选择素家族的分布及生物学功能研究进展

选择素广泛表达于白细胞、活化的内皮细胞以及血小板表面,可在血流状态下介导白细胞与血管内皮细胞和血小板的初始粘附,主要参与细胞与细胞之间选择性的相互作用.本文介绍选择素家族(L、P和E)蛋白分子的结构特征、生理病理分布及生理功能,并简要叙述近年来有关选择素功能、选择素与疾病相关性等研究进展情况.     

缺血再灌脑血管内皮损伤及GPⅢa表达的研究

缺 血再灌后脑微血管内皮细胞损伤、细胞粘附 ,已有一些研究[1,2 ] ,但缺血再灌后脑微血管血小板与内皮细胞之间粘附却研究不多 ,特别在脑缺血再灌的情况下 ,血小板粘附分子的表达和在体状态下血小板的粘附行为与粘附分子的表达之间的关系是否一致尚不十分明确。因此我们在活体状态下观察脑缺血再灌内皮细胞与血小板之间的粘附变化 ,结合组织免疫方法研究细胞粘附与粘附分子表达 ,确切地了解内皮损伤和血小板粘附的关系 ,为脑梗塞、血栓形成的防治提供重要的理论依据。1　材料和方法1.1　实验动物动物为蒙古沙土鼠 ,体重 6 5～ 75 ｇ ,雌雄…     

材料表面形态和微相结构

在体内和体外的试验中发现有亲水——疏水微相分离结构的嵌段共聚物具有极好的抗血栓性,这是由于明显地抑制粘附血小板的活化而引起的。在设计抗血栓性的聚合物时,我们认为亲水——疏水的微相结构表面是一个重要的参数。从这种观点出发,业已研究聚合物表面的形态、大小和化学结构对血液成分(如蛋白质、血小板)相互作用的     

生物材料表面粘附的血小板形态变化及分类研究

本文通过狗的股动静脉短路半体内循环试验,使12种高分子材料与血液接触,然后对材料表面粘附的血小板形态结构进行大量扫描电镜观察,发现材料表面血小板粘附是一个动态过程,而且粘附的血小板并不一定都发生变性(即被激活);在早期粘附的血小板中大多未变性,在血流作用下,其中许多又重新返回血流,并不导致血栓形成。因此目前流行的把粘附血小板数目作为评价血液相容性的指标有一定局限性,会出现假阳性,而应该把变性的血小板数目作为评价指标。作者把血小板形态变化分成五型和十二个亚型,提出了半定量评价变性血小板的方法。     

ICAM-1在疟原虫感染红细胞与内皮细胞粘附中功能的研究进展

细胞间粘附分子1(ICAM1),又名CD54,是免疫球蛋白超家族的成员之一,是一种重要的细胞表面粘附因子。ICAM1在介导疟原虫感染红细胞(PRBC)和血管内皮细胞粘附中起到重要的作用。重症疟疾患者血管内皮细胞表面的ICAM1表达上调。PRBC在脑微血管中的扣押是脑疟的致病机制之一,ICAM1与PRBC表面的PfEMP1分子的相互作用是扣押的重要的分子基础。ICAM1与CD36在介导粘附时有协同作用。本文综述了近几年ICAM1介导粘附的机制及PRBC内皮细胞之间相互作用的研究进展。     

肺微血管内皮细胞的分离及其在单核细胞粘附中的应用

目的 :研究肺微血管内皮细胞的分离和纯化方法 ,探讨内皮细胞的透明质酸对于单核细胞粘附的作用。方法 :用两次植块法分离狗和大鼠的肺微血管内皮细胞。通过粘附实验 ,观察单核细胞在内皮细胞单层上的粘附。结果 :第二次植块 3天后 ,内皮细胞自肺组织块边缘迁出 ,2周后内皮细胞生长形成单层。在扫描电镜下 ,内皮细胞表面有许多微绒毛和小凹。用透明质酸酶消化内皮细胞表面的透明质酸后 ,粘附的单核细胞数显著减少。结论 :两次植块法是一种理想的肺微血管内皮细胞的分离和纯化方法。微血管内皮细胞表面的透明质酸促进单核细胞的粘附     

选择素及其信号转导

选择素家族是表达于白细胞、内皮细胞和血小板表面的粘附分子。免疫和炎症反应时 ,选择素与其配体结合介导白细胞同内皮细胞和血小板的粘附作用。此外 ,选择素还可启动细胞内信号转导通路 ,如可引起细胞内第二信使Ca2 的增加、MAPK及 β2 整合素的活化等 ,进一步调节细胞在粘附时的功能反应。     

缺血性脑血管疾病与粘附分子

实 验与临床研究已经证实脑缺血后的病理过程中有明显的炎性反应 ,目前主要研究与炎性细胞浸润有关的粘附分子和脑血管内皮方面。1　内皮细胞产生的粘附蛋白分子目前报道较多的是内皮细胞与白细胞之间相互作用的粘附分子 ,因为白细胞与内皮细胞的粘附并跨内皮细胞造成浸润等过程需要粘附分子的介导。内皮细胞产生的粘附分子主要有Ｅ ｓｅｌｅｃｔｉｎ(内皮选择素 ,主要存在于内皮细胞 )、Ｐ ｓｅｌｅｃｔｉｎ(血小板选择素 ,主要存在于内皮细胞及活化血小板内 )、ＩＣＡＭ 1(细胞间粘附分子 1)、ＶＣＡＭ 1(血管内皮细胞粘附分子 1)、ＰＥ…     

PECAM-1在炎症微循环损伤中的作用

炎症过程的一个重要特征是白细胞粘附并穿越微血管内皮细胞,向炎症部位募集.外渗的白细胞释放细胞毒性物质,如氧自由基、蛋白水解酶等,造成组织损伤.在炎症反应中,白细胞与内皮细胞的相互作用是一重要环节,它决定了白细胞经内皮迁移以及粘附分子参与白细胞粘附的整个过程.在炎症所致微循环损伤中,血小板内皮细胞粘附分子 - 1( PECAM- 1, CD31) 扮演了重要角色.     

脑血栓形成病人自体血浆对红细胞与内皮细胞粘附的影响

本文采用流室系统，定量地研究了脑血栓形成病人和健康人自体血浆对红细胞与内皮细胞粘附特性影响的差异，并深入探讨了脑血栓形成病人自体血浆纤维蛋白原和自体血小板对红细胞与内皮细胞粘附的影响。通过显微观察和计数，结果表明：１）血浆能增强红细胞与内皮细胞的粘附，这在脑血栓形成病人表现得尤为明显；２）脑血栓形成病人自体血浆纤维蛋白原促进了红细胞与内皮细胞的粘附，自体血小板的作用有待进一步研究。     

Cell adhesion and proliferation are reduced on stainless steel coated with polysaccharide-based polymeric formulations

Hydromer's polymeric formulations F200 and F202 were evaluated after application to a synthetic substrate for effects on cell adhesion and proliferation. A significant reduction in cell adhesion was observed when cells grown on medical-grade stainless steel coated with these polymers were stained and examined under a fluorescence microscope. This reduction in cell adhesion/proliferation was confirmed when cells were isolated and analyzed by the MTS cell proliferation assay. The rate of growth of cells on F200- and F202-coated stainless steel monitored over a period of 7 days was significantly less than that observed on uncoated stainless steel, suggesting that the rate of growth of cells was reduced. The adhesion/proliferation of human umbilical vein endothelial cells (HUVEC) to coated substrates was also decreased significantly, indicating that the reduction in cell adhesion/proliferation is not restricted to only fibroblasts. Additional studies have indicated that the adhesion/proliferation of murine fibroblasts and human endothelial cells to stainless coated with a modified formulation exhibiting a high degree of lubricity was also significantly reduced. This lubricious formulation was also observed to be effective in reducing platelet adhesion, data supporting the view that lubricity also contributes to a reduction in cell and platelet adhesion. The application of these polymeric coatings on devices designed for medical implantation may not only prevent thrombus formation but may also retard the process of restenosis.     

Computational Model of Device-Induced Thrombosis and Thromboembolism

A numerical model of thrombosis/thromboembolism (T/TE) is presented that predicts the progression of thrombus growth and thromboembolization in low-shear devices (hemodialyzers, oxygenators, etc.). Coupled convection–diffusion-reaction equations were solved to predict velocities, platelet agonist (ADP, thromboxane A2, and thrombin) concentrations, agonist-induced and shear-induced platelet activation, and platelet transport and adhesion to biomaterial surfaces and adherent platelets (hence, thrombus growth). Single-platelet and thrombus embolization were predicted from shear forces and surface adhesion strengths. Values for the platelet-biomaterial reaction constant and the platelet adhesion strength were measured in specific experiments, but all other parameter values were obtained from published sources. The model generated solutions for sequential time steps, while adjusting velocity patterns to accommodate growing surface thrombi.Heparinized human blood was perfused (0.75 ml/min) through 580 μm-ID polyethylene flow cells with flow contractions (280 μm-ID). Thrombus initiation, growth, and embolization were observed with videomicroscopy, while embolization was confirmed by light scattering, and platelet adhesion was determined by scanning electron microscopy.Numerical predictions and experimental observations were similar in indicating: 1) the same three thrombotic locations in the flow cell and the relative order of thrombus development in those locations, 2) equal thrombus growth rates on polyethylene and silicon rubber (in spite of differing overall T/TE), and 3) similar effects of flow rate (1.5 ml/min versus 0.75 ml/min) on platelet adhesion and thrombosis patterns.     

In vitro platelet adhesion and in vivo antithrombogenicity of heparinized polyetherurethaneureas

We investigated in-vitro platelet adhesion to polyetherurethaneureas, to which heparin was bound covalently or by ionic bonding. When heparin was bound to polymers, platelet adhesion and platelet activation upon adhesion were suppressed with the increasing content of bound heparin in the polymer. Platelets were activated upon adsorption to different degrees according to the method of heparinization. The platelet adhesion and the platelet activation upon adhesion appeared to be regulated by the electrostatic repulsion between platelet and anionic surface of covalently or ionically heparinized polymer, rather than by the physiological action of bound heparin. The effect of the method of heparinization seemed to be related to the molecular heterogeneity of heparin. Heparinized polyurethanes which interacted very weakly with platelets in vitro were tested for in-vivo antithrombogenicity. The test was carried out by the implantation of a suture of the heparinized polyurethane into canine veins. Ionically heparinized polyurethane did not form a thrombus and maintained a smooth surface over a long period. On the other hand, covalently heparinized polyurethane formed a small amount of thrombus and grew endothelial cells from the insertion point.     

Platelet adhesion and fusion to endothelial cell facilitate the metastasis of tumor cell in hypoxia-reoxygenation condition

To investigate the relevant molecular mechanisms of platelet in promoting metastasis of tumor cell. The adhesion of fluorescence dye labeled-platelet to human liver sinusoidal endothelial cell (LSEC) line and tumor cell lines were detected by fluorescence microscope and fluorescence plate reader or laser scanning confocal microscope. The relevant adhesion molecules were analyzed by the antibody blockage experiment. The immune colloidal gold transmission electron microscope (TEM), flow cytometry and dye transfer were used to decipher the adhesion and fusion of platelet and LSEC. The tumor cells adhesion to vessels in ischemia condition was analyzed on mouse mesenteric vessels and the metastasis and neovascularization of metastatic foci in pulmonary tissue were also detected after tumor cells injected into nude mice via tail veil. After hypoxia-reoxygenation, tumor cell or LSEC markedly increased its adhesion with platelet, which could be blocked by different antibodies to platelet adhesion molecules. Platelet increased adhesion of tumor cell to LSEC in dose-dependent manner. The fusion of platelet and LSEC was demonstrated by translocation of fluorescent dye from platelet into the adherent LSEC; gpIIb emerged on the LSEC; and confirmed by TEM. The morphological examination found platelet presented between tumor cell and LSEC. Animal experiment indicated that the tumor adhesion to vessels was seldom in normal condition, but increased in ischemia-reperfusion condition, and further significantly enhanced by platelets. The number of tumor metastatic foci and the density of blood vessels within metastatic foci in lung were markedly increased by tumor cell pre-adhered with platelet. The adhesion or fusion of platelet to endothelial cell mediated by platelet surface adhesion molecules, which could promote the adhesion of tumor cell with endothelial cells and the tumor metastasis.     

Anti-CD31 delays platelet adhesion/aggregation at sites of endothelial injury in mouse cerebral arterioles.

The arterioles on the surface of the mouse brain (pial arterioles) were observed by in vivo microscopy. A focus of minor endothelial damage was produced in a single pial arteriole in each mouse by briefly exposing the site to a helium neon laser after an intravenous injection of Evans blue. Mice were injected 10 minutes before injury with a monoclonal antibody (MAb) to mouse CD31, also known as platelet endothelial cell adhesion molecule. This treatment doubled (P < .01) the time required for the laser to produce a recognizable platelet aggregate. In additional experiments, an MAb to mouse CD61 and an MAb to mouse intercellular adhesion molecule 1 had no effect. The data support previous observations indicating that platelet adhesion/aggregation in this model is induced by endothelial injury without exposure of basal lamina. The data are consistent with the hypothesis that the endothelial injury exposes or activates a platelet endothelial cell adhesion molecule on the endothelium which is blocked by the MAb directed against CD31. This may be the first demonstration of an effect of an anti-platelet endothelial cell adhesion molecule on platelet endothelial cell adhesion molecule on platelet adhesion/aggregation in vivo.     

Mathematical model of static platelet adhesion on a solid surface

The scheme of platelet/surface interaction and a kinetic model of platelet adhesion on a solid surface are suggested. The elaborated approach takes into account the platelet activation by the surface and accumulation of free activated cells in the bulk of the liquid phase. This effect has an especially important role in static experimental conditions. The suggested model explains three types of adhesion kinetic curves, obtained in experiments in vitro: sigmoid curves with or without saturation and an exponential curve with saturation. According to the model, the curve shape is determined by material surface properties, platelet functionality, and experimental conditions of the platelet/surface interaction. The data of static platelet adhesion from platelet rich plasma on glass, siliconized glass, hexadecyltrichlorosilane monolayers, and low-density polyethylene are described mathematically with the proposed model. Numerical parameters are calculated from approximation of experimental data by the model. These parameters allow quantitative characterization of platelet interaction with the material surface.     

In vitro studies of thromboresistance: the role of prostacyclin (PGI2) in platelet adhesion to cultured normal and virally transformed human vascular endothelial cells

Circulating blood platelets normally do not adhere to, or aggregate on, the vascular endothelial lining. We have developed an in vitro model system to study the mechanisms of endothelial resistance to platelet adhesion, and to determine the role of prostacyclin (PGI2) in this process. This system combines scanning electron microscopy and measurement of bound (3H)-adenine-labeled platelets to examine platelet adhesion to primary cultures of human endothelial cells, which generate PGI2-like activity, and to virally transformed endothelial cells, which lack this activity. Under basal conditions primary cultures bound less than one platelet per cell (228 +/- 8 c.p.m. per 10(4) cells, mean +/- standard error of the mean). Inhibition of endothelial PGI2 production by 50 microM aspirin or 2.8 microM indomethacin did not result in a significant change in platelet adherence. Stimulating prostaglandin production with arachidonic acid, or adding exogenous PGI2 did not depress platelet adhesion below the basal levels observed with untreated cultures. In contrast ot primary cultures, transformed endothelium showed markedly increased platelet adherence (3,993 +/- 194 c.p.m. per 10(4), mean +/- standard error of the mean), in the form of single platelets and clusters of two to five nonaggregated platelets. Although exogenous PGI2 was effective in hibiting platelet adherence to these transformed cells, even pharmacologic doses (1 microgram. per ml.) did not depress adhesion to the basal levels associated with normal cells. These results suggest that endothelial properties essential to blood compatibility are altered by viral transformation, and further, that generation of PGI2 by normal endothelium is not the key factor which prevents platelet adherence to the intact vessel wall.     

Platelet inhibition and endothelial cell adhesion on elastin-like polypeptide surface modified materials

Platelet adhesion and activation are important early markers of biomaterial blood compatibility, while surfaces that promote enhanced endothelial cell adhesion and eNOS expression are strategic targets for long term vascular graft applications. Materials surface modified with fluorinated surface modifiers, containing peptides inspired from elastin cross-linking domains, have been used for the cross-linking of elastin-like polypeptide 4 (ELP4) macromolecules onto polyurethane surfaces. In the present study, ELP4 modified polyurethanes were evaluated in vitro to assess platelet adhesion, microparticle formation and bulk platelet activation following blood-material interactions. Reduced platelet adhesion and bulk platelet activation were observed following contact between reconstituted human blood and the ELP4 materials, relative to the uncoated base polyurethane controls. ELP4 modified materials also promoted endothelial cell adhesion and retention over a period of one week and showed that the endothelial cells exhibited an organized actin cytoskeleton and enhanced endothelial nitric oxide synthase (eNOS) expression relative to the control surfaces. These results indicate that polyurethane elastomers modified with ELP4 covalently bound to fluorinated surface modifiers provide a promising approach for endowing synthetic elastomers with both reduced blood platelet activation properties and enhanced endothelial cell adhesion for potential use in vascular graft applications.     

海带多糖L01抑制血小板活性与血管内皮细胞保护作用

目的： 探讨海带多糖L01抑制血小板活性与保护血管内皮细胞（VEC）的关系。 方法： 采用注射肾上腺素（Adr）法建立大鼠VEC损伤模型，滤过法测定大鼠血小板黏附性，火棉胶玻片法观察血小板表面聚集活性，酶联免疫吸附双抗体夹心（ELISA）法测定大鼠血浆血管性血友病因子（vWF）含量，免疫组化检测主动脉完整内皮长度（μm）。结果： 模型组自造模第3 d起大鼠血小板聚集率、第4 d起血小板黏附率均分别高于生理盐水组(P<0.05，P<0.01)，L01高剂量（50 mg/kg）、低剂量（10 mg/kg）组第4 d和第5 d大鼠的血小板黏附率和聚集率低于模型组 (P<0.05，P<0.01)；造模第4 d，模型组大鼠血浆vWF水平高于生理盐水组(P<0.05);L01高剂量组大鼠血浆vWF水平低于模型组 (P<0.05);造模第5 d，模型组与生理盐水组比较、L01高、低剂量组与模型组比较，均呈现出同样的结果(P<0.05)；造模第4 d和第5 d免疫组化检测主动脉完整内皮长度显示，模型组长度小于生理盐水组，L01高剂量、低剂量组长度明显大于模型组（P<0.05）。 结论： L01抑制血小板活性的作用与保护VEC有关。     

Biological performances of collagen-based scaffolds for vascular tissue engineering

Collagen is widely used for biomedical applications and it could represent a valid alternative scaffold material for vascular tissue engineering. In this work, reconstituted collagen films were prepared from neutralized acid-soluble solutions for subsequent haemocompatibility and cell viability performance assays. First, haemoglobin-free, thrombelastography and platelet adhesion tests were performed in order to investigate the blood contact performance. Secondly, specimens were seeded with endothelial cells and smooth muscle cells, and cell viability tests were carried out by MTT and SEM. Results show that neutralized acid-soluble type I collagen films do not enhance blood coagulation, do not alter normal viscoelastic properties of blood and slightly activate platelet adhesion and aggregation. Cell culture shows that the samples are adequate substrates to support the adhesion and proliferation of endothelial and smooth muscle cells.