Construction of Oriented Structure in Inner Surface of Small-Diameter Artificial Blood Vessels:A Review

There is an urgent need for small-diameter artificial blood vessels in clinic.Physical,chemical and biological factors should be integrated to avoid thrombosis and intimal hyperplasia after implantation and to promote successful fabrication of small-diameter artificial blood vessels.From a physical perspective,the internal oriented structures of natural blood vessels plays an important role in guiding the directional growth of cells,improving the blood flow environment,and promoting the regeneration of vascular tissue.In this review,the effects of the oriented structures on cells,including endothelial cells(ECs),smooth muscle cells(SMCs)and stem cells,as well as the effect of the oriented structures on hemodynamics and vascular tissue remodeling and regeneration are introduced.Various forms of oriented structures(fibers,grooves,channels,etc.)and their construction methods are also reviewed.Conclusions and future perspectives are given.It is expected to give some references to relevant researches.

Bioprinting of Small-Diameter Blood Vessels

There has been an increasing demand for bioengineered blood vessels for utilization in both regenerative medicine and drug screening.However,the availability of a true bioengineered vascular graft remains limited.Three-dimensional(3D)bioprinting presents a potential approach for fabricating blood vessels or vascularized tissue constructs of various architectures and sizes for transplantation and regeneration.In this review,we summarize the basic biology of different blood vessels,as well as 3D bioprinting approaches and bioink designs that have been applied to fabricate vascular and vascularized tissue constructs,with a focus on small-diameter blood vessels.

Weavability of β-Hydroxybutyrate and β-Hydroxyvalerate Copolymers( PHBV ) /PLA Used in Artificial Blood Vessels

The β-hydroxybutyrate and β-hydroxyvalerate copolymers( PHBV) /polylactic acid( PLA) is a new biocompatible material,which is developed through bacterial fermentation in vivo systems.The PHBV / PLA material could be used to make continuous filaments.However,features of artificial blood vessels,especially small diameter vascular grafts made of PHVB / PLA materials are not known.This research are to evaluate and improve weavability of the PHBV / PLA material, and to explore feasibility of using it in artificial blood vessels.Preliminary results showed that weavability of PHBV / PLV was not good,but its weavability could be improved by using methods of weak chemical,such as sizing.In this research,scanning electron microscope( SEM) was adopted to evaluate weavability of PHBV / PLV after sizing and observe surfaces of yarns and fabrics.Also,in order to set proper parameters in heat settings,differential scanning calorimetry( DSC) was used to identify glass transition temperature.

Design and Development of PHBV/PLA Artificial Blood Vessels

In the research,a β-hydroxybutyrate and β-hydroxyvalerate copolymer(PHBV)/polylactic acid(PLA)artificial blood vessel was designed and developed,and it was also implanted in vivo for a period of time to observe its biocompatibility and degradation performance.The results showed that the developed PHBV/PLA artificial blood vessel could be used to replace the natural blood vessel,but its degradation rate was too fast and the mechanical supporting force was insufficient.Thus,properties of the PHBV/PLA need to be further improved.

Simulation and preparation of novel medium convex artificial blood vessel for reducing compliance mismatch

Compliance mismatch between artificial blood vessel and host vessel can cause abnormal hemodynamics and is the main mechanical trigger of intimal hyperplasia(IH)after transplantation.To explore the specific effects of the degree of compliance mismatch on hemodynamics,the concept of“compliance mismatch degree”was defined in this paper.Numerical results showed that when the compliance mismatch degree was less than-22.21%or more than 3.16%,the minimum WSS in the anastomotic site was less than the safety threshold of 0.5 Pa,which is easy to induce IH.In addition,the compliance mismatch caused different radial displacements first,which in turn affected the hemodynamics.Inspired by this,a novel medium convex artificial blood vessel was proposed,and the simulation results theoretically validated its desired effect on reducing the compliance mismatch.An increase of 0.22 mm in the diameter of the artificial blood vessel corresponded to a decrease of 0.88%in compliance mismatch degree.The feasibility of preparing real medium convex artificial blood vessel was also investigated.The PLCL medium convex artificial blood vessel with good mechanical properties was prepared by dip-coating and electrospinning composite method.These findings are valuable for the design and preparation of novel artificial blood vessel which can make up for the mismatch of compliance.

即穿型人工血管在血管通路中的应用效果及并发症分析

目的 研究即穿型人工血管在血管通路中的应用效果及并发症。方法 选取从2019年2月—2022年2月于资阳市人民医院接受人工血管内瘘手术的83例患者为研究对象。将流出道静脉直径>4mm分为即穿型人工血管组(n=41),流出道静脉直径3~4 mm分为膨体聚四氟乙烯(expanded polytetrafluoroethylen,ePTFE)人工血管组(n=42),分别选用即穿型人工血管、ePTFE人工血管进行造瘘手术。对所有患者均实施为期18个月的随访,比较2组手术后通畅率,治疗效果,手术后并发症,手术后生存率。结果 即穿型人工血管组与e PTFE人工血管组手术后6、12、18个月初级通畅率(t=1.437、0.609、0.595,P=0.231、0.435、0.441)及次级通畅率(t=2.108、0.149、0.310,P=0.147、0.699、0.578)对比无统计学差异。即穿型人工血管组首次穿刺时间、手术后透析导管移除时间均短于ePTFE人工血管组(t=78.386、21.491,均P<0.001);2组手术后透析血流量及人工血管使用率对比均不明显(t/χ^(2)=0.214、0.988,P=0.831、0.320)。即穿型人工血管组手术后肿胀、血栓形成发生率均低于ePTFE人工血管组(χ^(2)=24.418、7.540,P<0.001、0.006)。2组手术后6、12、18个月患者生存率对比均不明显(χ^(2)=1.037、0.239、0.183,P=0.309、0.625、0.668)。结论 即穿型人工血管应用于血管通路中可实现早期穿刺,通畅率高,且并发症发生风险较低,值得推广应用。

Hemocompatible polyurethane/gelatin-heparin nanofibrous scaffolds formed by a bi-layer electrospinning technique as potential artificial blood vessels

In this paper,a scaffold,which mimics the morphology and mechanical properties of a native blood vessel is reported.The scaffold was prepared by sequential bi-layer electrospinning on a rotating mandrel-type collector.The tubular scaffolds(inner diameter 4 mm,length 3 cm)are composed of a polyurethane(PU)fibrous outer-layer and a gelatin-heparin fibrous inner-layer.They were fabricated by electrospinning technology,which enables control of the composition,structure,and mechanical properties of the scaffolds.The microstructure,fiber morphology and mechanical properties of the scaffolds were examined by means of scanning electron microscopy(SEM)and tensile tests.The PU/gelatinheparin tubular scaffolds have a porous structure.The scaffolds achieved a breaking strength(3.7±0.13 MPa)and an elongation at break(110±8%)that are appropriate for artificial blood vessels.When the scaffolds were immersed in water for 1 h,the breaking strength decreased slightly to 2.2±0.3 MPa,but the elongation at break increased to 145
21%.In platelet adhesion tests the gelatin-heparin fibrous scaffolds showed a significant suppression of platelet adhesion.Heparin was released from the scaffolds at a fairly uniform rate during the period of 2nd day to 9th day.The scaffolds are expected to mimic the complex matrix structure of native arteries,and to have good biocompatibility as an artificial blood vessel owing to the heparin release.

History,progress and future challenges of artificial blood vessels:a narrative review

Cardiovascular disease serves as the leading cause of death worldwide,with stenosis,occlusion,or severe dysfunction of blood vessels being its pathophysiological mechanism.Vascular replacement is the preferred surgical option for treating obstructed vascular structures.Due to the limited availability of healthy autologous vessels as well as the incidence of postoperative complications,there is an increasing demand for artificial blood vessels.From synthetic to natural,or a mixture of these components,numerous materials have been used to prepare artificial vascular grafts.Although synthetic grafts are more appropriate for use in medium to large-diameter vessels,they fail when replacing small-diameter vessels.Tissue-engineered vascular grafts are very likely to be an ideal alternative to autologous grafts in small-diameter vessels and are worthy of further investigation.However,a multitude of problems remain that must be resolved before they can be used in biomedical applications.Accordingly,this review attempts to describe these problems and provide a discussion of the generation of artificial blood vessels.In addition,we deliberate on current state-of-the-art technologies for creating artificial blood vessels,including advances in materials,fabrication techniques,various methods of surface modification,as well as preclinical and clinical applications.Furthermore,the evaluation of grafts both in vivo and in vitro,mechanical properties,challenges,and directions for further research are also discussed.

蚕丝基小口径人工血管研究进展

心血管疾病居全球死亡率首位,其中冠状动脉和周边堵塞性血管疾病威胁巨大。为了降低该疾病对人类生命的严重威胁,小口径人工血管移植术(搭桥)是较为普遍的治疗手段,但目前常用的制备方法和材料存在长期通畅率低、易形成血栓和难以在体内促进血管内皮化等问题。桑蚕丝因具备良好的力学性能、生物相容性及可控的生物降解性而被广泛用于小口径人工血管。本文综述了蚕丝基小口径人工血管在动物体内的应用,总结了以蚕丝基为材料制备小口径血管的优势,分析了存在的缺陷和改进方向,以期为蚕丝基小口径人工血管的研究发展提供参考。

基于纺织材料的人造血管制备及应用进展

为了制备具有良好顺应性、安全性能高的纺织人造血管,从人造血管的研究背景、研究价值和发展历程出发,阐述了涤纶(PET)、聚氨酯(PU)、聚四氟乙烯(PTFE)和丝素蛋白(SF)等几种用于人造血管的主要材料的特点,阐述了机织、针织、编织、非织造及3D打印制备人造血管主要方法的特点、适用范围及最新研究进展,归纳了在人造血管领域目前现存的问题,最后对未来纺织材料在人造血管中的应用研究趋势进行了展望,以期为开发理想的人造血管提供一定的参考。

多孔聚四氟乙烯人工血管制备及功能化改性研究的进展

背景:中、大口径的聚四氟乙烯人工血管已被广泛应用于临床,但主要依赖进口;小口径的聚四氟乙烯人工血管易形成血栓和内膜增生,存在远期通畅率低的问题,难以满足临床应用要求。目的:梳理并总结聚四氟乙烯在人工血管领域的研究进展,为小口径聚四氟乙烯人工血管的功能化改性及提高其远期通畅率提供参考。方法:由第一作者检索CNKI、Web of Science、Wiley Online Library、SpringerLink、Science Direct和IOP Science数据库中的相关文献,检索时间为2022年10月至2023年3月,中文检索词为“多孔聚四氟乙烯,人工血管,电纺,医学应用和功能化改性”,英文检索关键词为“ePTFE,Porous polytetrafluoroethylene,vascular graft,electrospinning,medical application,functional modification”,检索国内外有关聚四氟乙烯人工血管制备及其改性的相关文献。结论与结论:多孔聚四氟乙烯人工血管的制备和功能性改性仍是研究的热点与难点,从近几年的国内外研究进展来看,多孔聚四氟乙烯人工血管的制备主要采用快速热拉伸法,但静电纺丝法制备聚四氟乙烯人工血管是一种很有前景的新型方法;其次,通过分析和总结不同的功能化改性方法发现,多孔聚四氟乙烯人工血管的远期通畅率得到改善,但小口径聚四氟乙烯人工血管的功能化改性仍需进一步探索和优化。

小口径人工血管的研究现状及展望

近年来,由于心血管疾病发生率逐渐上升,临床上对再生血管的需求日益增加。目前,大口径人工血管(直径>6 mm)已成功应用于临床,小口径人工血管(直径<6 mm)由于血栓形成、内膜增生、炎症反应和顺应性差导致血流动力学改变等原因,使其移植后远期通畅率低,距离临床应用尚有一段距离。其中,快速内皮化、抑制血栓形成及与自体血管相匹配的顺应性仍是解决问题的关键。本文简述制备小口径人工血管常用材料及技术的特点,重点讨论提高人工血管生物相容性和顺应性的策略,并对未来的研究工作进行展望。

MRI与CT评价上腔静脉切除置换术后患者人工血管通畅度的对比研究

目的探讨MRI在上腔静脉切除人工血管置换术后患者人工血管通畅度复查中的应用价值。方法收集2021年1月—2022年10月于四川大学华西医院行上腔静脉切除人工血管置换术后返院复查的患者42例,均施行MRI检查(MRI组)和上腔静脉CT血管成像(CTA组)。对MRI血管图像进行主观评价和客观评价。以CTA图像为参照标准,测量人工血管的血管长度,人工血管端口、中部和尾端的血管直径宽度,采用Bland-Altman图对两种扫描方法的测量值进行一致性分析。结果42例患者共置换人工血管52根。MRI组的图像质量平均评分稍低于CTA组[(4.53±0.50)分vs(4.94±0.24)分,χ^(2)=13.14,P=0.002];Bland-Altman图所得MRI和CT两种方法的差值服从正态分布,两种方法具有较好的一致性。结论与CTA相比,MRI无辐射、无需对比剂就能获得良好的人工血管成像,对人工血管是否通畅具有重要的临床应用价值。

心血管领域的难点及细菌纳米纤维素的应用潜力

心血管疾病(心肌梗死、冠状动脉粥样硬化、高血压等)已成为全球人类死亡的主要原因,这些疾病目前主要依靠药物治疗,严重时需心脏冠脉搭桥等外科手术治疗。文中简述了小口径人工血管及人工心脏瓣膜需求的急迫性以及细菌纳米纤维素(BNC)的特点,回顾了BNC在心血管领域的最新研究进展并预测了今后的发展方向。细菌纳米纤维素因其形状可塑性、具有类细胞外基质的3D纤维网络结构、高持水性、血液和细胞相容性好等优点,在心血管领域中的应用潜力非常突出,为其今后在该领域中的发展奠定了基础。

腹主动脉离断经胸腹腔镜人工血管转流术影像学分析

目的分析CT血管成像对成人腹主动脉离断的诊断及经胸腹腔镜人工血管转流术(胸主动脉-腹主动脉搭桥)后疗效评估、随访的应用价值。方法对我院确诊的1例成人腹主动脉离断患者手术前后的临床和影像资料,以及追踪该患者根据临床诊疗评估需要术后2年随访的影像资料一并进行分析。结果术前首次CTA检查:腹主动脉中段(右肾动脉下方层面-腰3椎体上缘水平)未见显示,范围约50mm,考虑闭塞或发育异常。肠系膜上动脉主干及分支明显迂曲扩张,其一分支与下腹主动脉相连。术后1周复查:降主动脉远段与腹主动脉远段间人工血管术后,人工血管通畅。术后第1年和第2年CTA随访结果无明显变化:降主动脉远段与腹主动脉远段间人工血管术后,人工血管通畅,人工血管下段接口处见少量非钙化性斑块形成,管腔未见明显狭窄。结论CT血管成像可以作为腹主动脉离断的术前诊断、胸腹腔镜人工血管转流术术后疗效评估及随访的首选影像检查方法。

华通胶修饰的聚己内酯静电纺丝人工血管支架的构建及性能分析

目的构建华通胶(WJ)修饰的聚己内酯(PCL)静电纺丝人工血管支架,并分析其性能。方法采用胰蛋白酶法对WJ组织进行脱细胞处理,通过组织学染色和生化成分定量分析WJ组织的脱细胞效率,以及脱细胞前后WJ组织生化成分的差异。通过酶联免疫吸附试验(ELISA)法检测脱细胞前后WJ组织生物活性因子的水平差异。将经过处理的WJ与PCL混合制备纺丝液,并采用静电纺丝技术制备管状的WJ/PCL静电纺丝人工血管支架,分析其纳米纤维结构、纤维直径分布、生物力学性能及血液相容性。结果通过胰蛋白酶法脱细胞处理可有效去除WJ基质的细胞核成分,保留了WJ基质的大部分生化成分[包括糖胺聚糖(GAG)、蛋白质、纤维、透明质酸和羟脯氨酸]以及生物活性因子[包括血管内皮生长因子(VEGF)、血小板源性生长因子(PDGF)、转化生长因子-β1(TGF-β1)和成纤维细胞生长因子-2(FGF-2)]。经静电纺丝技术制备的WJ/PCL静电纺丝人工血管支架呈现典型的纳米纤维结构,且经傅立叶红外光谱(FTIR)验证,其同时含有WJ和PCL的特征峰。WJ/PCL静电纺丝人工血管支架表现出良好的生物力学特性和血液相容性,可有效抑制血小板黏附。结论WJ是一种理想的天然材料,可用于与PCL等合成材料复合,制备具有理想生物特性的静电纺丝人工血管支架。

1例左肺上沟瘤切除伴锁骨下动脉部分置换病人术后的护理

总结1例左肺上沟瘤侵犯颈胸交界处病人行肿瘤切除伴锁骨下动脉部分置换术后的护理经验。护理要点包括:个案护理小组多举措干预,全力保障急性创伤期安全;加强人造血管置换术后护理,提高人工血管存活率;全程呼吸道管理,改善呼吸功能;持续负压吸引,提升引流效能,促进皮下气肿消散;个体化营养支持联合生长抑素治疗,有效控制乳糜胸进展;“互联网+”随访模式,提供延续性护理服务。经积极治疗与护理,病人术后恢复良好,40 d后顺利出院。

Numerical simulation to study the impact of compliance mismatch between artificial and host blood vessel on hemodynamics

Small-diameter artificial blood vessels are prone to cause intimal hyperplasia(IH)after transplantation,which leads to restenosis and low long-term patency rates.The main biomechanical factor for IH formation is the compliance mismatch between the artificial and host blood vessels which can cause abnormal hemodynamics.Although there have been many studies on vascular compliance mismatches,however,little attention has been paid to the effect of the degree of compliance mismatch between graft and the host vessel on hemodynamics.At present,the research on compliance mismatch between the artificial and host blood vessels is still very limited,especially with regard to the specific impact of the compliance mismatch degree on hemodynamics.Therefore,three end-to-end anastomosis models(the compliance of the artificial blood vessel is lower than,similar to,and higher than that of the host blood vessel,called model 1,model 2,model 3,respectively)were constructed and simulated in this study.Simulation results showed that the radial displacement difference between the artificial and host blood vessels were 0.281 mm,0.183 mm and 0.485 mm in model 1,model 2 and model 3,respectively.A low-velocity recirculation zone near the distal anastomosis was formed in model 1 which resulted in excessively low TAWSS(9.261 E-5Pa)and high OSI(0.497).Similarly,a low-velocity recirculation zone near the proximal anastomosis was formed in model 3 and lead to low TAWSS(6.007 E-4Pa)and high OSI(0.480).However,there was no low-velocity recirculation zone near the anastomosis stoma in model 2.The results are instructive for the design and preparation of artificial blood vessels.

基于多准则决策分析法构建人工血管移植物内瘘穿刺及维护的集束化干预策略

目的:基于多准则决策分析法(MCDA)构建人工血管移植物内瘘(AVG)穿刺及维护的集束化干预策略。方法:计算机检索美国国立指南网、国际指南协作网、安大略注册护士协会、新西兰准则小组、澳大利亚国家健康和医学研究委员会、中国医脉通6个指南网和PubMed、UpToDate、Cochrane Library、万方数据库、中国知网数据库中有关AVG穿刺及维护的相关文献。检索时间为2010年1月—2022年1月。然后由10名有关血液透析、血管通路专家采用基于MCDA分析法对AVG穿刺及维护的集束化干预子策略进行打分,最后根据最终评分排序形成AVG穿刺及维护集束化护理策略的推荐意见。结果:10名函询专家权威系数为0.822,最初拟订了10项AVG穿刺及维护的集束化干预策略,根据得分从高到低排序最终形成6项为优化后的干预策略,分别为指导病人的自我管理、穿刺方法的选择与评估、重视血压管理、定期随访及超声检测、合理控制体重增长、透析后正确规范按压止血。结论:基于MCDA分析法构建的AVG穿刺及维护的集束化干预策略可靠,可为护士穿刺和病人日常维护提供依据。

静电纺丝在构建小口径仿生人工血管中的研究进展

人工血管在治疗冠状动脉和周边堵塞性疾病中具有重要意义,但制备出性能优异的小口径人工血管仍然具有挑战性。当口径较小时(<6 mm),人工血管容易产生血栓和内膜增生等问题,进而导致血管再狭窄和堵塞,对人类健康造成严重危害。为了构建性能良好的小口径人工血管,人们探索了多种制备方法。静电纺丝可以构建具有极大的比较面积和孔隙率的纳米纤维网络。而这种纳米纤维网络与动物细胞外基质(ECM)结构非常相似,可以极大地促进内皮细胞的黏附生长和繁殖,从而促进使移植后的人工血管具有快速形成完整的内皮细胞层。内皮细胞层的形成可以有效减缓人工血管中血细胞、纤连蛋白和血小板沉积,降低血栓形成及血管堵塞的概率。本论文综述了静电纺丝技术在构建小口径人工血管方面的研究进展。