剪切应力对家兔血管内膜增生及动脉粥样硬化斑块形成的影响

目的设计局部狭窄而导致血流动力学改变的实验模型,探讨剪切应力对血管内膜增生以及动脉粥样硬化斑块形成的影响。方法兔颈总动脉平直段套环形成狭窄度为40%的局部狭窄,饲以正常饮食4周;数值计算的方法模拟血流流场和剪切应力分布及其特征;HE染色检测颈总动脉病理改变;Verhoeff法染色观察血管弹力纤维分布;油红O染色观察斑块内的脂质沉积;高效液相色谱检测血管壁脂质含量。结果套环形成局部狭窄后,颈总动脉血流流场发生显著的扰动,狭窄远心端有涡流以及二次流形成;狭窄近心端形成局部高剪切应力区域(6Pa),而在远心端形成振荡的低剪切应力区域(0～0.3Pa);HE染色显示颈总动脉狭窄的近心端和远心端均有明显的内膜增生以及动脉粥样硬化斑块形成,近心端比远心端病变更严重,近心端增生内膜厚度为165.6±28.3μm,远心端增生内膜厚度为38.5±12.7μm,并且近心端增生内膜的细胞成分主要为圆形的泡沫细胞而远心端增生内膜的细胞成分主要为梭形平滑肌细胞;Verhoeff染色显示病变处弹力纤维排列紊乱,部分内弹力板断裂;油红O染色发现增生的斑块中有大量的脂质沉积;高效液相色谱检测也表明狭窄近心端胆固醇含量(7.6±2.1mg/g)以及远心端胆固醇含量(5.6±1.8mg/g)较对照侧(1.3±0.5mg/g)明显增加。结论高剪切应力以及低振荡剪切应力均引发动脉粥样硬化病变的形成,但不同的剪切应力对斑块的组成和特性有着不同的作用。     

异常剪切应力上调组织蛋白酶L在动脉粥样硬化斑块中表达

目的观察组织蛋白酶L(Cathepsin L)在异常剪切切应力诱导的动脉粥样硬化斑块中的表达,探讨Cathepsin L在动脉粥样硬化病变中的作用。方法采用套环法建立兔颈总动脉局部狭窄的动物模型,喂养4周;数值模拟法模拟局部狭窄远心端和近心端流场特性以及剪切应力分布;酶法测定血浆中总胆固醇、甘油三酯以及HDL水平;HE染色观察病理学改变;油红O染色观察病变处脂质的蓄积;免疫组织化学法检测Cathepsin L的表达。结果 4周后,兔血脂水平没有明显改变。套环形成局部狭窄后,颈总动脉血流流场发生显著的扰动,狭窄远心端有涡流以及二次流形成;狭窄近心端形成局部高剪切应力区域,而在远心端形成振荡的低剪切应力区域(0～0.3 Pa)。HE染色显示颈总动脉狭窄的近心端和远心端均有明显的内膜增生以及动脉粥样硬化斑块形成,近心端比远心端病变更严重。油红O染色显示有大量的脂质沉积;免疫组织化学染色结果表明病变中有大量的Cathepsin L表达,主要分布于斑块中的巨噬细胞和平滑肌细胞,并且近心端Cathepsin L的表达量明显高于远心端量,而对照侧血管仅有微量的Cathepsin L表达。结论切应力特性调节Cathepsin...     

干细胞分化为平滑肌细胞参与血管病变

动脉粥样硬化,冠状动脉介入术后再狭窄以及器官移植相关的血管病变,以增生内膜平滑肌细胞增殖,分泌细胞外基质为主要特点。传统观点认为增生内膜的平滑肌细胞系血管中层平滑肌细胞向内膜迁移,增殖的结果。现代认为干细胞能分化为血管平滑肌细胞,参与上述疾病的发生、发展。     

动脉粥样硬化发生中高脂血症与动脉狭窄的作用比较

目的分析比较高脂血症和动脉狭窄在动脉粥样硬化形成中的作用,并探讨其可能的作用机制。方法采用颈总动脉套环术加高脂高胆固醇饲料喂养新西兰白兔,建立兔颈总动脉粥样硬化模型。血浆总胆固醇、甘油三酯和高密度脂蛋白胆固醇的浓度均用酶法测定。用数字剪影动脉造影技术来检测手术效果和动脉狭窄程度。通过病理技术观察血管壁组织形态并进行图象分析。结果喂养9周后,无论是对照组还是高脂组,套环的颈总动脉均发现了大量的泡沫细胞,尤以高脂组更为显著。此时,高脂组兔的主动脉弓部可见脂质条纹,病变面积占主动脉面积的30.8%±6.3%。而对照组兔未见动脉粥样硬化病变。结论结果提示采用颈总动脉套环术,可以使兔颈总动脉在较短时间内在明确预定的部位形成动脉粥样硬化病变。动脉粥样硬化病变的形成与高脂血症和血流动力学的变化密切相关。动脉狭窄可通过血流动力学作用引发粥样硬化病变,该作用可不依赖于高脂血症的存在。动脉狭窄引发的病变在狭窄远心端较近心端严重。     

低剪切应力促进基质细胞衍生因子1在动脉粥样硬化斑块中表达

目的探讨基质细胞衍生因子1在局部狭窄远心端低切应力诱导的动脉粥样硬化斑块中的表达,从而探讨基质细胞衍生因子1在动脉粥样硬化病变中的作用。方法建立颈总动脉局部狭窄动物模型,数值模拟局部狭窄远心端流场以及剪切应力分布,HE染色观察局部狭窄远心端病理学改变,免疫组织化学法观察基质细胞衍生因子1在病变处的表达。结果在局部狭窄远心端形成低剪切应力区域(0~0.3 Pa),并有明显的动脉粥样硬化病变,有明显的内膜增生形成(对照组为8±3μm,处理组4周为38.5±12.7μm,8周为95.3±19.6μm)。免疫组织化学检测发现病变中有大量的基质细胞衍生因子1表达,对照侧血管无基质细胞衍生因子1表达,并且随着病变程度的增加,基质细胞衍生因子1表达量明显增加。结论基质细胞衍生因子1可能在低剪切应力诱导的动脉粥样硬化斑块的发生发展中起着重要的调节作用。     

adipophilin及蛋白激酶C在动脉粥样硬化模型中的表达

目的探讨动脉粥样硬化病变区动脉壁增厚与adipophilin表达及蛋白激酶C(PKC)活性三者之间的关系。方法将24只新西兰白兔随机分为对照组(12只)和实验组(12只)。高TC饮食喂饲12周,动脉切片HE染色;采用PepTagAssay法检测PKC活性变化,Western blot印迹和免疫组织化学染色检测PKCα和adipophilin表达。并进一步在细胞学水平观察平滑肌细胞、巨噬细胞和内皮细胞PKC活性的分布及adipophilin的表达。结果主动脉病变区可见内膜增生、中层增厚,脂质条纹突起,增生内膜内蓄积大量的泡沫细胞。病变区PKC活性和adi-pophilin表达上调,与adipophilin阳性颗粒仅局限于增生内膜不同,PKCα在内膜、近内膜的中层区均呈强阳性表达。细胞学实验显示adipophilin表达于巨噬细胞,而PKC活性则以平滑肌细胞最强,内皮细胞最弱。结论动脉粥样硬化病变区内膜增生、中层增厚可能与PKC介导的细胞增殖凋亡紊乱及adipophilin介导的脂质蓄积有关。在巨噬细胞adipophilin的表达可能与细胞膜PKC活性的改变有着某种潜在联系。     

富集在平滑肌中的长链非编码RNA调控细胞增殖

正血管平滑肌细胞(vascular smooth muscle cells,VSMC)从收缩到合成状态的表型转换涉及到不同的血管病变,包括动脉粥样硬化,斑块稳定和新生内膜增生。而长链非编码RNA(long non coding RNA,lncRNA)在上述过程中的作用尚未知。该研究旨在探讨lncRNA在VSMC生物学和病理学中的作用。方法和结果:研究人员利用RNA测序,确定了数量300个lncRNA,其在人大隐静脉VSMC中的表达随着白细胞介素1α和血小板源性生长因子的刺激而     

沙利度胺抑制异常剪切应力诱导的动脉粥样硬化形成

目的 研究沙利度胺对异常剪切应力诱导的兔颈总动脉粥样硬化病变形成的作用.方法 新西兰兔分为3组,每组13只:正常饮食组、高脂组(给予2%高胆固醇饮食)和高脂加药组(2%高胆固醇饮食+20 mg/kg沙利度胺).39只新西兰兔均予以右颈总动脉硅胶管套环,套环长度为8咖,内径为1.4mm.9周后处死动物,0周和第9周收集血清测量总胆固醇、低密度脂蛋白、高密度脂蛋白及甘油三酯等血脂指标水平.2个月后宰杀动物,取整条颈总主动脉行苏丹Ⅳ染色检测癌变面积,HE染色检测病变的病变程度.结果 0周和9周时三组动物体重差异没有显著性,一般体征无明显变化,表明动物对沙利度胺有很好耐受性.高脂组和高脂加药组总胆固醇、低密度脂蛋白、高密度脂蛋白及甘油三酯血清水平较对照组明显升高,高脂组和高脂加药组血脂指标间差异无显著性.颈总动脉苏丹Ⅳ染色结果发现,高脂组远心段和近心段有明显的红染区域示动脉粥样硬化病变形成,且近心段动脉粥样硬化病变更加明显,狭窄段基本上没有动脉粥样硬化病变形成;高脂加药组主要在近心段有少量动脉粥样硬化病变存在;正常饮食组整条颈总动脉都无可见动脉粥样硬化病变.HE染色发现,高脂组近心段有明显的动脉粥样硬化病变存在,管腔明显狭窄,动脉粥样硬化病变中有大量的脂质蓄积和细胞浸润;高脂组套环段管壁明显变薄,元明显动脉粥样硬化病变存在;高脂组远心段动脉粥样硬化病变程度较近心段轻.高脂加药组仅在近心段有内膜增生病变存在.正常饮食组内膜无明显改变.结论 剪切应力改变可以导致不同程度动脉粥样硬化病变的形成;沙利度胺对异常剪切应力诱导的兔颈总动脉粥样硬化病变的形成有抑制作用.     

细胞增殖动脉粥样硬化与血小板

现已公认动脉粥样硬化的发生主要是内膜平滑肌的增殖。动脉粥样硬化的形成可分为3期:(1)脂肪条索状块;这时只有少数增殖细胞,内膜只轻度增厚,但由于广泛的脂肪沉积,使病变部位呈黄色。显微镜检查黄色条索状块主要是平滑肌细胞及巨噬细胞内脂质的沉积。(2)纤维斑块;此时内膜显著增厚,且有大量的平滑肌细胞增殖且形成新的结缔组织。斑块的深部含有细胞碎屑及脂质,且被一层密集的结缔组织所复盖。(3)晚期病变的纤维斑块,常含有钙质沉积,形态不规则。重者可引起心肌梗死及脑血管栓塞。作者 Rose 指出,在动脉粥样硬化形成的过程     

冠状动脉狭窄对血管血流动力学的影响

目的运用计算流体动力学技术,模拟冠状动脉不同狭窄程度的血流动力学变化,探索冠状动脉血流动力学变化和血流分布与冠状动脉不同狭窄病变的关系。方法以正常人右冠状动脉CT图像数据为基础,重建冠状动脉几何模型,人工建立狭窄程度分别为0%(正常)、30%(轻度狭窄)、60%(中度狭窄)和90%(重度狭窄)的4种血管模型,并分别构建血管血流动力学模型,最后分别进行数值模拟,分析比较4种血管模型血流动力学的差别。结果通过比较4种血管模型的血流动力学数值模拟可发现,随着冠状动脉狭窄程度增加,狭窄远心端血流涡旋愈加明显,狭窄处血流速度以及狭窄前血管壁面压力(WP)逐渐增加,而狭窄远心端WP逐渐下降;狭窄处壁面切应力(WSS)分布一直处于高值,并且当血管狭窄程度达到中重度狭窄,狭窄远心端血管可见明显的高WSS区域,而狭窄远心端血管其他区域呈现低WSS;狭窄前后血管血流速度以及血流分布也发生了改变。结论在CT图像上,可能能较准确重建出冠状动脉血流动力学模型,并模拟出不同狭窄程度冠状动脉模型。中重度冠状动脉狭窄远心端血流动力学表现为明显的血流涡旋以及高WSS区域,这种血流动力学变化可能会加重血管动脉粥样硬化,从而进一步加重血管狭窄。     

Adventitial progenitor cells contribute to arteriosclerosis

Accumulating evidence indicates the involvement of vascular progenitor cells in the development of arteriosclerosis, including transplant arteriosclerosis, angioplasty-induced restenosis, vein graft atherosclerosis, and spontaneous atherosclerosis. Recently, it was found that the adventitia of the arterial wall contains a large number of progenitor cells, which can differentiate into smooth muscle cells in vitro and in vivo. These progenitor cells were able to migrate from the adventitia into the intima, where they accumulate to contribute to atherosclerotic lesions of vein grafts in apoE-deficient mice. Thus, these cells may be a source of smooth muscle cells and might have implications for cellular, genetic, and tissue engineering approaches to vascular disease.     

Neonatal intima formation in the human coronary artery.

Intimal masses develop in the human coronary arteries of all humans, becoming atherosclerotic in later life either because of focal accumulation of lipid or the resulting response to injury. We evaluated the time course of formation of the intimal mass in the proximal left anterior descending coronary artery in autopsy specimens from 91 patients between 17 weeks' gestation and 23 months of postnatal age. Intima was rarely found before 30 weeks' gestation; however, the frequency with which at least some intimal cells were observed increased to 35% between 36 weeks' gestation and birth. By 3 months after birth, all patients had an intimal mass at this coronary location. The mean intima/media ratio was 0.1 just after birth and increased continuously to the second postnatal year. Replication of medial smooth muscle cells, indicated by proliferating cell nuclear antigen staining, was high before birth and decreased between birth and 2 years of age. However, the replication index of the intima remained at 2% to 5%. Thus, coronary intimal cells appearing in the perinatal period may arise by migration after replication of medial smooth muscle, as is seen in models of carotid artery balloon injury. In conclusion, formation of the coronary artery intima is a rapid process, beginning in the peripartum or postpartum period. Given the clonality of the adult lesion and the lack of proliferation in later stages of lesion formation, it is intriguing to speculate that this event may form the basis for atherosclerosis in later life.     

Ultrastructural studies on the phenotypic modulation of human intimal smooth muscle cells

The present study was carried out to clarify the mechanism of intimal thickening at the ostia of celiac and superior mesenteric arteries. The cell components involved in the process were analyzed under electron microscope. Autopsy samples from cases without significant atherosclerotic diseases were examined and the percentages of smooth muscle cells in either synthetic or contractile state, macrophages, and foam cells in the intima of mesenteric and celiac arteries were calculated. Smooth muscle cells in the synthetic state were predominant in the proximal region and those in the contractile state were predominant in the distal region. Few macrophages were present in both regions. The intima in the proximal and distal regions of celiac arteries in autopsy samples was further divided into three layers and the percentages of various smooth muscle cell phenotypes in each layer were calculated and compared in patients at different ages. In the proximal region, the phenotype of the smooth muscle cells changed from the synthetic to the contractile state from the deeper to the superficial layers with the advance of age. In the distal region, the contractile state was dominant regardless of the age. These results suggest that the phenotypic modulation of human intimal smooth muscle cells is reversible dedifferentiation-redifferentiation process; this phenomenon plays an important role in the initiation of atherosclerosis.     

Effects of fibrinogen and fibrin on the migration of vascular smooth muscle cells in vitro

The migration of vascular smooth muscle cells from the media into the intima and their proliferation in the intima play an important role in the pathogenesis of atherosclerosis. We examined the effects of fibrinogen and fibrin on the migration of cultured bovine aortic smooth muscle cells using a modified Boyden chamber assay. The cells migrated to a gradient of soluble fibrinogen. Checkerboard analysis indicated that the effect was largely directional in nature (chemotaxis). The cells also migrated in a dose-dependent manner to a gradient of substrate-bound fibrinogen (haptotaxis). Fibrin, converted from substrate-bound fibrinogen by thrombin, also induced haptotaxis of smooth muscle cells. These observations suggest that, by recruiting smooth muscle cells from the media into the intima, fibrinogen and fibrin may be involved in the pathogenesis of arterial intimal thickening, atherosclerosis, and the organization of a thrombus.     

阿托伐他汀对THP1巨噬细胞脂质蓄积及CD36表达的影响

目的观察阿托伐他汀对氧化型低密度脂蛋白诱导的THP1巨噬细胞脂质蓄积及CD36表达的影响。方法用50mg/L氧化型低密度脂蛋白与不同浓度(0μmol/L、0.312μmol/L、1.25μmol/L和5μmol/L)的阿托伐他汀共同孵育24h,空白组作为对照,用液体闪烁计数法检测细胞[3H]胆固醇流入情况,油红     

Inflammatory-immunological cellular reaction in intima of the aorta and pulmonary artery and development of atherosclerosis

AIM: To assess morphological manifestations of inflammation at initial stages of atherosclerosis development in intima of the aorta and pulmonary artery both in its intact (lipid free) zones and those with lipoidosis. METHODS: Histological, histochemical and immune cytochemical methods with the use of monoclonal antibodies to monocytes/macrophages (CD-11) and T-lymphocytes (CD-4, CD-5, CD-8) were applied for the study of cellular elements in membranous preparations of intima and transverse cross-sections of the aorta and pulmonary artery from 64 apparently healthy persons aged 4 months-49 years who died of accidental causes. RESULTS: Signs of inflammatory cellular reaction (infiltration with monocytes/macrophages) were permanently present in aortic and pulmonary artery intima and progressed with age. This cellular reaction was consistently accompanied by infiltration of intima with mast cells. Compared with intact intima infiltration with lymphocytes/monocytes was more pronounced in zones with lipoidosis where helper-lymphocytes prevailed among T-cells and number of monocytes/macrophages was substantially increased. CONCLUSION: Mononuclear cellular infiltration with participation of mast cells was persistently present in aortic and pulmonary artery intima and obviously preceded its atherosclerotic changes. However there was no straightforward relationship between severity of this reaction and development of atherosclerosis in the aorta and especially in pulmonary artery.     

Changes of coronary artery morphology and distribution of smooth muscle cells during progression of coronary atherosclerosis after heart transplantation

To examine the changes in coronary artery morphology and the distribution of smooth muscle cells during the progression of coronary atherosclerosis after cardiac transplantation, intimal and medial tissues were evaluated and the density of smooth muscle cells in the media were measured 30 and 60 days after transplantation by microspectrophotometry from rats receiving both auto- and allo-transplantation. Transplanted animals were given cyclosporine A to prevent graft rejection. Signs of rejection were not seen in the animals receiving auto-transplants. Rejection gradually progressed after transplantation in animals receiving allografts. The intima of the coronary arteries in the allograft group was significantly thickened at both 30 and 60 days after transplantation. The total intimal area in the day 60 group was significantly increased relative to the day 30 group among animals receiving allo-transplantation. The medial area of the coronary arteries in the group receiving allotransplantation was significantly less than that of the auto-transplantation group at both 30 and 60 days after transplantation. Azocarmine G stain revealed that the principal component of the thickened intima was smooth muscle cells. Coronary arteries in the allotransplantation group had disruption of the internal elastic lamina. We therefore hypothesized that the smooth muscle cells (SMCs) in the intima are probably derived from the media. The density of SMCs in the media was measured by microspectrophotometry. The density of SMCs was significantly decreased in the allo-transplantation group relative to the autotransplantation group. We conclude that intimal thickening of the coronary arteries is due to SMC proliferation, the myocytes being from the media through disruption of the internal elastic lamina. This process is similar to the mechanism of the development of atherosclerosis.     

Locally acting growth factors for vascular smooth muscle cells: endogenous synthesis and release from platelets

Release of platelet-derived growth factor (PDGF) from platelets has been postulated to stimulate at least some of the cell proliferation seen at sites of tissue damage, both beneficially (wound healing) and perniciously (during formation of atherosclerotic lesions). Two other growth factors have been localized to the platelet: epidermal growth factor and transforming growth factor. These factors may function synergistically with PDGF in promoting smooth muscle cell proliferation in the injured vessel wall. PDGF-like molecules (PDGF-c) that bind to the PDGF receptor and are at least partially recognized by antiserum against PDGF may also be synthesized by vessel wall cells themselves under certain circumstances. Arterial endothelial cells secrete several mitogens, one of which is a PDGF-c. Release is greatly stimulated by exposure of the cells to physiologic concentrations of thrombin. Also, aortic smooth muscle cells from 2-week-old rats secrete mitogenic levels of PDGF-c. In this case, PDGF-c accounts for all the mitogenic activity in conditioned medium (when assayed on 3T3 cells). Smooth muscle cells obtained from adult rat aortae secrete 150-fold less PDGF-c. In a third example, when adult rat carotid arteries are damaged with a balloon catheter, smooth muscle cells migrate into the intima of the artery and proliferate. By 2 weeks, the number of smooth muscle cells in the artery has doubled. When these intimal smooth muscle cells are cultured, they are found to secrete PDGF-c. These findings suggest that activation of endogenous synthesis of PDGF-c may contribute to the smooth muscle cell proliferation seen in response to vascular injury.     

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) in atherogenesis.

Lectin-like oxidized low density lipoprotein receptor-1 (LOX-1) is a type-II membrane protein belonging to the C-type lectin family molecules, which can act as a cell surface endocytosis receptor for atherogenic oxidized LDL (Ox-LDL). LOX-1 is synthesized as a 40 kDa precursor protein with N-linked high mannose-type carbohydrate, which is further glycosylated and processed into a 50 kDa mature form. LOX-1 expression is not constitutive but can be induced by proinflammatory, oxidative, and mechanical stimuli. In addition to endothelial cells, macrophages and activated vascular smooth muscle cells express LOX-1. In vivo, endothelial cells covering early atherosclerotic lesions and macrophages and smooth muscle cells accumulated in the intima of advanced atherosclerotic plaques express LOX-1. LOX-1 is cleaved at membrane proximal extracellular domain by some protease activities and released from the cell surface. Measurement of soluble LOX-1 in vivo may provide novel diagnostic strategy for the evaluation and prediction of atherosclerosis and vascular diseases.     

LOX-1在动脉粥样硬化中的作用研究新进展

动脉粥样硬化(AS)是一种血管慢性炎症性病变,其中内皮细胞功能异常、单核细胞的黏附和迁移、平滑肌细胞的凋亡、泡沫细胞的形成和血小板的活化是AS形成的关键环节,最终结果是形成大、中动脉内膜下的粥样硬化斑块,造成管腔狭窄,远端组织器官供血不足甚至栓塞。低密度脂蛋白（LDL） 氧化形成的氧化型LDL（ox-LDL）在AS发生、发展过程中起着重要作用。目前在与AS发生、发展相关的细胞（如血管内皮细胞、血管平滑肌细胞、单核细胞、巨噬细胞以及泡沫细胞）上已经发现和鉴定了多种oxLDL受体,其中瘦素样氧化型低密度脂蛋白受体(LOX)-1表达于血管内皮细胞、巨噬细胞、血小板上,是ox-LDL的主要受体［1］,在AS的发生、发展中起着重要作用,本文将着重阐述近年来LOX-1影响AS发生发展相关效应与机制的新进展。