An improved method for isolation of microvascular endothelial cells from normal and inflamed human lung

Enzyme-injected method of enzymatic dispersion at low temperature is effective for isolation of smooth muscle cells from human esophagogastric junction

The present study was conducted to examine the feasibility of in vitro isolation and primary culture of smooth muscle cells (SMCs) from the esophagogastric junction (EGJ). Smooth muscles of EGJ were harvested from 23 patients with esophageal cancer during esophagostomy from January 2015 to December 2017. Enzymatic dispersion (ED) was performed for isolation. Collagenase II and Trypsin/EDTA were applied by enzyme injection (EI) into tissue fragments or immersion of tissue fragments into enzyme solution. Growth characteristics and proliferation [Cell Counting Kit-8 (CCK-8)] of cells were recorded for both smooth muscle cell medium (SMCM) and DMEM/F12 containing 10% newborn bovine serum (10%-F12). All ED methods could isolate primary cells; EI was the most effective method with low collagenase II concentration (0.5 mg/ml) at 4˚C for 14-24 h. Primary cells demonstrated mainly spindle- and long-spindle-shaped with ‘hills and valleys’ morphology. The CCK-8 assay in SMCM showed better proliferation results than in 10%-F12. After passaging for 4-8 generations in SMCM or 2-4 generations in 10%-F12, cells enlarged gradually with passages and lost spindle structures. mRNA and proteins of α-smooth muscle actin (α-SMA), smooth muscle 22 α (SM22α), vimentin, desmin, CD90 and proliferating cell nuclear antigen were detected in tissues and cells with different levels of expression. SMCs of esophageal circular muscle, esophageal longitudinal muscle, gastric circular muscle near sling in gastric bottom and gastric circular muscle near clasp in lesser gastric curvature, all cultured in 10%-F12, exhibited superior smooth muscle phenotypes compared with SMCs cultured in SMCM in terms of α-SMA, SM22α and vimentin expression. The EI method of ED at low temperature appears effective for isolation and primary culture of SMCs from human EGJ in vitro.

[Effect of globular adiponectin on proliferation, migration and tube formation of ovarian microvascular endothelial cells]

OBJECTIVE

To analyze the effect of globular adiponectin on angiogenesis of ovarian microvascular endothelial cells (OMECs).

METHODS

Mouse OMECs were isolated and purified by density gradient centrifugation with Percoll and identified by immunofluorescence analysis of follicle-stimulating hormone receptor (FSHR), luteinizing hormone receptor (LHR), and endothelial cell marker von Willebrand factor (vWF). The capillary-like tube formation of OMECs was determined by vascular endothelial growth factor A (VEGFA) treatment in Matrigel matrix. OMECs treated with recombinant globular adiponectin protein were examined for cell proliferation with MTS assay and cell migration with scratch wound healing assay, and capillary-like tube formation was tested in Matrigel matrix. Western blotting was performed to detect the effect of globular adiponectin on AMPK phosphorylation.

RESULTS

The signals of LHR and vWF, but not that of FSHR, were detected in the isolated cells. VEGFA treatment of the cells induced capillary-like tube formation, indicating their properties of ovarian-specific endothelial cells. Treatment with 1 and 3 µg/mL of recombinant globular adiponectin significantly increased the number of OMECs by (158.72∓14.50) % and (186.50∓4.20)% (P<0.01) and resulted in scratch wound closure rates of (49.43∓3.43)% (P<0.05) and (69.67∓1.2) % (P<0.01) respectively. The cells treated with 3 µg/mL globular adiponectin formed a capillary-tube length 6.63∓0.66 folds greater than that formed by the control cells (P<0.01). Treatment of the cells with 3 µg/mL globular adiponectin for 15 and 30 min resulted in pAMPK/AMPK ratios of 0.86∓0.08 and 0.66∓0.13, respectively significantly higher than that in the control cells (0.13∓0.12, P<0.01). Compound C obviously suppressed the tube formation and AMPK phosphorylation induced by globular adiponectin.

CONCLUSION

Globular adiponectin promotes angiogenesis of OMECs through activation of the AMPK signal pathway.

Revascularization of decellularized lung scaffolds: principles and progress

There is a clear unmet clinical need for novel biotechnology-based therapeutic approaches to lung repair and/or replacement, such as tissue engineering of whole bioengineered lungs. Recent studies have demonstrated the feasibility of decellularizing the whole organ by removal of all its cellular components, thus leaving behind the extracellular matrix as a complex three-dimensional (3D) biomimetic scaffold. Implantation of decellularized lung scaffolds (DLS), which were recellularized with patient-specific lung (progenitor) cells, is deemed the ultimate alternative to lung transplantation. Preclinical studies demonstrated that, upon implantation in rodent models, bioengineered lungs that were recellularized with airway and vascular cells were capable of gas exchange for up to 14 days. However, the long-term applicability of this concept is thwarted in part by the failure of current approaches to reconstruct a physiologically functional, quiescent endothelium lining the entire vascular tree of reseeded lung scaffolds, as inferred from the occurrence of hemorrhage into the airway compartment and thrombosis in the vasculature in vivo. In this review, we explore the idea that successful whole lung bioengineering will critically depend on 1) preserving and/or reestablishing the integrity of the subendothelial basement membrane, especially of the ultrathin respiratory membrane separating airways and capillaries, during and following decellularization and 2) restoring vascular physiological functionality including the barrier function and quiescence of the endothelial lining following reseeding of the vascular compartment. We posit that physiological reconstitution of the pulmonary vascular tree in its entirety will significantly promote the clinical translation of the next generation of bioengineered whole lungs.

Evaluation of the protective potential of brain microvascular endothelial cell autophagy on blood-brain barrier integrity during experimental cerebral ischemia-reperfusion injury

Brain microvascular endothelial cell (BMVEC) injury induced by ischemia-reperfusion (I/R) is the initial phase of blood-brain barrier (BBB) disruption, which results in a poor prognosis for ischemic stroke patients. Autophagy occurs in ischemic brain and has been shown to exhibit protective effects on endothelial cell against stress. However, the potential effects of BMVEC autophagy on BBB permeability during I/R and the mechanisms underlying these effects have yet to be elucidated. In the current study, we answered these questions by using chemical modulators of autophagy, including rapamycin and lithium carbonate acting, respectively, as mammalian target of rapamycin (mTOR)-dependent and mTOR-independent autophagy inducers and 3-methyladenine (3-MA) as an autophagy inhibitor. To mimic I/R injury, BMVECs were exposed to oxygen-glucose deprivation/reoxygenation (OGD/R), and a rat transient middle cerebral artery occlusion/reperfusion (MCAO/R) model was performed. All the drugs were given at 0.5 h before OGD/R or MCAO/R. First, enhancement of autophagy by rapamycin and lithium carbonate attenuated, whereas suppression of autophagy by 3-MA intensified BMVEC apoptosis and the high level of ROS induced by OGD/R. In addition, rapamycin and lithium carbonate pretreatments significantly reversed the decreased level of tight junction protein zonula occludens-1 (ZO-1) induced by OGD/R and promoted the distribution of ZO-1 on cell membranes. Finally, pretreatments with rapamycin and lithium carbonate reduced evans blue extravasation and brain water content in the ischemic hemisphere of the rat. In contrast, 3-MA pretreatment exerted opposite effects both in vitro and in vivo. These results may indicate a beneficial effect of BMVEC autophagy on BBB integrity during I/R injury.

Physiological predictors of survival during high-frequency oscillatory ventilation in adults with acute respiratory distress syndrome

INTRODUCTION

Data that provide clinical criteria for the identification of patients likely to respond to high-frequency oscillatory ventilation (HFOV) are scarce. Our aim was to describe physiological predictors of survival during HFOV in adults with severe acute respiratory distress syndrome (ARDS) admitted to a respiratory failure center in the United Kingdom.

METHODS

Electronic records of 102 adults treated with HFOV were reviewed retrospectively. We used logistic regression and receiving-operator characteristics curve to test associations with oxygenation and mortality.

RESULTS

Patients had severe ARDS with a mean (SD) Murray's score of 2.98 (0.7). Partial pressure of oxygen in arterial blood to fraction of inspired oxygen (PaO2/FiO2) ratio and oxygenation index improved only in survivors. The earliest time point at which the two groups differed was at three hours after commencing HFOV. An improvement of >38% in PaO2/FiO2 occurring at any time within the first 72 hours, was the best predictor of survival at 30 days (area under the curve (AUC) of 0.83, sensitivity 93%, specificity 78% and a positive likelihood ratio (LR) of 4.3). These patients also had a 3.5 fold greater reduction in partial pressure of carbon dioxide in arterial blood (PaCO2). Multivariate analysis showed that HFOV was more effective in younger patients, when instituted early, and in patients with milder respiratory acidosis.

CONCLUSIONS

HFOV is effective in improving oxygenation in adults with ARDS, particularly when instituted early. Changes in PaO2/FiO2 during the first three hours of HFOV can identify those patients more likely to survive.

Isolation and characterisation of human pulmonary microvascular endothelial cells from patients with severe emphysema

Background

Loss of the pulmonary microvasculature in the pathogenesis of emphysema has been put forward as a credible alternative to the classical inflammatory cell driven proteolysis hypothesis. Mechanistic studies in this area have to date employed animal models, immortalised cell lines, primary endothelial cells isolated from large pulmonary arteries and non-pulmonary tissues and normal human pulmonary microvascular endothelial cells. Although these studies have increased our understanding of endothelial cell function, their relevance to mechanisms in emphysema is questionable. Here we report a successful technique to isolate and characterise primary cultures of pulmonary microvascular endothelial cells from individuals with severe emphysema.

Methods

A lobe of emphysematous lung tissue removed at the time of lung transplantation surgery was obtained from 14 patients with severe end-stage disease. The pleura, large airways and large blood vessels were excised and contaminating macrophages and neutrophils flushed from the peripheral lung tissue before digestion with collagenase. Endothelial cells were purified from the cell mixture via selection with CD31 and UEA-1 magnetic beads and characterised by confocal microscopy and flow cytometry.

Results

Successful isolation was achieved from 10 (71%) of 14 emphysematous lungs. Endothelial cells exhibited a classical cobblestone morphology with high expression of endothelial cell markers (CD31) and low expression of mesenchymal markers (CD90, αSMA and fibronectin). E-selectin (CD62E) was inducible in a proportion of the endothelial cells following stimulation with TNFα, confirming that these cells were of microvascular origin.

Conclusions

Emphysematous lungs removed at the time of transplantation can yield large numbers of pulmonary microvasculature endothelial cells of high purity. These cells provide a valuable research tool to investigate cellular mechanisms in the pulmonary microvasculature relevant to the pathogenesis of emphysema.

Islet graft survival and function: concomitant culture and transplantation with vascular endothelial cells in diabetic rats

BACKGROUND

Human islet transplantation is a great potential therapy for type I diabetes. To investigate islet graft survival and function, we recently showed the improved effects after co-culture and co-transplantation with vascular endothelial cells (ECs) in diabetic rats.

METHODS

ECs were isolated, and the viability of isolated islets was assessed in two groups (standard culture group and co-culture group with ECs). Then streptozotocin-induced diabetic rats were divided into four groups before islet transplantation as follows: group A with infusion of islet grafts; group B with combined vascular ECs and islet grafts; groups C and D as controls with single ECs infusion and phosphate-buffered saline injection, respectively. Blood glucose and insulin concentrations were measured daily. Expression of vascular endothelial growth factor was investigated by immunohistochemical staining. The mean microvascular density was also calculated.

RESULTS

More than 90% of acridine orange-propidium iodide staining positive islets demonstrated normal morphology while co-cultured with ECs for 7 days. Compared with standard control, insulin release assays showed a significantly higher simulation index in co-culture group except for the first day (P<0.05). After transplantation, there was a significant difference in concentrations of blood glucose and insulin among these groups after 3 days (P<0.05). The mean microvascular density in co-culture group was significantly higher than that in single islet group (P=0.04).

CONCLUSION

Co-culture with ECs in vitro could improve the survival and function of isolated rat islet, and co-transplantation of islets with ECs could effectively prolong the islet graft survival in diabetic rats.

What can in vitro models of COPD tell us?

Chronic obstructive pulmonary disease (COPD) is a progressive lung disease characterised by chronic bronchitis, largely irreversible remodelling of the small airways, and emphysematous destruction of the alveoli. COPD is projected to be the third leading cause of death worldwide by 2020. COPD often results from prolonged exposure to irritants such as cigarette smoke or inhaled particulates. Current pharmacotherapies for COPD are unable to reverse the pathological changes of this disease, and this is partially due to a limited understanding of the intricate mechanisms by which chronic exposure lead to the different pathological components of COPD. This review examines how the mechanisms that underlie various components of COPD can be modelled in vitro, specifically using cigarette smoke extract with cells cultured from primary human lung tissue, and how the effectiveness of current and novel pharmacotherapies on successfully attenuating these pathological changes can also be examined in vitro.

Tanshinone IIA protects the human blood-brain barrier model from leukocyte-associated hypoxia-reoxygenation injury

To investigate the in vitro effect of tanshinone IIA on leukocyte-associated hypoxia-reoxygenation injury of human brain-blood barrier (BBB), we established the BBB model by culturing purified primary human brain microvascular endothelial cells (HBMVEC) to confluence on cell culture insert. BBB was identified by tight junction, transendothelial electrical resistance (TEER) and the permeability of BBB to horseradish peroxidase (HRP). The effect of tanshinone IIA on the permeability of BBB was tested at 2 h after hypoxia and 1h after reoxygenation with or without the supernatants of activated leukocytes. The effect of tanshinone IIA on leukocytes activation was analyzed by detection of MMP-9, cytokines and reactive oxygen species. The results showed that BBB formed by confluent HBMVECs had no cellular gap. Immunofluorescent staining for ZO-1 confirmed that the cells were connected by tight junction. Moreover, the BBB model had a higher TEER and a lower permeability for HRP than confluent HUVECs. The permeability of BBB for HRP was enhanced by hypoxia-reoxygenation and further greatly enhanced by adding the supernatants of activated leukocytes before reoxygenation. But such an effect was reversed by addition of tanshinone IIA before hypoxia. Moreover, tanshinone IIA could decrease the levels of MMP-9, TNF-α, IL-1α, IL-2, IFN-γ and reactive oxygen species in leukocytes. In conclusion, tanshinone IIA can protect BBB against leukocyte-associated hypoxia-reoxygenation injury by attenuating the activation of leukocytes and inhibiting the injury effects of leukocytic products. Tanshinone IIA may be a novel therapeutic agent for cerebral ischemia-reperfusion injury.

Improved islet survival and funtion with rat endothelial cells in vitro co-culture

OBJECTIVE

Pancreatic islet transplantation is an emerging therapy for type 1 diabetes. To preserve its function, transplanted islets must be revascularized because arterial and venous connections are disrupted during islet isolation. The current paradigm is that islet revascularization originates from the transplant recipient. This study was designed to test whether the function of isolated islets can be retained by co-culture with thoracic aorta endothelial cells in vitro.

METHODS

Sprague-Dawley rats were used in this study. The endothelial cells (ECs) were isolated from the thoracic aorta. The viability of the isolated islets was assessed by acridine orange/propidium iodide (AO/PI) double staining. The islets were either placed in standard cultures (group A) or in co-cultures with ECs (group B). Islet viablity was assessed by an insulin release assay.

RESULTS

The islets in group B exhibited normal morphology with >90% staining positive as detected by AO/PI with 7 days. Insulin release assays showed a significantly higher simulation index (SI) in group B compared with group A (P < .05) except on the first day.

CONCLUSION

This study suggested that co-cultrue of freshly isolated rat islets with ECs improves postculture survival and islet function in vitro.

The role of adhesion molecules, alpha v beta 3, alpha v beta 5 and their ligands in the tumor cell and endothelial cell adhesion

Tumor metastasis is a complex process involving the interaction between tumor cells and endothelial cells in which some adhesion molecules play an important role. It was our aim to investigate the role of the adhesion molecules, alpha v beta 3 and alpha v beta 5 and their ligands, developmental endothelial locus-1 (Del-1) and L1, in tumor cell adhesion to endothelial cells in vitro. In this study, the expression and regulation of alpha v beta 3, alpha v beta 5 and intercellular adhesion molecule -1 on liver sinusoidal endothelial cells and liver cancer endothelial cells (T3A) were analyzed by real-time PCR and fluorescent-activated cell sorter. The expression and regulation of the integrin ligands, Del-1 and L1, in six tumor cell lines were analyzed by real-time PCR and western blot. We found the expressions of alpha v beta 3 and alpha v beta 5 were higher on T3A than that on liver sinusoidal endothelial cells, whereas expression of intercellular adhesion molecule-1 was lower on T3A than that on liver sinusoidal endothelial cells. After 24 h hypoxia, the expressions of alpha v beta 3 and alpha v beta 5 were upregulated on T3A and liver sinusoidal endothelial cells; the expression of intercellular adhesion molecule-1 was increased on liver sinusoidal endothelial cells, but remained unchanged on T3A. Del-1 and L1 expression levels were obviously diverse in various tumor cell lines and differentially modulated after 12 h hypoxia. The adhesion of tumor cells with Del-1 and L1 expression was higher in T3A than that in liver sinusoidal endothelial cells, and was significantly increased under hypoxic conditions. Interestingly, the tumor cell adherence could be inhibited by antibodies against alpha v beta 5 and alpha v beta 5, but not by an antibody against intercellular adhesion molecule-1. The adhesion of tumor cells without Del-1 and L1 expression was also higher on T3A than that on liver sinusoidal endothelial cells, but the adhesion could not be inhibited by antibodies against alpha v beta 5, alpha v beta 5 or intercellular adhesion molecule-1, suggesting that other receptors are involved. In conclusion, alpha v beta 5, alpha v beta 5 and their ligands Del-1 and L1 play an important role in the process of tumor cells moving from the original place.

Phenotypic and Functional Differences between Human Liver Cancer Endothelial Cells and Liver Sinusoidal Endothelial Cells

BACKGROUND/AIMS

The phenotypic and functional characteristics of microvascular endothelial cells derived from human liver cancer (HLCEC) were analyzed in vitro and compared with those of human liver sinusoidal endothelial cells (LSEC).

METHODS AND RESULTS

Flow-cytometric and real-time PCR analysis indicated that expressions of tumor necrosis factor receptor (TNFR) p75, alphavbeta3 and alphavbeta5 were increased, while those of TNFR p55 and intercellular-adhesion molecule 1 (ICAM-1) were decreased in HLCEC compared with LSEC. The functional analysis indicated that HLCEC exhibited higher angiogenic ability than LSEC, including proliferation capacity, ability to form capillary-like networks and release of matrix metalloproteinases. In response to tumor necrosis factor, LSEC exhibited a significant dose-dependent cytotoxicity, while HLCEC did not. Moreover, the coagulant and fibrinolytic capacity was increased in HLCEC. In addition, tumor cell adherence was significantly higher on HLCEC than on LSEC, while leukocyte adherence was lower on HLCEC than on LSEC. The cytoadherence of HLCEC was inhibited by antibodies against alphavbeta3 and alphavbeta5,and of LSEC by antibodies against ICAM-1.

CONCLUSION

These results indicate that tumor-derived endothelial cells are phenotypically and functionally different from those derived from normal liver tissue. These differences are valuable for understanding tumor angiogenesis and metastasis.

Construction of human liver cancer vascular endothelium cDNA expression library and screening of the endothelium-associated antigen genes

AIM: To gain tumor endothelium associated antigen genes from human liver cancer vascular endothelial cells (HLCVECs) cDNA expression library, so as to find some new possible targets for the diagnosis and therapy of liver tumor.

METHODS: HLCVECs were isolated and purified from a fresh hepatocellular carcinoma tissue sample, and were cultured and proliferated in vitro. A cDNA expression library was constructed with the mRNA extracted from HLCVECs. Anti-sera were prepared from immunized BALB/c mice through subcutaneous injection with high dose of fixed HLCVECs, and were then tested for their specificity against HLCVECs and angiogenic effects in vitro, such as inhibiting proliferation and inducing apoptosis of tumor endothelial cells, using immunocytochemistry, immunofluorescence, cell cycle analysis and MTT assays, etc. The identified xenogeneic sera from immunized mice were employed to screen the library of HLCVECs by modified serological analyses of recombinant cDNA expression libraries (SEREX). The positive clones were sequenced and analyzed by bio-informatics.

RESULTS: The primary cDNA library consisted of 2 × 10⁶ recombinants. Thirty-six positive clones were obtained from 6 × 10⁵ independent clones by immunoscreening. Bio-informatics analysis of cDNA sequences indicated that 36 positive clones represented 18 different genes. Among them, 3 were new genes previously unreported, 2 of which were hypothetical genes. The other 15 were already known ones. Series analysis of gene expression (SAGE) database showed that ERP70, GRP58, GAPDH, SSB, S100A6, BMP-6, DVS27, HSP70 and NAC alpha in these genes were associated with endothelium and angiogenesis, but their effects on HLCVECs were still unclear. GAPDH, S100A6, BMP-6 and hsp70 were identified by SEREX in other tumor cDNA expression libraries.

CONCLUSION: By screening of HLCVECs cDNA expression library using sera from immunized mice with HLCVECs, the functional genes associated with tumor endothelium or angiogenesis were identified. The modified SEREX, xenogeneic functional serum screening, was demonstrated to be effective for isolation and identification of antigen genes of tumor endothelium, and also for other tumor cell antigen genes. These antigen genes obtained in this study could be a valuable resource for basic and clinical studies of tumor angiogenesis, thus facilitating the development of anti- angiogenesis targeting therapy of tumors.

Expression of genes involved in vascular development and angiogenesis in endothelial cells of adult lung

Profiling gene expression in endothelial cells advances the understanding of normal vascular physiology and disease processes involving angiogenesis. However, endothelial cell purification has been challenging because of the difficulty of isolating cells and their low abundance. Here we examine gene expression in endothelial cells freshly isolated from lung capillaries after in vivo labeling with fluorescent cationic liposomes and purification by fluorescence-activated cell sorting (FACS). Of the 39,000 genes and expressed sequence tags evaluated on custom oligonucleotide arrays, 555 were enriched in endothelial cell fraction. These included familiar endothelial cell-associated genes such as VEGF, VEGF receptor (VEGFR)-1, VEGFR-2, angiopoietin-2, Tie1, Tie2, Edg1 receptor, VE-cadherin, claudin 5, connexin37, CD31, and CD34. Also enriched were genes in semaphorin/neuropilin (Sema3c and Nrp1), ephrin/Eph (ephrin A1, B1, B2, and EphB4), delta/notch (Hey1, Jagged 2, Notch 1, Notch 4, Numb, and Siah1b), and Wingless (Frizzled-4 and Tle1) signaling pathways involved in vascular development and angiogenesis. Expression of representative genes in alveolar capillary endothelial cells was verified by immunohistochemistry. Such expression reflects features that endothelial cells of normal lung capillaries have in common with embryonic and growing blood vessels. About half of the enriched genes, including exostosin 2, lipocalin 7, phospholipid scramblase 2, pleckstrin 2, protocadherin 1, Ryk, scube 1, serpinh1, SNF-related kinase, and several tetraspanins, had little or no previous association with endothelial cells. This approach can readily be used to profile genes expressed in blood vessels in tumors, chronic inflammation, and other sites in which endothelial cells avidly take up cationic liposomes.

Induction of pulmonary hypertension by an angiopoietin 1/TIE2/serotonin pathway

Smooth muscle cell proliferation around small pulmonary vessels is essential to the pathogenesis of pulmonary hypertension. Here we describe a molecular mechanism and animal model for this vascular pathology. Rodents engineered to express angiopoietin 1 (Ang-1) constitutively in the lung develop severe pulmonary hypertension. These animals manifest diffuse medial thickening in small pulmonary vessels, resulting from smooth muscle cell hyperplasia. This pathology is common to all forms of human pulmonary hypertension. We demonstrate that Ang-1 stimulates pulmonary arteriolar endothelial cells through a TIE2 (receptor with tyrosine kinase activity containing IgG-like loops and epidermal growth factor homology domains) pathway to produce and secrete serotonin (5-hydroxytryptamine), a potent smooth muscle mitogen, and find that high levels of serotonin are present both in human and rodent pulmonary hypertensive lung tissue. These results suggest that pulmonary hypertensive vasculopathy occurs through an Ang-1/TIE2/serotonin paracrine pathway and imply that these signaling molecules may be targets for strategies to treat this disease.

New human microvascular endothelial cell lines with specific adhesion molecules phenotypes

Vascular endothelial cells recognize blood-borne circulating cells and allow them to extravasate in a tissue-specific manner. Because this property determines the selectivity of lymphocyte homing, it is fundamental in physiological as well as pathological processes (inflammation, autoimmune diseases, metastasis). As a tool to assess the molecular basis of endothelium selectivity, microvascular endothelial cell lines of distinct tissue origin were established. Endothelial cells, isolated from lymphoid tissues (lymph nodes and appendix) and from nonlymphoid immune sites--intestine, lung, and skin--were immortalized in vitro. Their general endothelial characteristics, such as the presence of von Willebrand factor (wWf), angiotensin-converting enzyme (ACE), VE-cadherin, and the intracellular E-selectin, were preserved. This article shows that these cell lines display phenotypic characteristics related to their tissue origin. Hence, endothelial cells from lymph nodes expressed peripheral lymph node addressins (PNAds). Endothelial cells from nonlymphoid tissues were ICAM-1 (intercellular adhesion molecule-1) and CD49e positive, whereas P-selectin was not equally distributed among the cell lines. Endothelial cells from mucosal sites reacted with antibody against human MAdCAM-1 (mucosal addressin cell adhesion molecule). In the adhesion test, lymphoid and myeloid cells adhere to endothelial cell lines in a distinct manner. These lines could be useful to study molecular mechanisms involved in tissue-specific cell-cell interaction.

Histological markers for endothelial cells in endogenous and transplanted rodent pancreatic islets

BACKGROUND/AIMS

To obtain a selective marker to identify endothelial cells is difficult, due to the heterogeneity of these cells. Most described markers perform well in some applications, but fail in others. The aim of this study was to identify a selective and specific marker for rodent microvascular endothelial cells, especially for use in studies on the vascular system of pancreatic islets.

METHODS

A biotin-labelled form of the lectin Bandeiraea or Griffonia simplicifolia in combination with a streptAB-Complex with alkaline phosphatase was used to stain endothelium in paraffin-embedded tissue sections from C57BL/6 mice, Sprague-Dawley or Wistar-Furth rats.

RESULTS

We were consistently able to selectively stain microvascular endothelial cells in lungs, small intestines, white and brown adipose tissue, pancreas and islets of Langerhans with the lectin Bandeiraea simplicifolia. Furthermore, we were able to visualise the vasculature in syngenically transplanted islets of Langerhans in Wistar-Furth rats and C57BL/6 mice. Attempts to stain rodent endothelial cells with antibodies against CD34, CD31, CD200, Ox43, von Willebrand factor and the lectin Ulex europaeus were not uniformly successful.

CONCLUSION

The lectin Bandeiraea simplicifolia is a versatile marker for rodent endothelial cells, and may be used to study revascularisation after transplantation of pancreatic islet in rodents.

Isolation and culture of rat microvascular endothelial cells

The purpose of this study is to identify the separation techniques that result in pure cultures of rat microvascular endothelial cells (MECs). A multistep process is used to optimize the separation of the cells from rat epididymal fat pads, obtaining as pure a culture as possible within a relatively short processing time. The process initially employs the digestion, filtration, and density gradient separation steps. We further describe the use of an attachment phase that allows the differential adherence of contaminating cell types. Immunomagnetic purification is the final step in the process and is performed using anti-PECAM-1 (CD31) monoclonal antibody-labeled DynaBeads.

Labelling of rat endothelial cells with antibodies to vWF, RECA-1, PECAM-1, ICAM-1, OX-43 and ZO-1

Labelling with endothelium specific monoclonal antibodies, von Willebrand Factor (vWF), rat endothelial cell antigen-1 (RECA-1), platelet-endothelial cell adhesion molecule-1 (PECAM-1), intercellular adhesion molecule-1 (ICAM-1), OX-43 and zonula occludentes-1 (ZO-1), was investigated in cryostat sections of vessels from rats of different ages using a confocal microscope. The results showed that labelling of the vWF was positive in endothelial cells from adult, fetal and different ages of embryonic rat. Labelling with RECA-1 was weakly positive in adult rat aorta and lung endothelial cells but not in embryonic yolk sac endothelial cells. Labelling using PECAM-1, ICAM-1 and OX-43 was negative in both adult and embryonic endothelial cells. ZO-1 showed positive but very weak reactivity in embryonic yolk sac endothelial cells. The expression of vWF on vessels from adult and 19.5-day fetal tissues was strongly positive. However, the expression of vWF in embryonic endothelial cells was dependent on the gestational age. While the 11.5-day yolk sac vessels stained weakly, staining gradually increased in 13.5-, 15.5- and 17.5-day-old yolk sac vessels. The results suggest that vWF is a reliable endothelial cell marker in rat vascular endothelial cells, including both fetal and embryonic stages.