Endothelial progenitors

The studies carried out during the last two decades have represented a great effort in trying to identify and define cell populations endowed with the phenotypic and functional properties of endothelial progenitors. From these studies a scenario now emerges indicating that in the blood there are very rare endothelial progenitor cells, called endothelial colony-forming cells (ECFCs) or late outgrowth endothelial cells, not originated from bone marrow, capable of generating phenotypically and functionally competent endothelial cells, capable to be incorporated in vivo into growing vessels. ECFCs are present in the circulation as well as cells resident in the vascular endothelial intima. In addition to these progenitors, there are some hematopoietic progenitor cells capable of generating a monocytic cell progeny exerting a pro-angiogenic activity in vivo, but unable to be directly incorporated into growing vessels. These cells exert a pro-angiogenic effect in vivo through a paracrine mechanism based on the secretion of growth factors and cytokines.     

Endothelial aging

Aging is considered to be the major risk factor for the development of atherosclerosis and, therefore, for coronary artery disease. Apart from age-associated remodeling of the vascular wall, which includes luminal enlargement, intimal and medial thickening, and increased vascular stiffness, endothelial function declines with age. This is most obvious from the attenuation of endothelium-dependent dilator responses, which is a consequence of the alteration in the expression and/or activity of the endothelial NO synthase, upregulation of the inducible NO synthase, and increased formation of reactive oxygen species. Aging is also associated with a reduction in the regenerative capacity of the endothelium and endothelial senescence, which is characterized by an increased rate of endothelial cell apoptosis.     

体外反搏对冠心病患者血管内皮及其功能的影响

目的:通过增强型体外反搏治疗经皮冠状动脉腔内成形和支架置入术后的冠心病患者,观察对血管内皮舒张功能影响,以及是否会对血管内皮造成损伤。方法:将51例冠心病患者(均为经皮冠状动脉腔内成形和支架置入术后)分成两组,按1:2匹配,反搏组17例,对照组34例。两组均给予常规药物治疗,此外反搏组予以3个疗程的体外反搏治疗。血流介导的血管舒张反应(FMD)和硝酸甘油介导的血管舒张反应(NMD)采用Celermajer法;高敏C反应蛋白(hsCRP)的检测采用免疫比浊法。结果:对照组治疗后FMD、NMD、hsCRP较治疗前无明显变化(P＞0.05),反搏组治疗后FMD明显升高(P＜0.01), NMD也有升高(P＜0.05),hsCRP无明显变化(P＞0.05);组间比较发现,反搏组FMD和NMD的提高程度较对照组明显(P＜0.01),两组间hsCRP的改变无明显差异(P＞0.05)。结论:增强型体外反搏通过提高对血管壁内皮细胞的切应力,改善了经皮冠状动脉腔内成形和支架置入术后冠心病患者的内皮功能,使血管的舒张功能增加,且没有造成血管内皮的损伤,为冠心病患者的综合治疗提供了实验依据。     

内皮源性一氧化氮合酶的活性调节

内皮源性一氧化氮合酶(eNOS)代谢精氨酸产生的一氧化氮(NO)在调节血管的稳态中发挥着重要作用,内皮功能失调所致疾病多与NO的释放和活性受损有关。近年来关于eNOS活性词节的研究很多,机制主要包括乙酰化修饰所决定的亚细胞定位,蛋白-蛋白相互作用以及磷酸化修饰。许多体液因子和机械刺激可通过不同的方式调节eNOS活性。为了更好地认识eNOS的活性调节,本文就该领域最新的研究进展进行归纳总结。     

内皮功能障碍的生物标志物

急性心肌梗死、急性脑卒中等缺血性心脑血管疾病是世界范围内致死和致残的重要原因之一。目前的研究结果显示,动脉粥样硬化斑块的破裂及急性血栓形成是导致上述急性心脑血管事件的主要原因。但是由于动脉粥样硬化进展至不稳定斑块阶段后,病变难以逆转,而且此时进行治疗花费巨大,其效果却不尽如人意。因此,早期检出动脉粥样硬化高危人群,并进行包括生活方式以及药物治疗在内的早期干预,是降低动脉粥样硬化性心脑血管事件发生率的有效方法。     

不同剂量的阿托伐他汀对心肌损伤大鼠内皮祖细胞动员及血管内皮功能的影响

目的观察不同剂量的阿托伐他汀对心肌损伤后大鼠骨髓和外周血内皮祖细胞动员及血管内皮功能的影响。方法S-D大鼠背部皮肤多点注射异丙肾上腺素(5mg/kg)制造心肌损伤模型后,随机分为生理盐水对照组和不同剂量的阿托伐他汀组[5、10、20、40及80mg/(kg.d)]。4周后,流式细胞仪检测大鼠外周血CD34 和血管内皮生长因子受体2 双阳性细胞数。骨髓和外周血单个核细胞于M199培养基培养,FITC标记的异凝集素和DiI标记的乙酰化低密度脂蛋白染色双阳性细胞为正在分化的内皮祖细胞,倒置荧光显微镜计数3个随机高倍视野数。阿托伐他汀灌胃3天后测定血清一氧化氮浓度。结果阿托伐他汀各剂量组骨髓培养内皮祖细胞均较对照组明显增加(P<0.05),其中40mg/(kg.d)组内皮祖细胞数量最多,较对照组增加了2.4倍(P<0.05),80mg/(kg.d)组与40mg/(kg.d)组比较稍有下降,但无统计学差异;阿托伐他汀组外周血培养内皮祖细胞较对照组明显增加,40mg/(kg.d)组增加最明显(P<0.05);心肌损伤后外周血CD34 /血管内皮生长因子受体2 细胞较损伤前增加(P<0.05),其中80mg/(kg.d)组最明显,较对照组增加了4.18倍(P<0.05),40mg/(kg.d)组与80mg/(kg.d)组无统计学差异;阿托伐他汀各剂量组血清一氧化氮浓度较对照组明显增加,其中80mg/(kg.d)组增加最明显,并随剂量增加一氧化氮浓度增加。结论阿托伐他汀具有显著的剂量依赖性骨髓动员、促进外周血中内皮祖细胞迁移、改善血管内皮功能的作用。     

Circulating Endothelial Cells and Endothelial Progenitor Cells in Obstructive Sleep Apnea

Increased circulating endothelial cells (CECs) have been observed in patients with vascular injury associated with acute myocardial infarction, pulmonary hypertension, and congestive heart failure. Decreased circulating endothelial progenitor cells (EPCs) have been observed in patients with risk factors for cardiovascular disease. Obstructive sleep apnea (OSA) is associated with increased risk of cardiovascular disease and endothelial dysfunction. Subjects were recruited from patients referred for overnight polysomnograms; 17 subjects had OSA and 10 control subjects did not have OSA. All subjects lacked vascular disease and risk factors for vascular disease. Peripheral blood was obtained from fasting subjects in the morning, following sleep studies. CECs and EPCs were quantified using magnetic bead separation with UV epifluorescence microscopy and flow cytometry immunophenotyping, respectively. Cell counts and demographic variables were compared using unpaired t tests. Regression analysis was performed comparing cell counts with the apnea-hypopnea index (AHI) and nadir SaO(2). Subjects with OSA and controls did not differ significantly in terms of age and body mass index. Subjects with OSA had higher AHI, lower nadir SaO(2), and greater sleepiness (Epworth Sleepiness Scale scores). There were no significant differences in CEC (7.0+/-1.5 vs. 4.9+/-0.9, p>0.05) or EPC (1077+/-318 vs. 853+/-176, p>0.05) between controls and OSA cases, respectively. In this small study, we found no differences in CECs or circulating EPCs between patients with OSA and controls. OSA may not be associated with these markers of vascular endothelial cell injury in patients with no concomitant vascular disease.     

以内皮细胞微粒为靶点治疗内皮功能障碍的研究进展

内皮细胞微粒是内皮细胞在活化或凋亡时释放的一种直径约0.1～1μm的微粒。目前的研究证实内皮细胞微粒是内皮功能障碍的一种关键标志,早期改善内皮细胞功能是防治内皮功能障碍的关键途径,本文就针对以内皮细胞微粒为治疗靶点的国内外研究现状做一概述。     

内皮缝隙连接在介导细胞间交联和损伤血管内皮修复中的作用

目的探讨内皮缝隙连接在介导细胞间通讯及在损伤血管内皮修复中的作用。方法采用植块法培养大鼠主动脉内皮细胞,细胞免疫荧光染色法检测大鼠主动脉内皮细胞缝隙连接蛋白37、40及47的表达,荧光漂白后恢复技术检测缝隙连接介导的细胞间通讯。机械划痕建立内皮损伤模型,每24h摄像一次以定量分析内皮损伤修复速度,并观察缝隙连接特异性阻断剂18α-甘草次酸对内皮损伤后修复的影响。结果缝隙连接蛋白37、40及47在内皮细胞中均有表达。荧光物质能够通过缝隙连接在相邻细胞间进行传递,孤立细胞荧光恢复率显著低于相邻细胞(5.70%±0.63%比82.26%±1.68%,P<0.01);而18α-甘草次酸能够抑制缝隙连接介导的细胞间通讯,18α-甘草次酸干预组荧光恢复率显著低于对照组(53.58%±1.73%比82.26%±1.68%,P<0.05)。内皮划痕宽度在对照组与18α-甘草次酸干预组之间无显著性差异(396.57±25.32μm比370.12±19.40μm,P>0.05),内皮损伤24h后,18α-甘草次酸干预组划痕宽度显著大于对照组(237.38±20.40μm比126.29±21.40μm,P<0.05)。18α-甘草次酸干预组内皮损伤完全愈合时间显著多于对照组(4.2±0.2天比2.6±0.3天,P<0.05)。结论内皮细胞间存在缝隙连接介导的细胞间通讯,而18α-甘草次酸能抑制这种细胞间通讯并减慢内皮损伤修复速度及延长其愈合时间,提示内皮细胞缝隙连接在内皮损伤后修复过程中起重要作用。     

内皮祖细胞对PCI术后内皮损伤的修复作用研究进展

经皮冠状动脉介入治疗(PCI)是治疗冠心病的重要手段。然而PCI会导致机械性血管损伤,进一步导致冠状动脉血管再狭窄和支架内急性血栓事件。研究发现内皮祖细胞(EPC)在动脉粥样硬化病变发展过程中可能起着重要作用,现就EPC的作用特点、机制、预测机制和治疗作用等方面阐述EPC对PCI术后冠心病患者内皮损伤的修复作用。     

Endothelial protective effects of preconditioning

The consequences of cardiac ischemia-reperfusion are not limited to myocytes but also extend to the coronary endothelium, where they are characterized by decreased nitric oxide (NO)-dependent relaxations. Given the essential role of the endothelium and NO in the regulation of vascular tone as well as platelet and leukocyte function, protection of coronary endothelial cells is an important therapeutic target. In this context, several studies have shown that both early and delayed preconditioning may prevent endothelial dysfunction after index ischemia-reperfusion. This endothelial protection most likely results from the inhibitory effects of preconditioning on expression of endothelial adhesion molecules, resulting in reduced neutrophil-endothelial interactions. The mechanisms of early endothelial preconditioning resemble those described at the level of the myocytes, and may involve mediators such as adenosine, bradykinin, NO and free radicals, together with activation of protein kinase C and opening of ATP-sensitive potassium channels. With regard to delayed preconditioning, recent studies have shown that both NO and free radicals are involved as triggers of this second window of endothelial protection. The complex interactions between these two radical species ultimately lead to a delayed increase in NO production, most likely responsible for the decreased adhesion of neutrophils to endothelial cells. Further identification of the triggers and mediators of this endothelial protection will allow the development of new therapeutic agents targeting both the myocardium and the coronary vasculature.