Generation of human pulmonary microvascular endothelial cell lines.

The limited lifespan of human microvascular endothelial cells in cell culture represents a major obstacle for the study of microvascular pathobiology. To date, no endothelial cell line is available that demonstrates all of the fundamental characteristics of microvascular endothelial cells. We have generated endothelial cell lines from human pulmonary microvascular endothelial cells (HPMEC) isolated from adult donors. HPMEC were cotransfected with a plasmid encoding the catalytic component of telomerase (hTERT) and a plasmid encoding the simian virus 40 (SV40) large T antigen. Cells transfected with either plasmid alone had an extended lifespan, but the cultures eventually entered crisis after several months of proliferation. Only those cells that were transfected with both plasmids acquired the capacity to grow in vitro without demonstrating major crisis, and these cells have been in culture for 24 months. HPMEC isolated from two different donors were used, generating two populations of immortalized cells, HPMEC-ST1 and HPMEC-ST2. Single cell-derived clones of the immortalized cells HPMEC-ST1 exhibited growth characteristics that were similar to those of the parental HPMEC. One selected clone, HPMEC-ST1.6R, displayed all major constitutively expressed and inducible endothelial phenotypic markers, including platelet endothelial cell adhesion molecule (PECAM-1, CD31), von Willebrand factor (vWF), and the adhesion molecules, intercellular adhesion molecule (ICAM-1), vascular adhesion molecule (VCAM-1), and E-selectin. In addition, an angiogenic response was demonstrated by sprout formation on a biological extracellular matrix (Matrigel). The HPMEC-ST1.6R cells did not form tumors in nude mice. The microvascular endothelial cell line, HPMEC-ST1.6R, will be a valuable tool for the study of microvascular endothelial physiology and pathology including gene expression, angiogenesis, and tumorigenesis.     

体外培养人视网膜微血管内皮细胞屏障功能的研究

目的： 研究原代培养的人视网膜微血管内皮细胞屏障功能。方法: 对人视网膜微血管内皮细胞进行原代培养并鉴定,第4代细胞接种于Polyester(PET)膜上,不同时点对滤膜表面行显微镜观察,通过紧密连接相关蛋白occludin的表达,间接反映细胞之间紧密连接的形成,应用共聚焦免疫显微镜观察2、3、4周occludin表达的变化;跨膜电阻（TER）检测屏障的稳定性,并通过测量正常培养条件和5 μg/L的血管内皮生长因子（VEGF）干预下辣根过氧化物酶(HRP)通透性的改变反映屏障特性。结果: 成功培养了人视网膜微血管内皮细胞,纯度可达95.8%。细胞接种1周后融合为单层,接种后2、3、4周细胞密度无明显变化,细胞接触紧密,呈单层生长,可见occludin在细胞相邻边界规则的表达;occludin在2、3、4周,在细胞内的分布逐渐移向相邻细胞交界处;2周时视网膜微血管内皮细胞跨上皮细胞电阻达（120.62±3.97）Ω/cm2,2、3、4周差异无显著（P>0.05）;单层细胞的通透性检测结果显示,HRP从滤膜上方到达下方随时间延长呈线性增加,且在VEGF的干预下,各时点通透率明显增加（P<0.05）。结论: 利用体外培养的人原代视网膜微血管内皮细胞建立单层细胞具有典型的屏障功能特性,可作为体外研究血视网膜内屏障的有用模型。     

Improved microvascular network in vitro by human blood outgrowth endothelial cells relative to vessel-derived endothelial cells

Evidence suggests that bone marrow-derived cells circulating in adult blood, sometimes called endothelial progenitor cells, contribute to neovascularization in vivo and give rise to cells expressing endothelial markers in culture. To explore the utility of blood-derived cells expressing an endothelial phenotype for creating tissue-engineered microvascular networks, we employed a three-dimensional in vitro angiogenesis model to compare microvascular network formation by human blood outgrowth endothelial cells (HBOECs) with three human vessel-derived endothelial cell (EC) types: human umbilical vein ECs (HUVECs), and adult and neonatal human microvascular ECs. Under every condition investigated, HBOECs within collagen gels elongated significantly more than any other cell type. Under all conditions investigated, gel contraction and cell elongation were correlated, with HBOECs demonstrating the largest generation of force. HBOECs did not exhibit a survival advantage, nor did they enhance elongation of HUVECs when the two cell types were cocultured. Network formation of both HBOECs and HUVECs was inhibited by blocking antibodies to alpha2beta1, but not alpha(v)beta3, integrins. Taken together, these data suggest that superior network exhibited by HBOECs relative to vessel-derived endothelial cells is not due to a survival advantage, use of different integrins, or secretion of an autocrine/paracrine factor, but may be related to increased force generation.     

Mast cell granules cause proliferation of human microvascular endothelial cells

To investigate the possible role of mast cells in blood vessel formation, rat mast cell granules were studied for their proliferative effect on human microvascular endothelial cells. It was found that granules had a marked proliferative effect and that most of this activity was restricted to a dialyzable fraction. The dialyzable mast cell granule constituent histamine was found to be mitogenic, an effect that was shown with the use of specific agonists and antagonists to be mediated through an H1 receptor. H1 antagonists reduced the proliferation caused by the untreated mast cell granules to the level of proliferation caused by dialyzed granules, suggesting that all the dialyzable mitogenic activity was due to histamine. Histamine was also shown to cause proliferation of cells that were growth arrested by serum deprivation, suggesting that it is an endothelial growth factor. The compound responsible for the undialyzable mitogenic activity could not be identified but was shown not to be mast cell heparin. This demonstration of mast cell granule-induced endothelial proliferation suggests that the mast cell may be of importance in the process of angiogenesis.     

A self-assembled fibroblast-endothelial cell co-culture system that supports in vitro vasculogenesis by both human umbilical vein endothelial cells and human dermal microvascular endothelial cells

The construction of vascularized connective tissues is an important goal in tissue engineering in that the presence of a patent bio-engineered vasculature should facilitate vascularization of an implant. Fibroblasts play an essential role in the angiogenic process through their production of extracellular matrix molecules and through their release of essential growth factors. Therefore, the aim of this study is to develop a thin 3-dimensional model in which fibroblasts support endothelial cells in the formation of tube-like structures. Macro- and microvascular endothelial cells were seeded onto confluent lawns of human fibroblasts and were cultured in the presence of high levels of ascorbate 2-phosphate to create a tissue-like structure in which endothelial cell organized into tube-like structures. The process was visualized in the culture dish through labeling of cells with a long-lasting fluorescent vital dye. Intact sheet-like structures were created in which endothelial cell tube-like structures were encased by fibroblasts and were surrounded by a basement membrane. These structures appeared to contain a lumen and remained stable for up to 5 weeks in culture. This culture system provides an in vitro method to study fibroblast-endothelial cell interactions and to study the effects of pro- and anti-angiogenic factors on endothelial cell differentiation. This system also provides an experimental basis for developing vascularized tissue-engineered connective tissue.     

小鼠肺微血管内皮细胞的培养鉴定及其血管形成功能的研究

目的: 建立一种简单有效的小鼠肺微血管内皮细胞(PMVECs)原代培养方法,并对其体外血管形成功能进行研究。方法: 取小于1周龄的C57BL/6小鼠的肺组织边缘,采用组织贴块法培养原代PMVECs。经形态学观察、免疫细胞化学鉴定后,以每孔2×10⁴的密度接种于铺有基质胶的96孔细胞板,在倒置显微镜下观察(2 h 1次)其24 h 体外血管形成过程。结果: 镜下可见原代培养的PMVECs呈梭形或多角形,单层融合呈铺路石样。细胞抗Ⅷ因子相关抗原(ⅧF-Ag)染色阳性。免疫荧光显微镜下可见大部分细胞摄取四甲基吲哚碳花青标记的乙酰化低密度脂蛋白(DiI-Ac-LDL),胞质呈现红色荧光,细胞膜表面与异硫氰酸荧光素标记的异植物血凝素(FITC-BSI)结合,呈现黄绿色荧光。PMVECs接种4~6 h后出现明显的管腔结构,10~12 h呈蜂窝状结构,此后管腔结构逐渐减少。结论: 组织贴块法培养原代PMVECs操作简单,细胞得率和纯度高,并可在体外成功建立血管形成模型进行相关研究。     

Acanthamoeba interactions with human brain microvascular endothelial cells

Acanthamoeba are opportunistic protozoan parasites that can cause fatal granulomatous amoebic encephalitis, however, the pathogenic mechanisms associated with this disease remain unclear. One of the primary factors in Acanthamoeba encephalitis is the haematogenous spread, followed by invasion of the blood-brain barrier resulting in the transmigration of Acanthamoeba into the central nervous system. In this study, we have used human brain microvascular endothelial cells, which constitute the blood-brain barrier and studied their interactions with Acanthamoeba. Using in vitro cultures, we showed that Acanthamoeba isolates belonging to genotypes T3, T4 and T11, exhibited increased cytotoxicity on human brain microvascular endothelial cells as well as exhibited higher binding and were considered potential pathogens. In contrast, Acanthamoeba isolates belonging to genotypes T2 and T7 exhibited minimal cytotoxicity and significantly less binding to human brain microvascular endothelial cells (P< 0.01). Furthermore, exogenous alpha-mannose inhibited binding but increased cytotoxicity of human brain microvascular endothelial cells. This is the first demonstration of Acanthamoeba interactions with primary human brain microvascular endothelial cells.     

Interaction of Listeria monocytogenes with human brain microvascular endothelial cells: an electron microscopic study

Internalization of Listeria monocytogenes into human brain microvascular endothelial cells (HBMEC) has recently been demonstrated to be dependent upon the inlB gene. In the present scanning electron microscopic study we show that L. monocytogenes efficiently interacts with the surface of HBMEC in an inlB-independent manner which is also different from invasion. The inlB-dependent invasion of HBMEC by L. monocytogenes is accompanied by intracellular multiplication, movement, and production of bacterium-containing protrusions. These protrusions extend from the cell surface without perturbation of any adjacent cellular membrane.     

改良贴壁法结合内皮细胞培养基培养小鼠肺微血管内皮细胞*☆

背景：肺微血管内皮细胞是研究微循环的重要内皮细胞模型之一,众多培养方法中单纯贴壁法操作相对简便,但耗时长,杂质细胞多,是批量培养细胞的最大障碍。 目的：建立优化的小鼠肺微血管内皮细胞体外培养方案,观察细胞生长状态并鉴定细胞性质。 方法：无菌状态下快速剪碎5日龄C57BL/6J小鼠的肺叶外周组织,肺组织颗粒贴壁法获得肺微血管内皮细胞,并用内皮细胞培养基培养。倒置显微镜观察培养细胞生长和行为状态,Ⅷ因子相关抗原免疫组化和免疫荧光进行细胞鉴定。 结果与结论：肺组织块培养24 h内可见梭形细胞爬出,传代后细胞生长迅速,形态规则呈鹅卵石状,纯度高达98%以上,结合Ⅷ因子相关抗原检测证实其为内皮细胞。结果可见联合运用肺组织颗粒贴壁和内皮细胞培养基可高效获得原代小鼠肺微血管内皮细胞。关键词：肺微血管内皮细胞;细胞培养;优化;鉴定;小鼠;血管组织工程 缩略语注释：PMVECs: pulmonary microvascular endothelial cells,肺微血管内皮细胞 doi:10.3969/j.issn.1673-8225.2012.15.007     

Viral susceptibility of an immortalized human microvascular endothelial cell line.

CDC/EU.HMEC-1 is the first immortalized human microvascular endothelial cell line that retains morphologic, phenotypic, and functional characteristics of a normal human microvascular endothelial cell. This study evaluates a variety of viruses and their effects on this human endothelial cell line. The data indicate that adenoviruses, some herpesviruses, reoviruses and most picornaviruses grow well in HMEC-1, with distinctive cytopathic effects. The paramyxoviruses, however, do not appear to propagate, nor does HIV. The findings indicate that microvascular endothelial cells may act as a reservoir of these viruses; it also suggests the possibility that microvascular endothelium could be involved in the processing and presentation of antigen to immune cells.     

Modulation of mesangial cell proliferation by endothelial cells in coculture.

The effects of direct cell contact between endothelial (ECs) and mesangial cells (MCs) on MCs proliferation were examined in a coculture system in vitro. Mitomycin C treated ECs (M-ECs) were plated on culture dishes and MCs were cocultured with these M-ECs. Cell number was measured at the end of days 1, 3, and 5. In the coculture system with direct contact, the growth of cocultured MCs was modulated as follows: 1) the growth of MCs was inhibited up to day 3, and 2) a high level of proliferation was observed between days 3 and 5. This biphasic pattern of growth could not be detected in coculture of fibroblasts with MCs. In coculture without direct contact, using intercup chambers, the kinetics in cell proliferation between cocultured MCs and MCs alone were essentially the same. Conditioned media derived from cocultures up to day 3 in a contact-dependent manner inhibited the 3H-thymidine uptake of MCs. From these results, it would thus appear that MCs proliferation is regulated by intercellular contact with ECs.     

Three-dimensional model of angiogenesis: coculture of human retinal cells with bovine aortic endothelial cells in the NASA bioreactor

Ocular angiogenesis is the leading cause of blindness and is associated with diabetic retinopathy and age-related macular degeneration. We describe, in this report, our preliminary studies using a horizontally rotating bioreactor (HRB), developed by the National Aeronautics and Space Administration (NASA), to explore growth and differentiation-associated events in the early phase of ocular angiogenesis. Human retinal (HRet) cells and bovine endothelial cells (ECs) were cocultured on laminin-coated Cytodex-3 microcarrier beads in an HRB for 1-36 days. Endothelial cells grown alone in the HRB remained cuboidal and were well differentiated. However, when HRet cells were cocultured with ECs, cordlike structures formed as early as 18-36 h and were positive for von Willebrand factor. In addition to the formation of cords and capillary-like structures, ECs showed the beginning of sprouts. The HRB seems not only to promote accelerated capillary formation, but also to enhance differentiation of retinal precursor cells. This leads to the formation of rosette-like structures (which may be aggregates of photoreceptors that were positive for rhodopsin). Upregulation of vascular endothelial growth factor and basic fibroblast growth factor was seen in retinal cells grown in the HRB as compared with monolayers and could be one of the factors responsible for accelerated capillary formation. Hence, the HRB promotes three-dimensional assembly and differentiation, possibly through promoting cell-to-cell interaction and/or secretion of growth and differentiation factors.     

Interactions between lymphocytes and cells of the blood-retina barrier: mechanisms of T lymphocyte adhesion to human retinal capillary endothelial cells and retinal pigment epithelial cells in vitro

We have studied the adhesion of human CD4+ lymphocytes to cultured human retinal vascular endothelial cells (EC) and human retinal pigment epithelial cells (RPE), both of which comprise the cellular components of the blood-retina barrier. We have observed differences in the lymphocyte-RPE and the lymphocyte-EC interactions. Firstly, RPE cells were found to express high levels of the adhesion molecule ICAM-1 constitutively, whereas EC expressed ICAM-1 only after induction with IFN-gamma. In addition, lymphocyte binding to normal and minimally stimulated RPE (5 U/ml, 4 hr) was predominantly ICAM-1 dependent, but after maximal stimulation (500 U/ml, 4 days), increased lymphocyte adhesiveness included an ICAM-1-independent component, which was apparently not due to involvement of MHC class II or CD2 molecules. In contrast, binding of lymphocytes to unstimulated EC involved both an ICAM-1-dependent and an ICAM-1-independent mechanism, the latter being subject to inhibition by monoclonal antibody to CD2. Studies of adhesion at 4 indicated that no binding occurred to normal or stimulated RPE, but binding to EC was observed, albeit reduced to 50% of the 37 binding level, and this implies that the LFA-3/CD2 adhesion pathway may also be involved in lymphocyte binding to EC. Overall, the results indicate a functional difference between RPE and EC affecting T-cell adhesion, migration and activation at the blood-retinal barrier, which must be considered when devising therapies to prevent lymphocyte infiltration of the eye.     

P120 catenin attenuates lipopolysaccharide-induced blood-brain barrier dysfunction and inflammatory responses in human brain microvascular endothelial cells

Increasing evidences suggest that p120 catenin (p120ctn) exerts important functions in the regulation of pro-inflammatory molecules. However, the relationship among p120ctn, inflammatory responses and blood-brain barrier (BBB) dysfunction as they are the initiator of sepsis is not unknown. In this study, we found that p120ctn expression was correlated with an increase in the permeability of BBB and a decrease in the expression of tight-junction proteins in human brain microvascular endothelial cells (HBMECs) after LPS challenge. Transfection with p120ctn small interfering RNA (siRNA) induced disruption of BBB integrity, monocyte migration across BBB and inflammatory responses at basal level and after LPS treatment. Conversely, over-expression of p120ctn with adenovirus significantly ameliorated BBB disruption and inflammatory responses in LPS-treated cells. Mechanistically, up-regulation of p120ctn inhibited LPS-induced NF-κB activation by suppressing IKKβ and IκBα phosphorylation, IκBα degradation. Therefore, we conclude that p120ctn improves the BBB dysfunction and inflammatory responses through the inhibition of NF-κB activation, suggesting that forced p120ctn expression may provide a novel therapeutic strategy to attenuate LPS-induced BBB compromise and sepsis.     

Human herpesvirus-8 infection of primary pulmonary microvascular endothelial cells

Human herpesvirus-8 (HHV-8) is the causative agent of Kaposi's sarcoma and is associated with the angioproliferative disorders primary effusion lymphoma and multicentric Castleman's disease. Evidence of HHV-8 infection within the pulmonary vasculature of patients with idiopathic pulmonary arterial hypertension (IPAH) has been described. We hypothesize that HHV-8 infection of pulmonary microvascular endothelial cells results in an apoptotic-resistant phenotype characteristic of severe pulmonary arterial hypertension. Our objective was to investigate the ability of HHV-8 to infect human pulmonary microvascular endothelial cells in vitro and characterize the phenotypic effect of this infection. Human pulmonary microvascular endothelial cells were exposed to HHV-8 using two methods (direct virus and co-culture technique). The presence of lytic and latent infection was confirmed. Changes in endothelial cell gene and protein expression and effects on cellular apoptosis were measured. HHV-8 can both lytically and latently infect primary human pulmonary microvascular endothelial cells in vitro. HHV-8 infection results in significant changes in gene expression, including alterations of pathways important to cellular apoptosis. HHV-8 infection also alters expression of genes integral to the bone morphogenic protein pathway, including down-regulation of bone morphogenic protein-4. Other genes previously implicated in the development of PAH are affected by HHV-8 infection, and cells infected with HHV-8 are resistant to apoptosis.     

Splenic endothelial cell lines support development of dendritic cells from bone marrow

Although growth factors are commonly used to generate dendritic cells (DCs) in vitro, the role of the microenvironment necessary for DC development is still poorly understood. The mixed splenic stromal cell population STX3 defines an in vitro microenvironment supportive of DC development. Dissection of cellular components of the STX3 stroma should provide information about a niche for DC development. STX3 was therefore cloned by single-cell sorting, and a panel of 102 splenic stromal cell lines was established. Four representative splenic stromal cell lines that support hematopoiesis from bone marrow are described here in terms of stromal cell type and DC production. All four stromal lines express the endothelial genes Acvrl1, Cd34, Col18a1, Eng, Flt1, Mcam, and Vcam1 but not Cd31 or Vwf. Three of the four lines form tube-like structures when cultured on Matrigel. Their endothelial maturity correlates with the ability to support myeloid DC development from bone marrow. A fourth cell line, unable to form tube-like structures in Matrigel, produced large granulocytic cells expressing CD11b and CD86 but not CD11c and CD80. Conditioned media from splenic stromal cell lines also support DC production, indicating that soluble growth factors and cytokines produced by stromal lines drive DC development. This article reports characterization of immature endothelial cell lines derived from spleen that are supportive of DC development and predicts the existence of such a cell type in vivo which regulates DC development within spleen.     

Vascularization of PEG-grafted macroporous hydrogel sponges: a three-dimensional in vitro angiogenesis model using human microvascular endothelial cells

The native extracellular matrix (ECM) of elastic tissues is strong and flexible and supports cell adhesion and enzymatic matrix remodeling. In an attempt to convey these ECM properties to a synthetic scaffold appropriate for soft tissue engineering applications, a biodegradable, elastomeric poly(ester urethane)urea (PEUU) was combined with type I collagen at various ratios (2.5, 5, 10, 20, 50, 60, 70, 80, and 90 wt% collagen) and electrospun to construct elastic matrices. Randomly orientated fibers in the electrospun matrices ranged in diameter from 100-900 nm, dependent on initial polymer concentration. Picrosirius red staining of matrices and CD spectroscopy of released collagen confirmed collagen incorporation and preservation of collagen structure at the higher collagen mass fractions. Matrices were strong and distensible possessing strengths of 2-13 MPa with breaking strains of 160-280% even with low PEUU content. Collagen incorporation significantly enhanced smooth muscle cell adhesion onto electrospun scaffolds. An approach has been demonstrated that mimics elastic extracellular matrices by using a synthetic component to provide mechanical function together with a biomacromolecule, collagen. Such matrices may find application in engineering soft tissue.     

自噬减轻模拟缺血/再灌注微环境中肺微血管内皮细胞损伤

目的:观察体外模拟缺血/再灌注(ischemia/reperfusion,I/R)微环境下人肺微血管内皮细胞(human pulmonary microvascular endothelial cells,HPMVECs)的自噬变化,研究自噬在维持I/R条件下HPMVECs细胞存活及内皮屏障完整性中的作用。方法:用雷帕霉素(rapamycin,RAP)预处理HPMVECs,在缺糖缺氧/恢复糖和氧供(oxygen-glucose deprivation/oxygen-glucose restoration,OGD)模拟的I/R微环境中孵育细胞。应用Western blot及透射电镜法检测细胞自噬变化,用流式细胞术检测细胞凋亡,通透性小室法检测HPMVECs通透性。结果:OGD条件下HPMVECs的自噬水平明显升高,RAP预处理进一步上调了OGD条件下的细胞自噬。OGD组细胞凋亡率明显增高,细胞通透性增加。RAP预处理不仅降低了OGD引起的细胞凋亡率,而且减轻了OGD条件下细胞通透性。结论:自噬在I/R诱发的肺微血管内皮细胞损伤中发挥保护性作用,提高自噬水平有助于减少I/R条件下细胞凋亡并维持内皮屏障完整性。