Endothelial Cell Population Research Articles

Highly Multiplexed Mass Cytometry Identifies the Immunophenotype in the Skin of Dermatomyositis

Dermatomyositis (DM) is a rare, systemic autoimmune disease that most frequently affects the skin, muscles, and lungs. The inflammatory infiltrate in the skin has not been fully characterized, and, in this study, we took a single-cell, unbiased approach using imaging mass cytometry. Substantial monocyte‒macrophage diversity was observed, with the CD14+ population correlating positively with Cutaneous Dermatomyositis Disease Area and Severity Index scores (P= 0.031). The T-cell compartment revealed CD4+ T, CD8+ T, and FOXP3+ T cells. Activated (CD69+) circulating memory T cells correlated positively with Cutaneous Dermatomyositis Disease Area and Severity Index scores (P= 0.0268). IFN-β protein was highly upregulated in the T-cell, macrophage, dendritic cell, and endothelial cell populations of DM skin. Myeloid dendritic cells expressed phosphorylated peroxisome proliferator‒activated receptor γ, phosphorylated IRF3, IL-4, and IL-31, and their quantity correlated with itch as measured in Skindex-29. Plasmacytoid dendritic cells colocalized with IFN-γ in addition to the known colocalization with IFN-β. Nuclear phosphorylated peroxisome proliferator‒activated receptor γ expression was found in the DM endothelium. Imaging mass cytometry allows us to characterize single cells in the immune cell population and identify upregulated cytokines and inflammatory pathways in DM. These findings have important implications for the development of future targeted therapies for DM.

Somatic MAP3K3 and PIK3CA mutations in sporadic cerebral and spinal cord cavernous malformations.

Cavernous malformations affecting the CNS occur in ∼0.16-0.4% of the general population. The majority (85%) of cavernous malformations are in a sporadic form, but the genetic background of sporadic cavernous malformations remains enigmatic. Of the 81 patients, 73 (90.1%) patients were detected carrying somatic missense variants in two genes: MAP3K3 and PIK3CA by whole-exome sequencing. The mutation spectrum correlated with lesion size (P = 0.001), anatomical distribution (P < 0.001), MRI appearance (P = 0.004) and haemorrhage events (P = 0.006). PIK3CA mutation was a significant predictor of overt haemorrhage events (P = 0.003, odds ratio = 11.252, 95% confidence interval = 2.275-55.648). Enrichment of endothelial cell population was associated with a higher fractional abundance of the somatic mutations. Overexpression of the MAP3K3 mutation perturbed angiogenesis of endothelial cell models in vitro and zebrafish embryos in vivo. Distinct transcriptional signatures between different genetic subgroups of sporadic cavernous malformations were identified by single cell RNA sequencing and verified by pathological staining. Significant apoptosis in MAP3K3 mutation carriers and overexpression of GDF15 and SERPINA5 in PIK3CA mutation carriers contributed to their phenotype. We identified activating MAP3K3 and PIK3CA somatic mutations in the majority (90.1%) of sporadic cavernous malformations and PIK3CA mutations could confer a higher risk for overt haemorrhage. Our data provide insights into genomic landscapes, propose a mechanistic explanation and underscore the possibility of a molecular classification for sporadic cavernous malformations.

Tmem100-BAC-EGFP mice to selectively mark and purify embryonic endothelial cells of large caliber arteries in mid-gestational vascular formation.

Embryonic vascular development is achieved through the complex arrays of differentiation, proliferation, migration and mutual interaction of different cell types, and visualization as well as purification of unique cell populations are fundamental in studying its detailed mechanisms using in vivo experimental models. We previously demonstrated that Tmem100 was a novel endothelial gene encoding a small transmembrane protein, and that Tmem100 null mice showed embryonic lethality due to severe impairment of vascular formation. In the present study, we generated an EGFP reporter mouse line using a 216 kb genomic region containing mouse Tmem100 gene. A novel line designated as Tmem100-BAC-EGFP mice precisely recapitulated the Tmem100 expression profile at the mid-gestational stage, which was highly enriched in endothelial cells of large caliber arteries in mouse embryos. FACS experiments demonstrated that Tmem100-BAC-EGFP mice served to selectively purify a specific population of arterial endothelial cells, indicating their usefulness not only for the research concerning Tmem100 expression and function but also for comparative analysis of multiple endothelial cell subgroups in embryonic vascular development.

Assessing the Angiogenic Efficacy of Pleiotrophin Released from Injectable Heparin-Alginate Gels.

With this work, we design alginate-based hydrogels for therapeutically directing revascularization and repair processes in vivo. We immobilize pleiotrophin (PTN) in injectable hydrogel formulations as the target factor to stimulate proangiogenic responses in endothelial cells. The optimized heparin-alginate/chitosan hydrogels, produced by internal crosslinking with calcium carbonate, show good biocompatibility and injectability and allow controlling the release of immobilized proteins in the subcutaneous tissue over a period of 7 days. In vitro assays, performed with translational human induced pluripotent stem cell-derived endothelial cells, and the in vivo Matrigel plug assay are conducted to demonstrate the angiogenic effects of PTN on endothelial cells. Our results indicate that PTN stimulates endothelial cell morphogenesis in vitro and the migration of endothelial cells and macrophages as soon as 4 days after injections of the developed hydrogels, promoting the formation of structures similar to the healthy granulation tissue, which is an indicator of healing in ischemic wounds. These studies provide the rationale for further investigating this novel therapeutic for pursuing increased vascular density for efficient regeneration of ischemic tissues, by leveraging the host endothelial cell population to initiate angiogenic and reparative processes in vivo. Impact statement Localized, sustained, and controlled delivery of angiogenic factors is crucial for enabling the formation of novel vascular networks in ischemic tissues. This study describes the development of an injectable heparin-alginate/collagen hydrogel for controlling the in vivo release and bioactivity of pleiotrophin (PTN), a heparin-binding factor with significant angiogenic activity. We demonstrate that PTN promotes angiogenesis in an in vitro model of hypoxia and in preclinical subcutaneous models. These results advance our understanding of PTN function in guiding therapeutic angiogenesis and are critical to inform the development of novel translational strategies for ischemic tissue repair and regeneration.

Generation of a Novel In Vitro Model to Study Endothelial Dysfunction from Atherothrombotic Specimens

PurposeEndothelial dysfunction is central to the pathogenesis of acute coronary syndrome. The study of diseased endothelium is very challenging due to inherent difficulties in isolating endothelial cells from the coronary vascular bed. We sought to isolate and characterise coronary endothelial cells from patients undergoing thrombectomy for myocardial infarction to develop a patient-specific in vitro model of endothelial dysfunction.MethodsIn a prospective cohort study, 49 patients underwent percutaneous coronary intervention with thrombus aspiration. Specimens were cultured, and coronary endothelial outgrowth (CEO) cells were isolated. CEO cells, endothelial cells isolated from peripheral blood, explanted coronary arteries, and umbilical veins were phenotyped and assessed functionally in vitro and in vivo.ResultsCEO cells were obtained from 27/37 (73%) atherothrombotic specimens and gave rise to cells with cobblestone morphology expressing CD146 (94 ± 6%), CD31 (87 ± 14%), and von Willebrand factor (100 ± 1%). Proliferation of CEO cells was impaired compared to both coronary artery and umbilical vein endothelial cells (population doubling time, 2.5 ± 1.0 versus 1.6 ± 0.3 and 1.2 ± 0.3 days, respectively). Cell migration was also reduced compared to umbilical vein endothelial cells (29 ± 20% versus 85±19%). Importantly, unlike control endothelial cells, dysfunctional CEO cells did not incorporate into new vessels or promote angiogenesis in vivo.ConclusionsCEO cells can be reliably isolated and cultured from thrombectomy specimens in patients with acute coronary syndrome. Compared to controls, patient-derived coronary endothelial cells had impaired capacity to proliferate, migrate, and contribute to angiogenesis. CEO cells could be used to identify novel therapeutic targets to enhance endothelial function and prevent acute coronary syndromes.

Micro- and nanoscale biophysical cues for cardiovascular disease therapy

After cardiovascular injury, numerous pathological processes adversely impact the homeostatic function of cardiomyocyte, macrophage, fibroblast, endothelial cell, and vascular smooth muscle cell populations. Subsequent malfunctioning of these cells may further contribute to cardiovascular disease onset and progression. By modulating cellular responses after injury, it is possible to create local environments that promote wound healing and tissue repair mechanisms. The extracellular matrix continuously provides these mechanosensitive cell types with physical cues spanning the micro- and nanoscale to influence behaviors such as adhesion, morphology, and phenotype. It is therefore becoming increasingly compelling to harness these cell–substrate interactions to elicit more native cell behaviors that impede cardiovascular disease progression and enhance regenerative potential. This review discusses recent in vitro and preclinical work that have demonstrated the therapeutic implications of micro- and nanoscale biophysical cues on cell types adversely affected in cardiovascular diseases — cardiomyocytes, macrophages, fibroblasts, endothelial cells, and vascular smooth muscle cells.

Trem-2 Promotes Emergence of Restorative Macrophages and Endothelial Cells During Recovery From Hepatic Tissue Damage.

Macrophages are pivotal in mounting liver inflammatory and tissue repair responses upon hepatic injury, showing remarkable functional plasticity. The molecular mechanisms determining macrophage transition from inflammatory to restorative phenotypes in the damaged liver remain unclear. Using mouse models of acute (APAP) and chronic (CCl4) drug-induced hepatotoxic injury we show that the immune receptor Trem-2 controls phenotypic shifts of liver macrophages and impacts endothelial cell differentiation during tissue recovery. Trem-2 gene ablation led to a delayed re-population of Kupffer cells correlating with deterred resolution of hepatic damage following acute and chronic injury. During tissue recovery, we found that macrophages transitioning to Kupffer cells expressed high levels of Trem-2. Acquisition of the transition phenotype was associated with a unique transcriptomic profile denoting strong responsiveness to oxidative stress and downmodulation of the pro-inflammatory phenotype, which was not observed in absence of Trem-2. During tissue recovery, lack of Trem-2 favored accumulation of a liver-damage associated endothelial cell population (LDECs), whose transcriptional program was compatible with endothelial de-differentiation. Accordingly, LDECs precursor potential is supported by the downregulation of surface endothelial cell markers and by striking in vitro morphological changes towards typical endothelial cells. In conclusion, we found that the dynamics of liver macrophages in response to liver injury are critically controlled by Trem-2 and this regulation is interlinked with the de-differentiation of endothelial cells and heightened liver pathology. We propose that Trem-2 promotes the transition from pro-inflammatory to tissue repair phase by driving the acquisition of restorative properties in phagocytic macrophages.

New reporter zebrafish line unveils heterogeneity among lymphatic endothelial cells during development.

In zebrafish, lymphatic endothelial cells (LECs) originate from multiple/several distinct progenitor populations and generate organ-specific lymphatic vasculatures. Cell fate and tissue specificities were determined using a combination of genetically engineered transgenic lines in which the promoter of a LEC-specific gene drives expression of a fluorescent reporter protein. We established a novel zebrafish transgenic line expressing eGFP under the control of part of the zebrafish batf3 promoter (Basic Leucine Zipper ATF-Like Transcription Factor 3). Spatiotemporal examination of Tg(batf3MIN:eGFP) transgenic fish revealed a typical lymphatic expression pattern, which does not perfectly recapitulate the expression pattern of existing LEC transgenic lines. eGFP+ cells constitute a heterogeneous endothelial cell population, which expressed LEC and/or blood endothelial cells (BEC) markers in different tissues. In addition, we characterize the renal eGFP+ cell as a population of interest to study kidney diseases and regeneration. Our Tg(batf3MIN:eGFP) reporter zebrafish line provides a useful system to study LEC populations, of which heterogeneity depends on origin of progenitors, tissue environment and physiological conditions. We further developed a novel fish-adapted tissue clearing method, which allows deep imaging and 3D-visualization of vascular and lymphatic networks in the whole organism.

Generation of Functional Vascular Endothelial Cells and Pericytes from Keratinocyte Derived Human Induced Pluripotent Stem Cells.

Human induced pluripotent stem cell (hiPSC)-derived endothelial cells (ECs) and pericytes provide a powerful tool for cardiovascular disease modelling, personalized drug testing, translational medicine, and tissue engineering. Here, we report a novel differentiation protocol that results in the fast and efficient production of ECs and pericytes from keratinocyte-derived hiPSCs. We found that the implementation of a 3D embryoid body (EB) stage significantly improves the differentiation efficiency. Compared with the monolayer-based technique, our protocol yields a distinct EC population with higher levels of EC marker expression such as CD31 and vascular endothelial cadherin (VE-cadherin). Furthermore, the EB-based protocol allows the generation of functional EC and pericyte populations that can promote blood vessel-like structure formation upon co-culturing. Moreover, we demonstrate that the EB-based ECs and pericytes can be successfully used in a microfluidic chip model, forming a stable 3D microvascular network. Overall, the described protocol can be used to efficiently differentiate both ECs and pericytes with distinct and high marker expression from keratinocyte-derived hiPSCs, providing a potent source material for future cardiovascular disease studies.

Single-cell RNA sequencing in vision research: Insights into human retinal health and disease.

Gene expression provides valuable insight into cell function. As such, vision researchers have frequently employed gene expression studies to better understand retinal physiology and disease. With the advent of single-cell RNA sequencing, expression experiments provide an unparalleled resolution of information. Instead of studying aggregated gene expression across all cells in a heterogenous tissue, single-cell technology maps RNA to an individual cell, which facilitates grouping of retinal and choroidal cell types for further study. Single-cell RNA sequencing has been quickly adopted by both basic and translational vision researchers, and single-cell level gene expression has been studied in the visual systems of animal models, retinal organoids, and primary human retina, RPE, and choroid. These experiments have generated detailed atlases of gene expression and identified new retinal cell types. Likewise, single-cell RNA sequencing investigations have characterized how gene expression changes in the setting of many retinal diseases, including how choroidal endothelial cells are altered in age-related macular degeneration. In addition, this technology has allowed vision researchers to discover drivers of retinal development and model rare retinal diseases with induced pluripotent stem cells. In this review, we will overview the growing number of single-cell RNA sequencing studies in the field of vision research. We will summarize experimental considerations for designing single-cell RNA sequencing experiments and highlight important advancements in retinal, RPE, choroidal, and retinal organoid biology driven by this technology. Finally, we generalize these findings to genes involved in retinal degeneration and outline the future of single-cell expression experiments in studying retinal disease.

Identification of diverse tumor endothelial cell populations in malignant glioma.

Glioblastoma is the most common and aggressive type of primary brain tumor, as most patients succumb to the disease less than two years after diagnosis. Critically, studies demonstrate that glioma recruits surrounding blood vessels, while some work suggests that tumor stem cells themselves directly differentiate into endothelial cells, yet the molecular and cellular dynamics of the endothelium in glioma are poorly characterized. The goal of this study was to establish molecular and morphological benchmarks for tumor associated vessels (TAVs) and tumor derived endothelial cells (TDECs) during glioblastoma progression. Using In-Utero Electroporation and CRISPR/Cas9 genome engineering to generate a native, immunocompetent mouse model of glioma, we characterized vascular-tumor dynamics in three dimensions during tumor progression. We employed bulk and single-cell RNA-Sequencing to elucidate the relationship between TAVs and TDECs. We confirmed our findings in a patient derived orthotopic xenograft (PDOX) model. Using a mouse model of glioma, we identified progressive alteration of vessel function and morphogenesis over time. We also showed in our mouse model that TDECs are a rare subpopulation that contributes to vessels within the tumor, albeit to a limited degree. Furthermore, transcriptional profiling demonstrates that both TAVs and TDECs are molecularly distinct, and both populations feature extensive molecular heterogeneity. Finally, the distinct molecular signatures of these heterogeneous populations are also present in human glioma. Our findings show extensive endothelial heterogeneity within the tumor and tumor microenvironment and provide insights into the diverse cellular and molecular mechanisms that drive glioma vascularization and angiogenesis during tumorigenesis.

YAP Orchestrates Heterotypic Endothelial Cell Communication via HGF/c-MET Signaling in Liver Tumorigenesis.

The oncogene yes-associated protein (YAP) controls liver tumor initiation and progression via cell extrinsic functions by creating a tumor-supporting environment in conjunction with cell autonomous mechanisms. However, how YAP controls organization of the microenvironment and in particular the vascular niche, which contributes to liver disease and hepatocarcinogenesis, is poorly understood. To investigate heterotypic cell communication, we dissected murine and human liver endothelial cell (EC) populations into liver sinusoidal endothelial cells (LSEC) and continuous endothelial cells (CEC) through histomorphological and molecular characterization. In YAPS127A-induced tumorigenesis, a gradual replacement of LSECs by CECs was associated with dynamic changes in the expression of genes involved in paracrine communication. The formation of new communication hubs connecting CECs and LSECs included the hepatocyte growth factor (Hgf)/c-Met signaling pathway. In hepatocytes and tumor cells, YAP/TEA domain transcription factor 4 (TEAD4)-dependent transcriptional induction of osteopontin (Opn) stimulated c-Met expression in EC with CEC phenotype, which sensitized these cells to the promigratory effects of LSEC-derived Hgf. In human hepatocellular carcinoma, the presence of a migration-associated tip-cell signature correlated with poor clinical outcome and the loss of LSEC marker gene expression. The occurrence of c-MET-expressing CECs in human liver cancer samples was confirmed at the single-cell level. In summary, YAP-dependent changes of the liver vascular niche comprise the formation of heterologous communication hubs in which tumor cell-derived factors modify the cross-talk between LSECs and CECs via the HGF/c-MET axis. SIGNIFICANCE: YAP-dependent changes of the liver vascular niche comprise the formation of heterologous communication hubs in which tumor cell-derived factors modify the cross-talk between EC subpopulations. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/24/5502/F1.large.jpg.

Gene Regulatory Network Analysis and Engineering Directs Development and Vascularization of Multilineage Human Liver Organoids.

SUMMARYPluripotent stem cell (PSC)-derived organoids have emerged as novel multicellular models of human tissue development but display immature phenotypes, aberrant tissue fates, and a limited subset of cells. Here, we demonstrate that integrated analysis and engineering of gene regulatory networks (GRNs) in PSC-derived multilineage human liver organoids direct maturation and vascular morphogenesis in vitro. Overexpression of PROX1 and ATF5, combined with targeted CRISPR-based transcriptional activation of endogenous CYP3A4, reprograms tissue GRNs and improves native liver functions, such as FXR signaling, CYP3A4 enzymatic activity, and stromal cell reactivity. The engineered tissues possess superior liver identity when compared with other PSC-derived liver organoids and show the presence of hepatocyte, biliary, endothelial, and stellate-like cell populations in single-cell RNA-seq analysis. Finally, they show hepatic functions when studied in vivo. Collectively, our approach provides an experimental framework to direct organogenesis in vitro by systematically probing molecular pathways and transcriptional networks that promote tissue development.

Abstract 13667: Programming to S1PR1 + Endothelial Cell Population Promotes the Restoration of Vascular Integrity in vivo

Introduction: Increased endothelial permeability and failure to repair is the hallmark of several vascular diseases including acute lung injury (ALI). However, little is known about the intrinsic pathways that activate the endothelial cell (EC) regenerative programs facilitating thereby tissue repair. Studies have invoked a crucial role of sphingosine-1-phosphate (S1P) in resolving endothelial hyperpermeability through activation of the G-protein coupled receptor, sphingosine-1-phosphate receptor 1 (S1PR1). Hypothesis: We postulate that S1PR1 + EC serve as an endogenous means to prevent endothelial injury. Methods: Studies were made using EC-S1PR1 null mice and S1PR1-GFP reporter mice to trace the generation and characteristics of S1PR1 + EC by exploiting immuno-histochemical analysis and FACS. RNA-seq analysis was performed to identify the genetic signature of S1PR1 + EC. Combination of genetic and pharmacological strategies were included for mechanistic study. Transplantation of S1PR1 + EC and edema measurement was performed in EC-S1PR1 null mice. Results: We observed in a mouse model of endotoxemia that LPS via generation of S1P induced the programming of S1PR1 lo EC to S1PR1 + EC, comprising 80% of lung EC. Their generation preceded the vascular repair phase and these cells were required for reestablishing the endothelial barrier function. Thus, conditional deletion of S1PR1 in EC spontaneously increased lung vascular permeability. RNA-seq analysis of S1PR1 + EC showed enrichment of genes regulating S1P synthesis and transport, sphingosine kinase 1 (SPHK1) and SPNS2, respectively, as well as transcription factors EGR1 and STAT3. EGR1 and STAT3 were essential for transcribing SPHK1 and SPNS2, respectively to increase S1P concentration that served to amplify S1PR1 + EC transition. Transplantation of S1PR1 + EC into injured lung vasculature of EC-S1PR1 -/- mice restored endothelial integrity. Conclusions: Findings illustrate that generation of a specialized S1PR1 + EC population has the potential to activate key endothelial regenerative program mediating vascular endothelial repair raising the possibility of activating this pathway to restore vascular homeostasis in inflammatory lung injury.

Abstract 15530: Single-cell Analysis in Aortic Aneurysmal Tissue From Patients With Marfan Syndrome Reveals Increased Tgf-beta Production but Downregulation of Downstream Canonical Tgf-beta Signaling Pathways

Background: Marfan syndrome (MFS) is caused by mutations in the gene for fibrillin-1 ( FBN1 ); however, the mechanisms by which these mutations cause aortic aneurysms are poorly understood. Although it was hypothesized previously that dysregulation of the complex TGF-β signaling pathway leads to aortic aneurysm formation, FBN1 mutations appear to have a paradoxical effect on TGF-β signaling in MFS. In this study, we evaluated cell-specific TGF-β expression in non-immune cells in MFS aortic tissue. Methods: We performed single-cell RNA sequencing of ascending aortic aneurysm tissues from MFS patients (n=3) undergoing aneurysm repair and age-matched, non-aneurysmal control tissue from cardiac transplant donors and recipients (n=4). Non-immune cells were separated out from the data and analyzed using the Seurat package in R. Differentially expressed genes were identified using edgeR. Results: Conserved gene expression was used to identify populations of smooth muscle cells (SMCs; n=6), fibroblasts (n=3), and endothelial cells (ECs; n=3). We found that TGFB1 was significantly upregulated in quiescent fibroblasts (identified by increased expression of DCN , LUM , and complement factors) with log2FC of 1.30 and FDR 8.25x10 -8 , as well as in activated fibroblasts (identified by increased expression of genes involved in blood vessel repair and healing including ACTA2 , NOTCH3 , THBS2 , and PDGFRB ) with log2FC of 1.25 and FDR 6.15x10 -22 . Despite this increase in TGFB1 , expression of TGF-β receptor genes (predominately TGFBR2 ) as well as downstream SMAD genes was downregulated significantly in the SMC, fibroblast, and endothelial cell clusters. Finally, genes involved in the non-canonical TGF-β pathway, including ERK , JNK, and p38, were not differentially expressed in non-immune cells in MFS compared with control tissues. Conclusion: Increased expression of TGFB1 in non-immune cells in MFS was driven by two clusters of fibroblasts. Despite this, our data do not support associated upregulation of other genes in the canonical or non-canonical TGF-β pathways and in fact support downregulation of canonical TGF-β signaling in non-immune cells of aneurysmal tissues from MFS patients with advanced aortic disease.

Abstract 14880: Single-cell Transcriptomes Identify Unique Endothelial Subpopulation (FABP4 + TMEM100 - ) With Lipid Metabolism Dysfunction in Pulmonary Arterial Hypertension

Introduction: Pulmonary arterial hypertension (PAH) is a disaster disease characterized by obliterative vascular remodeling and persistent increase of vascular resistance, leading to right heart failure and premature death. Understanding the cellular and molecular mechanisms will help develop novel therapeutic approaches for PAH patients. Hypothesis: We hypothesis that endothelial plasticity or distinct cell populations are critical for obstructive vascular remodeling in the pathogenesis of PAH. Methods: Here we applied single-cell RNA sequencing (ScRNA-seq) to profile the pulmonary cells in a severe mouse model ( Egln1 Tie2Cre mice) of PAH. Human hPAEC from idiopathic PAH patients and healthy donors were used to measure FABP4 and FABP5 expression. siRNA mediated knockdown of FABP4 and FABP5 was performed to study cell proliferation and apoptosis. Mice with Fabp4 and Fabp5 deletion ( Fabp45 -/- ) and wild type (WT) mice were incubated with hypoxia (10% O 2 ) to induced PAH. Egln1 Tie2Cre mice were bred with Fabp45 -/- mice to generate Egln1 Tie2Cre / Fabp45 -/- mice. Results: We identified five distinct EC subpopulations in both WT and Egln1 Tie2Cre mice via scRNA-seq. Unexpectedly, the number of Cluster (EC2, 49.8%) was markedly increased in Egln1 Tie2Cre lung compared with WT lung (2.8%). EC2 cluster (mainly from Egln1 Tie2Cre lung) was characterized by little expression of Tmem100 , Cldn5 , Tspan7 , Calcrl and Foxf1 and high expression of Fabp4, Cdh13, Sparl1 and Fabp5 . Fatty acid-binding protein (FABP) 4 and FABP5 (FABP4-5) were highly induced in PAECs from IPAH patients. Knockdown of FABP4-5 reduced EC proliferation and starvation-induced Caspase 3/7 activity. Fabp45 -/- mice were protected from hypoxia-induced PAH compared to WT mice. Moreover, Egln1 Tie2Cre / Fabp45 -/- mice also exhibited a reduction of RVSP and RV hypertrophy compared to Egln1 Tie2Cre mice. Conclusions: ScRNA-seq analysis identifies a unique endothelial population (FABP4 + TMEM100 - ) highly enriched in the lung of severe PAH mice. Knockdown of FABP4-5 reduces EC proliferation starvation-induced injury. Genetic deletion of FABP4-5 protects from hypoxia and Egln1 deficiency-induced PAH in mice.

A Flux-Limited Model for Glioma Patterning with Hypoxia-Induced Angiogenesis

We propose a model for glioma patterns in a microlocal tumor environment under the influence of acidity, angiogenesis, and tissue anisotropy. The bottom-up model deduction eventually leads to a system of reaction–diffusion–taxis equations for glioma and endothelial cell population densities, of which the former infers flux limitation both in the self-diffusion and taxis terms. The model extends a recently introduced (Kumar, Li and Surulescu, 2020) description of glioma pseudopalisade formation with the aim of studying the effect of hypoxia-induced tumor vascularization on the establishment and maintenance of these histological patterns which are typical for high-grade brain cancer. Numerical simulations of the population level dynamics are performed to investigate several model scenarios containing this and further effects.

Association of Angiogenic Cells in the Tumour Microenvironment and the Circulating Matured Endothelial Cells in Astrocytic Glioma

Introduction: Astrocytic gliomas are the most common and lethal intracranial brain tumours and rely on angiogenesis for the tumour development. Endothelial progenitor cells (EPCs) contribute to the angiogenesis of glioma tumour. Objectives: The study aimed to investigate the matured circulating endothelial cells population in the peripheral blood mononuclear cells (PBMCs) and its associations with tissue resident angiogenic cells in astrocytic glioma patients. Methods: A total of 22 astrocytic glioma patients were recruited from Hospital Universiti Sains Malaysia. Tumour were sliced and stained with CD133+ and VEGFA+ for angiogenic cells (n=22). The circulating (CD133-/VEGFR2+) matured endothelial cells in PBMCs (n=22) were quantified using FACS. The paired t-test and Pearson correlation test were used for the data analysis. Results: The angiogenic cells in brain tumour tissue were significantly higher compared to adjacent normal brain tissue (median 1.07±0.96% vs. median 0.69±0.68%; Wilcoxon signed rank test Z=-3.100; p=0.002). Positive correlation was found between the angiogenic cells of brain tumour tissue and adjacent normal brain tissue (Spearman’s rho correlation test, r=0.56; p=0.007). Significant positive correlation was found between matured endothelial cells in peripheral circulating systems and angiogenic cells in tumour of astrocytic glioma patients (Pearson correlation test, r=0.60, p=0.003).Conclusion:The findings of the study give support to the possible roles of EPCs in astrocytic glioma patients. Thus targeting tissue resident angiogenic cells and matured circulating endothelial cells by antiangiogenic treatment might be useful to prevent the tumour growth.

Miyeloproliferatif Neoplazilerde JAK2V617F Mutasyonunun Endotel Hücresine Etkisi ve SOCS1-4 Gen Anlatımlarına Yansıması

Objective: Patients with myeloproliferative neoplasms (MPN) are at an increased risk of developing thrombosis which leads to significant levels of morbidity and mortality. Although this propensity for thrombosis has been attributed to increased blood counts, other factors such as endothelial cell (EC) dysfunction likely play an important role. Previous studies have provided evidence of EC involvement by JAK2V617F which is known to be present in blood cells of 50-95% of patients with MPN. Furthermore, the morphological and functional changes of this mutation, a single nucleotide mutation in the cytosolic tyrosine kinase, Janus kinase 2 (JAK2) has not been shown in EC. In addition, the role of epigenetic factors including suppressors of cytokine signaling (SOCS) proteins is also unknown for MPN. In this study, the effects of the JAK2V617F mutation on EC and the SOCS 1-4 genes expression and their methylation profiles were investigated. Materials and Methods: The in vitro transduction method of green fluorescent protein (GFP) labeled lentivirus carrying the JAK2 (wild form) or JAK2V617F mutation into human cord vein endothelial cell (HUVEC) was applied. GFP was determined and analyzed with the flow cytometer. Afterwards, the genetically modified EC population was isolated, gating for GFP signal by cell sorter and then DNA and RNA isolations were performed. Gene expressional changes of SOCS1-4 genes were determined in real time RT-PCR and methylation specific PCR was performed with bisulfite modification of DNA. Results: The successful infection of JAK2, JAK2V617F and GFP vectors into EC were achieved. The comparison of the genetically modified EC revealed no morphological differences. A significant increase in the expressions of SOCS1-4 were detected in mutant EH compared to JAK2 and GFP. It was determined that methylation had no effect on suppression of SOCS1-4 expression detected in GFP and JAK2 EC. Conclusion: Future studies will further enlighten the effects of JAK2V617F on EC and its role in thrombotic events.&nbsp;

Flow-Induced Transcriptomic Remodeling of Endothelial Cells Derived From Human Induced Pluripotent Stem Cells.

The vascular system is essential for the development and function of all organs and tissues in our body. The molecular signature and phenotype of endothelial cells (EC) are greatly affected by blood flow-induced shear stress, which is a vital component of vascular development and homeostasis. Recent advances in differentiation of ECs from human induced pluripotent stem cells (hiPSC) have enabled development of in vitro experimental models of the vasculature containing cells from healthy individuals or from patients harboring genetic variants or diseases of interest. Here we have used hiPSC-derived ECs and bulk- and single-cell RNA sequencing to study the effect of flow on the transcriptomic landscape of hiPSC-ECs and their heterogeneity. We demonstrate that hiPS-ECs are plastic and they adapt to flow by expressing known flow-induced genes. Single-cell RNA sequencing showed that flow induced a more homogenous and homeostatically more stable EC population compared to static cultures, as genes related to cell polarization, barrier formation and glucose and fatty acid transport were induced. The hiPS-ECs increased both arterial and venous markers when exposed to flow. Interestingly, while in general there was a greater increase in the venous markers, one cluster with more arterial-like hiPS-ECs was detected. Single-cell RNA sequencing revealed that not all hiPS-ECs are similar even after sorting, but exposing them to flow increases their homogeneity. Since hiPS-ECs resemble immature ECs and demonstrate high plasticity in response to flow, they provide an excellent model to study vascular development.