Human Cardiac Microvascular Endothelial Cells Research Articles

The transcription factor PPARA mediates SIRT1 regulation of NCOR1 to protect damaged heart cells.

Heart failure (HF) is a clinical syndrome with a high risk. Our previous research showed a regulatory relationship between Sirtuin 1 (SIRT1), peroxisome proliferator-activated receptor α (PPARA) and nuclear receptor co-repressor 1 (NCOR1). This study aimed to investigate the regulatory mechanism of SIRT1/PPARA/NCOR1 axis in HF. HF models in vitro were established by doxorubicin (DOX)-induced AC16 and human cardiac microvascular endothelial cell (HCMEC) lines. The contents of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), interleukin-1β (IL-1β), and IL-18 were detected using enzyme-linked immunosorbent assay. Then, we assessed the levels of reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD) and adenosine triphosphate (ATP). Moreover, the relationship between SIRT1 and PPARA was detected using the co-immunoprecipitation (Co-IP) analysis. The connection between PPARA and NCOR1 was analyzed using chromatin immunoprecipitation (ChIP). Overexpression of SIRT1 or PPARA could reduce apoptosis in DOX-induced AC16 and HCMEC cells, the levels of IL-1β, IL-18, ANP, BNP, ROS and MDA, while increasing the levels of SOD and ATP. In addition, overexpression of PPARA could increase the viability of DOX-induced cells and the levels of myosin heavy chain 6 (Myh6) and Myh7. Co-IP showed that SIRT1 interacted with PPARA. Silencing PPARA could reverse the effect of SIRT1 overexpression on DOX-induced AC16 and HCMEC cells. ChIP assay demonstrated that PPARA could bind to the promoter region of NCOR1. Silencing NCOR1 could reverse the effect of PPARA overexpression on DOX-induced AC16 and HCMEC cells. This study revealed that PPARA could mediate SIRT1 to promote NCOR1 expression and thus protect damaged heart cells. The finding provided an important reference for the treatment of HF.

Bioinformatics Identification and Validation of Angiogenesis-Related Genes in Myocardial Ischemic Reperfusion Injury.

Angiogenesis plays a critical protective role in myocardial ischemia-reperfusion injury (MIRI); however, therapeutic targeting of associated genes remains constrained. To bridge this gap, we conducted bioinformatics analysis to identify pivotal angiogenesis-related genes in MIRI, potentially applicable for preventive and therapeutic interventions. We collected two mouse heart I/R expression datasets (GSE61592 and GSE83472) from Gene Expression Omnibus, utilizing the Limma package to identify differentially expressed genes (DEGs). Angiogenesis-related genes (ARGs) were extracted from GeneCards, and their overlap with DEGs produced differentially expressed ARGs (ARDEGs). Further analyses included Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and disease ontology to explore biological functions. Weighted gene correlation network analysis (WGCNA) was used to investigate molecular modules linked to MIRI. Additionally, a protein-protein interaction (PPI) network was constructed to pinpoint hub genes relevant to MIRI. Receiver operating characteristic curves were used to assess the diagnostic efficacy of these hub genes for MIRI. An ischemia-reperfusion injury model was established using human cardiac microvascular endothelial cells (HCMECs), with the expression of hub genes validated within this experimental framework. We identified 47 ARDEGs, 41 upregulated and 6 downregulated. PPI network analysis revealed suppressor of cytokine signaling 3 (Socs3), C-X-C motif chemokine ligand 1 (Cxcl1), interleukin 1 beta (Il1b), and matrix metallopeptidase 9 (Mmp9) as hub genes. Receiver operating characteristic (ROC) curve analysis demonstrated strong diagnostic potential for Socs3, Cxcl1, Il1b, and Mmp9. In vitro validation corroborated the mRNA and protein expression predictions. Our study highlights the pivotal role of Socs3, Cxcl1, Il1b, and Mmp9 in MIRI development, their significance in immune cell infiltration, and their diagnostic accuracy. These findings offer valuable insights for MIRI diagnosis and treatment, presenting potential molecular targets for future research.

PEDF and 34-mer peptide inhibit cardiac microvascular endothelial cell ferroptosis via Nrf2/HO-1 signalling in myocardial ischemia-reperfusion injury.

Myocardial ischemia-reperfusion injury (MIRI) represents a critical pathology in acute myocardial infarction (AMI), which is characterized by high mortality and morbidity. Cardiac microvascular dysfunction contributes to MIRI, potentially culminating in heart failure (HF). Pigment epithelium-derived factor (PEDF), which belongs to the non-inhibitory serpin family, exhibits several physiological effects, including anti-angiogenesis, anti-inflammatory and antioxidant properties. Our study aims to explore the impact of PEDF and its functional peptide 34-mer on both cardiac microvascular perfusion in MIRI rats and human cardiac microvascular endothelial cells (HCMECs) injury under hypoxia reoxygenation (HR). It has been shown that MIRI is accompanied by ferroptosis in HCMECs. Furthermore, we investigated the effect of PEDF and its 34-mer, particularly regarding the Nrf2/HO-1 signalling pathway. Our results demonstrated that PEDF 34-mer significantly ameliorated cardiac microvascular dysfunction following MIRI. Additionally, they exhibited a notable suppression of ferroptosis in HCMECs, and these effects were mediated through activation of Nrf2/HO-1 signalling. These findings highlight the therapeutic potential of PEDF and 34-mer in alleviating microvascular dysfunction and MIRI. By enhancing cardiac microvascular perfusion and mitigating endothelial ferroptosis, PEDF and its derivative peptide represent promising candidates for the treatment of AMI.

Catecholamine induces endothelial dysfunction via Angiotensin II and intermediate conductance calcium activated potassium channel

Endothelial dysfunction contributes to the pathogenesis of Takotsubo syndrome (TTS). However, the exact mechanism underlying endothelial dysfunction in the setting of TTS has not been completely clarified. This study aims to investigate the roles of angiotensin II (Ang II) and intermediate-conductance Ca2+-activated K+ (SK4) channels in catecholamine-induced endothelial dysfunction. Human cardiac microvascular endothelial cells (HCMECs) were exposed to 100 µM epinephrine (Epi), mimicking the setting of TTS. Epi treatment increased the ET-1 concentration and reduced NO levels in HCMECs. Importantly, the effects of Epi were found to be mitigated in the presence of Ang II receptor blockers. Furthermore, Ang II mimicked Epi effects on ET-1 and NO production. Additionally, Ang II inhibited tube formation and increased cell apoptosis. The effects of Ang II could be reversed by an SK4 activator NS309 and mimicked by an SK4 channel blocker TRAM-34. Ang II also inhibited the SK4 channel current (ISK4) without affecting its expression level. Ang II could depolarize the cell membrane potential. Ang II promoted ROS release and reduced protein kinase A (PKA) expression. A ROS blocker prevented Ang II effect on ISK4. The PKA activator Sp-8-Br-cAMPS increased SK4 channel currents. Epinephrine enhanced the activity of ACE by activating the α1 receptor/Gq/PKC signal pathway, thereby promoting the secretion of Ang II. The study suggested that high-level catecholamine can increase Ang II release from endothelial cells by α1 receptors/Gq/PKC signal pathway. Ang II can inhibit SK4 channel current by increasing ROS generation and reducing PKA expression, thereby contributing to endothelial dysfunction.

Characterization of extracellular vesicles from patients with severe aortic stenosis undergoing transcatheter aortic valve implantation and assessment of their coagulation potential

Abstract Funding Acknowledgements None. Background The pathogenesis of aortic stenosis (AS) includes processes of inflammation and calcification. Patients with aortic stenosis have increased risk of stroke. The amount of circulating extracellular vesicles (EVs) is elevated in patients with severe AS and decreases following valve intervention. The function of these EVs in the clinical setting of severe AS is not fully known. Aim With flow cytometry characterize EVs in patients with severe AS before and after Transcatheter Aortic Valve Implantation (TAVI). To investigate whether these EVs have a procoagulant effects by themselves or when incubated with human aortic endothelial cells (hAoECs), human cardiac microvascular endothelial cells (hCMVEC), human cardiac myocytes (hCM) and spheroids of hCMVEC and hCM. Methods 25 patients with severe AS were included in the study and blood samples collected before and 2 months after TAVI. The CytoFLEX flow cytometer (Beckman Coulter) was used for characterization of surface antigens on purified EVs. 2D-cultures of hAoECs, hCMVEC and hCM were incubated with EVs (100 mg/mL) for 6 hours (h) and spheroids of hCM and hCMVEC with EVs for 48h. An inhouse assay determining Tissue Factor (TF) activity by means of FXa generation in cell lysates were utilized. TF activity in purified EVs alone was determined using Tissue Factor Activity Assay kit (Human, colorimetric) from abcam. Results We found an increased level of TF positive EVs, phosphatidylserine (PS) positive EVs as well as double positive PS / TF expressing EVs in AS patients before TAVI compared to healthy controls and reduction of PS+ and TF+/PS+ expressing EVs after TAVI (Fig 1). When analyzing TF activity by means of FXa generation we found no procoagulant effect in the purified EVs alone nor when incubating EVs with hAoEC or hCM. In contrast, we found an increased TF activity in hCMVEC and spheroids of hCM and hCMVEC after incubation with EVs from AS patients compared to healthy EVs. Conclusion Patients with AS have increased amount of EVs expressing typically procoagulant surface antigens. The EVs by themselves have no procoagulant activity. However, upon interaction with hCMVEC and spheroids, consisting of hCMVEC and hCM, EVs appear to induce procoagulant activity in the recipient cells thus suggesting a possible link to thromboembolic events in coronary arteries. Additional studies are warranted to elaborate the mechanism and function of these TF, PS and TF / PS positive EVs.

Poricoic acid A promotes angiogenesis and myocardial regeneration by inducing autophagy in myocardial infarction

Myocardial infarction (MI) is a kind of cardiovascular diseases with high morbidity and mortality. Poricoic acid A (PAA) is the main active substance in Poria cocos, which has been discovered to exhibit an ameliorative role in the progression of many diseases. However, no report has been focused on the regulatory effects of PAA on MI progression. In this study, at first, oxygen glucose deprivation (OGD) treatment was performed in human cardiac microvascular endothelial cells (HCMECs) to mimic MI cell model. Our findings demonstrated that cell proliferation was reduced post OGD treatment, but which was reversed by PAA treatment. Moreover, PAA suppressed cell apoptosis in OGD-triggered HCMEC cells. Next, it revealed that PAA induced autophagy in OGD-treated HCMEC cells through enhancing LC3-II/LC3-I level and reducing P62 level. In addition, PAA strengthened the angiogenesis ability and migration ability in OGD-induced HCMEC cells. Lastly, it was uncovered that PAA modulated the AMPK/mTOR signaling pathway through affecting the p-mTOR/mTOR and p-AMPK/AMPK levels. In conclusion, PAA can promote angiogenesis and myocardial regeneration after MI by inducing autophagy through modulating the AMPK/mTOR pathway. This work suggested that PAA may be a potential and useful drug for MI treatment.

FOXO6 transcription inhibition of CTRP3 promotes OGD/R-triggered cardiac microvascular endothelial barrier disruption via SIRT1/Nrf2 signalling.

C1q/TNF-related protein 3 (CTRP3) has been clarified to display its protective roles in cardiac function. The current study is concentrated on exploring the impacts of CTRP3 on myocardial ischaemia. Oxygen and glucose hypoxia/reoxygenation (OGD/R) model was constructed in human cardiac microvascular endothelial cells (HCMECs). Reverse transcription-quantitative polymerase chain reaction and western blot analysis of CTRP3 expression were conducted. CCK-8 assay was to estimate cell activity and lactate dehydrogenase (LDH) assay kit was to test LDH release. TUNEL assay and western blot were to judge apoptosis. Endothelial barrier function was detected by in vitro vascular permeability assay kit. Zonula occludens-1 (ZO-1) expression was evaluated by immunofluorescence assay. The interaction between CTRP3 promoter and Forkhead Box O6 (FOXO6) was predicted by JASPAR database and verified by chromatin immunoprecipitation and luciferase reporter assays. After OGD/R-induced HCMECs were co-transfected with CTRP3 overexpression and FOXO6 overexpression plasmids, the above functional experiments above were conducted again. Lastly, the expression of sirtuin 1 (SIRT1)/nuclear factor erythroid 2-related factor 2 (Nrf2) signalling-related proteins was examined by western blot. CTRP3 was down-regulated in OGD/R-induced HCMECs. CTRP3 enhanced the viability and barrier integrity while reduced the apoptosis and permeability of OGD/R-insulted HCMECs. This process may be regulated by FOXO6 transcription. Also, FOXO6 inhibition-mediated CTRP3 up-regulation activated the SIRT1/Nrf2 signalling. FOXO6 transcription inhibition of CTRP3 promotes OGD/R-triggered cardiac microvascular endothelial barrier disruption via SIRT1/Nrf2 signalling.

Superoxide dismutase mimetic nanozymes attenuate cardiac microvascular ischemia–reperfusion injury associated with hyperhomocysteinemia

The combination of homocysteine (Hcy) and copper ion (Cu2+) induces cardiac microvascular ischemia–reperfusion injury (IRI) by causing oxidative stress in the reperfusion treatment of ischemic cardiopathy. Therefore, antioxidant elimination of reactive oxygen species (ROS) shows great potential in the treatment of IRI. Herein, cerium vanadate nanorods (CVNRs) were designed and developed as an efficient ROS scavenger for the treatment of myocardial IRI in hyperhomocysteinemic rat (HHcyR) model. Thanks to its outstanding superoxide dismutase (SOD)-like activity, the CVNRs showed a significant antioxidant effect in human cardiac microvascular endothelial cells treated with Hcy and Cu2+ under hypoxia/reperfusion condition and greatly preserved the morphology and function of mitochondria. Further intravenous administration of CVNRs significantly maintained the integrity and perfusion of microvasculature, minimized the microcirculation malfunction, and finally reduced the myocardial infarction and maintained the heart function after IRI. Moreover, the administration of CVNRs in HHcyR exhibited negligible organ toxicity and inflammation response, indicating their excellent biocompatibility and biosafety. Collectively, the SOD-mimicking CVNRs can serve as a promising antioxidant nanozyme to treat cardiac microvascular IRI complicated with hyperhomocysteinemia, providing a new prospect for the development of antioxidant nanozyme in IRI treatment even with other risk factors.

Circulating exosomal mir-16-2-3p is associated with coronary microvascular dysfunction in diabetes through regulating the fatty acid degradation of endothelial cells

BackgroundCoronary microvascular dysfunction (CMD) is a frequent complication of diabetes mellitus (DM) characterized by challenges in both diagnosis and intervention. Circulating levels of microRNAs are increasingly recognized as potential biomarkers for cardiovascular diseases.MethodsSerum exosomes from patients with DM, DM with coronary microvascular dysfunction (DM-CMD) or DM with coronary artery disease (DM-CAD) were extracted for miRNA sequencing. The expression of miR-16-2-3p was assessed in high glucose-treated human aortic endothelial cells and human cardiac microvascular endothelial cells. Fluorescence in situ hybridization (FISH) was used to detect miR-16-2-3p within the myocardium of db/db mice. Intramyocardial injection of lentivirus overexpressing miR-16-2-3p was used to explore the function of the resulting gene in vivo. Bioinformatic analysis and in vitro assays were carried out to explore the downstream function and mechanism of miR-16-2-3p. Wound healing and tube formation assays were used to explore the effect of miR-16-2-3p on endothelial cell function.ResultsmiR-16-2-3p was upregulated in circulating exosomes from DM-CMD, high glucose-treated human cardiac microvascular endothelial cells and the hearts of db/db mice. Cardiac miR-16-2-3p overexpression improved cardiac systolic and diastolic function and coronary microvascular reperfusion. In vitro experiments revealed that miR-16-2-3p could regulate fatty acid degradation in endothelial cells, and ACADM was identified as a potential downstream target. MiR-16-2-3p increased cell migration and tube formation in microvascular endothelial cells.ConclusionsOur findings suggest that circulating miR-16-2-3p may serve as a biomarker for individuals with DM-CMD. Additionally, miR-16-2-3p appears to alleviate coronary microvascular dysfunction in diabetes by modulating ACADM-mediated fatty acid degradation in endothelial cells.

MiRNA-146a-5p Inhibits Hypoxia-Induced Myocardial Fibrosis Through EndMT.

Cardiac Vascular disease particularly myocardial infarction (MI) is a threat to health worldwide. microRNAs (miRNAs) have been shown to regulate myocardial fibrosis. Therefore, it is potential to investigate the mechanism of miRNA and fibrosis following myocardial infarction. Hypoxia human cardiac microvascular endothelial cells (HCMECs) were selected for the vitro experimental model. The miR-146a-5p expression was tested via RT-qPCR. The level of endothelial-to-mesenchymal transition (EndMT) and fibrosis markers were detected by Western blotting and immunofluorescence. Then, the inflammation, cell viability and apoptosis were investigated. The target was predicted by an online database and verified by a dual-luciferase activity assay. An MI mouse model was created to validate that miR-146a-5p regulates cardiac fibrosis in vivo. MI mouse was transfected with miR-146a-5p lentivirus. Subsequently, its effect on cardiac fibrosis of infarcted hearts was assessed by In situ hybridization (ISH), Immunohistochemistry (IHC), Triphenylterazolium chloride (TTC) staining and Masson staining. Herein, we confirmed that miR-146a-5p was down-regulated in hypoxia HCMECs. Overexpression of miR-146a-5p inhibited hypoxia-induced cardiac fibrosis following myocardial infarction by inhibiting EndMT in HCMECs. Thioredoxin-interacting protein (TXNIP) was a target that was negatively regulated by miR-146a-5p. Up-regulation of miR-146a-5p inhibited cardiac fibrosis via regulating EndMT by targeting TXNIP, and it also regulated EndMT to inhibit cardiac fibrosis in vivo.

Cardiac endothelial ischemia/reperfusion injury-derived protein damage-associated molecular patterns disrupt the integrity of the endothelial barrier

Human cardiac microvascular endothelial cells (HCMECs) are sensitive to ischemia and vulnerable to damage during reperfusion. The release of damage-associated molecular patterns (DAMPs) during reperfusion induces additional tissue damage. The current study aimed to identify early protein DAMPs in human cardiac microvascular endothelial cells subjected to ischemia-reperfusion injury (IRI) using a proteomic approach and their effect on endothelial cell injury. HCMECs were subjected to 60 min of simulated ischemia and 6 h of reperfusion, which can cause lethal damage. DAMPs in the culture media were subjected to liquid chromatography-tandem mass spectrometry proteomic analysis. The cells were treated with endothelial IRI-derived DAMP medium for 24 h. Endothelial injury was assessed by measuring lactate dehydrogenase activity, morphological features, and the expression of endothelial cadherin, nitric oxide synthase (eNOS), and caveolin-1. The top two upregulated proteins, DNAJ homolog subfamily B member 11 and pyrroline-5-carboxylate reductase 2, are promising and sensitive predictors of cardiac microvascular endothelial damage. HCMECs expose to endothelial IRI-derived DAMP, the lactate dehydrogenase activity was significantly increased compared with the control group (10.15 ± 1.03 vs 17.67 ± 1.19, respectively). Following treatment with endothelial IRI-derived DAMPs, actin-filament dysregulation, and downregulation of vascular endothelial cadherin, caveolin-1, and eNOS expressions were observed, along with cell death. In conclusion, the early protein DAMPs released during cardiac microvascular endothelial IRI could serve as novel candidate biomarkers for acute myocardial IRI. Distinct features of impaired plasma membrane integrity can help identify therapeutic targets to mitigate the detrimental consequences mediated of endothelial IRI-derived DAMPs.

Roles and Mechanisms of Dopamine Receptor Signaling in Catecholamine Excess Induced Endothelial Dysfunctions.

Endothelial dysfunction may contribute to pathogenesis of Takotsubo cardiomyopathy, but mechanism underlying endothelial dysfunction in the setting of catecholamine excess has not been clarified. The study reports that D1/D5 dopamine receptor signaling and small conductance calcium-activated potassium channels contribute to high concentration catecholamine induced endothelial cell dysfunction. For mimicking catecholamine excess, 100 μM epinephrine (Epi) was used to treat human cardiac microvascular endothelial cells. Patch clamp, FACS, ELISA, PCR, western blot and immunostaining analyses were performed in the study. Epi enhanced small conductance calcium-activated potassium channel current (ISK1-3) without influencing the channel expression and the effect was attenuated by D1/D5 receptor blocker. D1/D5 agonists mimicked the Epi effect, suggesting involvement of D1/D5 receptors in Epi effects. The enhancement of ISK1-3 caused by D1/D5 activation involved roles of PKA, ROS and NADPH oxidases. Activation of D1/D5 and SK1-3 channels caused a hyperpolarization, reduced NO production and increased ROS production. The NO reduction was membrane potential independent, while ROS production was increased by the hyperpolarization. ROS (H2O2) suppressed NO production. The study demonstrates that high concentration catecholamine can activate D1/D5 and SK1-3 channels through NADPH-ROS and PKA signaling and reduce NO production, which may facilitate vasoconstriction in the setting of catecholamine excess.

Scalable and stable human pluripotent stem cell-derived microvascular-like endothelial cells for cardiac regeneration and disease modelling applications

Abstract Introduction The microvasculature is a vital constituent of the adult human vasculature 1. Cardiac tissue engineering, in vitro models of cardiac remodelling and regeneration, and disease models of the microvasculature would benefit from the inclusion of well-characterised, phenotypically stable microvascular-like endothelial cells (ECs) that could be generated at scale without xenogeneic reagents. Primary microvascular ECs have been utilised for such applications however, they are susceptible to passaging-induced senescence². Moreover, alternative solutions including current protocols for the derivation of human pluripotent stem cell-derived ECs (hPSC-ECs) generate cells with a heterogenous vascular identity that often transdifferentiate into non-EC lineages³. Purpose The purpose of this study was to create a 3D, xenogeneic-free differentiation protocol that yielded stable hPSC-derived microvascular-like ECs (hPSC-MVECs) at scale. Methods Endothelial differentiation of hPSCs was conducted in 2D adherent monolayers and within stirred 3D bioreactors for 12 days. Thereafter, CD31pos ECs were isolated via fluorescence-activated cell sorting (FACS) and cultured for a further 14 days. Gene expression analysis of hPSCs undergoing 2D and 3D differentiation was evaluated via RT-qPCR. The day 26 hPSC-ECs were treated with VEGFA (0 – 50 ng/ml) for a further 7 days and evaluated for CD31 expression via high-content image analysis. The angiogenic profiles of 2D-, 3D-, and 3D-hPSC-ECs cultured in high concentration VEGFA (herein, 3D+V), relative to primary Human Cardiac Microvascular Endothelial Cells (HMVEC-Cs) was assessed using the Proteome Profiler Human Angiogenesis Array. Transcriptomic analysis of these EC populations was subsequently conducted via single-cell RNA sequencing (scRNA-seq). Results Complex vascular clusters emerged by day 12 of the 3D differentiation protocol (fig. 1). The emergent 3D hPSC-ECs had a comparable expression of PECAM1 and CDH5 relative to 2D-derived hPSC-ECs however, VEGFA expression was significantly reduced (P<0.01, fig. 2A). VEGFA treatment at 50 ng/ml yielded phenotypically stable hPSC-ECs (3D+V, fig. 2B). Principal component analysis of the angiogenic factors assayed for revealed 3D+V hPSC-ECs clustered with HMVEC-Cs (fig. 2C). scRNA-seq identified a subset of 3D-derived hPSC-ECs expressing genes associated with microvascular vessels (GMFG, PLVAP), capillary ECs (RGCC, GLUL), and angiogenic tip cells (ESM1, HSPG2). Conclusion The scalable and xenogeneic-free 3D protocol outlined within allows for the attainment of hPSC-derived microvascular-like ECs with high angiogenic potential. The absence of Matrigel enhances the translational capacity of the hPSC-MVECs arising from this protocol that could now be derived from patient-specific hPSC lines for evaluation in pre-clinical models of post-myocardial infarction cardiac regeneration or for in vivo models of cardiac remodelling and microvasculature disease.

Identifying pro-angiogenic lncRNAs to regenerate the damaged myocardium following myocardial infarction

Abstract Cardiovascular diseases are the most common cause of death worldwide and Myocardial Infarction (MI) is the primary symptom of cardiovascular disease. In MI, Damage-Associated Molecular Patterns (DAMPs) released by dying cells play an important role in driving the inflammatory response following myocardial damage with potentially adverse or pro-regenerative outcomes. Since angiogenesis is a key process to ameliorate the sequelae of MI and the effect of DAMPs on cardiac cells are still widely unknown, hereby we present a novel model to study how DAMPs affect the gene expression of human Cardiac Microvascular Endothelial Cells (CMECs), one of the most abundant cell types in the heart, aiming to identify lncRNA targets to induce regenerative angiogenesis in patients with MI. To generate a cocktail of DAMPs, cells were isolated from the heart tissue of patients undergoing septal myectomy via collagenase treatment and exposed to repeated cycles of freeze-thawing to induce cell rupture. The release of endogenous molecules (DAMPs), such as DNA, was confirmed by nano drop. CMECs were then stimulated with DAMPs for 24h and RNA sequencing was performed. Finally, to predict potential co-regulation between lncRNAs and angiogenic proteins, a combination of PLAIDOH and NoRCE were used. The RNA sequencing revealed a total of 1294 Differently Expressed Genes (DEGs) in CMECs stimulated with DAMPs, of which 218 were lncRNAs annotated in GENCODE v42. Among the top 50 DEGs were found proteins involved in cell growth, proliferation, and immune response such as FGF5, CEP128, and IL32 and the GSE analysis revealed that proliferation (mitosis), migration, and angiogenesis were among the most enriched terms. The analysis with PLAIDOH and NoRCe revealed ∼25 differentially expressed lncRNAs which correlate with proteins involved in cell cycle and mitotic entry (Pearson 0.6-0.99 and p-value < 0.05). Among these were found HIF1A-AS3, TGFB-OT1, TGFB-AS1. Following the in-silico analysis, results were confirmed by qPCR. qPCR for HIFA1A-AS3 showed a significant reduction of 40% when CMECs were stimulated with DAMPs (p-value: 0.04) confirming the sequencing results. Whether HIFA1A-AS3 is involved in cell proliferation will now be validated with KO experiments. In conclusion, the administration of DAMPs to CMECs for 24h induced genes involved in proliferation, migration, and angiogenesis, processes that are also highly regulated in MI. By combining PLAIDOH and NoRCE we were able to identify lncRNAs which correlate in expression with protein-coding genes involved in these processes indicating co-regulation. These experiments recapitulate the main endothelial cell processes found in MI via administration of DAMPs and enable us to identify lncRNA targets to promote regenerative angiogenesis. Hence, this brings us one step closer to identifying gene therapy targets capable of inducing regenerative angiogenesis in patients with MI.

Endothelial cell-expressed long non-coding RNAs in cardiac regeneration

Abstract Endothelial cells (ECs) are the most abundant non-myocyte cell types in the heart. Upon cardiac injury, revascularization can occur through proliferation and migration of ECs from existing blood vessels in the surrounding myocardium. In animal models, revascularization is crucial to stimulate cardiomyocyte survival and regeneration. In the human heart, establishing blood flow could improve outcomes of tissue engineering or cell based therapy to regenerate the heart after injury. In addition to establishing blood flow, EC also secrete factors in a paracrine manner which can act on neighbouring cardiomyocytes. We investigate a role for non-coding RNA in the regulation of endothelial cell function and their potential role in neovascularization and cardiac regeneration. A large portion of the genome is transcribed into non-coding RNA, which does not encode protein. Many long non-coding RNAs (lncRNAs) have been shown to be involved in important regulatory processes such as genomic imprinting and chromatin modification. To identify lncRNAs which could be involved in cardiac regeneration, we isolated ECs from neonatal mice at postnatal day 1 and 5.5. The potential for cardiac regeneration was observed in mice at postnatal day 1, but this capacity is lost by day 5.5. Differential expression of lncRNAs in ECs was assessed by RNA sequencing. Three potential target lncRNAs, which also have a human homologue, were selected. NR2F2-AS1 and HAND2-AS1 were upregulated at postnatal day 1, whereas FOXD2-AS1 was upregulated at day 5.5. These genes were selected for further validation in human cardiac microvascular endothelial cells (CMEC). Knockdown of NR2F2-AS1 resulted in a decrease in proliferation but did not affect angiogenic sprouting. Loss of HAND2-AS1 resulted in a trend to impaired sprouting but did not affect proliferation. FOXD2-AS1 knockdown resulted in a significant decrease in angiogenic sprouting. We observed no change in the rate of migration after knockdown of any of the three genes. Knockdown of the lncRNAs did not affect expression of the antisense protein coding transcripts, therefore the effects we observe are likely mediated by the lncRNAs. In conclusion, lncRNAs NR2F2-AS1, HAND2-AS1 and FOXD2-AS1 regulate different aspects of EC function such as proliferation and sprouting. Modulation of expression of these transcripts therefore may be considered as a therapeutic tool to promote cardiac regeneration.

RETRACTED ARTICLE: circABCA3 knockdown relieves hypoxia-induced human cardiac microvascular endothelial cell dysfunction by targeting the miR-671-5p/PCSK9 axis.

Endothelial cell dysfunction is one of the important stages in the development of acute myocardial infarction (AMI). However, whether circABCA3 (hsa_circ_0037516) mediates AMI development by regulating endothelial cell dysfunction remains unclear. The GEO database (GSE169594 and GSE160717) was used to screen the differentially expressed circRNAs. Hypoxia-induced human cardiac microvascular endothelial cells (HCMECs) were used to mimic AMI cell model. The expression of circABCA3, microRNA (miR)-671-5p, and proprotein convertase subtilisin/kexin type 9 (PCSK9) was detected by quantitative real-time PCR. Cell proliferation, migration, angiogenesis, and apoptosis were measured using cell counting kit 8 assay, EdU assay, transwell assay, wound healing assay, tube formation assay, and flow cytometry. RNA interaction was verified using dual-luciferase reporter assay and RIP assay. The protein expression of PCSK9 and apoptosis-related markers was analyzed by western blot. According to the screening of GEO database, circABCA3 was a highly expressed circRNA in blood samples of AMI patients. circABCA3 was overexpressed in AMI patients and hypoxia-induced HCMECs. Silencing of circABCA3 enhanced proliferation, migration, and angiogenesis and inhibited apoptosis in hypoxia-induced HCMECs. circABCA3 sponged miR-671-5p to positively regulate PCSK9 expression. miR-671-5p inhibitor or PCSK9 overexpression overturned the regulation of circABCA3 knockdown on hypoxia-induced HCMEC dysfunction. circABCA3 might be a potential target for alleviating AMI process, in which knockdown relieved hypoxia-induced HCMEC dysfunction by regulating the miR-671-5p/PCSK9 axis.

Abstract P3014: Human Pluripotent Stem Cell-derived Organoids Yield Microvascular-like Endothelial Cells

Introduction: Coronary microvascular disease (CMD) can manifest as microvascular angina or HFpEF and is implicated in post-STEMI remodelling and COVID-19. Superior in vitro models would aid the development of therapies for CMD. This study outlines the creation of a 3D differentiation protocol that yields stable human pluripotent stem cell-derived microvascular-like endothelial cells (hPSC-MVECs). Hypothesis: We hypothesised that the 3D organoid environment would allow for recapitulation of the microvasculature. Methods: Growth factor-mediated endothelial differentiation of hPSCs was conducted for 12 days in stirred tank bioreactors devoid of exogenous matrix substrates such as Matrigel. CD31 pos 3D-derived hPSC-ECs were isolated via fluorescence-activated cell sorting and evaluated via RT-qPCR for their gene expression of endothelial markers relative to 2D-derived hPSC-ECs. 3D hPSC-ECs were subsequently treated with high concentration VEGFA for 7 days (3D+V) and assessed for CD31 expression via high content image analysis. A proteome profiler human angiogenesis array was employed to investigate the angiogenic landscape of the generated hPSC-ECs relative to primary Human Cardiac Microvascular Endothelial Cells (HMVEC-Cs). Transcriptomic analysis of the ECs was conducted via Single-Cell RNA sequencing (scRNA-seq). Results: Organoids attained on day 12 of the 3D differentiation protocol displayed a complex vascular network. Isolated 3D hPSC-ECs displayed comparable levels of PECAM1 and CDH5 relative to 2D hPSC-ECs however, the expression of VEGFA was significantly reduced (P<0.01). The resultant high-concentration treatment with exogenous VEGFA gave rise to phenotypically stable hPSC-ECs that had an angiogenic profile comparable to HMVEC-Cs. scRNA-seq for 3D+V hPSC-ECs revealed expression of several reported microvascular markers including GJA4 (arteriole), S100A4 (post-arteriole capillary), TCF15 (capillary), SOX17 (pre-venular capillary), CD34 (venule), and the coronary vessel marker FABP4 . Conclusions: These data suggest that 3D organoid differentiation facilitates the generation of cardiac microvascular-like ECs herein termed hPSC-MVECs.

Abstract P2127: A Novel Arnt Dependent Hif2a Singling In Protecting Against Cardiac Microvascular Endothelial Barrier Dysfunction Following Myocardial Infarction

Rationale: Cardiac microvascular leakage and inflammation are triggered during myocardial infarction (MI) and contribute to heart failure. Hypoxia-inducible factor 2α ( Hif2α ) is highly expressed in endothelial cells (ECs) and rapidly activated by myocardial ischemia, but its impact in microvascular endothelial barrier function during MI is unclear. Objective: To test our hypothesis that the expression of Hif2α in ECs regulates cardiac microvascular permeability in infarcted hearts, which is through its binding partner aryl hydrocarbon nuclear translocator. (ARNT). Methods and Results: Experiments were conducted with mice carrying an inducible EC-specific Hif2α -knockout ( ecHif2α -/- ) mutation, with mouse cardiac microvascular endothelial cells (CMVECs) isolated from the hearts of ecHif2α -/- mice after the mutation was induced, and with human CMVECs and umbilical-vein endothelial cells transfected with ecHif2α siRNA. After MI induction, echocardiographic assessments of cardiac function were significantly lower, while measures of cardiac microvascular leakage (Evans blue assay), plasma IL6 levels, and cardiac neutrophil accumulation and fibrosis (histology) were significantly greater, in ecHif2α -/- mice than in control mice, and RNA-sequencing analysis of heart tissues from both groups indicated that the expression of genes involved in vascular permeability and collagen synthesis was enriched in ecHif2α -/- hearts. In cultured ECs, ec Hif2α deficiency was associated with declines in endothelial barrier function (electrical cell impedance assay) and the reduced abundance of tight-junction proteins, as well as an increase in the expression of inflammatory markers, all of which were largely reversed by the overexpression of ARNT. We also found that ARNT, but not Hif2α, binds directly to the IL6 promoter and suppresses IL6 expression. Conclusions: Endothelial HIF-2a protects from hypoxia-induced cardiac microvascular barrier dysfunction, promotes inflammation damage and represents a potential therapeutic target for cardioprotection, and prevention of fibrosis following acute ischemic injury.

MiR-125b-5p alleviates the damage of myocardial infarction by inhibiting the NFAT2 to reduce F2RL2 expression.

Aim: To explore the effect of miR-125b-5p/nuclear factor of activated T cells 1 (NFAT2)/F2RL2 on myocardial infarction (MI). Method: After establishment of MI mouse model and oxygen glucose deprivation (OGD)-induced cell model, the effects of NFAT2 on the process of MI were observed, the effects of miR-125b-5p/NFAT2/F2RL2 on the cell viability, apoptosis, and inflammatory factors levels were determined. Result: NFAT2 silencing relieved MI and inhibited the inflammation in MI model mice. In OGD-induced human coronary artery endothelial cellsand human cardiac microvascular endothelial cells, miR-125b-5p enhanced cell viability, yet repressed cell apoptosis and inflammatory factors and NFAT2 levels. NFAT2 overexpression reversed the effects of miR-125b-5p, while F2RL2 silencing offset the effects of NFAT2 overexpression. Conclusion: MiR-125b-5p alleviates MI injury by inhibiting NFAT2 level to reduce F2RL2 expression.

LncRNA DANCR deficiency promotes high glucose-induced endothelial to mesenchymal transition in cardiac microvascular cells via the FoxO1/DDAH1/ADMA signaling pathway

Cardiac fibrosis is the main pathological basis of diabetic cardiomyopathy (DCM), and endothelial-to-meschenymal transition (EndMT) is a key driver to cardiac fibrosis and plays an important role in the pathogenesis of DCM. Asymmetric dimethylarginine (ADMA), a crucial pathologic factor in diabetes mellitus, is involved in organ fibrosis. This study aims to evaluate underlying mechanisms of ADMA in DCM especially for EndMT under diabetic conditions. A diabetic rat model was induced by streptozotocin (STZ) injection, and human cardiac microvascular endothelial cells (HCMECs) were stimulated with high glucose to induce EndMT. Subsequently, the role of ADMA in EndMT was detected either by exogenous ADMA or by over-expressing dimethylarginine dimethylaminohydrolase 1 (DDAH1, degradation enzyme for ADMA) before high glucose stimulation. Furthermore, the relationships among forkhead box protein O1 (FoxO1), DDAH1 and ADMA were evaluated by FoxO1 over-expression or FoxO1 siRNA. Finally, we examined the roles of LncRNA DANCR in FoxO1/DDAH1/ADMA pathway and EndMT of HCMECs. Here, we found that EndMT in HCMECs was induced by high glucose, as evidenced by down-regulated expression of CD31 and up-regulated expression of FSP-1 and collagen Ⅰ. Importantly, ADMA induced EndMT in HCMECs, and over-expressing DDAH1 protected from developing EndMT by high glucose. Furthermore, we demonstrated that over-expression of FoxO1-ADA with mutant phosphorylation sites of T24A, S256D, and S316A induced EndMT of HCMECs by down-regulating of DDAH1 and elevating ADMA, and that EndMT of HCMECs induced by high glucose was reversed by FoxO1 siRNA. We also found that LncRNA DANCR siRNA induced EndMT of HCMECs, activated FoxO1, and inhibited DDAH1 expression. Moreover, over-expression of LncRNA DANCR could markedly attenuated high glucose-mediated EndMT of HCMECs by inhibiting the activation of FoxO1 and increasing the expression of DDAH1. Collectively, our results indicate that LncRNA DANCR deficiency promotes high glucose-induced EndMT in HCMECs by regulating FoxO1/DDAH1/ADMA pathway.