PECAM-1: a multi-functional molecule in inflammation and vascular biology

Perinatal Inflammation: Could Partial Blocking of Cell Adhesion Molecule Function Be a Solution?

In spite of the great advances made in recent years in prenatal and perinatal medicine, inflammation can still frequently result in injury to vital organs and often constitutes a major cause of morbidity. It is today well established that in neonates—though vulnerability to infection among neonates is triggered by functional impairments in leukocyte adhesion—the decreased expression of cell adhesion molecules also decreases the inflammatory response. It is also clear that the cell adhesion molecules, namely, the integrins, selectins, and the immunoglobulin (Ig) gene super family, all play a crucial role in the inflammatory cascade. Thus, by consolidating our knowledge concerning the actions of these vital cell adhesion molecules during the prenatal period as well as regarding the genetic deficiencies of these molecules, notably leukocyte adhesion deficiency (LAD) I, II, and III, which can provoke severe clinical symptoms throughout the first year of life, it is anticipated that intervention involving blocking the function of cell adhesion molecules in neonatal leukocytes has the potential to constitute an effective therapeutic approach for inflammation. A promising perspective is the potential use of antibody therapy in preterm and term infants with perinatal inflammation and infection focusing on cases in which LAD is involved, while a further important scientific advance related to this issue could be the combination of small peptides aimed at the inhibition of cellular adhesion.

Age-Dependent Dysregulation of Muscle Vasculature and Blood Flow Recovery after Hindlimb Ischemia in the mdx Model of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD), caused by a lack of functional dystrophin, is characterized by progressive muscle degeneration. Interestingly, dystrophin is also expressed in endothelial cells (ECs), and insufficient angiogenesis has already been hypothesized to contribute to DMD pathology, however, its status in mdx mice, a model of DMD, is still not fully clear. Our study aimed to reveal angiogenesis-related alterations in skeletal muscles of mdx mice compared to wild-type (WT) counterparts. By investigating 6- and 12-week-old mice, we sought to verify if those changes are age-dependent. We utilized a broad spectrum of methods ranging from gene expression analysis, flow cytometry, and immunofluorescence imaging to determine the level of angiogenic markers and to assess muscle blood vessel abundance. Finally, we implemented the hindlimb ischemia (HLI) model, more biologically relevant in the context of functional studies evaluating angiogenesis/arteriogenesis processes. We demonstrated that both 6- and 12-week-old dystrophic mice exhibited dysregulation of several angiogenic factors, including decreased vascular endothelial growth factor A (VEGF) in different muscle types. Nonetheless, in younger, 6-week-old mdx animals, neither the abundance of CD31⁺α-SMA⁺ double-positive blood vessels nor basal blood flow and its restoration after HLI was affected. In 12-week-old mdx mice, although a higher number of CD31⁺α-SMA⁺ double-positive blood vessels and an increased percentage of skeletal muscle ECs were found, the abundance of pericytes was diminished, and blood flow was reduced. Moreover, impeded perfusion recovery after HLI associated with a blunted inflammatory and regenerative response was evident in 12-week-old dystrophic mice. Hence, our results reinforce the hypothesis of age-dependent angiogenic dysfunction in dystrophic mice. In conclusion, we suggest that older mdx mice constitute an appropriate model for preclinical studies evaluating the effectiveness of vascular-based therapies aimed at the restoration of functional angiogenesis to mitigate DMD severity.

COVID-19 and Oxidative Stress

Pathogenesis of the novel coronavirus infection COVID-19 is the subject of active research around the world. COVID-19 caused by the SARS-CoV-2 is a complex disease in which interaction of the virus with target cells, action of the immune system and the body’s systemic response to these events are closely intertwined. Many respiratory viral infections, including COVID-19, cause death of the infected cells, activation of innate immune response, and secretion of inflammatory cytokines. All these processes are associated with the development of oxidative stress, which makes an important contribution to pathogenesis of the viral infections. This review analyzes information on the oxidative stress associated with the infections caused by SARS-CoV-2 and other respiratory viruses. The review also focuses on involvement of the vascular endothelium in the COVID-19 pathogenesis.

Biomechanical Regulation of Hematopoietic Stem Cells in the Developing Embryo

PURPOSE OF REVIEW

The contribution of biomechanical forces to hematopoietic stem cell (HSC) development in the embryo is a relatively nascent area of research. Herein, we address the biomechanics of the endothelial-to-hematopoietic transition (EHT), impact of force on organelles, and signaling triggered by extrinsic forces within the aorta-gonad-mesonephros (AGM), the primary site of HSC emergence.

RECENT FINDINGS

Hemogenic endothelial cells undergo carefully orchestrated morphological adaptations during EHT. Moreover, expansion of the stem cell pool during embryogenesis requires HSC extravasation into the circulatory system and transit to the fetal liver, which is regulated by forces generated by blood flow. Findings from other cell types also suggest that forces external to the cell are sensed by the nucleus and mitochondria. Interactions between these organelles and the actin cytoskeleton dictate processes such as cell polarization, extrusion, division, survival, and differentiation.

SUMMARY

Despite challenges of measuring and modeling biophysical cues in the embryonic HSC niche, the past decade has revealed critical roles for mechanotransduction in governing HSC fate decisions. Lessons learned from the study of the embryonic hematopoietic niche promise to provide critical insights that could be leveraged for improvement in HSC generation and expansion ex vivo.

Meta-analysis of global and high throughput public gene array data for robust vascular gene expression discovery in chronic rhinosinusitis: Implications in controlled release

BACKGROUND

Chronic inflammation is known to cause alterations in vascular homeostasis that directly affects blood vessel morphogenesis, angiogenesis, and tissue permeability. These phenomena have been investigated and exploited for targeted drug delivery applications in the context of cancers and other disease processes. Vascular pathophysiology and its associated genes and signaling pathways, however, have not been systematically investigated in patients with chronic rhinosinusitis (CRS). Understanding the interplay between key vascular signaling pathways and top biomarkers associated with CRS may facilitate the development of new targeted delivery strategies and treatment paradigms. Herein, we report findings from a gene meta-analysis to identify key vascular pathways and top genes involved in CRS.

METHODS

Proprietary software (Illumina BaseSpace Correlation Engine) and open-access data sets were used to perform a gene meta-analysis to systematically determine significant differences between key vascular biomarkers and vascular signaling pathways expressed in sinonasal tissue biopsies of controls and patients with CRS.

RESULTS

Thirteen studies were initially identified, and then reduced to five after applying exclusion principle algorithms. Genes associated with vasculature development and blood vessel morphogenesis signaling pathways were identified to be overexpressed among the top 15 signaling pathways. Out of many significantly upregulated genes, the levels of pro angiogenic genes such as early growth response (EGR3), platelet endothelial cell adhesion molecule (PECAM1) and L-selectin (SELL) were particularly significant in patients with CRS compared to controls.

DISCUSSION

Key vascular biomarkers and signaling pathways were significantly overexpressed in patients with CRS compared to controls, suggesting a contribution of vascular dysfunction in CRS pathophysiology. Vascular dysregulation and permeability may afford opportunities to develop drug delivery systems to improve efficacy and reduce toxicity of CRS treatment.

Microvasculature in murine tracheal allografts after combined therapy with clopidogrel and everolimus

OBJECTIVES

Survival after lung transplantation is mainly limited by the development of chronic lung allograft dysfunction. Previous studies have suggested T-cell mediated proliferation and microvascular changes in experimental small airways models as potential therapeutic targets. The aim of this study was to assess microvascular changes in murine orthotopic tracheal allografts after treatment with everolimus alone or in combination with clopidogrel.

METHODS

C57Bl/6 (H-2b) donor tracheas were orthotopically transplanted into CBA (H-2k) recipients. Mice received daily injections of everolimus (0.05 mg/kg) alone or combined with clopidogrel (1 mg/kg). Twenty-eight days after transplantation, ratio of the thickness of tracheal epithelium and lamina propria was measured as an indicator for chronic rejection. Additionally, graft oxygenation and graft perfusion were detected on postoperative days 4, 10 and 28. Quantitative reverse transcription polymerase chain reaction analysis was used for gene expression analysis.

RESULTS

While syngeneic grafts showed a stable tissue pO2 and undisturbed microvascular perfusion, rejecting allografts had a drastic decline in both parameters as well as a flattened epithelium and an increased thickness of the lamina propria. Treatment with everolimus reduced allogeneic fibroproliferation, but had no protective effects on the microvasculature; polymerase chain reaction analysis indicated hypoxic stress and inflammation. Combining everolimus with clopidogrel improved microvascular integrity in the tracheal grafts, but had no synergistic effect in preventing obliterative bronchiolitis development.

CONCLUSIONS

These data demonstrate that the ability of everolimus to reduce the development of post-transplant obliterative bronchiolitis is not caused by microvascular protection and has no synergistic effects with clopidogrel in acute airway rejection.

The exosome of platelet endothelial cell adhesion molecule-1 (PECAM1) protein: A potential risking star in high blood pressure patients (HBPP)

A number of studies have demonstrated that exosomes were involved in important physiological and pathological processes through cell-to-cell communication in cardiovascular disease, which contained nucleic acids, proteins, and lipid contents. In our study, we found that the protein platelet endothelial cell adhesion molecule-1 (PECAM1) was an extracellular vesicle in the blood of high blood pressure patients (HBPP).Isolated the vesicles from the blood of HBPP and health examiners and detected its size and morphology with nanoparticle tracking analysis, then we identified its surface protein CD63, CD81, and the protein expression of PECAM1 in the exosome with western blot. Furthermore, we analyzed the correlation between the expression of PECAM1 and the high blood degree with linear regression analysis.Our results showed that the morphology of extracellular vesicles was more evident in high blood pressure groups than healthy controls, and the protein expression of PECAM1 was also abundant in the vesicles of HBPP, however, there were no extracellular vesicles in the blood samples of healthy controls. Besides, linear regression showed the linear correlation coefficient R = 0.901, P < .01 between the expression of PECAM1 and the systolic blood pressure of the high blood patients. Therefore, the exosome of protein of PECAM1 was a potential risking star in HBPP.

Preservation of microvascular integrity and immunomodulatory property of prevascularized human mesenchymal stem cell sheets

Prevascularization is essential to ensure the viability, functionality, and successful integration of tissue-engineered three-dimensional (3D) constructs with surrounding host tissues after transplantation. Human mesenchymal stem cell (hMSC) sheet can be prevascularized by coculturing with endothelial cells (ECs), and then be further used as building blocks for engineering 3D complex tissues. In addition, predifferentiation of hMSCs into a tissue-specific lineage in vitro has been proven to promote graft engraftment and regeneration. However, it is unclear if the prevascularized hMSC sheets can still maintain their microvascular integrity as well as the immune-regulatory properties after their tissue-specific differentiation. The objective of this study was to investigate the effects of differentiation cues on the microvascular structure, angiogenic factor secretion, and immunogenic responses of prevascularized hMSC sheets. The results showed that upon coculturing with ECs, hMSC sheets successfully formed microvascular network, while maintaining hMSCs' multi-lineage differentiation capability. The next step, osteogenic and adipogenic induction, damaged the preformed microvascular structures and compromised the angiogenic factor secretion ability of hMSCs. Nonetheless, this effect was mitigated by adjusting the concentration of differentiation factors. The subcutaneous transplantation in an immunocompetent rat model demonstrated that the osteogenic differentiated prevascularized hMSC sheet preserved its microvascular structure and immunomodulatory properties comparable to the undifferentiated prevascularized hMSC sheets. This study suggested that a balanced and optimal differentiation condition can effectively promote the tissue-specific predifferentiation of prevascularized hMSC sheet while maintaining its immunomodulatory and tissue integration properties.

Camouflage strategies for therapeutic exosomes evasion from phagocytosis

Background

Even though exosome-based therapy has been shown to be able to control the progression of different pathologies, the data revealed by pharmacokinetic studies warn of the low residence time of exogenous exosomes in circulation that can hinder the clinical translation of therapeutic exosomes. The macrophages related to the organs of the mononuclear phagocytic system are responsible primarily for the rapid clearance and retention of exosomes, which strongly limits the amount of exosomal particles available to reach the target tissue, accumulate in it and release with high efficiency its therapeutic cargo in acceptor target cells to exert the desired biological effect.

Aim of review

Endowing exosomes with surface modifications to evade the immune system is a plausible strategy to contribute to the suppression of exosomal clearance and increase the efficiency of their targeted content delivery. Here, we summarize the current evidence about the mechanisms underlying the recognition and sequestration of therapeutic exosomes by phagocytic cells. Also, we propose different strategies to generate 'invisible' exosomes for the immune system, through the incorporation of different anti-phagocytic molecules on the exosomes’ surface that allow increasing the circulating half-life of therapeutic exosomes with the purpose to increase their bioavailability to reach the target tissue, transfer their therapeutic molecular cargo and improve their efficacy profile.

Key scientific concepts of review

Macrophage-mediated phagocytosis are the main responsible behind the short half-life in circulation of systemically injected exosomes, hindering their therapeutic effect. Exosomes ‘Camouflage Cloak’ strategy using antiphagocytic molecules can contribute to the inhibition of exosomal clearance, hence, increasing the on-target effect. Some candidate molecules that could exert an antiphagocytic role are CD47, CD24, CD44, CD31, β2M, PD-L1, App1, and DHMEQ. Pre- and post-isolation methods for exosome engineering are compatible with the loading of therapeutic cargo and the expression of antiphagocytic surface molecules.

Abstinence from ethanol dependence produces concomitant cortical gray matter abnormalities, microstructural deficits and cognitive dysfunction

Previous studies demonstrate that ethanol dependence induced by repeating cycles of chronic intermittent ethanol vapor exposure (CIE) followed by protracted abstinence (CIE-PA) produces significant alterations in oligodendrogenesis in the rodent medial prefrontal cortex (mPFC). Specifically, CIE-PA produced an unprecedented increase in premyelinating oligodendroglial progenitor cells and myelin, which have been associated with persistent elevated drinking behaviors during abstinence. The current study used neuroimaging and electron microscopy to evaluate the integrity of enhanced myelin and microstructural deficits underlying enhanced myelination in the mPFC in male rats experiencing forced abstinence for 1 day (D), 7D, 21D and 42D following seven weeks of CIE. In vivo diffusion tensor imaging (DTI) detected altered microstructural integrity in the mPFC and corpus callosum (CC). Altered integrity was characterized as reduced fractional anisotropy (FA) in the CC, and enhanced mean diffusivity (MD) in the mPFC in 7D abstinent rats. Increased MD occurred concomitantly with increases in myelin associated proteins, flayed myelin and enhanced mitochondrial stress in the mPFC in 7D abstinent rats, suggesting that the increases in myelination during abstinence was aberrant. Evaluation of cognitive performance via Pavlovian conditioning in 7D abstinent rats revealed reduced retrieval and recall of fear memories dependent on the mPFC. These findings indicate that forced abstinence from moderate to severe alcohol use disorder produces gray matter damage via myelin dysfunction in the mPFC and that these microstructural changes were associated with deficits in PFC dependent behaviors.

Junctional Localization of Septin 2 Is Required for Organization of Junctional Proteins in Static Endothelial Monolayers

OBJECTIVE

Septin 2 is localized at junctions in human microvascular endothelial monolayers. The junctional localization of septin 2 is necessary for organization of cell-cell adhesion proteins of endothelial cells. Approach and Results: Septin 2 was depleted at junctions by suppression of expression using shRNA, treatment with inflammatory cytokine, TNF (tumor necrosis factor)-α, and ectopic overexpression of septin 2 phosphatidylinositol 4,5-bisphosphate binding mutant defect in interaction with plasma membrane. Under those conditions, organizations and expression levels of various junctional proteins were analyzed. Confocal images of immunofluorescence staining showed substantial disorganization of adherens junctional proteins, nectin-2 and afadin, TJP (tight junction protein), ZO (zonula occludens)-1, and intercellular adhesion protein, PECAM-1 (platelet-endothelial cell adhesion molecule-1). Immunoblots for those proteins did not show significant changes in expression except for nectin-2 that highly increased in expression. Significant differential gene expression profiles and biological pathway analysis by septin 2 suppression and by TNF-α treatment using RNA-seq showed common overlapping pathways. The commonalities in expression may be consistent with the similar effects on the overall organization of cell-cell adhesion proteins.

CONCLUSIONS

Localization of septin 2 at cell junctions are required for the arrangement of junctional proteins and the integrity of the barrier formed by endothelial monolayers.

Identification of key genes associated with lung adenocarcinoma by bioinformatics analysis

Lung adenocarcinoma (LUAD) is the most common histological type of lung cancer, comprising around 40% of all lung cancer. Until now, the pathogenesis of LUAD has not been fully elucidated. In the current study, we comprehensively analyzed the dysregulated genes in lung adenocarcinoma by mining public datasets. Two sets of gene expression datasets were obtained from the Gene Expression Omnibus (GEO) database. The dysregulated genes were identified by using the GEO2R online tool, and analyzed by R packages, Cytoscape software, STRING, and GPEIA online tools. A total of 275 common dysregulated genes were identified in two independent datasets, including 54 common up-regulated and 221 common down-regulated genes in LUAD. Gene Ontology (GO) enrichment analysis showed that these dysregulated genes were significantly enriched in 258 biological processes (BPs), 27 cellular components (CCs), and 21 molecular functions (MFs). Furthermore, protein-protein interaction (PPI) network analysis showed that PECAM1, ENG, KLF4, CDH5, and VWF were key genes. Survival analysis indicated that the low expression of ENG was associated with poor overall survival (OS) of LUAD patients. The low expression of PECAM1 was associated with poor OS and recurrence-free survival of LUAD patients. The cox regression model developed based on age, tumor stage, ENG, PECAM1 could effectively predict 5-year survival of LUAD patients. This study revealed some key genes, BPs, CCs, and MFs involved in LUAD, which would provide new insights into understanding the pathogenesis of LUAD. In addition, ENG and PECAM1 might serve as promising prognostic markers in LUAD.

Strategies for Mast Cell Inhibition in Food Allergy

Mast cells are tissue resident allergic effector cells that drive IgE-mediated food allergies. There are several steps leading to mast cell activation in the context of allergic disease that can be targeted to prevent mast cell activation and degranulation. These include blocking IgE-FcεRI crosslinking and type 2 cytokine receptor activation; modulating cell-surface neural chemical receptors; stabilizing mast cell membranes to prevent co-localization of activating receptors; impeding intracellular signaling; and engaging cell surface inhibitory receptors. This review highlights several ITIM-containing inhibitory mast cell surface receptors that could serve as pharmaceutical targets to prevent mast cell activation and degranulation in the context of food allergy. When activated, these ITIM-containing inhibitory receptors recruit the phosphatases SHP-1, SHP-2, and/or SHIP to dephosphorylate the tyrosine kinases responsible for activation signals downstream of the IgE-FcεRI complex. We describe several members of the Ig and Ig-like inhibitory receptor and C-type lectin inhibitory receptor superfamilies. Fundamental studies exploring the behavior of these receptors within the context of experimental food allergy models are needed. A deeper understanding of how these receptors modulate mast cell-driven food allergic responses will shape future strategies to harness these inhibitory receptors to treat food allergy.

Src kinase: Key effector in mechanosignalling

Cells have developed a unique set of molecular mechanisms that allows them to probe mechanical properties of the surrounding environment. These systems are based on deformable primary mechanosensors coupled to tension transmitting proteins and enzymes generating biochemical signals. This modular setup enables to transform a mechanical load into more versatile biochemical information. Src kinase appears to be one of the central components of the mechanotransduction network mediating force-induced signalling across multiple cellular contexts. In tight cooperation with primary sensors and the cytoskeleton, Src functions as an effector molecule necessary for transformation of mechanical stimuli into biochemical outputs executing cellular response and adaptation to mechanical cues.

Single-cell gene profiling and lineage tracing analyses revealed novel mechanisms of endothelial repair by progenitors

Stem/progenitor cells (SPCs) have been implicated to participate in vascular repair. However, the exact role of SPCs in endothelial repair of large vessels still remains controversial. This study aimed to delineate the cellular heterogeneity and possible functional role of endogenous vascular SPCs in large vessels. Using single-cell RNA-sequencing (scRNA-seq) and genetic lineage tracing mouse models, we uncovered the cellular heterogeneity of SPCs, i.e., c-Kit+ cells in the mouse aorta, and found that endogenous c-Kit+ cells acquire endothelial cell fate in the aorta under both physiological and pathological conditions. While c-Kit+ cells contribute to aortic endothelial turnover in the atheroprone regions during homeostasis, recipient c-Kit+ cells of nonbone marrow source replace both luminal and microvessel endothelial cells in transplant arteriosclerosis. Single-cell pseudotime analysis of scRNA-seq data and in vitro cell experiments suggest that vascular SPCs display endothelial differentiation potential and undergo metabolic reprogramming during cell differentiation, in which AKT/mTOR-dependent glycolysis is critical for endothelial gene expression. These findings demonstrate a critical role for c-Kit lineage cells in aortic endothelial turnover and replacement, and may provide insights into therapeutic strategies for vascular diseases.

Leaf extracts of Campomanesia xanthocarpa positively regulates atherosclerotic-related protein expression

Atherosclerosis is caused by a monocyte-mediated inflammatory process that, in turn, is stimulated by cytokines and adhesion molecules. Monocytes are then differentiated into macrophages, leading to the formation of arterial atherosclerotic plaques. Recently, guavirova leaf extracts from Campomanesia xanthocarpa (EG) have shown potential effects on the treatment of plaque formation by reducing cholesterol, LDL levels and serum oxidative stress. We evaluated the effect of EG on the viability of human monocytic and endothelial cell lines at three time points (24, 48 and 72 hours) and whether it can modulate the migration and in vitro expression of CD14, PECAM-1, ICAM-1, HLA-DR and CD105. Cell viability was affected only at higher concentrations and times. We observed decreased ICAM-1 expression in cells treated with 50 μg/ml EG and CD14 expression with IFN-γ and without IFN-γ. CD14 also decreased endothelial cell expression in the presence of IFN-γ and GE. We also found decreased expression of PECAM-1 when treated with EG and IFN-γ. In addition, EG-treated endothelial cells showed higher migration than the control group. Reduced expression of these markers and increased migration may lead to decreased cytokines, which may be contributing to decreased chronic inflammatory response during atherosclerosis and protecting endothelial integrity.

Increased circulating CD31+/CD42b-EMPs in Perthes disease and inhibit HUVECs angiogenesis via endothelial dysfunction

AIMS

Endothelial microparticles (EMPs) are extracellular vesicles secreted by endothelial cells. The purpose of this research is to explore that the clinical significance and roles in angiogenesis and endothelial dysfunction of circulating microparticles in Perthes disease.

MAIN METHODS

We collected platelet-poor plasma (PPP) from patients and controls, then microparticles (MPs) were extracted. Flow cytometry was performed to calculate the concentrations of CD31+/CD42b-, CD62E+ and CD31+/CD42b+ MPs. ELISA was performed to detect the expression level of biomarkers of endothelial dysfunction and inflammatory factors in plasma. In vitro experiments to evaluate the effect of circulating MPs and EMPs derived from IL-6-stimulated human umbilical vein endothelial cells (HUVECs) on angiogenesis and endothelial dysfunction.

KEY FINDINGS

Our results revealed that the CD31+/CD42b- EMPs were significantly higher in Perthes disease group than in the control group. The Perthes-MPs being taken up by HUVECs promoted endothelial cell apoptosis, endothelial dysfunction and inhibited angiogenesis in vitro. Moreover, the level of IL-6 in plasma significantly increased in patients with Perthes, which was tightly correlated with the elevated level of circulating CD31+/CD42b- EMPs. IL-6 promoted HUVECs to secrete CD31+/CD42b- MPs, and EMPs derived from high concentration IL-6-stimulated (100 and 1000 pg/mL) HUVECs promoted endothelial cell apoptosis, endothelial dysfunction and inhibited angiogenesis.

SIGNIFICANCE

In summary, our study suggests that circulating EMPs in the phenotypic spectrum revealed unique phenotypes of endothelial dysfunction, showing close correlation with the secretion of IL-6. These circulating EMPs may give rise to endothelial cell apoptosis, endothelial dysfunction and angiogenesis in Perthes disease.

The Involvement of Cell Adhesion Molecules, Tight Junctions, and Gap Junctions in Human Placentation

Placentation is a major determinant of the success of pregnancy. It is regulated by several factors such as cell adhesion molecules, tight junctions, and gap junctions. The cell adhesion molecules are integrins, cadherins, immunoglobulins, nectins, and selectins. The tight junctions are composed of claudins, occludin, and junction adhesion molecule proteins while the gap junctions are composed of connexins of varying molecular weights. During placentation, some of these molecules regulate trophoblast proliferation, trophoblast fusion, trophoblast migration, trophoblast invasion, trophoblast-endothelium adhesion, glandular remodeling, and spiral artery remodeling. There is a dysregulated placental expression of some of these molecules during obstetric complications. We have, hereby, indicated the expression patterns of the subunits of each of these molecules in the various trophoblast subtypes and in the decidua, and have highlighted their involvement in physiological and pathological placentation. The available evidence points to the relevance of these molecules as distinguishing markers of the various trophoblast lineages and as potential therapeutic targets in the management of malplacentation-mediated diseases.

Substances of abuse and the blood brain barrier: Interactions with physical exercise

Substance use disorders pose a common medical, social and financial problem. Among the pathomechanisms of substance use disorders, the disruption and increased permeability of the blood-brain barrier has been recently revealed. Physical exercise appears to be a relatively inexpensive and feasible way to implement behavioral therapy counteracting the blood-brain barrier impairment. Concomitantly, there are also studies supporting a potential protective role of selected substances of abuse in maintaining the blood-brain barrier integrity. In this review, we aim to provide a summary on the modulatory influence of physical exercise, a non-pharmacological intervention, on the blood-brain barrier alterations caused by substances of abuse. Further studies are needed to understand the precise mechanisms that underlie various effects of physical exercise in substance use disorders.

Tunicamycin induced endoplasmic reticulum stress in the small intestine

Because the small intestine is exposed to variety of foreign substances, it participates in host immune response. We investigated whether the expression levels of intestinal MAdCAM-1, PECAM-1 (CD31) and CAV-1 are affected by endoplasmic reticulum (ER) stress following brief treatment with tunicamycin (TN). We administered a single dose of TN intraperitoneally. Twenty-four hours later, MAdCAM-1, PECAM-1 and CAV-1 expression levels in Peyer's patches and villi were examined using immunohistochemistry (IHC), immunofluorescence (IF) and western blotting. Immunostaining of MAdCAM-1 and CAV-1 in control and TN treated Peyer's patches and villi exhibited similar staining patterns. The immunoreactivity of PECAM-1 was similar for the control and TN treated Payer's patches, whereas staining was decreased significantly in TN treated villi. Our findings suggest that short term TN treatment did not affect leukocyte movement to lymphoid compartments of the small intestine, but it altered villus architecture due to decreased PECAM-1 expression.

Comparative gene expression profiling of milk somatic cells of Sahiwal cattle and Murrah buffaloes

India is the world's largest milk producing country because of massive contribution made by cattle and buffaloes. In the present investigation, comprehensive comparative profiling of transcriptomic landscape of milk somatic cells of Sahiwal cattle and Murrah buffaloes was carried out. Genes with highest transcript abundance in both species were enriched for biological processes such as lactation, immune response, cellular oxidant detoxification and response to hormones. Analysis of differential expression identified 377 significantly up-regulated and 847 significantly down-regulated genes with fold change >1.5 in Murrah buffaloes as compared to Sahiwal cattle (p_adj <0.05). Marked enrichment of innate and adaptive immune response related GO terms and higher expression of genes for various host defense peptides such as lysozyme, defensin β and granzymes were evident in buffaloes. Genes related to ECM-receptor interaction, complement and coagulation cascades, cytokine-cytokine receptor interaction and keratinization pathway showed more abundant expression in cattle. Network analysis of the up-regulated genes delineated highly connected genes representing immunity and haematopoietic cell lineage (CBL, CD28, CD247, PECAM1 and ITGA4). For the down-regulated dataset, genes with highest interactions were KRT18, FGFR1, GPR183, ITGB3 and DKK3. Our results lend support to more robust immune mechanisms in buffaloes, possibly explaining lower susceptibility to mammary infections as compared to cattle.

A new approach for examining the neurovascular structure with phalloidin and calcitonin gene-related peptide in the rat cranial dura mater

The neurovascular structures in the cranial dura mater have been studied with various histological techniques in the past years. In order to obtain a proper approach to reveal the detailed structures, different labeling methods for the cranial vessels and nerve fibers were tested in this study. Firstly, the labeling characteristics of phalloidin, alpha smooth muscle actin (α-SMA), and CD31 were compared in rat whole-mount cranial dura mater by using fluorescent immunohistochemistry or histochemistry. Secondly, according to their properties, phalloidin and α-SMA were selected to combine with calcitonin gene-related peptide (CGRP) to further demonstrate the cranial neurovascular structure. By these approaches, a three-dimensional map of blood vessels and nerve fibers within the whole-mount rat cranial dura mater was obtained. The results showed that phalloidin, α-SMA, and CD31 were preferably expressed in the wall of cranial vessels, corresponding to the arteriors, venules, and capillaries, respectively. Additionally, CGRP + nerve fibers were clearly demonstrated together with phalloidin + or α-SMA + vessels, forming a delicate neurovascular network in the cranial dura mater. The thick nerve bundles ran closely to the phalloidin + or α-SMA + vessels in parallel pattern, while the thin nerve fibers branched off from the bundles tending to surround the phalloidin + arterioles rather than α-SMA + venules. These findings suggest that phalloidin could be an appropriate biochemical maker to be effectively used together with CGRP for experiments examining the detailed spatial correlation of cranial blood vessels and nerve fibers in a three-dimensional view, which may provide clues for understanding the underlying mechanisms of cranial neurovascular disorders.

Moderate Alcohol Consumption Targets S100β+ Vascular Stem Cells and Attenuates Injury-Induced Neointimal Hyperplasia

BACKGROUND

Stem cells present in the vessel wall may be triggered in response to injurious stimuli to undergo differentiation and contribute to vascular disease development. Our aim was to determine the effect of moderate alcohol (EtOH) exposure on the expansion and differentiation of S100 calcium-binding protein B positive (S100β⁺ ) resident vascular stem cells and their contribution to pathologic vessel remodeling in a mouse model of arteriosclerosis.

METHODS AND RESULTS

Lineage tracing analysis of S100β⁺ cells was performed in male and female S100β-eGFP/Cre/ERT2-dTomato transgenic mice treated daily with or without EtOH by oral gavage (peak BAC: 15 mM or 0.07%) following left common carotid artery ligation for 14 days. Carotid arteries (ligated or sham-operated) were harvested for morphological analysis and confocal assessment of fluorescent-tagged S100 β ⁺ cells in FFPE carotid cross sections. Ligation-induced carotid remodeling was more robust in males than in females. EtOH-gavaged mice had less adventitial thickening and markedly reduced neointimal formation compared to controls, with a more pronounced inhibitory effect in males compared to females. There was significant expansion of S100β⁺ -marked cells in vessels postligation, primarily in the neointimal compartment. EtOH treatment reduced the fraction of S100β⁺ cells in carotid cross sections, concomitant with attenuated remodeling. In vitro, EtOH attenuated Sonic Hedgehog-stimulated myogenic differentiation (as evidenced by reduced calponin and myosin heavy chain expression) of isolated murine S100β⁺ vascular stem cells.

CONCLUSIONS

These data highlight resident vascular S100β⁺ stem cells as a novel target population for alcohol and suggest that regulation of these progenitors in adult arteries, particularly in males, may be an important mechanism contributing to the antiatherogenic effects of moderate alcohol consumption.

Retinal Physiology and Circulation: Effect of Diabetes

In this article, we present a discussion of diabetes and its complications, including the macrovascular and microvascular effects, with the latter of consequence to the retina. We will discuss the anatomy and physiology of the retina, including aspects of metabolism and mechanisms of oxygenation, with the latter accomplished via a combination of the retinal and choroidal blood circulations. Both of these vasculatures are altered in diabetes, with the retinal circulation intimately involved in the pathology of diabetic retinopathy. The later stages of diabetic retinopathy involve poorly controlled angiogenesis that is of great concern, but in our discussion, we will focus more on several alterations in the retinal circulation occurring earlier in the progression of disease, including reductions in blood flow and a possible redistribution of perfusion that may leave some areas of the retina ischemic and hypoxic. Finally, we include in this article a more recent area of investigation regarding the diabetic retinal vasculature, that is, the alterations to the endothelial surface layer that normally plays a vital role in maintaining physiological functions. © 2020 American Physiological Society. Compr Physiol 10:933-974, 2020.

Generation of Pecam1 endothelial specific dual reporter mouse model

Endothelial cells are specialized epithelium lining the interior surface of vessels and play fundamental roles in angiogenesis, vascular permeability, and immune response. To identify endothelial cells in vivo, we constructed a Pecam1^{nlacZ-H2B-GFP/+} knock-in mouse model in which the endothelial cells are labeled by nuclear LacZ (nlacZ) expression. When Pecam1^{nlacZ-H2B-GFP/+} mice are bred with germline Cre deleter mice, Pecam1^H2B-GFP/+ line is created with native nuclear GFP (H2B-GFP) expression in the endothelium of various organs. This dual reporter mouse provides us with a powerful genetic tool for definitive identification of endothelial cells and monitoring this important cell population throughout development, homeostasis, and disease conditions in mammals.

Alterations of aorta intima and media transcriptome in swine fed high-fat diet over 1-year follow-up period and of the switch to normal diet

BACKGROUND AND AIM

We previously showed that 12-month high-fat diet (HFD) in pigs led to fattening and increased artery intima-media-thickness, which were partly reversed after 3-month return to control diet (CD). The aim of this study was to decipher underlying mechanism of action by using transcriptomic analyses of intima and media of aorta.

METHODS AND RESULTS

Thirty-two pigs were divided into three groups: CD for 12 months; HFD for 12 months; switch diet group (regression diet; RD): HFD for 9 months followed by CD for 3 months. After 12 months, RNA was isolated from aorta intima and media for nutrigenomic analyses. HFD significantly affected gene expression in intima, while RD gene expression profile was distinct from the CD group. This suggests that switch to CD is not sufficient to correct gene expression alterations induced by HFD but counteracted expression of a group of genes. HFD also affected gene expression in media and as for intima, the expression profile of media of pigs on RD differed from that of these on CD.

CONCLUSIONS

This study revealed nutrigenomic modifications induced by long-term HFD consumption on arterial intima and media. The return to CD was not sufficient to counteract the genomic effect of HFD.

Selection and validation of reference genes for normalisation of gene expression in ischaemic and toxicological studies in kidney disease

Normalisation to standard reference gene(s) is essential for quantitative real-time polymerase chain reaction (RT-qPCR) to obtain reproducible and comparable results of a gene of interest (GOI) between subjects and under varying experimental conditions. There is limited evidence to support selection of the commonly used reference genes in rat ischaemic and toxicological kidney models. Employing these models, we determined the most stable reference genes by comparing 4 standard methods (NormFinder, qBase+, BestKeeper and comparative ΔCq) and developed a new 3-way linear mixed-effects model for evaluation of reference gene stability. This new technique utilises the intra-class correlation coefficient as the stability measure for multiple continuous and categorical covariates when determining the optimum normalisation factor. The model also determines confidence intervals for each candidate normalisation gene to facilitate selection and allow sample size calculation for designing experiments to identify reference genes. Of the 10 candidate reference genes tested, the geometric mean of polyadenylate-binding nuclear protein 1 (PABPN1) and beta-actin (ACTB) was the most stable reference combination. In contrast, commonly used ribosomal 18S and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) were the most unstable. We compared the use of PABPN1×ACTB and 2 commonly used genes 18S and GAPDH on the expression of 4 genes of interest know to vary after renal injury and expressed by different kidney cell types (KIM-1, HIF1α, TGFβ1 and PECAM1). The less stable reference genes gave varying patterns of GOI expression in contrast to the use of the least unstable reference PABPN1×ACTB combination; this improved detection of differences in gene expression between experimental groups. Reduced within-group variation of the now more accurately normalised GOI may allow for reduced experimental group size particularly for comparison between various models. This objective selection of stable reference genes increased the reliability of comparisons within and between experimental groups.

Progressive long-term spatial memory loss following repeat concussive and subconcussive brain injury in mice, associated with dorsal hippocampal neuron loss, microglial phenotype shift, and vascular abnormalities

There is considerable concern about the long‐term deleterious effects of repeat head trauma on cognition, but little is known about underlying mechanisms and pathology. To examine this, we delivered four air blasts to the left side of the mouse cranium, a week apart, with an intensity that causes deficits when delivered singly and considered “concussive,” or an intensity that does not yield significant deficits when delivered singly and considered “subconcussive.” Neither repeat concussive nor subconcussive blast produced spatial memory deficits at 4 months, but both yielded deficits at 14 months, and dorsal hippocampal neuron loss. Hierarchical cluster analysis of dorsal hippocampal microglia across the three groups based on morphology and expression of MHCII, CX3CR1, CD68 and IBA1 revealed five distinct phenotypes. Types 1A and 1B microglia were more common in sham mice, linked to better neuron survival and memory, and appeared mildly activated. By contrast, 2B and 2C microglia were more common in repeat concussive and subconcussive mice, linked to poorer neuron survival and memory, and characterized by low expression levels and attenuated processes, suggesting they were de‐activated and dysfunctional. In addition, endothelial cells in repeat concussive mice exhibited reduced CD31 and eNOS expression, which was correlated with the prevalence of type 2B and 2C microglia. Our findings suggest that both repeat concussive and subconcussive head injury engender progressive pathogenic processes, possibly through sustained effects on microglia that over time lead to increased prevalence of dysfunctional microglia, adversely affecting neurons and blood vessels, and thereby driving neurodegeneration and memory decline.

IL-18 immunoadjuvanted xenogeneic canine MMP-7 DNA vaccine overcomes immune tolerance and supresses the growth of murine mammary tumor

The development of the tumorigenesis and angiogenesis through proteolytic cleavage of extracellular matrix protein and basement membranes is promoted by Matrix metelloproteinases-7 (MMP-7). Consequently, MMP-7 is presumed as potential target for mammary cancer immunotherapy. However, MMP-7 is an endogenous tumor associated antigen (TAA); therefore, immunization is challenging. In current study, a potent anti-tumor immune response has been elicited through recombinant bivalent plasmid pVIVO2.IL18.cMMP7 which subside the highly metastatic 4 T1 cell line induced mammary tumors and efficiently negate the existing challenge of using MMP-7 as immunotherapeutic target. Balb/c mice were immunized with canine MMP-7 (cMMP-7) using interleukine-18 (IL-18), as an immunoadjuvant, to explore the potential of the combination regarding elicitation of a potent anti-tumor immune response. Mice vaccinated with pVIVO2.IL18.cMMP7 DNA plasmid reduced the tumor growth significantly along with augmentation of the immune response to fight against tumor antigen as depicted by substantial enrichment of CD4+ and CD8+ population in splenocytes, infiltration of immune system cells in tumor tissue and enhanced survival time of mice. Further, splenocyte supernatant examination of the cytokines revealed that Th1 cytokines (IFN-γ and IL-2) were remarkably up-regulated demonstrating the stimulation of cell-mediated immune response. Thus the current observations vividly portray that administration of xenogeneic MMP-7 DNA vaccine bypasses the tolerance barrier.

A Rationale for the Use of Clotted Vertebral Bone Marrow to Aid Tissue Regeneration Following Spinal Surgery

Vertebral body bone marrow aspirate (V-BMA), easily accessible simultaneously with the preparation of the site for pedicle screw insertion during spinal procedures, is becoming an increasingly used cell therapy approach in spinal surgery. However, the main drawbacks for V-BMA use are the lack of a standardized procedure and of a structural texture with the possibility of diffusion away from the implant site. The aim of this study was to evaluate, characterize and compare the biological characteristics of MSCs from clotted V-BMA and MSCs from whole and concentrate V-BMAs. MSCs from clotted V-BMA showed the highest cell viability and growth factors expression (TGF-β, VEGF-A, FGF2), the greatest colony forming unit (CFU) potency, cellular homogeneity, ability to differentiate towards the osteogenic (COL1AI, TNFRSF11B, BGLAP) and chondrogenic phenotype (SOX9) and the lowest ability to differentiate toward the adipogenic lineage (ADIPOQ) in comparison to all the other culture conditions. Additionally, results revealed that MSCs, differently isolated, expressed different level of HOX and TALE signatures and that PBX1 and MEIS3 were down-regulated in MSCs from clotted V-BMA in comparison to concentrated one. The study demonstrated for the first time that the cellular source inside the clotted V-BMA showed the best biological properties, representing an alternative and advanced cell therapy approach for patients undergoing spinal surgery.

Differential Expression of CD31 and Von Willebrand Factor on Endothelial Cells in Different Regions of the Human Brain: Potential Implications for Cerebral Malaria Pathogenesis

Cerebral microvascular endothelial cells (CMVECs) line the vascular system of the brain and are the chief cells in the formation and function of the blood brain barrier (BBB). These cells are heterogeneous along the cerebral vasculature and any dysfunctional state in these cells can result in a local loss of function of the BBB in any region of the brain. There is currently no report on the distribution and variation of the CMVECs in different brain regions in humans. This study investigated microcirculation in the adult human brain by the characterization of the expression pattern of brain endothelial cell markers in different brain regions. Five different brain regions consisting of the visual cortex, the hippocampus, the precentral gyrus, the postcentral gyrus, and the rhinal cortex obtained from three normal adult human brain specimens were studied and analyzed for the expression of the endothelial cell markers: cluster of differentiation 31 (CD31) and von-Willebrand-Factor (vWF) through immunohistochemistry. We observed differences in the expression pattern of CD31 and vWF between the gray matter and the white matter in the brain regions. Furthermore, there were also regional variations in the pattern of expression of the endothelial cell biomarkers. Thus, this suggests differences in the nature of vascularization in various regions of the human brain. These observations also suggest the existence of variation in structure and function of different brain regions, which could reflect in the pathophysiological outcomes in a diseased state.

Cleaved CD31 as a target for in vivo molecular imaging of inflammation

There is a need for new targets to specifically localize inflammatory foci, usable in a wide range of organs. Here, we hypothesized that the cleaved molecular form of CD31 is a suitable target for molecular imaging of inflammation. We evaluated a bioconjugate of D-P8RI, a synthetic peptide that binds all cells with cleaved CD31, in an experimental rat model of sterile acute inflammation. Male Wistar rats were injected with turpentine oil into the gastrocnemius muscle two days before ^99mTc-HYNIC-D-P8RI (or its analogue with L-Proline) SPECT/CT or [¹⁸F]FDG PET/MRI. Biodistribution, stability study, histology, imaging and autoradiography of ^99mTc-HYNIC-D-P8RI were further performed. Biodistribution studies revealed rapid elimination of ^99mTc-HYNIC-D-P8RI through renal excretion with almost no uptake from most organs and excellent in vitro and in vivo stability were observed. SPECT/CT imaging showed a significant higher ^99mTc-HYNIC-D-P8RI uptake compared with its analogue with L-Proline (negative control) and no significant difference compared with [¹⁸F]FDG (positive control). Moreover, autoradiography and histology revealed a co-localization between ^99mTc-HYNIC-D-P8RI uptake and inflammatory cell infiltration. ^99mTc-HYNIC-D-P8RI constitutes a new tool for the detection and localization of inflammatory sites. Our work suggests that targeting cleaved CD31 is an attractive strategy for the specific in vivo imaging of inflammatory processes.

The Many Roles of Cell Adhesion Molecules in Hepatic Fibrosis

Fibrogenesis is a progressive scarring event resulting from disrupted regular wound healing due to repeated tissue injury and can end in organ failure, like in liver cirrhosis. The protagonists in this process, either liver-resident cells or patrolling leukocytes attracted to the site of tissue damage, interact with each other by soluble factors but also by direct cell–cell contact mediated by cell adhesion molecules. Since cell adhesion molecules also support binding to the extracellular matrix, they represent excellent biosensors, which allow cells to modulate their behavior based on changes in the surrounding microenvironment. In this review, we focus on selectins, cadherins, integrins and members of the immunoglobulin superfamily of adhesion molecules as well as some non-classical cell adhesion molecules in the context of hepatic fibrosis. We describe their liver-specific contributions to leukocyte recruitment, cell differentiation and survival, matrix remodeling or angiogenesis and touch on their suitability as targets in antifibrotic therapies.

Generation of PECAM-1 (CD31) conditional knockout mice

Platelet endothelial cell adhesion molecule 1 (PECAM-1) is an adhesion and signaling receptor that is expressed on endothelial and hematopoietic cells and plays important roles in angiogenesis, vascular permeability, and regulation of cellular responsiveness. To better understanding the tissue specificity of PECAM-1 functions, we generated mice in which PECAM1, the gene encoding PECAM-1, could be conditionally knocked out. A targeting construct was created that contains loxP sites flanking PECAM1 exons 1 and 2 and a neomycin resistance gene flanked by flippase recognition target (FRT) sites that was positioned upstream of the 3' loxP site. The targeting construct was electroporated into C57BL/6 embryonic stem (ES) cells, and correctly targeted ES cells were injected into C57BL/6 blastocysts, which were implanted into pseudo-pregnant females. Resulting chimeric animals were bred with transgenic mice expressing Flippase 1 (FLP1) to remove the FRT-flanked neomycin resistance gene and mice heterozygous for the floxed PECAM1 allele were bred with each other to obtain homozygous PECAM1 ^flox/flox offspring, which expressed PECAM-1 at normal levels and had no overt phenotype. PECAM1 ^flox/flox mice were bred with mice expressing Cre recombinase under the control of the SRY-box containing gene 2 (Sox2Cre) promoter to delete the floxed PECAM1 allele in offspring (Sox2Cre;PECAM1 ^del/WT ), which were crossbred to generate Sox2Cre; PECAM1 ^del/del offspring. Sox2Cre; PECAM1 ^del/del mice recapitulated the phenotype of conventional global PECAM-1 knockout mice. PECAM1 ^flox/flox mice will be useful for studying distinct roles of PECAM-1 in tissue specific contexts and to gain insights into the roles that PECAM-1 plays in blood and vascular cell function.

CD31 Acts as a Checkpoint Molecule and Is Modulated by FcγR-Mediated Signaling in Monocytes

Monocytes and macrophages express FcγR that engage IgG immune complexes such as Ab-opsonized pathogens or cancer cells to destroy them by various mechanisms, including phagocytosis. FcγR-mediated phagocytosis is regulated by the concerted actions of activating FcγR and inhibitory receptors, such as FcγRIIb and SIRPα. In this study, we report that another ITIM-containing receptor, PECAM1/CD31, regulates FcγR function and is itself regulated by FcγR activation. First, quantitative RT-PCR and flow cytometry analyses revealed that human monocyte FcγR activation leads to a significant downregulation of CD31 expression, both at the message level and at surface expression, mainly mediated through FcγRIIa. Interestingly, the kinetics of downregulation between the two varied, with surface expression reducing earlier than the message. Experiments to analyze the mechanism behind this discrepancy revealed that the loss of surface expression was because of internalization, which depended predominantly on the PI3 kinase pathway and was independent of FcγR internalization. Finally, functional analyses showed that the downregulation of CD31 expression in monocytes by small interfering RNA enhanced FcγR-mediated phagocytic ability but have little effect on cytokine production. Together, these results suggest that CD31 acts as a checkpoint receptor that could be targeted to enhance FcγR functions in Ab-mediated therapies.

Protective Effects of Flavone from Tamarix aphylla against CCl4-Induced Liver Injury in Mice Mediated by Suppression of Oxidative Stress, Apoptosis and Angiogenesis

The current study aimed to investigate, for the first time, the beneficial effects of 3,5-dihydroxy-4',7-dimethoxyflavone isolated from Tamarix aphylla L. against liver injury in mice. Liver injury was induced by intraperitoneal (i.p.) injection of carbon tetrachloride (CCl₄) at a dose of 0.4 mL/kg mixed in olive oil at ratio (1:4) twice a week for 6 consecutive weeks. The administration of CCl₄ caused significant histopathological changes in liver tissues while the pre-treatment with the flavone at dose of 10 and 25 mg/kg ameliorated the observed liver damages. Also, it markedly reduced hepatic malondialdehyde (MDA) level as well as increased the activities of liver superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (Gpx) compared with their recorded levels in CCl₄ model group. Moreover, the immunohistochemical analysis demonstrated the enhancement in the protein level of B-cell lymphoma-2 (Bcl-2) while the protein levels of cysteine-aspartic acid protease-3 (caspase-3), Bcl-2-associated x protein (Bax), transforming growth factor-β1 (TGF-β1) and CD31 were suppressed following the flavone treatement. These results suggest that the flavone can inhibit liver injury induced in mice owning to its impact on the oxidation, apoptotic and angiogenesis mechanisms. Further pharmacological investigations are essential to determine the effectiveness of the flavone in human.

Hyperglycemia-induced ubiquitination and degradation of β-catenin with the loss of platelet endothelial cell adhesion molecule-1 in retinal endothelial cells

OBJECTIVE

Increased retinal vascular permeability is one of the earliest manifestations of diabetic retinopathy. The aim of this study was to investigate the role of hyperglycemia-induced platelet endothelial cell adhesion molecule-1 loss on retinal vascular permeability via the β-catenin pathway.

METHODS

Type I diabetes was induced in male Wistar rats using streptozotocin injections, with age-matched non-diabetic rats as controls. Rat retinal microvascular endothelial cells were grown under normal or high glucose conditions for 6 days. Small interfering Ribonucleic Acid was used to knock down platelet endothelial cell adhesion molecule-1 in rat retinal microvascular endothelial cells for loss-of-function studies. Retinas and rat retinal microvascular endothelial cells were subjected to Western blot, immunofluorescence labeling, and co-immunoprecipitation analyses to assess protein levels and interactions. A biotinylated gelatin and fluorescein isothiocyanate-avidin assay was used for retinal endothelial cell permeability studies.

RESULTS

β-catenin, β-catenin/platelet endothelial cell adhesion molecule-1 interaction, active Src homology 2 domain-containing protein tyrosine phosphatase were significantly decreased, while β-catenin ubiquitination levels and endothelial permeability were significantly increased, in hyperglycemic retinal endothelial cells. Similar results were observed with platelet endothelial cell adhesion molecule-1 partial knockdown, where β-catenin and active Src homology 2 domain-containing protein tyrosine phosphatase levels were decreased, while phospho-β-catenin and retinal endothelial cell permeability were increased.

CONCLUSION

Platelet endothelial cell adhesion molecule-1 loss may contribute to increased retinal endothelial cell permeability by attenuating β-catenin levels under hyperglycemic conditions.

Gene expression profiles of differentiated and undifferentiated adipose derived mesenchymal stem cells dynamically seeded onto a processed nerve allograft

BACKGROUND

Differentiation of mesenchymal stem cells (MSCs) into Schwann-like cells onto processed nerve allografts may support peripheral nerve repair. The purpose of this study was to understand the biological characteristics of undifferentiated and differentiated MSCs before and after seeding onto a processed nerve allograft by comparing gene expression profiles.

METHODS

MSCs from Lewis rats were cultured in maintenance media or differentiated into Schwann-like cells. Both treatment groups were dynamically seeded onto decellularized nerve allografts derived from Sprague-Dawley rats. Gene expression was quantified by quantitative polymerase chain reaction (qPCR) analysis of representative biomarkers, including neurotrophic (GDNF, PTN, GAP43, PMP22), angiogenic (CD31, VEGF1), extracellular matrix (ECM) (COL1A1, COL3A1, FBLN1, LAMB2) or cell cycle (CAPS3, CCBN2) genes. Gene expression values were statistically evaluated using a 2-factor ANOVA with repeated measures.

RESULTS

Baseline gene expression of undifferentiated and differentiated MSCs was significantly altered upon interaction with processed nerve allografts. Interaction between processed allografts and undifferentiated MSCs enhanced expression of neurotrophic (NGF, GDNF, PMP22), ECM (FBLN1, LAMB2) and regulatory cell cycle genes (CCNB2) during a 7-day time course. Interactions of differentiated MSCs with nerve allografts enhanced expression of neurotrophic (NGF, GDNF, GAP43), angiogenic (VEGF1), ECM (FBLN1) and regulatory cell cycle genes (CASP3, CCNB2) within one week.

CONCLUSIONS

Dynamic seeding onto processed nerve allografts modulates temporal gene expression profiles of differentiated and undifferentiated MSCs. These changes in gene expressions may support the reparative functions of MSCs in supporting nerve regeneration in different stages of axonal growth.

Biological characterization of the UW402, UW473, ONS-76 and DAOY pediatric medulloblastoma cell lines

Medulloblastoma (MB) is the most common malignant brain tumor in children. Recent advances in molecular technologies allowed to classify MB in 4 major molecular subgroups: WNT, SHH, Group 3 and Group 4. In cancer research, cancer cell lines are important for examining and manipulating molecular and cellular process. However, it is important to know the characteristics of each cancer cell line prior to use, because there are some differences among them, even if they originate from the same cancer type. This study aimed to evaluate the similarities and differences among four human medulloblastoma cell lines, UW402, UW473, DAOY and ONS-76. The medulloblastoma cell lines were analyzed for (1) cell morphology, (2) immunophenotyping by flow cytometry for some specifics surface proteins, (3) expression level of adhesion molecules by RT-qPCR, (4) proliferative potential, (5) cell migration, and (6) in vivo tumorigenic potential. It was observed a relationship between cell growth and CDH1 (E-chaderin) adhesion molecule expression and all MB cell lines showed higher levels of CDH2 (N-chaderin) when compared to other adhesion molecule. ONS-76 showed higher gene expression of CDH5 (VE-chaderin) and higher percentage of CD144/VE-chaderin positive cells when compared to other MB cell lines. All MB cell lines showed low percentage of CD34, CD45, CD31, CD133 positive cells and high percentage of CD44, CD105, CD106 and CD29 positive cells. The DAOY cell line showed the highest migration potential, the ONS-76 cell line showed the highest proliferative potential and only DAOY and ONS-76 cell lines showed tumorigenic potential in vivo. MB cell lines showed functional and molecular differences among them, which it should be considered by the researchers in choosing the most suitable cellular model according to the study proposal.

Passing the Vascular Barrier: Endothelial Signaling Processes Controlling Extravasation

A central function of the vascular endothelium is to serve as a barrier between the blood and the surrounding tissue of the body. At the same time, solutes and cells have to pass the endothelium to leave or to enter the bloodstream to maintain homeostasis. Under pathological conditions, for example, inflammation, permeability for fluid and cells is largely increased in the affected area, thereby facilitating host defense. To appropriately function as a regulated permeability filter, the endothelium uses various mechanisms to allow solutes and cells to pass the endothelial layer. These include transcellular and paracellular pathways of which the latter requires remodeling of intercellular junctions for its regulation. This review provides an overview on endothelial barrier regulation and focuses on the endothelial signaling mechanisms controlling the opening and closing of paracellular pathways for solutes and cells such as leukocytes and metastasizing tumor cells.

Differential regulation of blood vessel formation between traumatic temporomandibular joint fibrous ankylosis and bony ankylosis in a sheep model

OBJECTIVES

Clinical and experimental studies show that the etiology of traumatic temporomandibular joint (TMJ) fibrous ankylosis and bony ankylosis are associated with the severity of trauma. However, how the injury severity affects the tissue differentiation is not clear. We tested the hypothesis that angiogenesis affects the outcomes of TMJ trauma, and that enhanced neovascularization after severe TMJ trauma would promote the development of bony ankylosis.

METHODS

Bilateral condylar sagittal fracture and discectomy were performed for each sheep, with the glenoid fossa receiving either severe trauma to induce bony ankylosis or minor trauma to induce fibrous ankylosis. At days 7, 14, 28, and 56 after surgery, total RNA was extracted from the ankylosed callus. Temporal gene expressions of several molecules functionally important for blood vessel formation were studied by real-time PCR.

RESULTS

Histological examination revealed a prolonged hematoma phase and a lack of cartilage formation in fibrous ankylosis. mRNA expression levels of HIF-1α, VEGF, VEGFR2, SDF1, Ang1, Tie2, vWF, CYR61, FGF2, TIMP1, MMP2, and MMP9 were distinctly lower in fibrous ankylosis compared with bony ankylosis at several time points.

CONCLUSIONS

Our study indicates that inhibition of angiogenesis after TMJ trauma might be a promising strategy for preventing bony ankylosis in the future.

Endothelial Cell Biomechanical Responses are Dependent on Both Fluid Shear Stress and Tensile Strain

Introduction

The goal of this study was to investigate how concurrent shear stress and tensile strain affect endothelial cell biomechanical responses.

Methods

Human coronary artery endothelial cells were exposed to concurrent pulsatile shear stress and cyclic tensile strain in a programmable shearing and stretching device. Three shear stress-tensile strain conditions were used: (1) pulsatile shear stress at 1 Pa and cyclic tensile strain at 7%, simulating normal stress/strain conditions in a healthy coronary artery; (2) shear stress at 3.7 Pa and tensile strain at 3%, simulating pathological stress/strain conditions near a stenosis; (3) shear stress at 0.7 Pa and tensile strain at 5%, simulating pathological stress/strain conditions in a recirculation zone. Cell morphology was quantified using immunofluorescence microscopy. Cell surface PECAM-1 phosphorylation, ICAM-1 expression, ERK1/2 and NF-κB activation were measured using ELISA or Western blot.

Results

Simultaneous stimulation from pulsatile shear stress and cyclic tensile strain induced a significant increase in cell area, compared to that induced by shear stress or tensile strain alone. The combined stimulation caused significant increases in PECAM-1 phosphorylation. The combined stimulation also significantly enhanced EC surface ICAM-1 expression (compared to that under shear stress alone) and transcriptional factor NF-κB activation (compared to that under control conditions).

Conclusion

Pulsatile shear stress and cyclic tensile strain could induce increased but not synergistic effect on endothelial cell morphology or activation. The combined mechanical stimulation can be relayed from cell membrane to nucleus. Therefore, to better understand how mechanical conditions affect endothelial cell mechanotransduction and cardiovascular disease development, both shear stress and tensile strain need to be considered.

Sustainable Dual Release of Antibiotic and Growth Factor from pH-Responsive Uniform Alginate Composite Microparticles to Enhance Wound Healing

Hydrogel-based wound dressings provided a moist microenvironment and local release of bioactive molecules. Single drug loading along with fast release rates and usually in hydrogel sheets limited their performance. Hence, uniform alginate/CaCO₃ composite microparticles (∼430 μm) with tunable compositions for sustainable release of drug and pH-sensitivity were successfully fabricated using microfluidic technology. Due to the presence of CaCO₃ and the strong interactions with alginate molecules, lyophilized composite microparticles reverted to hydrogel state after rehydration. Regardless of microparticle states (hydrogel or lyophilized) and pH values (6.4 or 7.4), in vitro release rates of model drug were inversely related with CaCO₃ concentrations and much lower than that for pure alginate microparticles. The release rate at pH 6.4 (simulating wound microenvironment) was always slower than that at pH 7.4 for the same type of microparticles. Rifamycin and basic fibroblast growth factor (bFGF) were independently encapsulated into AD-5-R and AD-40-F to achieve a fast release of rifamycin and a slower, more sustained release of bFGF, respectively; CD-F-R was a mixture of AD-5-R and AD-40-F at weight ratio 1/1. For AD-5-R and CD-F-R, inhibition zones of S. aureus were observed until day 5, showing a sustained antibacterial property. On the basis of in vitro wound healing model of NIH-3T3 cell micropattern on glass coverslips with a hole array, it was found that AD-40-F and CD-F-R significantly promoted cell proliferation and migration rates. In a full-thickness skin wound model of rats, CD-F-R microparticles significantly accelerated wound healing with higher granulation tissue thickness and better bioactivity to stimulate angiogenesis than the control group. Furthermore, CD-F-R microparticles demonstrated a good biocompatibility and biodegradability in vivo. Taken together, CD-F-R composite microparticles may ideally meet the requirements for different stages during wound healing and demonstrated a good potential to be used as dressing materials.

Lecithin-based deferoxamine nanoparticles accelerated cutaneous wound healing in diabetic rats

Nanoparticles have higher frequency of being exposed to cells or tissue, and are thus more likely to gain access into cytoplasm or nuclei to modulate molecular events due to significantly larger surface area to volume ratio. As a result, they present amplified response or even different physiochemical and biomedical properties from bigger particles. Deferoxamine accelerates wound healing in diabetic rats by increased neovascularization, reduced inflammation and improved maturation of wound. We investigated the wound healing potential of deferoxamine-nanoparticles in diabetic rats. Lecithin based nanoparticles of deferoxamine were prepared and characterized. The diabetic rats were divided into five Groups, of which Group I was treated with pluronic-gel f-127 (25%), Group II with deferoxamine 0.1% and Group III, IV and V were treated with deferoxamine-nanoparticles incorporated in pluronic-gel f-127 25% at 0.03% (0.01% deferoxamine), 0.1% (0.03% deferoxamine) and 0.3% (0.1% deferoxamine) w/v respectively. The wound closure was significantly accelerated in group V as compared to control groups. HIF-1α, VEGF, SDF-1α, TGF-β₁, and IL-10 protein levels were significantly higher in group V. The collagen deposition and neovascularization was greater in deferoxamine-nanoparticle treated rats. In contrast, TNF-α level was lowest in group V. In summary, the deferoxamine-nanoparticle formulation we developed, when applied topically on diabetic wounds results in faster wound healing as compared to simple deferoxamine formulation. This formulation may prove to be an effective therapy for treatment of diabetic wounds.

Neovascularization with chronic inflammation characterizes ascending aortic dissection

Objective:

Neovascularization of the aortic wall may be associated with aortic dissection (AD). Aortic wall endothelial CD31 deposition together with chronic inflammation indicates angiogenesis that may lead to tissue disruption. We studied the presence of neovascularization of the ascending aortic wall by characterizing CD31 positive endothelial cells.

Methods:

Aortic wall routine histology and immunohistochemistry for CD31, T- and B-lymphocytes, plasma cells, macrophages, endothelial cells, smooth muscle cells, and cell proliferation were performed on 35 selected patients who underwent surgery for the ascending aorta, and the samples were grouped according to the presence of AD.

Results:

Three subjects with Marfan syndrome were excluded from the study. A total of 14 out of 32 patients had AD. A total of 18 patients were operated on due to dilatation only. Chronic inflammation of the adventitia (p=0.003), media (p=0.001), and intima (p=0.005) was increased in AD. Neovascularization was predominant in the outer third medial layer in AD (p=0.037), corresponding to the site of aortic wall disruption. A receiver operating characteristic curve analysis showed that neovascularization was associated with AD (AUC 0.750; SE 0.092; p=0.022; 95% CI 0.570–0.930).

Conclusion:

Endothelial immunohistochemistry confirms neovascularization of the outer third medial layer during AD. Aortic wall remodeling including neovascularization characterizes AD. Chronic inflammation and neovascularization of the dilated ascending aorta suggest susceptibility for AD.

Fracture Healing and the Underexposed Role of Extracellular Vesicle-Based Cross Talk

The process of fracture healing is complex and requires an interaction of multiple organ systems. Cell-cell communication is known to be very important during this process. Extracellular vesicles (EVs) are small membranous vesicles generated from a variety of cells. Proteins, RNAs, small molecules, and mitochondria DNA were found to be transported among cells through EVs. EV-based cross talk represents a substantial cell-cell communication pattern that can both interact with cells through molecular surfaces and transfer molecules to cells. These interactions can assist in the synchronization of cellular functions among cells of the same kind, and coordinate the functions of different types of cells. After activation, platelets, neutrophils, macrophages, osteoblasts, osteoclasts, and mesenchymal stem cell (') all secrete EVs, promoting the fracture healing process. Moreover, some studies have found evidence that EVs may be used for diagnosis and treatment of delayed fracture healing, and may be significantly involved in the pathophysiology of fracture healing disturbances. In this review, we summarize recent findings on EVs released by fracture healing-related cells, and EV-mediated communications during fracture healing. We also highlight the potential applications of EVs in fracture healing. Lastly, the prospect of EVs for research and clinical use is discussed.

Mechanotransduction, immunoregulation, and metabolic functions of CD31 in cardiovascular pathophysiology

Biomechanical changes in the heart and vessels drive rapid and dynamic regulation of blood flow, a vital process for meeting the changing metabolic needs of the peripheral tissues at any given point in time. The fluid movement of the blood exerts haemodynamic stress upon the solid elements of the cardiovascular system: the heart, vessels, and cellular components of the blood. Cardiovascular diseases can lead to prolonged mechanical stress, such as cardiac remodelling during heart failure or vascular stiffening in atherosclerosis. This can lead to a significantly reduced or increasingly turbulent blood supply, inducing a shift in cellular metabolism that, amongst other effects, can trigger the release of reactive oxygen species and initiate a self-perpetuating cycle of inflammation and oxidative stress. CD31 is the most abundant constitutive co-signalling receptor glycoprotein on endothelial cells, which line the cardiovascular system and form the first-line of cellular contact with the blood. By associating with most endothelial receptors involved in mechanosensing, CD31 regulates the response to biomechanical stimuli. In addition, by relocating in the lipid rafts of endothelial cells as well as of cells stably interacting with the endothelium, including leucocytes and platelets, CD31–CD31 trans-homophilic engagement guides and restrains platelet and immune cell accumulation and activation and at sites of damage. In this way, CD31 is at the centre of mediating mechanical, metabolic, and immunological changes within the circulation and provides a single target that may have pleiotropic beneficial effects.

Endothelial Microparticles in Uremia: Biomarkers and Potential Therapeutic Targets

Endothelial microparticles (EMPs) are vesicles derived from cell membranes, which contain outsourced phosphatidylserine and express adhesion molecules, such as cadherin, intercellular cell adhesion molecule-1 (ICAM-1), E-selectin, and integrins. EMPs are expressed under physiological conditions and continue circulating in the plasma. However, in pathologic conditions their levels increase, and they assume a pro-inflammatory and pro-coagulant role via interactions with monocytes; these effects are related to the development of atherosclerosis. Chronic kidney dysfunction (CKD) characterizes this dysfunctional scenario through the accumulation of uremic solutes in the circulating plasma, whose toxicity is related to the development of cardiovascular diseases. Therefore, this review aims to discuss the formation of EMPs and their biological effects in the uremic environment. Data from previous research demonstrate that uremic toxins are closely associated with the activation of inflammatory biomarkers, cardiovascular dysfunction processes, and the release of EMPs. The impact of a decrease in circulating EMPs in clinical studies has not yet been evaluated. Thus, whether MPs are biochemical markers and/or therapeutic targets has yet to be established.

Circulating microparticles as biomarkers of stroke: A focus on the value of endothelial- and platelet-derived microparticles

Stroke is one of the leading causes of mortality and disability worldwide. Numerous pathophysiological mechanisms involving blood vessels, coagulation and inflammation contribute to the vascular occlusion. Perturbations in these pathways can be detected by numerous methods including changes in endoplasmic membrane remodeling and rearrangement leading to the shedding of microparticles (MPs) from various cellular origins in the blood. MPs are small membrane-derived vesicles that are shed from nearly all cells in the body in resting state or upon stimulation. MPs act as biological messengers to transfer information to adjacent and distant cells thus regulating various biological processes. MPs may be important biomarkers and tools for the identification of the risk and diagnosis of cerebrovascular diseases. Endothelial activation and dysfunction and altered thrombotic responses are two of the main features predisposing to stroke. Endothelial MPs (EMPs) have been recognized as both biomarkers and effectors of endothelial cell activation and injury while platelet-derived MPs (PMPs) carry a strong procoagulant potential and are activated in thrombotic states. Therefore, we reviewed here the role of EMPs and PMPs as biomarkers of stroke. Most studies reported high circulating levels of EMPs and PMPs in addition to other cell origins in stroke patients and have been linked to stroke severity, the size of infarction, and prognosis. The identification and quantification of EMPs and PMPs may thus be useful for the diagnosis and management of stroke.