仿生技术构建小口径人造血管

目的：研究以改性猪小肠粘膜下层组织(SIS)为支架,利用仿生技术构建小口径人造血管的可行性。方法：自犬隐动脉分离出血管内皮细胞和平滑肌细胞,与胶原蛋白凝胶均匀混合,分别种植于改性SIS膜表面,制成3 mm 仿生三层人造血管为实验组;制成单层人造血管为对照组,分别植入修复15例犬双侧股动脉缺损,术后进行彩超、组织学检测和电镜检测鉴定。结果：植入12周,14个仿生人造血管保持通畅,通畅率93.3%,有血管样生物结构形成,管腔内壁有完整的内皮覆盖,管壁中层见大量平滑肌细胞;对照组通畅率60%,有少许内皮细胞覆盖。结论：仿生小口径人造血管具有良好的血液相容性,并能在体内保持良好通畅性, 修复动脉缺损效果满意。     

人造血管内皮化旋转培养装置的设计及制作

人造血管内皮化研究需在人造血管内壁均匀粘附上一层内皮细胞。以往静态培养,细胞难以在其内壁均匀粘附生长,效果不理想。我们设计了一种内皮化人造血管旋转培养装置,很好地解决了上述问题。该装置体积小,整体可以放入二氧化碳培养箱,因而可维持细胞的生长环境不受影响。装置由三个部分组成:①旋转驱动器(蠕动泵)。②人造血管内皮细胞     

人造血管的纺织设计与加工技术

1 引言 当人体内血管由于动脉硬化、血管瘤、血栓、血管老化或破损等原因不能正常工作时,需要进行血管移植。血管代用品的主要来源为生物血管、人造血管及复合血管。生物血管含自体血管、同种异体血管和异种血管3种。后两种由于通畅率低,易发生退行性变及强烈的排异作用,目前临床已经很少应用。自体血管在外周血管重建中,用作为小口径血管的优良代用品,但其来源少,口径和长度也受     

一种带有旋动流引导器的新型小口径人造血管流场的数值模拟

大尺寸人造血管的临床应用已取得很大成功,但用于冠状动脉等旁路搭桥的小口径人造血管的急性血栓堵塞问题,至今仍未解决．因此,本文设计了一种可装于小口径人造血管前的旋流导引器,以期使进入人造血管内的血流产生旋动．对带有旋流导引器的人造血管内的血流流场进行了计算机数值模拟分析,并与常规人造血管内的血流流场进行了比较．数值模拟分析揭示,这种旋流导引器的确能使人造血管内的血流产生旋动,从而改变人造血管内的血流流场和流速分布,使近壁面血液的流速和壁面剪切应力得到极大提高．本研究认为,血液在人造血管壁面的流速和壁面剪切应力的提高,可抑制小口径人造血管内急性血栓的形成,从而达到提高小口径人造血管的通畅率的目的．     

纺织基人造血管几何特征表征的实验研究

人造血管的壁厚和松弛内径是其主要的几何特征参数。本文中首先依据国际标准ISO 7198的要求设计了测试人造血管松弛内径的测试定规,并对人造血管样品进行了测试。然后对人造血管壁厚的测试方法进行了初步探讨。     

大相岭自然保护区珙桐群落植物区系、结构及动态

在多次调查的基础上,对四川大相岭自然保护区珙桐(Davidia involucrata)群落的植物区系组成、群落结构、更新现状以及群落演替进行了探究。结果表明:(1)大相岭自然保护区的植被为亚热带向温带过渡的区系类型,大量古老孑遗属的存在反映出珙桐群落植物区系的孑遗性和古老性。(2)群落整体径级结构呈偏正态分布型,高度级结构呈倒J型,群落结构发展趋势较为稳定。(3)大相岭自然保护区珙桐种群整体年龄结构近似呈金字塔型,为增长型种群。总体来说,珙桐纯林(C类型群落)搭配优势度最优,处于后期稳定型演替阶段,是大相岭自然保护区珙桐群落中的顶极群落。研究认为,设立专门的珙桐保护区开展就地保护是针对此类珙桐原生群落有效的保护方法。     

大相岭自然保护区珙桐群落植物区系、结构及动态

在多次调查的基础上,对四川大相岭自然保护区珙桐(Davidia involucrata)群落的植物区系组成、群落结构、更新现状以及群落演替进行了探究。结果表明:(1)大相岭自然保护区的植被为亚热带向温带过渡的区系类型,大量古老孑遗属的存在反映出珙桐群落植物区系的孑遗性和古老性。(2)群落整体径级结构呈偏正态分布型,高度级结构呈倒J型,群落结构发展趋势较为稳定。(3)大相岭自然保护区珙桐种群整体年龄结构近似呈金字塔型,为增长型种群。总体来说,珙桐纯林(C类型群落)搭配优势度最优,处于后期稳定型演替阶段,是大相岭自然保护区珙桐群落中的顶极群落。研究认为,设立专门的珙桐保护区开展就地保护是针对此类珙桐原生群落有效的保护方法。     

经编人造血管顺应性的实验研究

对EP系列经编人造血管的径向顺应性和纵向顺应性进行了体外测试和研究,并分析了不同制备工艺对经编人造血管的径向顺应性的影响。实验结果表明,紧密化处理和波纹化热定性对人造血管的径向顺应性影响较大。测试压力段的选择对人造血管成品的纵向顺应性有较大的关系。     

小鼠胸主动脉血管管壁结构和平滑肌细胞表型的年龄变化

目的:通过研究小鼠胸主动脉血管直径和管壁厚度以及平滑肌细胞表型标志物波形蛋白(Vimentin)和平滑肌细胞肌动蛋白(α-SM-actin)的表达,探讨胸主动脉在发育、成熟和老化过程中血管管壁结构和平滑肌细胞表型的变化。方法:将24只昆明小鼠按年龄分成4组:3天组、3个月组、6个月组和16个月组。采用HE染色和免疫荧光术分别观察胸主动脉血管管壁结构以及Vimentin和α-SM-actin的表达变化。结果:随着年龄的增长,胸主动脉血管直径和管壁厚度增加,以16个月小鼠胸主动脉的直径最大和管壁最厚,但细胞密度减少。3天小鼠胸主动脉的Vimentin表达较高,6个月表达下降,16个月重新上调;而α-SM-actin在3天小鼠的胸主动脉表达较低,6个月表达增加,16个月表达出现下调,其差异均有统计学意义(P0.05)。结论:小鼠胸主动脉的直径和管壁的厚度随年龄的增长而增加,而细胞的密度则随着年龄增加而减少;平滑肌细胞的表型从幼龄时的合成表型转变为收缩表型,老龄时又转变为合成表型。     

美国生物材料在医疗器械工业发展近况

1930年初,生物材料仅仅是指木才、玻璃和金属。这些材料大多用于手术器械、肌体保护装置及一次性使用医疗器械产品。合成聚合物的出现改变了医疗卫生保健事业的整体特点。最初,作为商品出售的聚合体仅适用于可植入性修复术,后来亦用于心脏起搏器、血管植入物、人造皮肤及各种人造器官。 生物材料是增强或替代人体组织或器官功能的非药理性物质。生物材料在机械性能上具有规定的     

Differentiation of vascular pseudointima under normal and disturbed blood flow conditions: Ultrastructural observations in the rat

Summary To study the effect of haemodynamic stress on the morphological differentiation of pseudointima, the ultrastructure of the cells lining normally shaped and aneurysmal polyurethane vascular prostheses implanted into the abdominal aorta of rats was examined. In the normally shaped vascular prostheses the pseudointima was composed of several layers of smooth muscle cells, which varied in differentiation from normal smooth muscle cells to myofibroblasts, and which were lined by a continuous sheet of endothelial cells. In the aneurysmal vascular prostheses, a pseudointima, composed of only layers of smooth muscle cells had developed. Those smooth muscle cells which lined the lumen had a typical morphology: they were polygonal, flat cells of unequal size, with a distinct organelle-free zone, containing myofilaments, at the luminal peripheral cytoplasmic side. The other smooth muscle cells varied in differentiation from normal smooth muscle cells to myofibroblasts. Under severe haemodynamic stresses, such as occur in the aneurysmal vascular prostheses, the regeneration of endothelial cells is impaired and smooth muscle cells undergo morphological changes to form a pseudoendothelial lining.     

Small-calibre vascular grafting into the rat abdominal aorta with biodegradable prostheses

130 Male Wistar rats, 2-3 months old and weighing 250-350 g were operated on to implant biodegradable small-calibre vascular prostheses (length 10 mm; internal diameter 1.5 mm) in their infrarenal abdominal aorta. The mean operation time was 40 min, the mean aortic cross-clamping time 25 min. The early patency rate was 100%, the late patency rate was 97.7%, and the operative mortality was 3.1%. Microscopical examination of the biodegradable prostheses from 1 h up to 1 year after implantation demonstrated reproducible morphological results; in these prostheses a new arterial wall regenerated which had a structure very similar to the normal arterial wall. It was concluded that the rat is an appropriate experimental laboratory animal for testing new types of small-calibre vascular prostheses.     

Vascular prostheses with controlled release of antibiotics Part 2. In vitro biological evaluation of vascular prostheses treated by cyclodextrins

Viability tests by the colony forming method show no toxicity for all CDs (beta-CD, gamma-CD, HPbeta-CD and HPgamma-CD) and their associated polymer. A survival rate of 100% is observed for all CDs at high concentration 400 ppm. Proliferation tests revealed a low proliferation of L132 cells on grafted vascular prostheses and untreated prostheses and good proliferation on Melinex (film form of PET). A proliferation of 17% is observed after 3 days of incubation and decrease at 4% after 6 days on prostheses. Melinex exhibits a proliferation rate as the controls. Vitality tests confirm proliferation tests and show a good vitality of cells even for low cell amounts. From these experiments it becomes obvious that the decreasing proliferation rate is not a cytotoxic effect but is due to the chemical and/or physical surface characteristics. A similar result is obtained for cell adhesion kinetics between grafted vascular prostheses and control. After 2 h adhesion, a lower adhesion is observed on untreated prostheses. Theses results were confirmed by immunochemistry and morphology tests. This cell adhesion inhibiting effect of the PET prostheses contributes to a better "survival" of vascular prostheses without secondary obstruction or stenosis.     

A Water Control Device for Mounting Serial Ultrathin Sections

It is important to know the tissue reactions taking place in or near the wall and surroundings of plastic vascular prostheses transplanted into an organism. As is known, the porosity of the vascular prosthesis plays a significant role in the morphogenesis of vascular neogenesis (Sauvage 1971). for this purpose sections are needed in which the structure of the vascular prosthesis and the surrounding tissue are both well preserved.     

A New Embedding Medium for Firm Materials Applied to the Sectioning of Plastic Vascular Prostheses

It is important to know the tissue reactions taking place in or near the wall and surroundings of plastic vascular prostheses transplanted into an organism. As is known, the porosity of the vascular prosthesis plays a significant role in the morphogenesis of vascular neogenesis (Sauvage 1971). for this purpose sections are needed in which the structure of the vascular prosthesis and the surrounding tissue are both well preserved.     

The Effect of Mechanical Compatibility and of Thrombogenicity on the Ingrowth of a New Synthetic Vascular Prosthesis (Experimental Study)

Doklady Biochemistry and Biophysics - Common disadvantages of modern synthetic vascular prostheses are thrombogenicity and lack of biomechanical compatibility with the prothesized vessel. To...     

Scaffold-Free Tubular Tissues Created by a Bio-3D Printer Undergo Remodeling and Endothelialization when Implanted in Rat Aortae

BackgroundSmall caliber vascular prostheses are not clinically available because synthetic vascular prostheses lack endothelial cells which modulate platelet activation, leukocyte adhesion, thrombosis, and the regulation of vasomotor tone by the production of vasoactive substances. We developed a novel method to create scaffold-free tubular tissue from multicellular spheroids (MCS) using a “Bio-3D printer”-based system. This system enables the creation of pre-designed three-dimensional structures using a computer controlled robotics system. With this system, we created a tubular structure and studied its biological features.ConclusionsThe scaffold-free tubular tissues made of MCS using a Bio-3D printer underwent remodeling and endothelialization. Further studies are warranted to elucidate the underlying mechanism of endothelialization and its function, as well as the long-term results.