内皮祖细胞与血管重新内皮化

血管内皮是循环血液和血管壁组织间的一层天然屏障,在维持血管的正常形态和功能中起重要作用。内皮受损后可引起炎症反应、单核细胞浸润和血管平滑肌细胞增生,促发动脉粥样硬化和再狭窄。因此,直接修复受损血管内皮,促使血管重新内皮化已经成为防止动脉粥样硬化及再狭窄领域的重要课题。大量研究表明,内皮祖细胞(EPC)参与受损血管的重新内皮化。该文就内皮祖细胞的来源、鉴定、参与重新内皮化进行综述。     

血管内支架和支架内皮化

简要介绍了血管内支架产生的背景、发展进程及其应用于临床后出现的再狭窄问题,着重综述了十几年来内皮细胞种植血管内支架预防术后再狭窄的相关研究成果。血管内支架内皮化的最终实现可以使现行的血管支架具有正常血管内皮的生物相容性及生理功能,是控制支架植入术后再狭窄问题的很有前途的支架改进方法。     

内皮祖细胞移植加速鼠颈动脉内皮修复预防再狭窄的研究

目的：以安慰机组作对照,观察EPCs自体移植防治再狭窄的疗效以及该作用与血管再内皮化是否相关。方法：共30只雄性SD大鼠纳入实验,随机均分为假手术组、安慰剂组和EPCs移植组。造模前3周时取血3毫升,M199培养基培养传代,行EPCs鉴定,移植组在球囊损伤后即予尾静脉注射1×10^6个EPCs自体移植。4周后观察再狭窄和再内皮化程度。结果：与安慰剂组相比,EPCs自体移植组再内皮化程度提高,再狭窄程度减轻;EPCs移植组内膜／中膜比值与再内皮化率呈线性负相关。结论：EPCs体外扩增自体移植可预防再狭窄;其机制与加速再内皮化有关。     

粒细胞集落刺激因子动员内皮祖细胞预防再狭窄的研究

目的:观察粒细胞集落刺激因子是否能通过加速内皮修复预防再狭窄,并探讨该作用与其动员效应即EPCs数量和功能变化的相关性.方法:30只SD大鼠随机均分为假手术组、损伤未干预组和G-CSF组,后两组行颈总动脉球囊损造模,G-CSF组连续给药7天后观察各组外周血内皮祖细胞的数量和增值、粘附、迁移功能,4周后观察再狭窄和再内皮化程度.结果:G-CSF组再内皮化率高于对照组,再狭窄率低于对照组,再内皮化率和再狭窄率呈线性负相关;G-CSF组内皮祖细胞数量明显增加,内皮祖细胞增值、粘附、迁移功能也明显提高.结论:G-CSF通过加速内皮修复能预防再狭窄,该作用与其动员效应即内皮祖细胞数量的增加和增值、粘附、迁移功能的提高有关.     

血管再生中的内皮祖细胞

循环血液里存在一种被称为内皮祖细胞(endothelial progenitor cells,EPCs)的祖细胞亚群,具有在体内外分化为成熟内皮细胞的能力。根据内皮祖细胞与其他血液细胞的粘附能力的差异和内皮祖细胞的抗原特异性,内皮祖细胞可通过贴壁培养和免疫磁珠筛选而分离获得。内皮祖细胞可特异性表达三种祖细胞分子标志：CD133、CD34和血管内皮生长因子受体-2。当内皮祖细胞分化为成熟内皮细胞后,血小板内皮细胞粘附分子-1(CD31)、血管内皮粘附素(VE-cadherin,又称CD144)和Ⅷ因子(vWF)表达将上调。越来越多的证据显示,内皮祖细胞有利于体内内皮损伤后修复和血管再生。我们的研究发现,内皮祖细胞可修复apoE-缺陷小鼠血管移植物中的损伤内皮并且在动脉血管外膜中存在大量的血管祖细胞。然而,在机体的血管再生和动脉硬化的形成进程中,这些内皮祖细胞的作用和机制还不太明确。另外,有关机体内相应心血管疾病危险因素是如何影响内皮祖细胞功能的机制也不清楚。因此,对内皮祖细胞的归巢、释放和粘附机制的进一步深入研究将有助于人们探索内皮祖细胞的基础理论和临床应用价值。     

血管内皮祖细胞与炎性因子相关性的研究进展

内皮祖细胞(EPCs)是一种能直接分化为血管内皮细胞的前体细胞,不仅参与胚胎期的血管发生,还存在于骨髓、外周血和脐血中,在成体血管新生和受损内膜的再内皮化中发挥重要作用.然而,血管发生和炎症反应是两个密切联系的过程,血管损伤通常伴有局部促炎症介质的释放.多种炎症介质通过不同信号通路影响内皮祖细胞的数量和功能,从而影响损伤血管的修复和再生,参与炎症反应的发生和发展.本文结合近年来的研究进展,就EPCs与炎性相关因子如C-反应蛋白、肿瘤坏死因子-α、白细胞介素-1β、血管生成素、基质细胞衍生因子-1等的关系作一综述.     

内皮祖细胞(EPCs)研究进展

组织工程血管以及组织工程化组织的血管化因目前内皮种子细胞扩增能力和生物活力的不足而受到限制。EPCs(内皮祖细胞)是内皮细胞的前体细胞。在胚胎期,内皮细胞系与造血细胞系来源于血岛内共同的祖先细胞;出生后,EPCs存在于骨髓,并可被转移至外周血,参与缺血组织的血管重建和血管的内膜化。因此EPCs有望成为今后组织工程内皮种子细胞的重要来源。     

磷铵两性离子改性血管脱细胞支架可以有效体外抗血栓和内皮化

由于自体血管(由同一受体的血管用于血管移植材料)的有限可用性,以及非自体血管(人工制成的血管移植材料)的生长能力不足,组织工程血管越来越受到重视。文中构建了一种磷铵两性离子改性的血管脱细胞支架附以高度生物相容的骨髓源内皮祖细胞为内层的新型血管移植材料。通过一种简便的方法——共沉淀法改性血管脱细胞支架,评价其体外血小板粘附实验、溶血实验、复钙实验和细胞毒性等相关指标。磷铵两性离子改性后抗凝血活性提高,可以有效地促使类似于天然血管腔表面凹凸结构的脱细胞支架表面内皮祖细胞的附着。改性后的脱细胞支架具有与天然血管相似的力学性能,在体外可以有效地构建内皮化。研究结果为血管脱细胞支架通过改性实现体外抗血栓和内皮化方面进行了初步探索。     

血管内皮生长因子基因对兔髂动脉内膜损伤的组织形态变化过程的影响

探讨血管内皮细胞的特异丝裂原－血管内皮生长因子（VEGF）基因阻止血管内膜损伤后形成再狭窄的组织变化过程。建立球囊拉伤血管内膜的兔髂动脉模型,将携带VEGF目的基因的真核表达载体pcDNA3/VEGF经多聚赖氨酸处理的PTCA球囊导管导入拉伤的血管内膜。VEGF基因组拉伤2周时血管内壁有VEGF mRNA和蛋白的高表达。血管内膜内皮化较快。2周时即有许多血管内皮细胞呈岛状分布。4周时内膜基本恢复光滑。内膜平滑肌细胞增生明显减少,而对照组2周时血管内膜粗糙,基底膜暴露,拉伤后4周仍无内皮细胞再生,最后形成虫蚀样改变。血管中膜平滑肌细胞穿过内弹性膜进入内膜并大量增生,内膜增厚。VEGF基因定位导入血管内壁后。VEGF mRNA和蛋白高表达且发挥其生物学效应,内皮细胞岛状增生,加快内膜内皮化,减轻内膜增厚。     

整联蛋白调控血管新生内膜增生的研究进展

血管新生内膜增生是支架植入术、动静脉瘘术等血管手术以及动脉粥样硬化、高血压等心血管疾病的生理特征。整联蛋白介导的细胞黏附在新生内膜增生过程中起着重要作用。该文概述了整联蛋白在此过程中对白细胞黏附、平滑肌细胞迁移增殖、再内皮化的调控及目前用于研究新生内膜的相关动物模型。了解整联蛋白调节血管新生内膜增生的分子机制,为临床上防治新生内膜增生、解决术后血管再狭窄等相关研究提供参考。     

Mechanistic evaluation of long-term in-stent restenosis based on models of tissue damage and growth

Development and application of advanced mechanical models of soft tissues and their growth represent one of the main directions in modern mechanics of solids. Such models are increasingly used to deal with complex biomedical problems. Prediction of in-stent restenosis for patients treated with coronary stents remains a highly challenging task. Using a finite element method, this paper presents a mechanistic approach to evaluate the development of in-stent restenosis in an artery following stent implantation. Hyperelastic models with damage, verified with experimental results, are used to describe the level of tissue damage in arterial layers and plaque caused by such intervention. A tissue-growth model, associated with vessel damage, is adopted to describe the growth behaviour of a media layer after stent implantation. Narrowing of lumen diameter with time is used to quantify the development of in-stent restenosis in the vessel after stenting. It is demonstrated that stent designs and materials strongly affect the stenting-induced damage in the media layer and the subsequent development of in-stent restenosis. The larger the artery expansion achieved during balloon inflation, the higher the damage introduced to the media layer, leading to an increased level of in-stent restenosis. In addition, the development of in-stent restenosis is directly correlated with the artery expansion during the stent deployment. The correlation is further used to predict the effect of a complex clinical procedure, such as stent overlapping, on the level of in-stent restenosis developed after percutaneous coronary intervention.

     

Neoatherosclerosis causing edge in-stent restenosis: optical coherence tomography findings

A patient presenting with ‘edge’ in-stent restenosis 12 years after the implantation of a bare-metal stent in the mid-left anterior descending coronary artery is described. Optical coherence tomography disclosed the presence of ruptured neoatherosclerosis at the stent edge. The value of this imaging technique to unravel this unique underlying anatomic substrate is discussed. The therapy of choice for patients presenting with edge in-stent restenosis (ISR) is reviewed.     

Marked increase in the histamine content of neointima after stent implantation of pig coronary artery and growth-promoting effects of histamine in cultured smooth muscle cells

After coronary stent implantation, the unfavorable in-stent restenosis often occurs by the formation of neointima due to the proliferation of smooth muscle cells. Platelet-derived growth factor (PDGF) and other peptide growth factors contribute to this process, but little is known about the role of non-peptide factors in this process. In the present study, the role of histamine, a non-peptide factor, in the formation of neointima was investigated using a pig coronary model of in-stent restenosis and a culture system of coronary smooth muscle cells. A Palmaz-Schatz stent was implanted in the left anterior descending coronary artery of male pigs. At 1, 2 and 4 weeks after stenting, the histamine content of neointima was determined to be 326 +/- 82, 1427 +/- 280 and 440 +/- 69 pmol/mg protein, respectively, by HPLC fluorometry. In contrast, the histamine content of arterial media from the untreated control arteries was only 15.3 +/- 1.6 pmol/mg protein. These results demonstrate that the histamine content of neointima is about 20 to 90-fold that of the normal media. In vitro, histamine by itself did not stimulate the proliferation of cultured smooth muscle cells, but potentiated the PDGF-stimulated proliferation of the cultured cells via a mechanism independent of H1 and H2 histamine receptors. Thus, histamine may be an important non-peptide factor in the pathogenesis of in-stent restenosis.     

Biodegradable stents as a platform to drug loading

Despite technical and mechanical improvement in coronary stents the incidence of restenosis caused by in-stent neointimal hyperplasia remains high. Oral administration of numerous pharmacological agents has failed to reduce restenosis after coronary stenting in humans, possibly owing to insufficient local drug concentration. Therefore, drug-eluting stents were developed as a vehicle for local drug administration. The authors developed a new drug-eluting polymer stent that is made of poly-l-lactic acid polymer mixed with tranilast, an anti-allergic drug that inhibits the migration and proliferation of vascular smooth muscle cells induced by platelet-derived growth factor and transforming growth factor->1. Polymer stents might be superior to polymer-coated metallic stents as local drug delivery stents in terms of biodegradation and the amount of loaded drug. Drug-mixed polymer stents can be loaded with a larger amount of drug than can drug-coated metallic stents because the polymer stent struts can contain the drug. Clinical application is required to assess the safety and efficacy of drug-eluting polymer stents against stent restenosis.     

血清白细胞介素-18、氧化低密度脂蛋白与急性心肌梗死患者急诊PCI术后支架内再狭窄的关系

目的:探讨血清白细胞介素-18(IL-18)、氧化低密度脂蛋白(ox-LDL)与急诊经皮冠状动脉介入治疗(PCI)术后支架内再狭窄的关系。方法:75例急性心梗急诊介入术后8～12个月内接受冠状动脉造影复查,其中9例有再狭窄作为再狭窄组,66例无再狭窄作为对照组。2组术后均接受阿司匹林、氯吡格雷、他汀类等药物治疗。取2组患者PCI术前、术后冠状动脉造影复查时血清标本,采用酶联免疫吸附法(EL ISA)检测血清IL-18、ox-LDL水平。结果:①再狭窄组PCI术后IL-18、ox-LDL水平较术前均明显升高[(2.37±0.22):(0.85±0.19)mg/L、(6.99±0.98):(2.38±1.06)mg/L],均P<0.01;对照组PCI后IL-18、ox-LDL水平较术前明显下降[(0.48±0.11):(1.23±0.09)mg/L、(1.39±0.54):(4.45±0.87)mg/L],P<0.05。②再狭窄组和对照组PCI术前IL-18、ox-LDL水平差异无统计学意义,再狭窄组PCI术后IL-18、ox-LDL水平显著高于对照组(均P<0.01)。④再狭窄组和对照组术前、术后IL-18和o...     

Brachytherapy with gamma radiation of a coronary artery for in-stent restenosis may induce the regression of in-stent restenosis of an adjacent coronary artery without angioplasty. First case report and review of the literature

Here, we present a case of a 63-year-old male who presented with in-stent restenosis of two coronary arteries simultaneously (mid circumflex and proximal ramus). After the brachytherapy of the circumflex artery for in-stent restenosis, the patient refused the staged procedure for the ramus in-stent restenosis. After approximately 2 years, the patient underwent coronary angiography for recurrent chest pain. Surprisingly, the proximal ramus stent showed marked regression of in-stent restenosis. We hypothesized that the gamma brachytherapy of the circumflex artery could have induced the regression of in-stent restenosis of the adjacent ramus artery due to the deep tissue penetration of gamma radiation. Based on our observation, we believe that in the treatment of in-stent restenosis of a coronary artery, the initial balloon angioplasty may not be as important as the radiation itself. This observation warrants further study to evaluate the effect of external or internal radiation on in-stent restenosis without balloon angioplasty. If our hypothesis is confirmed, the treatment of in-stent restenosis with external radiation could substantially simplify the treatment of this disease. This case report follows a brief review of the literature.     

The effects of stenting on coronary endothelium from a molecular biological view: Time for improvement?

Coronary artery stenting following balloon angioplasty represents the gold standard in revascularization of coronary artery stenoses. However, stent deployment as well as percutaneous transluminal coronary angioplasty (PTCA) alone causes severe injury of vascular endothelium. The damaged endothelium is intrinsically repaired by locally derived endothelial cells and by circulating endothelial progenitor cells from the blood, leading to re‐population of the denuded regions within several weeks to months. However, the process of re‐endothelialization is often incomplete or dysfunctional, promoting in‐stent thrombosis and restenosis. The molecular and biomechanical mechanisms that influence the process of re‐endothelialization in stented segments are incompletely understood. Once the endothelium is restored, endothelial function might still be impaired. Several strategies have been followed to improve endothelial function after coronary stenting. In this review, the effects of stenting on coronary endothelium are outlined and current and future strategies to improve endothelial function after stent deployment are discussed.     

A Murine Model of Stent Implantation in the Carotid Artery for the Study of Restenosis

Despite the considerable progress made in the stent development in the last decades, cardiovascular diseases remain the main cause of death in western countries. Beside the benefits offered by the development of different drug-eluting stents, the coronary revascularization bears also the life-threatening risks of in-stent thrombosis and restenosis. Research on new therapeutic strategies is impaired by the lack of appropriate methods to study stent implantation and restenosis processes. Here, we describe a rapid and accessible procedure of stent implantation in mouse carotid artery, which offers the possibility to study in a convenient way the molecular mechanisms of vessel remodeling and the effects of different drug coatings.     

Current perspectives of biodegradable drug-eluting stents for improved safety

The introduction of the drug-eluting stent (DES) proved to be an important step forward in reducing the rates of restenosis and target lesion revascularization after percutaneous coronary intervention (PCI). However, the rapid implementation of DES in standard practice and the expansion of the indications for PCI to high-risk patients and complex lesions also introduced a new problem. DES in-stent restenosis (ISR) occurs in 3 ?? 20% of patients, depending on the patient, lesion characteristics and the DES type. The initial commercially available DES used a stainless steel platform coated with a permanent polymer to provide a controlled release of an anti-restenotic drug. The platform, polymer and drug are all targets for improvement. More advanced metallic and fully biodegradable stent platforms are currently under investigation. The permanent polymer coating, a likely contributor to adverse events, is being superseded by biocompatible and bioabsorbable alternatives. New drugs and drug combinations are also a research goal, as interventional cardiologists and the industry strive towards a safer anti-restenotic DES. This paper reviews the benefits, risks, and current status of biodegradable drug-eluting stents.     

Realistic finite element-based stent design: the impact of balloon folding

At present, the deployment of an intravascular stent has become a common and widely used minimally invasive treatment for coronary heart disease. To improve these coronary revascularization procedures (e.g. reduce in-stent restenosis rates) the optimal strategy lies in the further development of stent design, material and coatings. In the context of optimizing the stent design, computational models can provide an excellent research tool. In this study, the hypothesis that the free expansion of a stent is determined by the unfolding and expansion of the balloon is examined. Different expansion modeling strategies are studied and compared for a new generation balloon-expandable coronary stent. The trifolded balloon methodology presented in this paper shows very good qualitative and quantitative agreement with both manufacturer's data and experiments. Therefore, the proposed numerical expansion strategy appears to be a very promising optimization methodology in stent design.