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Alveolar Capillary Dysplasia with Misalignment of Pulmonary Veins (ACDMPV) is linked to heterozygous mutations in the FOXF1 gene, a key transcriptional regulator of pulmonary vascular development. There are no effective treatments for ACDMPV other than lung transplant, and new pharmacological agents activating FOXF1 signaling are urgently needed.Identify small molecule compounds that stimulate FOXF1 signaling.We used mass spectrometry, immunoprecipitation, and the in vitro ubiquitination assay to identify TanFe, a small molecule compound from the nitrile group, which stabilizes the FOXF1 protein in the cell. The efficacy of TanFe was tested in mouse models of ACDMPV and Acute Lung Injury and in human vascular organoids derived from iPSCs of ACDMPV patient.We identified HECTD1 as an E3 ubiquitin ligase involved in ubiquitination and degradation of the FOXF1 protein. The TanFe compound disrupted FOXF1-HECTD1 protein-protein interactions and decreased ubiquitination of the FOXF1 protein in pulmonary endothelial cells in vitro. TanFe increased protein levels of FOXF1 and its target genes Flk1, Flt1 and Cdh5 in LPS-injured mouse lungs, decreasing endothelial permeability and inhibiting lung inflammation. Treatment of pregnant mice with TanFe increased FOXF1 protein levels in lungs of Foxf1+/- embryos, stimulated neonatal lung angiogenesis, and completely prevented the mortality of Foxf1+/- mice after birth. TanFe increased angiogenesis in human vascular organoids derived from iPSCs of ACDMPV patient with FOXF1 deletion.TanFe is a novel activator of FOXF1, providing a new therapeutic candidate for treatment of ACDMPV and other neonatal pulmonary vascular diseases.

Objective: Mutations in BMPR2 (bone morphogenetic protein receptor 2) are associated with familial and sporadic pulmonary arterial hypertension (PAH). The functional and molecular link between loss of BMPR2 in pulmonary artery smooth muscle cells (PASMC) and PAH pathogenesis warrants further investigation, as most investigations focus on BMPR2 in pulmonary artery endothelial cells. Our goal was to determine whether and how decreased BMPR2 is related to the abnormal phenotype of PASMC in PAH. Methods: SMC-specific Bmpr2 −/− mice ( BKO SMC ) were created and compared to controls in room air, after 3 weeks of hypoxia as a second hit, and following 4 weeks of normoxic recovery. Echocardiography, right ventricular systolic pressure, and right ventricular hypertrophy were assessed as indices of pulmonary hypertension. Proliferation, contractility, gene and protein expression of PASMC from BKO SMC mice, human PASMC with BMPR2 reduced by small interference RNA, and PASMC from PAH patients with a BMPR2 mutation were compared to controls, to investigate the phenotype and underlying mechanism. Results: BKO SMC mice showed reduced hypoxia-induced vasoconstriction and persistent pulmonary hypertension following recovery from hypoxia, associated with sustained muscularization of distal pulmonary arteries. PASMC from mutant compared to control mice displayed reduced contractility at baseline and in response to angiotensin II, increased proliferation and apoptosis resistance. Human PASMC with reduced BMPR2 by small interference RNA, and PASMC from PAH patients with a BMPR2 mutation showed a similar phenotype related to upregulation of pERK1/2 (phosphorylated extracellular signal related kinase 1/2)-pP38-pSMAD2/3 mediating elevation in ARRB2 (β-arrestin2), pAKT (phosphorylated protein kinase B) inactivation of GSK3-beta, CTNNB1 (β-catenin) nuclear translocation and reduction in RHOA (Ras homolog family member A) and RAC1 (Ras-related C3 botulinum toxin substrate 1). Decreasing ARRB2 in PASMC with reduced BMPR2 restored normal signaling, reversed impaired contractility and attenuated heightened proliferation and in mice with inducible loss of BMPR2 in SMC, decreasing ARRB2 prevented persistent pulmonary hypertension. Conclusions: Agents that neutralize the elevated ARRB2 resulting from loss of BMPR2 in PASMC could prevent or reverse the aberrant hypocontractile and hyperproliferative phenotype of these cells in PAH.

Rationale: The role of neutrophils and their extracellular vesicles (EVs) in the pathogenesis of pulmonary arterial hypertension is unclear. Objectives: Relate functional abnormalities in pulmonary arterial hypertension neutrophils and their EVs to mechanisms uncovered by proteomic and transcriptomic profiling. Methods: Production of elastase, release of extracellular traps, adhesion and migration were assessed in neutrophils from pulmonary arterial hypertension patients and control subjects. Proteomic analyses were applied to explain functional perturbations, and transcriptomic data were used to find underlying mechanisms. CD66b-specific neutrophil EVs were isolated from plasma of patients with pulmonary arterial hypertension and we determined whether they produce pulmonary hypertension in mice. Measurements and Main Results: Neutrophils from pulmonary arterial hypertension patients produce and release increased neutrophil elastase, associated with enhanced extracellular traps. They exhibit reduced migration and increased adhesion attributed to elevated β1integrin and vinculin identified on proteomic analysis and previously linked to an antiviral response. This was substantiated by a transcriptomic interferon signature that we related to an increase in human endogenous retrovirus k envelope protein. Transfection of human endogenous retrovirus k envelope in a neutrophil cell line (HL-60) increases neutrophil elastase and interferon genes, whereas vinculin is increased by human endogenous retrovirus k dUTPase that is elevated in patient plasma. Neutrophil EVs from patient plasma contain increased neutrophil elastase and human endogenous retrovirus k envelope and induce pulmonary hypertension in mice, mitigated by elafin, an elastase inhibitor. Conclusions: Elevated human endogenous retroviral elements and elastase link a neutrophil innate immune response to pulmonary arterial hypertension.

Hypoplastic left heart syndrome (HLHS) is a severe form of single ventricle congenital heart disease characterized by an underdevelopment of the left ventricle. Early serial postmortem examinations revealed high rate of coronary artery abnormalities in HLHS fetal hearts, which may impact ventricular development and intra-cardiac hemodynamics, leading to a poor prognosis after surgical palliations. Previous study reported that endothelial cells (ECs) lining the coronary vessels showed DNA damage in the left ventricle of human fetal heart with HLHS, indicating that EC dysfunction may contribute to the coronary abnormalities in HLHS. To investigate the underlying mechanism of HLHS coronary artery abnormalities, we profiled both human fetal heart with an underdeveloped left ventricle (ULV) and ECs differentiated from induced pluripotent stem cells (iPSCs) derived from HLHS patients at single cell resolution. CD144+/NPR3- vascular ECs were selected and further classified as venous EC (NR2F2high), arterial EC (EFNB2high) and late arterial EC (GJA5high) subclusters based on previously reported marker genes. To study the arterial phenotype, we specifically generated iPSC-arterial ECs (AECs, CD34+CDH5+CXCR4+NT5E-/low) derived from three HLHS patients and three age-matched healthy controls to further dissect the phenotype of HLHS-AECs. As compared to normal human heart and control iPSC-ECs respectively, ULV late arterial EC subcluster and HLHS iPSC-EC arterial clusters showed significantly reduced expression of arterial genes GJA5, DLL4, and HEY1. Pathway enrichment analysis based on differentially expressed genes revealed several defects in late AEC cluster from ULV compared to normal human heart, such as impaired endothelial proliferation, development and Notch signaling. HLHS iPSCs exhibited impaired AEC differentiation as evidenced by the significantly reduced CXCR4+NT5E-/low AEC progenitor population. Consistent with human heart transcriptomic data, matured HLHS iPSC-AECs also showed a lower expression of the arterial genes such as GJA5, DLL4, HEY1 which are also downstream of NOTCH signaling. Additionally, matured HLHS iPSC-AECs showed significantly decreased expression of cell proliferation marker Ki67 and G1/S transition genes (CCND1, CCND2) compared with controls. Interestingly, NOTCH ligand Jag1 treatment significantly rescued this cell proliferation defect in HLHS AECs, accompanied by upregulation of various G1/S transition genes. In summary, we found that coronary AECs from HLHS showed impaired arterial development and proliferation downstream of NOTCH signaling. These functional defects in HLHS coronary AECs could contribute to the vascular structure malformation and impaired ventricular development.

The heterogeneity of endothelium across different organs was recently explored using single-cell RNA-sequencing analysis. Compared to other organs, the lung exhibits a distinct structure composed of a thin layer of capillary for efficient gas exchange. In this study, we demonstrate that Tmem100 is a lung-specific endothelium gene.

BackgroundValve remodeling is a complex process involving extracellular matrix organization, development of trilaminar structures, and physical elongation of valve leaflets. However, the cellular and molecular mechanisms regulating valve remodeling and their roles in congenital valve disorders remain poorly understood.MethodsSemilunar valves and atrioventricular valves from healthy and age-matched human fetal hearts with pulmonary stenosis (PS) were collected. Single-Cell RNA-sequencing (scRNA-seq) was performed to determine the transcriptomic landscape of multiple valvular cell subtypes in valve remodeling and disease. Spatial localization of newly-identified cell subtypes was determined via immunofluorescence and RNAin situhybridization. The molecular mechanisms mediating valve development was investigated utilizing primary human fetal heart valve interstitial cells (VICs) and endothelial cells (VECs).ResultsscRNA-seq analysis of healthy human fetal valves identified a novel APOE+elastin-producing VIC subtype (Elastin-VICs) spatially located underneath VECs sensing the unidirectional flow. Knockdown ofAPOEin fetal VICs resulted in significant elastogenesis defects. In pulmonary valve with PS, we observed decreased expression ofAPOEand other genes regulating elastogenesis such asEMILIN1andLOXL1, as well as elastin fragmentation. These findings suggested the crucial role of APOE in regulating elastogenesis during valve remodeling. Furthermore, cell-cell interaction analysis revealed that JAG1 from unidirectional VECs activates NOTCH signaling in Elastin-VICs through NOTCH3.In vitroJag1 treatment in VICs increased elastogenesis, while similar observations were found in VICs co-cultured with VECs in the presence of unidirectional flow. Notably, we found that the JAG1-NOTCH3 signaling pair was drastically reduced in the PS valves. Lastly, we demonstrated that APOE is indispensable for JAG1-induced NOTCH activation in VICs, reinforcing the presence of a synergistic intrinsic and external regulatory network involving APOE and NOTCH signaling that is responsible for regulating elastogenesis during human valve remodeling.ConclusionscRNA-seq analysis of human fetal valves identified a novel Elastin-VIC subpopulation, and revealed mechanism of intrinsic APOE and external NOTCH signaling in regulating elastogenesis during cardiac valve remodeling. These mechanisms may contribute to deciphering the pathogenesis of elastin malformation in congenital valve diseases.Clinical PerspectiveWhat Is New?High-resolution single-cell transcriptome atlas generated from healthy human fetal heart valves and valves affected by pulmonary stenosis during the early phase of valve remodeling prior to birth.A unique subset of valve interstitial cells (VICs) that produce elastin (Elastin-VICs) was identified.Elastin-VICs specifically located underneath the valve endothelial cells (VECs) sensing unidirectional flow, and played a crucial role in elastin maturation via the expression of APOE.Elastin-VICs communicated with adjacent VECs via the JAG1-NOTCH signaling, facilitating elastin formation and valve remodeling.What Are the Clinical Implications?Elastin-VICs from patient valvular tissues with Pulmonary Stenosis exhibit decreased APOE-NOTCH signaling and elastin fragmentation.Direct targeting of APOE and NOTCH signaling could be a novel approach to promote elastin fiber formation and valve remodeling in patients with valvular defects.

Given a general lack of emphasis on the molecular underpinnings of single ventricle (SV) congenital heart diseases (CHD), our review highlights and summarizes recent advances in uncovering the genetic and molecular mechanisms in SV CHD etiology.While common SV-associated genetic mutations were found in key cardiac transcription factors, other mutations were sporadic. With advances in genetic sequencing technologies and animal models, more disease-associated factors have been identified to act in critical cardiac signaling pathways such as NOTCH, Wnt, and TGF signaling. Recent studies have also revealed that different cardiac lineages play different roles in disease pathogenesis. SV defects are attributed to complex combinations of genetic mutations, indicating that sophisticated spatiotemporal regulation of gene transcription networks and functional cellular pathways govern disease progression. Future studies will warrant in-depth investigations into better understanding how different genetic factors converge to influence common downstream cellular pathways, resulting in SV abnormalities.

Cardiovascular diseases (CVDs) are a group of disorders of the blood vessels and heart, which are considered as the leading causes of death worldwide. The pathology of CVDs could be related to the functional abnormalities of multiple cell types in the heart. Single-cell RNA sequencing (scRNA-seq) technology is a powerful method for characterizing individual cells and elucidating the molecular mechanisms by providing a high resolution of transcriptomic changes at the single-cell level. Specifically, scRNA-seq has provided novel insights into CVDs by identifying rare cardiac cell types, inferring the trajectory tree, estimating RNA velocity, elucidating the cell–cell communication, and comparing healthy and pathological heart samples. In this review, we summarize the different scRNA-seq platforms and published single-cell datasets in the cardiovascular field, and describe the utilities and limitations of this technology. Lastly, we discuss the future perspective of the application of scRNA-seq technology into cardiovascular research.

Opioids are commonly used for treating chronic pain. However, with continued use, they may induce tolerance and/or hyperalgesia, which limits therapeutic efficacy. The human mechanisms of opioid-induced hyperalgesia are significantly understudied, in part, because current models cannot fully recapitulate human pathology. Here, we engineered novel human spinal microphysiological systems (MPSs) integrated with plug-and-play neural activity sensing for modeling human nociception and opioid-induced tolerance. Each spinal MPS consists of a flattened human spinal cord organoid derived from human stem cells and a 3D printed organoid holder device for plug-and-play neural activity measurement. We found that the flattened organoid design of MPSs not only reduces hypoxia and necrosis in the organoids, but also promotes their neuron maturation, neural activity, and functional development. We further demonstrated that prolonged opioid exposure resulted in neurochemical correlates of opioid tolerance and hyperalgesia, as measured by altered neural activity, reduced densities of glutamate transporter levels and downregulation of μ-opioid receptor expression of human spinal MPSs. The MPSs are scalable, cost-effective, easy-to-use, and compatible with commonly-used well-plates, thus allowing plug-and-play measurements of neural activity. We believe the MPSs hold a promising translational potential for studying human pain etiology, screening new treatments, and validating novel therapeutics for human pain medicine.

Deficiency of iron-sulfur (Fe-S) clusters promotes metabolic rewiring of the endothelium and the development of pulmonary hypertension (PH) in vivo. Joining a growing number of Fe-S biogenesis proteins critical to pulmonary endothelial function, recent data highlighted that frataxin (FXN) reduction drives Fe-S-dependent genotoxic stress and senescence across multiple types of pulmonary vascular disease. Trinucleotide repeat mutations in the FXN gene cause Friedreich’s ataxia, a disease characterized by cardiomyopathy and neurodegeneration. These tissue-specific phenotypes have historically been attributed to mitochondrial reprogramming and oxidative stress. Whether FXN coordinates both nuclear and mitochondrial processes in the endothelium is unknown. Here, we aim to identify the mitochondria-specific effects of FXN deficiency in the endothelium that predispose to pulmonary hypertension. Our data highlight an Fe-S-driven metabolic shift separate from previously described replication stress whereby FXN knockdown diminished mitochondrial respiration and increased glycolysis and oxidative species production. In turn, FXN-deficient endothelial cells exhibited a vasoconstrictive phenotype consistent with PH. These data were observed in both primary pulmonary endothelial cells after pharmacologic inhibition of FXN and inducible pluripotent stem cell-derived endothelial cells from patients with FXN mutations. Altogether, this study defines FXN as a shared upstream driver of pathologic aberrations in both metabolism and genomic stability. Moreover, our study highlights FXN-specific vasoconstriction, suggesting available and future therapies may be beneficial and targeted for PH subtypes with FXN deficiency.Graphical Abstract

Maintenance of stem-cell identity requires proper regulation of enhancer activity. Both transcription factors OCT4/SOX2/NANOG and histone methyltransferase complexes MLL/SET1 were shown to regulate enhancer activity, but how they are regulated in embryonic stem cells (ESCs) remains further studies. Here, we report a transcription factor BACH1, which directly interacts with OCT4/SOX2/NANOG (OSN) and MLL/SET1 methyltransferase complexes and maintains pluripotency in mouse ESCs (mESCs). BTB domain and bZIP domain of BACH1 are required for these interactions and pluripotency maintenance. Loss of BACH1 reduced the interaction between NANOG and MLL1/SET1 complexes, and decreased their occupancy on chromatin, and further decreased H3 lysine 4 trimethylation (H3K4me3) level on gene promoters and (super-) enhancers, leading to decreased enhancer activity and transcription activity, especially on stemness-related genes. Moreover, BACH1 recruited NANOG through chromatin looping and regulated remote NANOG binding, fine-tuning enhancer–promoter activity and gene expression. Collectively, these observations suggest that BACH1 maintains pluripotency in ESCs by recruiting NANOG and MLL/SET1 complexes to chromatin and maintaining the trimethylated state of H3K4 and enhancer–promoter activity, especially on stemness-related genes.

Tumor microenvironment crosstalk, in particular interactions between cancer cells, T cells, and myeloid-derived suppressor cells (MDSCs), mediates tumor initiation, progression, and response to treatment. However, current patient-derived models such as tumor organoids and 2D cultures lack some essential niche cell types (e.g., MDSCs) and fail to model complex tumor-immune interactions. Here, the authors present the novel acoustically assembled patient-derived cell clusters (APCCs) that can preserve original tumor/immune cell compositions, model their interactions in 3D microenvironments, and test the treatment responses of primary tumors in a rapid, scalable, and user-friendly manner. By incorporating a large array of 3D acoustic trappings within the extracellular matrix, hundreds of APCCs can be assembled within a petri dish within 2 min. Moreover, the APCCs can preserve sensitive and short-lived (≈1 to 2-day lifespan in vivo) tumor-induced MDSCs and model their dynamic suppression of T cell tumor toxicity for up to 24 h. Finally, using the APCCs, the authors succesully model the combinational therapeutic effect of a multi-kinase inhibitor targeting MDSCs (cabozantinib) and an anti-PD-1 immune checkpoint inhibitor (pembrolizumab). The novel APCCs may hold promising potential in predicting treatment response for personalized cancer adjuvant therapy as well as screening novel cancer immunotherapy and combinational therapy.

Perinatal inflammatory stress is associated with early life morbidity and lifelong consequences for pulmonary health. Chorioamnionitis, an inflammatory condition affecting the placenta and fluid surrounding the developing fetus, affects 25 to 40% of preterm births. Severe chorioamnionitis with preterm birth is associated with significantly increased risk of pulmonary disease and secondary infections in childhood, suggesting that fetal inflammation may markedly alter the development of the lung. Here, we used intra-amniotic lipopolysaccharide (LPS) challenge to induce experimental chorioamnionitis in a prenatal rhesus macaque ( Macaca mulatta ) model that mirrors structural and temporal aspects of human lung development. Inflammatory injury directly disrupted the developing gas exchange surface of the primate lung, with extensive damage to alveolar structure, particularly the close association and coordinated differentiation of alveolar type 1 pneumocytes and specialized alveolar capillary endothelium. Single-cell RNA sequencing analysis defined a multicellular alveolar signaling niche driving alveologenesis that was extensively disrupted by perinatal inflammation, leading to a loss of gas exchange surface and alveolar simplification, with notable resemblance to chronic lung disease in newborns. Blockade of the inflammatory cytokines interleukin-1β and tumor necrosis factor–α ameliorated LPS-induced inflammatory lung injury by blunting stromal responses to inflammation and modulating innate immune activation in myeloid cells, restoring structural integrity and key signaling networks in the developing alveolus. These data provide new insight into the pathophysiology of developmental lung injury and suggest that modulating inflammation is a promising therapeutic approach to prevent fetal consequences of chorioamnionitis.

The aging of the immune system drives systemic aging and the pathogenesis of age-related diseases. However, a significant knowledge gap remains in understanding immune-driven aging, especially in brain aging, due to the limited current in vitro models of neuro-immune interaction. Here we report the development of a human brain organoid microphysiological analysis platform (MAP) to discover the dynamic process of immune-driven brain aging. We create the organoid MAP by 3D printing that can confine organoid growth and perfuse oxygen and nutrients (and immune cells) to generate standardized human cortical organoids that promote viability, maturation, and commitment to human forebrain identity. Dynamic rocking flow is incorporated for the platform that allows us to perfuse primary monocytes from young (20 to 30-year-old) and aged (>60-year-old) donors and culture human cortical organoids for modeling and analyzing the aged immune cell interacting organoid tissues systematically. We discovered the aged monocytes had increased infiltration and promoted the expression of aging-related markers (e.g., p16 in astrocytes neighboring to monocytes) within human cortical organoids, indicating that aged monocytes may drive brain aging. We believe that our human brain organoid MAP provides promising solutions for basic research and translational applications in aging, neuroimmunological diseases, autoimmune disorders, and cancers.

SummaryCongenital heart defects, the most common birth disorders, are the clinical manifestation of anomalies in fetal heart development - a complex process involving dynamic spatiotemporal coordination among various precursor cell lineages. This complexity underlies the incomplete understanding of the genetic architecture of congenital heart diseases (CHDs). To define the multi-cellular epigenomic and transcriptional landscape of cardiac cellular development, we generated single-cell chromatin accessibility maps of human fetal heart tissues. We identified eight major differentiation trajectories involving primary cardiac cell types, each associated with dynamic transcription factor (TF) activity signatures. We identified similarities and differences of regulatory landscapes of iPSC-derived cardiac cell types and their in vivo counterparts. We interpreted deep learning models that predict cell-type resolved, base-resolution chromatin accessibility profiles from DNA sequence to decipher underlying TF motif lexicons and infer the regulatory impact of non-coding variants. De novo mutations predicted to affect chromatin accessibility in arterial endothelium were enriched in CHD cases versus controls. We used CRISPR-based perturbations to validate an enhancer harboring a nominated regulatory CHD mutation, linking it to effects on the expression of a known CHD gene JARID2. Together, this work defines the cell-type resolved cis-regulatory sequence determinants of heart development and identifies disruption of cell type-specific regulatory elements as a component of the genetic etiology of CHD.

Introduction Hypoplastic left heart syndrome (HLHS) is a severe developmental defect characterized by the underdevelopment of the left ventricle along with aortic and valvular defects. Multiple palliative surgeries are required for survival. Emerging studies have identified potential mechanisms for the disease onset, including genetic and hemodynamic causes. Genetic variants associated with HLHS include transcription factors, chromatin remodelers, structural proteins, and signaling proteins necessary for normal heart development. Nonetheless, current therapies are being tested clinically and have shown promising results at improving cardiac function in patients who have undergone palliative surgeries. Areas covered We searched PubMed and clinicaltrials.gov to review most of the mechanistic research and clinical trials involving HLHS. This review discusses the anatomy and pathology of HLHS hearts. We highlight some of the identified genetic variants that underly the molecular pathogenesis of HLHS. Additionally, we discuss some of the emerging therapies and their limitations for HLHS. Expert opinion While HLHS etiology is largely obscure, palliative therapies remain the most viable option for the patients. It is necessary to generate animal and stem cell models to understand the underlying genetic causes directly leading to HLHS and facilitate the use of gene-based therapies to improve cardiac development and regeneration.

Malformations of or injuries to the developing lung are associated with perinatal morbidity and mortality with lifelong consequences for subsequent pulmonary health. One fetal exposure linked with poor health outcomes is chorioamnionitis, which impacts up to 25-40% of preterm births. Severe chorioamnionitis with prematurity is associated with significantly increased risk of pulmonary disease and secondary infections in childhood, suggesting that fetal inflammation may significantly alter developmental ontogeny of the lung. To test this hypothesis, we used intra-amniotic lipopolysaccharide (LPS, endotoxin) to generate experimental chorioamnionitis in prenatal Rhesus macaque (Macaca mulatta), a model which shares critical structural and temporal aspects of human lung development. Inflammatory injury directly disrupts the developing gas exchange surface of the primate lung, with extensive damage to alveolar structure, particularly the close association and coordinated differentiation of alveolar type 1 pneumocytes and specialized alveolar capillary endothelium. Single cell RNA sequencing analysis defined a multicellular alveolar signaling niche driving alveologenesis which was extensively disrupted by perinatal inflammation, leading to loss of gas exchange surface and alveolar simplification similar to that found in chronic lung disease of newborns. Blockade of IL1β and TNFα ameliorated endotoxin-induced inflammatory lung injury by blunting stromal response to inflammation and modulating innate immune activation in myeloid cells, restoring structural integrity and key signaling networks in the developing alveolus. These data provide new insight into the pathophysiology of developmental lung injury and suggest that modulating inflammation is a promising therapeutic approach to prevent fetal consequences of chorioamnionitis.

The aging of the immune system drives systemic aging and the pathogenesis of age-related diseases. However, a significant knowledge gap remains in understanding immune-driven aging, especially in brain aging, due to the limited current in vitro models of neuroimmune interaction. Here, the authors report the development of a human brain organoid microphysiological analysis platform (MAP) to discover the dynamic process of immune-driven brain aging. The organoid MAP is created by 3D printing that confines organoid growth and facilitates cell and nutrition perfusion, promoting organoid maturation and their committment to forebrain identity. Dynamic rocking flow is incorporated into the platform that allows to perfuse primary monocytes from young (20 to 30-year-old) and aged (60-year-old) donors and culture human cortical organoids to model neuroimmune interaction. The authors find that the aged monocytes increase infiltration and promote the expression of aging-related markers (e.g., higher expression of p16) within the human cortical organoids, indicating that aged monocytes may drive brain aging. The authors believe that the organoid MAP may provide promising solutions for basic research and translational applications in aging, neural immunological diseases, autoimmune disorders, and cancer.

Neutrophil elastase (NE) is implicated in pulmonary arterial hypertension (PAH) but the role of neutrophils in the pathogenesis of PAH is unclear. Here we show that neutrophils from PAH vs. control subjects produce and release increased NE associated with enhanced extracellular trap formation. PAH neutrophils are highly adherent and show decreased migration consistent with increased vinculin, identified on proteomic analysis and previously linked to an antiviral response. This was substantiated by a transcriptomic interferon signature in PAH neutrophils and an increase in human endogenous retrovirus (HERV-K) envelope protein. NE and interferon genes are induced by HERV-K envelope and vinculin is increased by HERV-K dUTPase that is elevated in PAH plasma. Neutrophil exosomes from PAH plasma contain increased NE and HERV-K envelope and induce pulmonary hypertension in mice, that is mitigated by the NE inhibitor and antiviral agent, elafin. Thus, elevated HERVs explain pathological neutrophils linked to PAH induction and progression.

Hypoplastic left heart syndrome (HLHS) is one of the most challenging forms of congenital heart diseases. Previous studies were mainly focused on intrinsic defects in myocardium. However, this does not sufficiently explain the abnormal development of the cardiac valve, septum, and vasculature, known to originate from the endocardium. Here, using single-cell transcriptomic profiling, induced pluripotent stem cells (iPSC) derived endocardial cells (iEECs), human fetal heart tissue with underdeveloped left ventricle, as well as a Xenopus model, we identified a developmentally impaired endocardial population in HLHS. The intrinsic endocardial deficits contributed to abnormal endothelial to mesenchymal transition, NOTCH signaling, and extracellular matrix organization, all of which are key factors in valve formation. Consequently, in an endocardium-myocardium co-culture system, we found that endocardial abnormalities conferred reduced proliferation and maturation of iPSC derived cardiomyocyte (iPSC-CMs) judged by Ki67 staining, contractility, sarcomere organization, and related gene expressions through a disrupted fibronectin (FN1)-integrin interaction. Several recently described HLHS de novo mutations such as ETS1 and CHD7 showed reduced binding to FN1 promoter and enhancer in HLHS vs. control iEECs based on ChIP-qPCR analysis. Additionally, we found that suppression of the ETS1 in Xenopus caused reduced endocardial FN1 expression and impaired heart development. Supplementation of FN1 or ETS1 over-expression in HLHS iEECs could rescue dysfunctions in both endocardium and myocardium in HLHS. Our studies reveal a critical role of endocardial abnormality in causing HLHS, and provide a rationale for improving endocardial function in future regenerative strategies. Schematic illustration of the endocardial and myocardial defects in HLHS.

In the mammalian lung, an apparently homogenous mesh of capillary vessels surrounds each alveolus, forming the vast respiratory surface across which oxygen transfers to the blood1. Here we use single-cell analysis to elucidate the cell types, development, renewal and evolution of the alveolar capillary endothelium. We show that alveolar capillaries are mosaics; similar to the epithelium that lines the alveolus, the alveolar endothelium is made up of two intermingled cell types, with complex 'Swiss-cheese'-like morphologies and distinct functions. The first cell type, which we term the 'aerocyte', is specialized for gas exchange and the trafficking of leukocytes, and is unique to the lung. The other cell type, termed gCap ('general' capillary), is specialized to regulate vasomotor tone, and functions as a stem/progenitor cell in capillary homeostasis and repair. The two cell types develop from bipotent progenitors, mature gradually and are affected differently in disease and during ageing. This cell-type specialization is conserved between mouse and human lungs but is not found in alligator or turtle lungs, suggesting it arose during the evolution of the mammalian lung. The discovery of cell type specialization in alveolar capillaries transforms our understanding of the structure, function, regulation and maintenance of the air-blood barrier and gas exchange in health, disease and evolution.

Hypoplastic left heart syndrome (HLHS) is a single ventricle congenital heart disease that results in severe underdevelopment of the left ventricle, mitral valve, aortic valve, and ascending aorta. Early serial postmortem examinations also revealed a high rate of coronary anomalies in HLHS, which included multiple ventriculo-coronary arterial connections as well as thick-walled and kinked coronary arteries. A previous study showed that fetal hypoplastic left hearts had a reduced endothelial cell (EC) population and lower capillary density compared with normal hearts. However, the mechanism underlying coronary abnormalities associated with HLHS remains unknown. Thus, we generated induced pluripotent stem cells derived ECs (iPSC-ECs) from three HLHS patients and three age-matched controls. Single Cell RNA-Seq (scRNA-seq) profiling identified both endocardial (NPR3 + /CDH5 + ) and coronary endothelial populations (APLN + /CDH5 + ) from the heterogeneous iPSC-ECs. Intriguingly, a subcluster of the coronary endothelial cells (CECs) with cell cycle arrest was specifically enriched in HLHS patients. Further cell cycle analysis showed that 30.6% of the HLHS cells were trapped in the G1 phase, while the majority of the control CECs entered cell cycle normally. Additionally, the cell cycle differences between control and HLHS was only seen in CECs, not in the endocardial population. To verify our transcriptomic analysis, we applied negative cell sorting (NPR3 - /CDH5 + ) on iPSC-ECs to purify CECs (iCECs) and confirmed that HLHS iCECs showed profound reduction of cell cycle/proliferative genes ( KI67, PCNA, CCNA2, CCNB1 ) and abnormal induction of CCND2 , which is the hallmark of G1 phase. BrdU assays also indicated suppressed proliferation in HLHS iCECs. Furthermore, we profiled the transcriptome from a human heart with an underdevelopment left ventricle (ULV) at single cell resolution. When compared to the normal human heart, pathway enrichment analysis of differentially expressed genes in ULV hearts demonstrated reduced cell proliferation in the CEC subpopulation. Here, we identified that CECs from HLHS patients exerted proliferative defects that can potentially impede the development of vascular/capillary structure and cause related functional deficiencies. Reformation of the coronary defect provides a promising therapeutic strategy to prevent HLHS deterioration.

It has been shown that endocardial endothelial cells (EECs) and coronary endothelial cells (CECs) differ in origin, development, markers, and functions. Consequently, these two cell populations play unique roles in cardiac diseases. Current studies involving isolated endothelial cells investigate cell populations consisting of both EECs and CECs. This protocol outlines a method to independently isolate these two cell populations for cell-specific characterization. Following the collection of the left and right ventricular free wall, endothelial cells from the outer surface and inner surface are separately liberated using a digestion buffer solution. The sequential digestion of the outer surface and the inner endocardial layer retained separation of the two endothelial cell populations. The separate isolation of EECs and CECs is further verified through the identification of markers specific to each population. Based on previously published single cell RNA profiling in the mouse heart, the Npr3, Hapln1, and Cdh11 gene expression is unique to EECs; while Fabp4, Mgll, and Cd36 gene expression is unique to CECs. qPCR data revealed enriched expression of these characteristic markers in their respective samples, indicating successful EEC and CEC isolation, as well as maintenance of cell phenotype, enabling further cell-specific functional analysis.

Endothelial dysfunction is critically involved in the pathogenesis of pulmonary arterial hypertension (PAH) and that exogenously administered microRNA may be of therapeutic benefit. Lower levels of miR‐483 were found in serum from patients with idiopathic pulmonary arterial hypertension (IPAH), particularly those with more severe disease. RNA‐seq and bioinformatics analyses showed that miR‐483 targets several PAH‐related genes, including transforming growth factor‐β (TGF‐β), TGF‐β receptor 2 (TGFBR2), β‐catenin, connective tissue growth factor (CTGF), interleukin‐1β (IL‐1β), and endothelin‐1 (ET‐1). Overexpression of miR‐483 in ECs inhibited inflammatory and fibrogenic responses, revealed by the decreased expression of TGF‐β, TGFBR2, β‐catenin, CTGF, IL‐1β, and ET‐1. In contrast, inhibition of miR‐483 increased these genes in ECs. Rats with EC‐specific miR‐483 overexpression exhibited ameliorated pulmonary hypertension (PH) and reduced right ventricular hypertrophy on challenge with monocrotaline (MCT) or Sugen + hypoxia. A reversal effect was observed in rats that received MCT with inhaled lentivirus overexpressing miR‐483. These results indicate that PAH is associated with a reduced level of miR‐483 and that miR‐483 might reduce experimental PH by inhibition of multiple adverse responses., This study reveals a protective role for miR‐483 in the development of pulmonary arterial hypertension (PAH). Overexpression of miR‐483 in endothelial cells (ECs) inhibits inflammatory and fibrogenic responses and leads to ameliorated pulmonary hypertension phenotypes in rats.

Environmental and epigenetic factors often play an important role in polygenic disorders. However, how such factors affect disease-specific tissues at the molecular level remains to be understood. Here, we address this in pulmonary arterial hypertension (PAH). We obtain pulmonary arterial endothelial cells (PAECs) from lungs of patients and controls (n = 19), and perform chromatin, transcriptomic and interaction profiling. Overall, we observe extensive remodeling at active enhancers in PAH PAECs and identify hundreds of differentially active TFs, yet find very little transcriptomic changes in steady-state. We devise a disease-specific enhancer-gene regulatory network and predict that primed enhancers in PAH PAECs are activated by the differentially active TFs, resulting in an aberrant response to endothelial signals, which could lead to disturbed angiogenesis and endothelial-to-mesenchymal-transition. We validate these predictions for a selection of target genes in PAECs stimulated with TGF-β, VEGF or serotonin. Our study highlights the role of chromatin state and enhancers in disease-relevant cell types of PAH., Pulmonary arterial hypertension (PAH) is a heterogeneous disease, causing severe breathing problems and cardiac morbidity. Here, the authors study chromatin marks in pulmonary arterial endothelial cells from PAH patients and controls and find changes in transcription factor and enhancer activity that suggest an aberrant response to signalling in PAH.

Pulmonary arterial hypertension (PAH) is a progressive disorder leading to occlusive vascular remodeling. Current PAH therapies improve quality of life, but do not reverse structural abnormalities in the pulmonary vasculature. Here, we used high-throughput drug screening combined with in silico analyses of existing transcriptomic datasets to identify a promising lead compound to reverse PAH. Induced pluripotent stem cell-derived endothelial cells (iPSC-EC) generated from six patients with PAH were exposed to 4,500 compounds and assayed for improved cell survival after serum withdrawal using a chemiluminescent caspase assay. Subsequent validation of caspase activity and improved angiogenesis combined with data analyses using the Gene Expression Omnibus (GEO) and Library of Integrated Network-Based Cellular Signatures (LINCS) databases revealed that the lead compound AG1296 was positively associated with an anti-PAH gene signature. AG1296 increased abundance of bone morphogenetic protein receptors, downstream signaling and gene expression, and suppressed PAH smooth muscle cell proliferation. AG1296 induced regression of pulmonary arterial (PA) neointimal lesions in lung organ culture and PA occlusive changes in the Sugen/hypoxia rat model, and reduced right ventricular systolic pressure. Moreover, AG1296 improved vascular function and BMPR2 signaling, and showed better correlation with the anti-PAH gene signature than other tyrosine kinase inhibitors (TKIs). Specifically, AG1296 upregulated small mothers against decapentaplegic (SMAD)1/5 co-activators, cAMP-response element binding protein (CREB)3 and CREB5: CREB3 induced inhibitor of DNA binding 1 (ID1) and downstream genes that improved vascular function. Thus, drug discovery for PAH can be accelerated by combining phenotypic screening with in silico analyses of publicly available datasets.

Pulmonary arterial hypertension (PAH) is characterized by endothelial cell (EC) dysfunction, loss of peripheral pulmonary arterial (PA) microvessels, and proliferation of vascular cells in proximal PAs, leading to occlusion of the lumen. Loss of function mutations in bone morphogenetic protein receptor (BMPR)2 occur in over 70% of heritable form of PAH (HPAH) patients. Intriguingly, only 20% of the mutation carriers develop clinical symptoms, suggesting that genetic variation may provide modifiers that alleviate the disease. Induced pluripotent stem cell (iPSC)-derived vascular cells provide a new opportunity to further understand the disease mechanisms in a personalized manner. In our study, we demonstrated that iPSC-derived endothelial cell (iPSC-EC) recapitulates the functional and gene expression abnormalities in native PAEC from the same PAH patients compared with healthy controls. Interestingly, PAH PAEC and iPSC-EC also respond similarly to potential PAH therapies elafin and FK506 in terms of improved angiogenesis. We then used iPSC-ECs to further understand the reduced penetrance of the BMPR2 mutation. iPSC-EC was generated from three families with unaffected mutation carriers (UMC), HPAH patients, and gender-matched controls. We identified patient-specific features of preserved function in UMC iPSC-EC attributed to the regulators of BMPR2 signaling or to cell survival gene revealed by RNA-Seq analyses. Our findings therefore highlight protective modifiers for HPAH that could help inform development of future treatment strategies. Despite the site of disease in the lung and the particular vulnerability of the PA vasculature, iPSC-EC is a good surrogate for PAH modeling and drug testing.

Heart disease: Ion channels offer drug target for arrythmia Drugs that target ion channels involved in controlling heartbeats could help correct irregular cardiac rhythms. Dai-Min Zhang from Nanjing First Hospital, Nanjing Medical University, China, and colleagues reviewed the function of small-conductance calcium-activated potassium (SK) channels in the heart under normal and disease conditions. These pore-forming proteins, which are opened by calcium and allow potassium to cross the cell membrane, help re-establish a normal electrical balance at the end of each heartbeat. When the channels become overactive and misfire, they can cause arrhythmias and heart failure. The authors discuss how drugs that inhibit SK channels hold promise for treating diseases associated with cardiac arrhythmias, such as atrial fibrillation. Blockade of SK channels can, however, induce arrhythmias in certain clinical situations, so further research is needed to determine when this therapeutic strategy would be safe and appropriate.

Rationale: Idiopathic or heritable pulmonary arterial hypertension is characterized by loss and obliteration of lung vasculature. Endothelial cell dysfunction is pivotal to the pathophysiology, but different causal mechanisms may reflect a need for patient-tailored therapies.Objectives: Endothelial cells differentiated from induced pluripotent stem cells were compared with pulmonary arterial endothelial cells from the same patients with idiopathic or heritable pulmonary arterial hypertension, to determine whether they shared functional abnormalities and altered gene expression patterns that differed from those in unused donor cells. We then investigated whether endothelial cells differentiated from pluripotent cells could serve as surrogates to test emerging therapies.Methods: Functional changes assessed included adhesion, migration, tube formation, and propensity to apoptosis. Expression of bone morphogenetic protein receptor type 2 (BMPR2) and its target, collagen IV, signaling of the phosphorylated for...