等。因此随着近年组织工程学的进展，利用组织工程学的方法构建良好血管替代物的血管组织工程学成为了研究热点。理想的人工血管是利用组织工程技术，将活细胞种植到血管支架上，制造出一种与受体组织相容性好、无免疫原性、无致血栓形成、无感染、有活力、耐久性长、可塑性好及具有对周围环境生化信号和各种生长因子起反应活性的生物血管。这种理想的血管不但具有自我修复自我更新能力，移植后能维持管腔的长期通畅，而且具有增长能力适应成长的患儿，从而发挥一个功能完整健康的血管，可提高移植血管的长期疗效。组织工程化血管研究目前已经取得了较大的进展，主要涉及3个方面：细胞外基质替代物的研究；种子细胞制取、培养、种植的研究；组织工程化血管临床应用的研究。     

聚四氟乙烯纳米化新型小口径人造血管及其通畅率研究

目的 研究应用内表面覆盖多壁碳纳米管（MWNT）的聚四氟乙烯（PTFE）新型人造血管（PTFE-MWNT）对提高血管通畅率、减轻内膜增生的影响.方法 将MWNTs通过羧酸化及氨基化处理,分别得到功能化的MWNTs-COOH和MWNTs-NH2,然后在PTFE血管内表面层层自组装制成PTFE-MWNT人造血管.动脉模型选用羊股动脉血管移植.16只成年公绵羊,两侧股动脉随机选用两种不同的人造血管.8只于术后3个月,另外8只于术后9个月取下双侧人造血管标本进行组织学分析.统计方法采用配对t检验.结果 PTFE-MWNT血管术后通畅率（87.5%）高于PTFE血管（62.5%）,内膜增生程度较PTFE血管轻,血管内皮形成速度要快于PTFE人造血管,血管壁内的炎细胞浸润较轻;而PTFE人造血管壁内主要是炎细胞浸润,细胞增殖程度高于PTFE-MWNT人造血管.结论 用多壁碳纳米管覆盖聚四氟乙烯的内表面制成的新型人造血管,可以提高移植血管通畅率,减轻内膜增生,提高小口径人造血管移植手术的长期效果.     

人造血管透析通路的建立及其临床应用

对于因自身血管条件差或其它原因而不能建立理想自身血管内瘘的维持性血透患者，我们采用聚甲氟乙烯人造血管（ｐｏｌｙｔｅｒｔｒａｆｌｕｏｒｏｅｔｈｙｌｅｎｅ）为这类患者建立了永久性动静脉血管透析通路，并应用于临床取得满意效果。人造血管内瘘具有组织相容性好、通畅率高、血流量大、穿刺方便和使用时间长等特点。     

脱细胞脐血管在组织工程血管中的研究进展

随着心血管疾病患病率的增加,心血管外科临床上将需要大量血管替代物。由合成材料制造的大口径人工血管（直径〉10mm）已经应用于临床,而小口径血管（直径≤5mm）移植入人体内易发生吻合口处内膜增生和血栓形成,中远期通畅率不佳。所以研制出1种新型的小口径人工血管已成为目前的研究热点。组织工程血管,具有自我修复和重塑的潜能,提高了远期通畅率,有较好的应用前景。     

股-腘动脉人造血管旁路移植的手术护理配合

动脉硬化闭塞症是一种慢性退行性血管炎症性病变.病变一般呈全身性疾患,好发于某些大中型动脉,血管因内膜损伤,脂质浸润等原因而使变狭窄,以至完全闭塞,肢体末段组织产生缺血性坏死.股-胭动脉人造血管旁路移植手术是将病人的股动脉和膝下胭动脉之间用PTFE人造血管架设一座"桥梁",让血管可以绕过闭塞的股浅动脉灌注小腿以下的组织,从而改善足部缺血组织的血运状况.现将手术护理配合情况总结探讨如下:     

冠状动脉旁路移植术中全生物化组织工程血管的构建

由于自体血管有限，组织工程血管在冠状动脉旁路移植术中有着重要的临床应用价值。目前的人工血管及非生物体材料的组织工程血管在构建小口径血管方面效果不理想，而全生物化组织工程血管与机体正常血管结构功能相似，有良好的机械性能，可自我更新，且避免了排斥反应、降低了感染率，有利于提高远期通畅率。本文对全生物化组织工程血管的研究进展和在冠状动脉旁路移植术中的应用前景作一综述。     

疑难血管下肢人造血管内瘘血液透析的护理

我国维持性血液透析患者的数量日益增多,而糖尿病、老年、长期透析使血管耗竭的问题也日益突出。有效的血管通路是血液透析患者的生命线。由于自身血管条件的限制,人造血管因与组织相容性较好,已成为血管代用品。我科收治了一例有罕见复杂血管条件的患者,因深静脉多发血栓,行股动、静脉人造血管移植搭桥手术后予以透析治疗。     

冠状动脉旁路移植术中全生物化组织工程血管的构建

由于自体血管有限,组织工程血管在冠状动脉旁路移植术中有着重要的临床应用价值.目前的人工血管及非生物体材料的组织工程血管在构建小口径血管方面效果不理想,而全生物化组织工程血管与机体正常血管结构功能相似,有良好的机械性能,可自我更新,且避免了排斥反应、降低了感染率,有利于提高远期通畅率.本文对全生物化组织工程血管的研究进展和在冠状动脉旁路移植术中的应用前景作一综述.     

真丝人造血管移植后愈合过程的病理学研究

对30条犬的胸主动脉或腹主动脉移植一段真丝人造血管后24小时～13个月,分期处死,进行病理形态学观察。结果显示,人造血管的管腔面内衬内皮和平滑肌两种细胞。本文对上述两种细胞的来源、形态特点以及人造血管的新内、外膜形成过程等方面进行了讨论。     

The ideal small arterial substitute: Role of cell seeding and tissue engineering

Although autogenous vessels are useful in surgery, often patients cannot furnish suitable vessels. If there are not available, two possible alternatives for vessel replacements are to use vascular synthetic prostheses such as Dacron((R)) and polytetrafluoroethylene (PTFE) or cryopreserved allografts. However, their success has been limited to replace small-diameter (<6 mm) arterial vessel because of their high thrombogenicity and compliance mismatch. On account of a clear clinical need for a functional arterial substitute, tissue engineering techniques have been developed. This review encompasses the use of mature endothelial, endothelial progenitor and bone marrow cells combined with natural or synthetic scaffolds whose surface has been modified with multiple origin matrices.     

Silk Vascular Grafts with Optimized Mechanical Properties for the Repair and Regeneration of Small Caliber Blood Vessels

As the incidence of cardiovascular diseases has been growing in recent years, the need for small-diameter vascular grafts is increasing. Considering the limited success of synthetic grafts, vascular tissue engineering/repair/regeneration aim to find novel solutions. Silk fibroin (SF) has been widely investigated for the development of vascular grafts, due to its good biocompatibility, tailorable biodegradability, excellent mechanical properties, and minimal inflammatory reactions. In this study, a new generation of three-layered SF vascular scaffolds has been produced and optimized. Four designs of the SILKGraft vascular prosthesis have been developed with the aim of improving kink resistance and mechanical strength, without compromising the compliance with native vessels and the proven biocompatibility. A more compact arrangement of the textile layer allowed for the increase in the mechanical properties along the longitudinal and circumferential directions and the improvement of the compliance value, which approached that reported for the saphenous and umbilical veins. The higher braid density slightly affected the grafts’ morphology, increasing surface roughness, but the novel design mimicked the corrugation approach used for synthetic grafts, causing significant improvements in kink resistance.     

组织工程心脏瓣膜研究近况

目前临床使用的人工心脏瓣膜不论是机械瓣还是生物瓣 ,都有其自身无法克服的缺点 ,因而影响了瓣膜的耐久性和远期疗效。随着组织工程学的兴起 ,构建组织工程心脏瓣膜的研究已取得了初步进展。本文综述近年来组织工程心脏瓣膜研究进展情况 ,并从基质材料、种植细胞及动物实验各方面探讨构建组织工程心脏瓣膜的必要性、可行性及前景。     

Tissue engineering of small-diameter vascular grafts: a literature review

For the treatment of cardiovascular disease, functional arterial blood vessel prostheses with an inner diameter less than 6 mm are needed. This article gives an overview of the preparation of such vascular grafts by means of tissue engineering.     

Small-diameter artificial arteries engineered in vitro

Although the need for a functional arterial replacement is clear, the lower blood flow velocities of small-diameter arteries like the coronary artery have led to the failure of synthetic materials that are successful for large-diameter grafts. Although autologous vessels remain the standard for small diameter grafts, many patients do not have a vessel suitable for use because of vascular disease, amputation, or previous harvest. As a result, tissue engineering has emerged as a promising approach to address the shortcomings of current therapies. Investigators have explored the use of arterial tissue cells or differentiated stem cells combined with various types of natural and synthetic scaffolds to make tubular constructs and subject them to chemical and/or mechanical stimulation in an attempt to develop a functional small-diameter arterial replacement graft with varying degrees of success. Here, we review the progress in all these major facets of the field.     

Antithrombogenic property of bone marrow mesenchymal stem cells in nanofibrous vascular grafts

Nanostructured biomaterials have tremendous potential for tissue engineering. However, the performance and integration of the nanomaterials in vivo are not well understood. A challenge in vascular tissue engineering is to develop optimal scaffolds and establish expandable cell sources for the construction of tissue-engineered vascular grafts that are nonthrombogenic and have long-term patency. Here, we used tissue-engineered vascular grafts as a model to demonstrate the potential of combining nanofibrous scaffolds and bone marrow mesenchymal stem cells (MSCs) for vascular tissue engineering. Biodegradable nanofibrous scaffolds with aligned nanofibers were used to mimic native collagen fibrils to guide cell organization in vascular grafts. The results from artery bypass experiments showed that nanofibrous scaffolds allowed efficient infiltration of vascular cells and matrix remodeling. Acellular grafts (without MSCs) resulted in significant intimal thickening, whereas cellular grafts (with MSCs) had excellent long-term patency and exhibited well organized layers of endothelial cells (ECs) and smooth muscle cells (SMCs), as in native arteries. Short-term experiments showed that nanofibrous scaffolds alone induced platelet adhesion and thrombus formation, which was suppressed by MSC seeding. In addition, MSCs, as ECs, resisted platelet adhesion in vitro, which depended on cell-surface heparan sulfate proteoglycans. These data, together with the observation on the short-term engraftment of MSCs, suggest that the long-term patency of cellular grafts may be attributed to the antithrombogenic property of MSCs. These results demonstrate several favorable characteristics of nanofibrous scaffolds, the excellent patency of small-diameter nanofibrous vascular grafts, and the unique antithrombogenic property of MSCs.     

组织工程血管移植在血液透析通路中的应用

目的:探讨组织工程血管移植应用于血液透析(HD)通路的可行性。方法:广泛查阅近期有关组织工程血管应用于HD通路的文献,对其动物模型及临床研究进行总结评价。结果:分层构建法可获得具有足够机械强度的组织工程血管。此后出现的简化分层构建组织工程血管在一系列动物模型及临床实验中被证明可用于动静脉通路的建立。近期一种生物反应器构建组织工程血管在狒狒模型上进行动静脉搭桥试验也获得成功,有望成为较理想的动静脉内瘘移植血管。结论:组织工程血管移植应用于HD通路是可行的,值得进一步研究。     

心脏瓣膜组织工程研究新进展

瓣膜置换术是目前临床上治疗心脏瓣膜病的最终手段。但临床应用的各种人工心脏瓣膜在持久性和远期疗效上,都存在着难以克服的缺陷。而随着组织工程技术的发展,组织工程瓣膜以良好的组织相容性、经久耐用且具有生物活性等多方面的优势而成为近年来心脏外科领域的研究热点之一。现综述了近年来国外组织工程心脏瓣膜在瓣膜材料、培养方式及种子细胞等方面的最新进展并展望了该领域的研究未来。     

In vitro endothelialized ePTFE prostheses: clinical update 20 years after the first realization

The replacement of arteries with synthetic vascular prostheses often leads to failure when small-diameter or low-flow locations are concerned, due in part to the thrombogenicity of the graft surface. In order to improve long-term patency of these grafts, the concept of endothelial cell seeding has been suggested, the composite structure resulting from the combination of biologically active cells to prosthetic materials thus creating more biocompatible vascular substitutes. To achieve endothelialization of synthetic grafts, previous efforts aimed at "one-stage" procedure in the 1980's seemed clinically feasible but results of reported clinical trials were controversial and mostly disappointing. An alternative method is an in vitro complete and preformed endothelial lining at the time of implantation: the "two-stage" procedure which implies harvest and culture of autologous endothelial cells. Up to date, the latter approach demonstrated its superiority in terms of significantly increased patency of the grafts that underwent endothelialization several years earlier.