Endothelial Cells Of Microvessels Research Articles

IgM anti-ACE2 autoantibodies in severe COVID-19 activate complement and perturb vascular endothelial function.

BackgroundSome clinical features of severe COVID-19 represent blood vessel damage induced by activation of host immune responses initiated by the coronavirus SARS-CoV-2. We hypothesized autoantibodies against angiotensin-converting enzyme 2 (ACE2), the SARS-CoV-2 receptor expressed on vascular endothelium, are generated during COVID-19 and are of mechanistic importance.MethodsIn an opportunity sample of 118 COVID-19 inpatients, autoantibodies recognizing ACE2 were detected by ELISA. Binding properties of anti-ACE2 IgM were analyzed via biolayer interferometry. Effects of anti-ACE2 IgM on complement activation and endothelial function were demonstrated in a tissue-engineered pulmonary microvessel model.ResultsAnti-ACE2 IgM (not IgG) autoantibodies were associated with severe COVID-19 and found in 18/66 (27.2%) patients with severe disease compared with 2/52 (3.8%) of patients with moderate disease (OR 9.38, 95% CI 2.38–42.0; P = 0.0009). Anti-ACE2 IgM autoantibodies were rare (2/50) in non-COVID-19 ventilated patients with acute respiratory distress syndrome. Unexpectedly, ACE2-reactive IgM autoantibodies in COVID-19 did not undergo class-switching to IgG and had apparent KD values of 5.6–21.7 nM, indicating they are T cell independent. Anti-ACE2 IgMs activated complement and initiated complement-binding and functional changes in endothelial cells in microvessels, suggesting they contribute to the angiocentric pathology of COVID-19.ConclusionWe identify anti-ACE2 IgM as a mechanism-based biomarker strongly associated with severe clinical outcomes in SARS-CoV-2 infection, which has therapeutic implications.FUNDINGBill & Melinda Gates Foundation, Gates Philanthropy Partners, Donald B. and Dorothy L. Stabler Foundation, and Jerome L. Greene Foundation; NIH R01 AR073208, R01 AR069569, Institutional Research and Academic Career Development Award (5K12GM123914-03), National Heart, Lung, and Blood Institute R21HL145216, and Division of Intramural Research, National Institute of Allergy and Infectious Diseases; National Science Foundation Graduate Research Fellowship (DGE1746891)

Exendin-4 Preserves Blood-Brain Barrier Integrity via Glucagon-Like Peptide 1 Receptor/Activated Protein Kinase-Dependent Nuclear Factor-Kappa B/Matrix Metalloproteinase-9 Inhibition After Subarachnoid Hemorrhage in Rat.

In this study, we investigated the role of Exendin-4 (Ex-4), a glucagon-like peptide 1 receptor (GLP-1R) agonist, in blood-brain barrier (BBB) disruption after subarachnoid hemorrhage (SAH) in rats. The endovascular perforation model of SAH was performed in Sprague-Dawley rats. Ex-4 was intraperitoneally injected 1 h after SAH induction. To elucidate the underlying molecular mechanism, small interfering ribonucleic acid (siRNA) for GLP-1R and Dorsomorphin, a specific inhibitor of adenosine monophosphate-activated protein kinase (AMPK), were intracerebroventricularly injected 48 h before induction of SAH correspondingly. Immunofluorescence results supported GLP-1R expressed on the endothelial cells of microvessels in the brain after SAH. Administration of Ex-4 significantly reduced brain water content and Evans blue extravasation in both hemispheres, which improved neurological scores at 24 h after SAH. In the mechanism study, Ex-4 treatment significantly increased the expression of GLP-1R, p-AMPK, IκB-α, Occludin, and Claudin-5, while the expression of p-nuclear factor-kappa B (NF-κB) p65, matrix metalloproteinase-9 (MMP-9), and albumin was significantly decreased. The effects of Ex-4 were reversed by the intervention of GLP-1R siRNA or Dorsomorphin, respectively. In conclusion, Ex-4 could preserve the BBB integrity through GLP-1R/AMPK-dependent NF-κB/MMP-9 inhibition after SAH, which should be further investigated as a potential therapeutic target in SAH.

Features of Remodeling of Prostate Stroma in Chronic Abacterial Prostatitis.

We performed a complex morphological study of biopsy samples of prostate gland from 30 men (mean age 46±11 years) with chronic abacterial prostatitis who were exposed unfavorable anthropogenic factors. The ultrastructural heterogeneity of smooth muscle cells was shown, among which cells with destructive changes in organelles predominated, solitary cells with signs of secretory function were revealed. Most endothelial cells in microvessels were characterized by low pinocytotic activity, destruction of organelles; focal hyperplastic ultrastructural changes were noted in some endotheliocytes. Along with fibroblasts, the stroma contained single mast cells; no inflammatory infiltration was revealed. The results of the study attested to complex mechanisms of remodeling of the prostate gland stroma in chronic abacterial prostatitis involving microvessels, smooth muscle cells, and probably mast cells, which determines the development of degenerative, destructive, and fibrotic processes.

A Method to Isolate Pericytes From the Mouse Urinary Bladder for the Study of Diabetic Bladder Dysfunction.

PurposePericytes surround the endothelial cells in microvessels and play a distinct role in controlling vascular permeability and maturation. The loss of pericyte function is known to be associated with diabetic retinopathy and erectile dysfunction. This study aimed to establish a technique for the isolation of pericytes from the mouse urinary bladder and an in vitro model that mimics in vivo diabetic bladder dysfunction.MethodsTo avoid contamination with epithelial cells, the urothelial layer was meticulously removed from the underlying submucosa and detrusor muscle layer. The tissues were cut into multiple pieces, and the fragmented tissues were settled by gravity into collagen I-coated culture plates. The cells were cultured under normal-glucose (5 mmol/L) or high-glucose (30 mmol/L) conditions, and tube formation, cell proliferation, and TUNEL assays were performed. We also performed hydroethidine staining to measure superoxide anion production.ResultsWe successfully isolated high-purity pericytes from the mouse urinary bladder. The cells were positively stained for platelet-derived growth factor receptor-β and NG2 and negatively stained for smooth muscle cell markers (desmin and myosin) and an endothelial cell marker (CD31). The number of tubes formed and the number of proliferating cells were significantly lower when the pericytes were exposed to high-glucose conditions compared with normal-glucose conditions. In addition, there were significant increases in superoxide anion production and the number of apoptotic cells when the pericytes were cultured under high-glucose conditions.ConclusionsTo the best of our knowledge, this is the first study to isolate and culture pericytes from the mouse urinary bladder. Our model would be a useful tool for screening the efficacy of therapeutic candidates targeting pericyte function in diabetic bladder dysfunction and exploring the functional role of specific targets at the cellular level.

Human endometrial perivascular stem cells exhibit a limited potential to regenerate endometrium after xenotransplantation.

What are the localization, characteristics and potential for tissue regeneration of two perivascular stem cells, namely CD34+ adventitial cells and CD146+ pericytes, in human endometrium? Human endometrial CD34+ adventitial cells (located in the outermost layer of blood vessels and mainly in the basal layer) and CD146+ pericytes showed mesenchymal stem cell (MSC) phenotypes in in vitro culture, but presented limited potential to regenerate endometrium. Periodic endometrial regeneration is considered to be maintained by MSCs. Blood vessel wall, regarded as stem cell niche, harbors a large reserve of progenitor cells that may be integral to the origin of MSCs. However, a lack of validated markers has hampered the isolation of putative endometrial MSCs. Currently, CD146+ pericytes and Sushi Domain Containing 2 (SUSD2) positive cells have been identified in the endometrial perivascular region as sharing MSCs characteristics. The locations of adventitial cells and pericytes in the human endometrium were identified by immunofluorescence staining (n = 4). After CD34+CD146-CD45-CD56-CD144- adventitial cells and CD146+CD34-CD45-CD56-CD144- pericytes were isolated from the endometrium of normal women (n = 6) by fluorescence-activated cell sorting, their characteristics were investigated in culture. Adventitial cells and pericytes were induced to differentiate, respectively, into vascular endothelial-like cells or endometrial stromal-like cells in vitro, with their potential explored by in vivo xenotransplantation (n = 2 in each group) and eutopic transplantation (n = 2 in each group). CD34+ adventitial cells and CD146+ pericytes were cultured in the inducing medium to differentiate into endothelial-like cells in vitro, and then analyzed for CD31, von Willebrand factor immunofluorescent staining and tube formation. They were also cultured to differentiate into endometrial stromal cells in vitro, with the expression of vimentin and CD13 being detected by western blot before and after induction, and the expression of prolactin and insulin-like growth factor-binding protein 1 being determined as well. Single dispersed CD34+ adventitial cells and CD146+ pericytes were respectively transplanted under the kidney capsule of NOG mice to investigate their differentiation potential in vivo. A eutopic transplantation model was constructed by grafting recellularized uterine matrix loaded up with CM-Dil labeled adventitial cells or pericytes into the injury region of nude rat's uterus. CD34+ adventitial cells were mainly located at the outmost layer of endometrial large vessels, while CD146+ pericytes were found surrounding the inner endothelial cells of microvessels. A small proportion of CD34+ adventitial cells expressed SUSD2. The number of adventitial cells was ∼40 times higher than that of pericytes in the endometrium. Both adventitial cells and pericytes showed MSC phenotypes after in vitro culture. After in vitro induction into endometrial endothelial-like cells and stromal-like cells, adventitial cells showed higher plasticity than pericytes and a closer correlation with stromal-like cells. In the mouse xenotransplantation model, vimentin+ cells, CD31+ endothelial-like cells and CD146+ pericyte-like cells could be observed after adventitial cells were transplanted. CM-Dil-labeled adventitial cells or pericytes could survive in the immunocompromised nude rats after eutopic transplantation, and vimentin+ cells were detected. In addition, CM-Dil-labeled adventitial cells or pericytes did not express α-smooth muscle actin or E-cadherin after transplantation. N/A. CD34 was chosen as a novel marker to isolate adventitial cells from human endometrium according to previous literature. The association of endometrial CD34+ adventitial cells and SUSD2+ MSCs should be further investigated. The decellularized uterine matrix model might be useful in endometrial stem cell therapy. L.D. is supported by grants from National Key Research and Development Program of China (2018YFC1004700), Nature Science Foundation of China (81871128, 81571391) and Nanjing Medical Science Development Project (ZKX16042). H.S. is supported by a grant from Jiangsu Province Social Development Project (BE2018602). X.Z. was supported by grants from the Postgraduate Innovative Project of Jiangsu Province (KYCX19-1177). The authors declare no conflict of interest.

Severe COVID-19: A multifaceted viral vasculopathy syndrome

The objective of this study was to elucidate the pathophysiology that underlies severe COVID-19 by assessing the histopathology and the in situ detection of infectious SARS-CoV-2 and viral capsid proteins along with the cellular target(s) and host response from twelve autopsies. There were three key findings: 1) high copy infectious virus was limited mostly to the alveolar macrophages and endothelial cells of the septal capillaries; 2) viral spike protein without viral RNA localized to ACE2+ endothelial cells in microvessels that were most abundant in the subcutaneous fat and brain; 3) although both infectious virus and docked viral spike protein was associated with complement activation, only the endocytosed pseudovirions induced a marked up-regulation of the key COVID-19 associated proteins IL6, TNF alpha, IL1 beta, p38, IL8, and caspase 3 in endothelium. Importantly, this microvasculitis was associated with characteristic findings on hematoxylin and eosin examination that included endothelial degeneration and resultant basement membrane zone disruption and reduplication. It is concluded that serious COVID-19 infection has two distinct mechanisms: 1) a microangiopathy of pulmonary capillaries associated with a high infectious viral load where endothelial cell death releases pseudovirions into the circulation, and 2) the pseudovirions dock on ACE2+ endothelial cells most prevalent in the skin/subcutaneous fat and brain that activates the complement pathway/coagulation cascade resulting in a systemic procoagulant state as well as endothelial expression of cytokines that produce the cytokine storm. The data predicts a favorable response to therapies based on either removal of circulating viral proteins and/or blunting of the endothelial-induced response.

Cerebral Pathology in Hepatolenticular Degeneration (Wilson Disease)

Introduction. Hepatolenticular degeneration (HLD), or Wilson disease, is one of the severe progressive hereditary disorders of the nervous system. A number of questions regarding its pathogenesis and pathology are the subject of in-depth research. The aim of the study was to examine cerebral pathology and determine the leading factors in its pathogenesis in the autopsy cases of HLD. Materials and methods. A postmortem study was carried out in 15 deceased patients (14–35 years old) with HLD. In all cases, clinical diagnosis was based on the characteristic signs of CNS and liver damage, presence of the Kayser–Fleischer corneal ring, and specific biochemical abnormalities in copper and protein metabolism. A set of histological, neurohistological, and histochemical staining methods was used, including the histochemical study of copper after the fixation of brain slices in rubeanic acid. Results. In all cases, severe microcirculatory changes were found in the brain, characteristic of the angiotoxic component of HLD, with impaired vessel permeability and the development of persistent edema and spongiform changes in brain tissue. Changes were more often found in the basal nuclei area, as well as in the white matter of the cerebral hemispheres, cerebellum, and pons. The cytotoxic component of HLD was evident in the same regions of the brain, represented by degenerative changes in astrocytes and neurons, often ending in their death. The most frequent form of pathology was the appearance of Alzheimer type II glia with ‘naked’ nuclei, and much less frequently, Alzheimer type I glia. The histochemical study showed deposits of copper granules in the endothelial cells of microvessels, Alzheimer type II glia, and neurons – predominantly in the globus pallidus and the caudate nucleus. Conclusion. A set of pathogenic factors plays an essential role in the pathogenesis of the brain damage in HLD: the toxic effect of copper on the brain, the damage to and impaired permeability of the blood-brain barrier, severe metabolic disturbances caused by liver failure, and brain hypoxia.

Complement Membrane Attack Complexes Assemble NLRP3 Inflammasomes Triggering IL-1 Activation of IFN-γ-Primed Human Endothelium.

Complement activation contributes to multiple immune-mediated pathologies. In late allograft failure, donor-specific antibody deposits complement membrane attack complexes (MAC) on graft endothelial cells (ECs), substantially increasing their immunogenicity without causing lysis. Internalized MAC stabilize NIK (NF-κB [nuclear factor kappa-light-chain-enhancer of activated B cells]-inducing kinase) protein on Rab5+MAC+ endosomes, activating noncanonical NF-κB signaling. However, the link to increased immunogenicity is unclear. To identify mechanisms by which alloantibody and internalized MAC activate ECs to enhance their ability to increase T-cell responses. In human EC cultures, internalized MAC also causes NLRP3 (NOD-like receptor family pyrin domain containing 3) translocation from endoplasmic reticulum to Rab5+MAC+NIK+ endosomes followed by endosomal NIK-dependent inflammasome assembly. Cytosolic NIK, stabilized by LIGHT (lymphotoxin-like inducible protein that competes with glycoprotein D for herpesvirus entry on T cells), does not trigger inflammasome assembly, and ATP-triggered inflammasome assembly does not require NIK. IFN-γ (interferon-γ) primes EC responsiveness to MAC by increasing NLRP3, pro-caspase 1, and gasdermin D expression. NIK-activated noncanonical NF-κB signaling induces pro-IL (interleukin)-1β expression. Inflammasome processed pro-IL-1β, and gasdermin D results in IL-1β secretion that increases EC immunogenicity through IL-1 receptor signaling. Activation of human ECs lining human coronary artery grafts in immunodeficient mouse hosts by alloantibody and complement similarly depends on assembly of an NLRP3 inflammasome. Finally, in renal allograft biopsies showing chronic rejection, caspase-1 is activated in C4d+ ECs of interstitial microvessels, supporting the relevance of the cell culture findings. In response to antibody-mediated complement activation, IFN-γ-primed human ECs internalize MAC, triggering both endosomal-associated NIK-dependent NLRP3 inflammasome assembly and IL-1 synthesis, resulting in autocrine/paracrine IL-1β-mediated increases in EC immunogenicity. Similar responses may underlie other complement-mediated pathologies.

Role of Endothelial-to-Mesenchymal Transition in the Pathogenesis of Central Nervous System Hemangioblastomas

Hemangioblastomas (HBs) are benign vascular tumors of the central nervous system and histologically contain abundant microvessels. Therefore, they clinically exhibit vascular malformation-like characteristics. It has been described that endothelial-to-mesenchymal transition (EndMT) contributes to the pathogenesis of cerebral cavernous malformations. However, it remains unknown whether EndMT contributes to the pathogenesis of central nervous system HBs. The aim of our study was to investigate whether EndMT occurs in central nervous system HBs. Ten central nervous system HBs were immunohistochemically investigated. Cluster of differentiation (CD) 31 (an endothelial marker) and EndMT markers, such as α-smooth muscle actin (a mesenchymal marker) and CD44 (a mesenchymal stem cell marker), were expressed in the endothelial layer of microvessels in all cases. These findings suggest that endothelial cells (ECs) of microvessels in central nervous system HBs have acquired mesenchymal and stem cell-like characteristics and undergone EndMT. In all cases, both ephrin-B2 and EphB4, which are not detected in adult normal brain vessels, were expressed in the endothelial layer of microvessels. These data suggest that ECs of microvessels in central nervous system HBs are immature or malformed cells and have both arterial and venous characteristics. To our knowledge, this is the first report showing the possibility that EndMT contributes to the pathogenesis of central nervous system HBs. It is likely that ECs of microvessels in central nervous system HBs are immature or malformed cells and have both arterial and venous characteristics. EndMT is expected to be a new therapeutic target in central nervous system HBs.

Pigment epithelium-derived factor attenuates myocardial fibrosis via inhibiting Endothelial-to-Mesenchymal Transition in rats with acute myocardial infarction

Endothelial mesenchymal transition (EndMT) plays a critical role in the pathogenesis and progression of interstitial and perivascular fibrosis after acute myocardial infarction (AMI). Pigment epithelium-derived factor (PEDF) is shown to be a new therapeutic target owing to its protective role in cardiovascular disease. In this study, we tested the hypothesis that PEDF is an endogenous inhibitor of EndMT and represented a novel mechanism for its protective effects against overactive cardiac fibrosis after AMI. Masson’s trichrome (MTC) staining and picrosirius red staining revealed decreased interstitial and perivascular fibrosis in rats overexpressing PEDF. The protective effect of PEDF against EndMT was confirmed by co-labeling of cells with the myofibroblast and endothelial cell markers. In the endothelial cells of microvessels in the ischemic myocardium, the inhibitory effect of PEDF against nuclear translocation of β-catenin was observed through confocal microscopic imaging. The correlation between antifibrotic effect of PEDF and inactivation of β-catenin was confirmed by co-transfecting cells with lentivirus carrying PEDF or PEDF RNAi and plasmids harboring β-catenin siRNA(r) or constitutive activation of mutant β-catenin. Taken together, these results establish a novel finding that PEDF could inhibit EndMT related cardiac fibrosis after AMI by a mechanism dependent on disruption of β-catenin activation and translocation.

Zinc contributes to acute cerebral ischemia-induced blood–brain barrier disruption

Zinc ions are stored in synaptic vesicles and cerebral ischemia triggers their release from the terminals of neurons. Zinc accumulation in neurons has been shown to play an important role in neuronal death following ischemia. However, almost nothing is known about whether zinc is involved in ischemia-induced blood–brain barrier (BBB) disruption. Herein, we investigated the contribution of zinc to ischemia-induced acute BBB disruption and the possible molecular mechanisms using both cellular and animal models of cerebral ischemia. Zinc greatly increased BBB permeability and exacerbated the loss of tight junction proteins (Occludin and Claudin-5) in the endothelial monolayer under oxygen glucose deprivation conditions. In cerebral ischemic rats, a dramatically elevated level of zinc accumulation in microvessels themselves was observed in isolated microvessels and in situ, showing the direct interaction of zinc on ischemic microvessels. Treatment with a specific zinc chelator N,N,N′,N′-tetrakis(2-pyridylmethyl) ethylenediamine (TPEN), even at 60-min post-ischemia onset, could greatly attenuate BBB permeability in the ischemic rats as measured by Evan's Blue extravasation, edema volume and magnetic resonance imaging. Furthermore, zinc accumulation in microvessels activated the superoxide/matrix metalloproteinase-9/-2 pathway, which leads to the loss of tight junction proteins (Occludin and Claudin-5) and death of endothelial cells in microvessels themselves. Our findings reveal a novel mechanism of cerebral ischemia-induced BBB damage, and implicate zinc as an effective and viable new target for reducing acute BBB damage following ischemic stroke.

MP90-09 A NEW STRATEGY FOR THE TREATMENT OF PROSTATE CANCER BY TARGETING VASOHIBIN-2

INTRODUCTION AND OBJECTIVES: Recently, we isolated a novel angiogenic molecule, vasohibin-2 (VASH2) which is an intrinsic factor specifically expressed in activated vascular endothelial cells (ECs). Previous studies found that the expression of VASH2 was restricted to ECs and tumor cells. Although VASH2 promoting the angiogenesis in several cancers have been investigated, it has not been fully characterized yet that the VASH2 reflects the activity of tumor and the predictor of progression in prostate cancer (Pca). The aim of this study was to address the role of VASH2 expression and the treatment by targeting VASH2 in Pca. METHODS: We retrospectively analyzed the clinical records of patients with localized Pca performed radical prostatectomy and immunohistochemically analyzed the expression of VASH2. Furthermore, we analyzed the expression of VASH2 in human umbilical vein ECs (HUVEC) and Pca cell lines. The cell viability of these cells treated with anti-VASH2 antibody (V2-Ab) was determined by using the WST-1 assay. DU145 was injected subcutaneously in BALB/c nude mice and then V2-Ab was injected intraperitoneally in mice. RESULTS: The average follow-up period was 5.6 years. The expression of VASH2 was observed to ECs of microvessels in the tumor stroma and Pca cells. The density of VASH2 positive vessels were significantly associated with Gleason score and pathological T stage (p<0.05). High VASH2 density was significantly associated with preoperative PSA (p1⁄40.012), T stage (p1⁄40.026), and the intensity of VASH2 positive tumor cells (p1⁄40.048). The PSA recurrence-free survival rate was significantly worse in high VASH2 group than in low VASH2 group (p1⁄40.019). We showed that the protein level of VASH2 in HUVEC and DU145 was higher than that of the Pca cell lines (LNCap, C4-2). WST-1 assay indicated that the treatment with V2-Ab caused a decreased cell proliferation of HUVEC (67%, p<0.001) and DU145 (80%, p1⁄40.017) at high dose. We examined time course changes in DU145 tumor growth in mice. The average tumor size in the V2-Ab treatment group and in the control group on day 27 was 85mm and 389mm, respectively (p1⁄40.007). CONCLUSIONS: The present study clearly demonstrates VASH2 have the cell apoptosis mediated by V2-Ab. The results suggest that VASH2 could become a new therapeutic target in patients with CRPC.

Association of the endothelial protein C receptor (PROCR) rs867186-G allele with protection from severe malaria

BackgroundCytoadhesion of Plasmodium falciparum-infected erythrocytes to endothelial cells in microvessels is a remarkable characteristic of severe malaria. The endothelial protein C receptor (EPCR), encoded by the endothelial protein C receptor gene (PROCR), has recently been identified as an endothelial receptor for specific P. falciparum erythrocyte membrane protein 1 (PfEMP1) subtypes containing domain cassettes (DCs) 8 and 13. The PROCR rs867186-G allele (serine-to-glycine substitution at position 219 of EPCR; 219Gly) has been shown to be associated with higher levels of plasma soluble EPCR (sEPCR). In this study, the association of PROCR rs867186 with severe malaria is examined in Thai population.MethodsA total of 707 Thai patients with P. falciparum malaria (341 with severe malaria and 336 with mild malaria) were genotyped for rs867186. To assess the association of PROCR rs867186 with severe malaria, three models (dominant, recessive and allelic) were evaluated. The rates of non-synonymous and synonymous substitutions were estimated for the coding sequence of the PROCR gene.ResultsThe rs867186-GG genotype was significantly associated with protection from severe malaria (P-value = 0.026; odds ratio = 0.33; 95% confidence interval = 0.12–0.90). Evolutionary analysis provided no evidence of strong positive selection acting on the PROCR gene.ConclusionThe rs867186-GG genotype showed significant association with protection from severe malaria. The present results suggest that PfEMP1–EPCR interaction, which can mediate cytoadhesion and/or reduce cytoprotective and anti-inflammatory effects, is crucial to the pathogenesis of severe malaria.

Trends in Biomedical Nanotechnology

The nanotechnology, as defined by the US National Nanotechnology Initiative (NNI), is fabrication of materials with at least one dimension in 1-100 nm range [1]. The field of nanotechnology has generated tremendous excitement because these materials exhibit fundamental properties that are significantly different from that of bulk material, and are attributable to their small size (≤100 nm). For instance, quantum dots are nanoparticles (2-10 nm) of semi-conducting materials, usually selenides or sulfides of metals like zinc and cadmium. The quantum dots, owing to their nano size, exhibit superior signal brightness, size dependent emission of light, which, is resistant to photo bleaching, contrary to organic fluorescent dyes. Thus by controlling the size of quantum dots, it is possible to control the wavelength of emission for these nanomaterials. The size-based tunable light emission and resistance to photo bleaching observed in quantum dots is attributed to their nano size, and is not present in bulk materials. The main aim of nanotechnology is to take advantage of these unique properties in fabricating novel materials and devices, or developing unique applications. The major thrust of biomedical nanotechnology is to apply the benefits of nanotechnology to healthcare (e.g., imaging and diagnostics; nanodrugs; drug delivery; prostheses; and implants; etc.) [2,3]. Nanotechnology has been earlier used to improve drug properties. For example, pacliaxel (taxol), an anticancer drug, which is used to treat primary epithelial ovarian carcinoma, breast, colon, and lung cancers, exhibits low water solubility and, therefore, poor bioavailability. Therefore, it was formulated in Chremophor EL (polyethoxylated castor oil), which has been implicated in several drug associated toxicities. To overcome these shortcomings associated with the use of Cremophor, paclitaxel bound to albumin nanoparticles (Abraxane) were developed for clinical use. There is a huge interest in employing nanotechnology for cancer drug delivery. The interest in cancer drug delivery stems from the fact that the nanoparticles passively target tumors by a process called enhanced permeability and retention (EPR) effect, as elucidated by Maeda and coworkers [4-6]. It occurs because the tight junctions between endothelial cells of microvessels measure around 2 nm (6 nm in kidney, liver, and spleen), whereas the pore size of tumor microvessels varies from 100 to 1200 nm. Therefore, nanoparticles of appropriate size are able to extravasate into tumors, and not normal tissues, where they are retained because of slow venous return and poor

Ginsenoside Rb1 ameliorates lipopolysaccharide-induced albumin leakage from rat mesenteric venules by intervening in both trans- and paracellular pathway

Lipopolysaccharide (LPS) is one of the common pathogens that causes mesentery hyperpermeability- and intestinal edema-related diseases. This study evaluated whether ginsenoside Rb1 (Rb1), an ingredient of a Chinese medicine Panax ginseng, has beneficial effects on mesentery microvascular hyperpermeability induced by LPS and the underlying mechanisms. Male Wistar rats were continuously infused with LPS (5 mg · kg(-1) · h(-1)) via the left jugular vein for 90 min. In some rats, Rb1 (5 mg · kg(-1) · h(-1)) was administrated through the left jugular vein 30 min after LPS infusion. The dynamics of fluorescein isothiocynate-labeled albumin leakage from mesentery venules was assessed by intravital microscopy. Intestinal tissue edema was evaluated by hematoxylin and eosin staining. The number of caveolae in endothelial cells of microvessels was examined by electron microscopy. Confocal microscopy and Western blotting were applied to detect caveolin-1 (Cav-1) expression and phosphorylation, junction-related proteins, and concerning signaling proteins in intestinal tissues and human umbilical vein endothelial cells. LPS infusion evoked an increased albumin leakage from mesentery venules that was significantly ameliorated by Rb1 posttreatment. Mortality and intestinal edema around microvessels were also reduced by Rb1. Rb1 decreased caveolae number in endothelial cells of microvessels. Cav-1 expression and phosphorylation, VE-Cadherin phosphorylation, ZO-1 degradation, nuclear factor-κB (NF-κB) activation, and Src kinase phosphorylation were inhibited by Rb1. Rb1 ameliorated microvascular hyperpermeability after the onset of endotoxemia and improved intestinal edema through inhibiting caveolae formation and junction disruption, which was correlated to suppression of NF-κB and Src activation.

Shuttling glucose across brain microvessels, with a little help from GLUT1 and AMP kinase. Focus on “AMP kinase regulation of sugar transport in brain capillary endothelial cells during acute metabolic stress”

The Blood-Brain Barrier: a Gatekeeper of Brain “Individuality” The blood-brain barrier (BBB) maintains the individuality of brain fluid, while allowing it to selectively import nutrients and process toxic products. Its major constituent is a single layer of continuous, nonfenestrated endothelium lining the microvessels, whose unique features account in large part for the integrity of the barrier. The endothelial cell monolayer is the major determinant, but other cells in the central nervous system (e.g., pericytes and astrocytes) contribute to the integrity of the BBB. The interendothelial tight junctions of the BBB are one of its signature elements that greatly restrict paracellular permeability to solutes, fluid, and transmigrating cells. This is markedly distinct from the leakier, discontinuous, and fenestrated endothelium of liver microvessels (sinusoids). For example, the tight junctions of the cerebral endothelium (pial vessels) confer an electrical resistance (1,300 ·cm 2 ) far higher than other endothelia (6). Therefore, communication between blood and the brain interstitial fluid requires individually tailored molecular mechanisms. Transcytosis is the movement of molecules through a cellular barrier. Whereas proteins can traverse through vesicular carrier processes that could carry solutes through fluid phase endocytosis, the brain microvasculature is uniquely poor in plasmalemmal and cytoplasmic caveolae (1). Instead, bidirectional passage of small molecules across the BBB is stringently regulated by numerous transporters and receptors. These typically work in tandem across the luminal and abluminal membranes of the endothelial cell.

Correlation among DCE‐MRI measurements of bone marrow angiogenesis, microvessel density, and extramedullary disease in patients with multiple myeloma

Correlation among DCE‐MRI measurements of bone marrow angiogenesis, microvessel density, and extramedullary disease in patients with multiple myeloma

Surface Chemistry of Quantum Dots Determines Their Behavior in Postischemic Tissue

The behavior of quantum dots (QDs) in the microvasculature and their impact on inflammatory reactions under pathophysiological conditions are still largely unknown. Therefore, we designed this study to investigate the fate and effects of surface-modified QDs in postischemic skeletal and heart muscle. Under these pathophysiological conditions, amine-modified QDs, but not carboxyl-QDs, were strongly associated with the vessel wall of postcapillary venules and amplified ischemia-reperfusion-elicited leukocyte transmigration. Importantly, strong association of amine-QDs with microvessel walls was also present in the postischemic myocardium. As shown by electron microscopy and verified by FACS analyses, amine-modified QDs, but not carboxyl-QDs, were associated with endogenous microparticles. At microvessel walls, these aggregates were attached to endothelial cells. Taken together, we found that both the surface chemistry of QDs and the underlying tissue conditions (i.e., ischemia-reperfusion) strongly determine their uptake by endothelial cells in microvessels, their association to endogenous microparticles, as well as their potential to modify inflammatory processes. Thus, this study strongly corroborates the view that the surface chemistry of nanomaterials and the physiological state of the tissue are crucial for the behavior of nanomaterials in vivo.

CD44 expression in plexiform lesions of idiopathic pulmonary arterial hypertension

Plexiform lesions in pulmonary arteries are a characteristic histological feature for idiopathic pulmonary arterial hypertension (IPAH). The pathogenesis of the plexiform lesion is not fully understood, although it may be related to endothelial cell dysfunction and local inflammation. CD44 is a cell adhesion molecule and it is also involved in angiogenesis, endothelial cell proliferation and migration. The expression of CD44 was examined in lung plexiform lesions obtained from patients with IPAH (IPAH group, n= 7) and pulmonary arterial hypertension associated with atrial septal defect (ASD-PAH group, n= 4). Expression of CD44 was detected in 49 out of 52 plexiform lesions (93%) from all patients in the IPAH group, whereas 31 plexiform lesions obtained from the ASD-PAH group lacked CD44 positivity by immunohistochemistry. In the IPAH group, CD44 was localized in the endothelial cells of microvessels within plexiform lesions and activated T cells in and around the lesions. Furthermore, T cell infiltration and endothelial cell proliferation activity were prominent in the plexiform lesions of the IPAH group, compared to those of the ASD-PAH group. These findings suggest that CD44 and activated T cell infiltration play an important role in the development of plexiform lesions particularly in IPAH.

Abstract 9918: The ATP-Binding Cassette Transporter ABCG2 Protects Against Pressure Overload-Induced Cardiac Hypertrophy and Heart Failure by Promoting Angiogenesis and Antioxidant Response

Background: ATP-binding cassette transporter subfamily G member 2 (ABCG2), originally identified in cancer cells, was shown to be expressed in various normal organs, including the heart, and was suggested to regulate several tissue defense mechanisms via modulation of survival and function of ABCG2-expressing cells. However, its role in pressure overload-induced cardiac hypertrophy remains unknown. Methods and Results: Immunohistochemistry demonstrated that ABCG2 was mainly expressed in endothelial cells of microvessels in the heart. Pressure overload was induced in 8- to 12-week-old wild-type (WT) and Abcg2 knock-out (KO) mice by transverse aortic constriction (TAC). In the absence of pressure overload, cardiac function and morphology did not differ between WT and KO mice. In WT mice, ABCG2 mRNA expression was increased about 3 times at 4 days and 28 days after TAC compared with that before surgery. At 28 days after TAC, mortality due to heart failure was higher in KO mice than in WT mice (KO mice, 53.2%, n=62, versus WT mice, 21.2%, n=33, p=0.002). Most of dead KO mice died at 4 days after TAC. KO mice showed exaggerated concentric hypertrophy at 4 days after TAC, and exacerbated ventricular remodeling and impaired systolic function at 28 days after TAC compared with WT mice. At 4 days after TAC, impaired angiogenesis and exaggerated oxidative stress in myocardium were found in KO mice compared with those in WT mice, although expression levels of angiogenesis-related and antioxidant genes were comparable or higher in KO mice than in WT mice. In vitro experiments demonstrated that inhibition of ABCG2 led to impaired survival of human microvascular endothelial cells from the heart (HMVEC-Cs) under oxidative stress. In addition, ABCG2 inhibition resulted in impaired migration and tube formation of HMVEC-Cs even under normal condition. Moreover, ABCG2 regulated extracellular concentrations of glutathione, an important endogenous antioxidant, in HMVEC-Cs under external stimuli. Conclusions: ABCG2 protects against pressure overload-induced cardiac hypertrophy and subsequent heart failure by promoting angiogenesis and antioxidant response. ABCG2 may be of interest for a therapeutic target to improve clinical outcomes of hypertrophic heart disease.