脂肪间充质干细胞分化为内皮细胞并体外构建组织工程心脏瓣膜

背景：组织工程心脏瓣膜是利用组织工程技术将种子细胞种植于瓣膜支架上所构建的一种人工瓣膜,目前国内外研究主要集中于种子细胞来源及支架选择上。 目的：探讨人脂肪间充质干细胞体外向内皮细胞诱导分化后的细胞作为种子细胞,脱细胞猪主动脉瓣膜作为支架体外构建组织工程心脏瓣膜的可行性。 方法：利用吸脂术采集脂肪组织,分离、培养脂肪间充质干细胞,流式细胞仪鉴定细胞表型;免疫细胞化学方法及RT-PCR检测细胞分化标志物;应用Triton X-100联合胰蛋白酶的方法制备脱细胞猪主动脉瓣支架,将体外培养扩增的诱导分化后的内皮细胞种植于支架上构建组织工程心脏瓣膜,光镜及电镜下观察组织工程心脏瓣膜的组织学结构。 结果与结论：脂肪组织分离培养的脂肪间充质干细胞向内皮细胞诱导分化后表达CD31、CD34、CD144、Ⅷ因子和内皮型一氧化氮合成酶等内皮细胞特异性抗原;脱细胞猪主动脉瓣膜支架脱细胞完全,弹力纤维及胶原纤维保持完整;构建的组织工程心脏瓣膜可见支架上排列连续的单细胞层。提示脂肪间充质干细胞在体外向内皮细胞诱导分化后已初步具有内皮细胞功能,在脱细胞猪主动脉瓣膜支架上生长良好,可以在体外初步构建组织工程心脏瓣膜。     

组织工程心脏瓣膜细胞生物学研究进展

由于现有的机械瓣和生物瓣仍存在种种不足，如不具备生长性、需抗凝、易感染、不能生长和自我修复等。组织工程心脏瓣膜是一新兴的研究领域，涉及多门学科。构建组织工程心脏瓣膜应包括支架的制作、细胞的种植、瓣膜的体外培养和最终移植人人体。其中种植的细胞是组织工程心脏瓣膜的基本要素。就组织工程心脏瓣膜的细胞生物学研究进展做一综述。     

组织工程心脏瓣膜的构建：现状与前景

背景：目前临床上应用的心脏生物瓣和机械瓣都存在一些缺陷和不足,而组织工程心脏瓣膜有可能避免这些问题的出现,成为瓣膜替代物的理想选择。 目的：探讨构建组织工程心脏瓣膜的实验研究进展。 方法：应用数据库检索的方法分析关于组织工程心脏瓣膜的实验研究文献,组织工程心脏瓣膜的三大要素为种子细胞、支架材料和细胞种植。 结果与结论：心脏瓣膜修复和置换是目前治疗心脏瓣膜性疾病的主要外科手段。目前,主要用于构建组织工程心脏瓣膜的种子细胞有血管内皮细胞、内皮祖细胞以及骨髓间充质干细胞等。经脱细胞处理的支架具有良好的生物力学性能和组织相容性,细胞种植后支架表面会形成一层连续的细胞层,其构建的组织工程心脏瓣膜是可行的。组织工程心脏瓣膜有着良好的应用前景,但目前还有很多问题需要解决,还处于研究的初级阶段。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程全文链接：     

聚羟基丁酸及其共聚物在组织工程心脏瓣膜中应用的初步研究

应用组织工程支架，将活细胞种植于可生物降解的瓣膜支架上，制造出一种组织相容性好，不需抗凝，具有修复能力，且支持患终生的理想心脏瓣膜。对照进行聚羟基丁酸（polyhydroxybutyrate,PHB)、聚羟基丁酸／聚羟基戊酸共聚物（Polyhydroxybutyrate/hydroxyvalerate,PHBV)皮下包埋和种植细胞生长研究实验。结果表明PHBV皮下包埋8周仍基本保持膜状结构，10周完全降解，且生物相容性优于PHB。PHBV更适于组织工程心脏瓣膜支架材料的应用。     

组织工程心脏瓣膜研究进展

目前组织工程心脏瓣膜研究已在支架的选材、种子细胞的选择、种子细胞的种植与瓣膜构建方法三个方面取得进展，并已构建出三种代表性组织工程心脏瓣膜。对它们各自的特点进行综述。     

组织工程心脏瓣膜细胞生物学研究进展

由于现有的机械瓣和生物瓣仍存在种种不足,如不具备生长性、需抗凝、易感染、不能生长和自我修复等。组织工程心脏瓣膜是一新兴的研究领域,涉及多门学科。构建组织工程心脏瓣膜应包括支架的制作、细胞的种植、瓣膜的体外培养和最终移植入人体。其中种植的细胞是组织工程心脏瓣膜的基本要素。就组织工程心脏瓣膜的细胞生物学研究进展做一综述。     

组织工程心脏瓣膜的研究进展

组织工程心脏瓣膜(tissue engineering heart valve,TEHV)理论上能克服机械瓣及生物瓣的不足,具有广阔的发展前景.目前组织工程心脏瓣膜的研究主要集中在瓣膜支架材料的选取及制备、种子细胞的选择和种子细胞的种植及培养等三方面.本文将分别就这三方面研究进展进行介绍,分析目前存在的问题,并对其应用进行展望.     

聚羟基丁酸及其共聚物在组织工程心脏瓣膜中应用的初步研究

应用组织工程支架 ,将活细胞种植于可生物降解的瓣膜支架上 ,制造出一种组织相容性好 ,不需抗凝 ,具有修复能力 ,且支持患者终生的理想心脏瓣膜。对照进行聚羟基丁酸 (polyhydroxybutyrate ,PHB)、聚羟基丁酸 /聚羟基戊酸共聚物 (Poly-hydroxybutyrate/hydroxyvalerate ,PHBV)皮下包埋和种植细胞生长研究实验。结果表明PHBV皮下包埋 8周仍基本保持膜状结构 ,10周完全降解 ,且生物相容性优于PHB。PHBV更适于组织工程心脏瓣膜支架材料的应用。     

组织工程心脏瓣膜研究进展

目前组织工程心脏瓣膜研究已在支架的选材、种子细胞的选择、种子细胞的种植与瓣膜构建方法三个方面取得进展,并已构建出三种代表性组织工程心脏瓣膜。对它们各自的特点进行综述。     

组织工程心脏瓣膜支架材料的研究与进展

背景:组织工程心脏瓣膜有望克服生物瓣膜和机械瓣膜的缺点而从根本上解决瓣膜病外科面临的问题。其中,支架材料扮演着关键角色,而选择何种支架材料是经常困扰研究者的难题。目的:文章在强调细胞外基质与细胞的相互作用在组织动力学中有重要作用的基础上,对目前广泛使用的支架材料及其优缺点进行简要综述。方法:使用Pubmed文献检索数据库,采用医学主题词检索,检索词为"心脏瓣膜;组织工程",时间范围为2000-01/2009-08,语言限定为英文。共检索到186篇文章,其中综述34篇,实验研究152篇。选择文章主要内容与组织工程心脏瓣膜支架材料直接相关的、针对性强、代表性好、相关领域权威杂志的文章共39篇进行综述。结果与结论:天然支架材料因其优越的生物相容性和三维空间构象,具有其他材料不可比拟的仿生性。合成可降解高分子材料具有良好的可控性和力学性能也备受研究者青睐,而将天然材料和高分子材料融合一体构建的复合支架材料为组织工程心脏瓣膜的研究提供了新的策略和方向,具有广阔的应用前景。     

A knitted, fibrin-covered polycaprolactone scaffold for tissue engineering of the aortic valve

State-of-the-art tissue engineered heart valves are not strong enough to withstand aortic blood pressure levels. When a strong and slowly degrading scaffold is used, the starting position of valvular tissue engineering is a stronger valve and seeded cells are allowed more time to create a strong extracellular matrix. A polycaprolactone knitted patch with leaflets was developed as a valvular scaffold. It was sutured into a tube and covered with fibrin gel. The opening and closing behavior and leakage of knitted scaffolds without cells were studied and compared to those of stentless porcine valves. An MTT test was performed on polycaprolactone and fibrin. A loading device was developed to study the durability of the knitted scaffold. The scaffold showed proper opening and it showed coaptation upon closing, but a 39 +/- 3% (n = 3) leakage, compared to a 8 +/- 1% (n = 3) leakage of tested porcine valves. MTT tests showed that polycaprolactone and fibrin are biocompatible materials. Durability testing of the knitted scaffold (n = 1) did not show rupture after ten million loading cycles. A tissue engineering process that includes cell culture will have to show whether this scaffold, besides mechanically reliable and biocompatible, is suitable to lead to a functional, nonregurgitant, durable aortic valve.     

Application of stereolithography for scaffold fabrication for tissue engineered heart valves

A crucial factor in tissue engineering of heart valves is the functional and physiologic scaffold design. In our current experiment, we describe a new fabrication technique for heart valve scaffolds, derived from x-ray computed tomography data linked to the rapid prototyping technique of stereolithography. To recreate the complex anatomic structure of a human pulmonary and aortic homograft, we have used stereolithographic models derived from x-ray computed tomography and specific software (CP, Aachen, Germany). These stereolithographic models were used to generate biocompatible and biodegradable heart valve scaffolds by a thermal processing technique. The scaffold forming polymer was a thermoplastic elastomer, a poly-4-hydroxybutyrate (P4HB) and a polyhydroxyoctanoate (PHOH) (Tepha, Inc., Cambridge, MA). We fabricated one human aortic root scaffold and one pulmonary heart valve scaffold. Analysis of the heart valve included functional testing in a pulsatile bioreactor under subphysiological and supraphysiological flow and pressure conditions. Using stereolithography, we were able to fabricate plastic models with accurate anatomy of a human valvular homograft. Moreover, we fabricated heart valve scaffolds with a physiologic valve design, which included the sinus of Valsalva, and that resembled our reconstructed aortic root and pulmonary valve. One advantage of P4HB and PHOH was the ability to mold a complete trileaflet heart valve scaffold from a stereolithographic model without the need for suturing. The heart valves were tested in a pulsatile bioreactor, and it was noted that the leaflets opened and closed synchronously under subphysiological and supraphysiological flow conditions. Our preliminary results suggest that the reproduction of complex anatomic structures by rapid prototyping techniques may be useful to fabricate custom made polymeric scaffolds for the tissue engineering of heart valves.     

A Tri-Leaflet Nitinol Mesh Scaffold for Engineering Heart Valves

The epidemiology of valvular heart disease has significantly changed in the past few decades with aging as one of the main contributing factors. The available options for replacement of diseased valves are currently limited to mechanical and bioprosthetic valves, while the tissue engineered ones that are under study are currently far from clinical approval. The main problem with the tissue engineered heart valves is their progressive deterioration that leads to regurgitation and/or leaflet thickening a few months after implantation. The use of bioresorbable scaffolds is speculated to be one factor affecting these valves’ failure. We have previously developed a non-degradable superelastic nitinol mesh scaffold concept that can be used for heart valve tissue engineering applications. It is hypothesized that the use of a non-degradable superelastic nitinol mesh may increase the durability of tissue engineered heart valves, avoid their shrinkage, and accordingly prevent regurgitation. The current work aims to study the effects of the design features on mechanical characteristics of this valve scaffold to attain proper function prior to in vivo implantation.     

Scaffolds for tissue engineering of cardiac valves

Tissue engineered heart valves offer a promising alternative for the replacement of diseased heart valves avoiding the limitations faced with currently available bioprosthetic and mechanical heart valves. In the paradigm of tissue engineering, a three-dimensional platform – the so-called scaffold – is essential for cell proliferation, growth and differentiation, as well as the ultimate generation of a functional tissue. A foundation for success in heart valve tissue engineering is a recapitulation of the complex design and diverse mechanical properties of a native valve. This article reviews technological details of the scaffolds that have been applied to date in heart valve tissue engineering research.     

组织工程心脏瓣膜支架材料的选择与应用

背景：支架材料的选择在组织工程心脏瓣膜中起着至关重要的作用,支架材料的选择也就影响着组织工程心脏瓣膜的构建效果。 目的：评价组织工程心脏瓣膜支架材料的的优缺点,并对其选择进行总结。 方法：以 “组织工程,心脏瓣膜,支架材料,生物相容性”,为中文关键词;以:“tissue engineering,heart valves, scaffold material, biocompatibility” 为英文关键词,采用计算机检索1993-01/2009-10相关文章。纳入与有关生物材料与组织工程心脏瓣膜的相关的文章;排除重复研究及Meta分析类文章。 结果与结论：人工合成高分子材料有更大的可控性,可预先塑性,大量制备,孔径和孔隙率较容易控制,成本低廉;天然生物材料和合成高分子材料都存在一定不足,将人工可降解材料与天然材料相结合构建瓣膜支架,发挥两者各自的优势构建出性能良好的组织工程心脏瓣膜。组织工程心脏瓣膜的研究前景广阔。但距离临床应用还有很长的路要走,相信随着研究的不断深入以及支架材料的不断优化对组织工程心脏瓣膜构建方法的改进,在不远的将来造福于广大心脏瓣膜病患者。     

Current developments and future prospects for heart valve replacement therapy

Valve replacement is the most common surgical treatment in patients with advanced valvular heart disease. Mechanical and bio-prostheses have been the traditional heart valve replacements in these patients. However, currently the heart valves for replacement therapy are imperfect and subject patients to one or more ongoing risks, including thrombosis, limited durability, and need for re-operations due to the lack of growth in pediatric populations. Furthermore, they require an open heart surgery, which is risky for elderly and young children who are too weak or ill to undergo major surgery. This article reviews the current state of the art of heart valve replacements in light of their potential clinical applications. In recent years polymeric materials have been widely studied as potential prosthetic heart valve material being designed to overcome the clinical problems associated with both mechanical and bio-prosthetic valves. The review also addresses the advances in polymer materials, tissue engineering approaches, and the development of percutaneous valve replacement technology and discusses the future prospects in these fields.     

Bioreactors for Development of Tissue Engineered Heart Valves

Millions of people worldwide are diagnosed each year with valvular heart disease, resulting in hundreds of thousands of valve replacement operations. Prosthetic valve replacements are designed to correct narrowing or backflow through the valvular orifice. Although commonly used, these therapies have serious disadvantages including morbidity associated with long-term anticoagulation and limited durability necessitating repeat operations. The ideal substitute would be widely available and technically implantable for most cardiac surgeons, have normal hemodynamic performance, low risk for structural degeneration, thrombo-embolism and endocarditis, and growth potential for pediatric patients. Tissue engineered heart valves hold promise as a viable substitute to outperform existing valve replacements. An essential component to the development of tissue engineered heart valves is a bioreactor. It is inside the bioreactor that the scaffold and cells are gradually conditioned to the biochemical and mechanical environment of the valve to be replaced.     

不同类型生物材料的心脏瓣膜应用及安全性评价

背景:组织工程心脏瓣膜是应用工程学和生命科学的原理和方法构建具有生理功能和生物活性的瓣膜替代物,但仍处于动物实验阶段。 目的：总结常用的组织工程心脏瓣膜,对不同类型生物材料的心脏瓣膜应用的安全性进行评价。 方法：以“生物材料,心脏瓣膜,支架材料,综述文献,组织工程”为中文关键词,采用计算机检索2000-01/2010-12相关文章。纳入与生物材料与组织工程心脏瓣膜研究相关的文章;排除重复研究或Meta分析类文章。 结果与结论：共纳入生物材料与组织工程心脏瓣膜研究相关文献20篇。天然支架材料因其优越的生物相容性和三维空间构象,具有其他材料不可比拟的仿生性。合成可降解高分子材料具有良好的可控性和力学性能也备受研究者青睐,而将天然材料和高分子材料融合一体构建的复合支架材料为组织工程心脏瓣膜的研究提供了新的策略和方向,具有广阔的应用前景。