Publications

All Publications


  • Efficient Differentiation of Human Pluripotent Stem Cells to Endothelial Cells. Current protocols in human genetics Gu, M. 2018: e64

    Abstract

    Endothelial cells (ECs) line the interior surface of blood and lymphatic vessels, and play a key role in a variety of physiological or pathological processes such as thrombosis, inflammation, or vascular wall remodeling. Human-induced pluripotent stem cell (iPSCs)-derived ECs provide a new opportunity for vascular regeneration and serve as a model to study the mechanism and to screen for novel therapies. We use developmental cues in a monolayer differentiation approach to efficiently generate mesoderm cells from iPSCs via small-molecule activation of WNT signaling in chemically defined medium for 4 days, and subsequent EC specification using vascular endothelial growth factor and fibroblast growth factor for another 4 days. After 8 days of differentiation, mature ECs are further purified using magnetic-activated cell sorting for the EC surface marker CD144. These ECs exhibit molecular and cellular characteristics consistent with native ECs, such as expression of specific surface markers, formation of tube-like structures and acetylated low-density lipoprotein uptake. © 2018 by John Wiley & Sons, Inc.

    View details for PubMedID 29979824

  • Patient-Specific iPSC-Derived Endothelial Cells Uncover Pathways that Protect against Pulmonary Hypertension in BMPR2 Mutation Carriers. Cell stem cell Gu, M., Shao, N., Sa, S., Li, D., Termglinchan, V., Ameen, M., Karakikes, I., Sosa, G., Grubert, F., Lee, J., Cao, A., Taylor, S., Ma, Y., Zhao, Z., Chappell, J., Hamid, R., Austin, E. D., Gold, J. D., Wu, J. C., Snyder, M. P., Rabinovitch, M. 2016

    Abstract

    In familial pulmonary arterial hypertension (FPAH), the autosomal dominant disease-causing BMPR2 mutation is only 20% penetrant, suggesting that genetic variation provides modifiers that alleviate the disease. Here, we used comparison of induced pluripotent stem cell-derived endothelial cells (iPSC-ECs) from three families with unaffected mutation carriers (UMCs), FPAH patients, and gender-matched controls to investigate this variation. Our analysis identified features of UMC iPSC-ECs related to modifiers of BMPR2 signaling or to differentially expressed genes. FPAH-iPSC-ECs showed reduced adhesion, survival, migration, and angiogenesis compared to UMC-iPSC-ECs and control cells. The "rescued" phenotype of UMC cells was related to an increase in specific BMPR2 activators and/or a reduction in inhibitors, and the improved cell adhesion could be attributed to preservation of related signaling. The improved survival was related to increased BIRC3 and was independent of BMPR2. Our findings therefore highlight protective modifiers for FPAH that could help inform development of future treatment strategies.

    View details for DOI 10.1016/j.stem.2016.08.019

    View details for PubMedID 28017794

  • iPSC Model of Pulmonary Arterial Hypertension Reveals Novel Gene Expression and Patient Specificity. American journal of respiratory and critical care medicine Sa, S., Gu, M., Chappell, J., Shao, N., Ameen, M., Elliott, K. A., Li, D., Grubert, F., Li, C. G., Taylor, S., Cao, A., Ma, Y., Fong, R., Nguyen, L., Wu, J. C., Snyder, M. P., Rabinovitch, M. 2016: -?

    Abstract

    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.Endothelial cells differentiated from induced pluripotent stem cells were compared to 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.Functional changes assessed included adhesion, migration, tube formation, and propensity to apoptosis. Expression of BMPR2 and its target, collagen IV, pSMAD1/5 signaling and transcriptomic profiles were also analyzed.Native pulmonary arterial and induced pluripotent stem cell-derived endothelial cells from idiopathic and heritable pulmonary arterial hypertension patients compared to controls, showed a similar reduction in adhesion, migration, survival, and tube formation, decreased BMPR2 and downstream signaling and collagen IV expression. Transcriptomic profiling revealed high KISS1 related to reduced migration and low CES1, to impaired survival in patient cells. A beneficial angiogenic response to potential therapies, FK-506 and Elafin, was related to reduced SLIT3, an anti-migratory factor.Despite the site of disease in the lung our study indicates that induced pluripotent stem cell derived endothelial cells are useful surrogates to uncover novel features related to disease mechanisms and to better match patients to therapies.

    View details for PubMedID 27779452

  • Epigenetic Regulation of Phosphodiesterases 2A and 3A Underlies Compromised ß-Adrenergic Signaling in an iPSC Model of Dilated Cardiomyopathy. Cell stem cell Wu, H., Lee, J., Vincent, L. G., Wang, Q., Gu, M., Lan, F., Churko, J. M., Sallam, K. I., Matsa, E., Sharma, A., Gold, J. D., Engler, A. J., Xiang, Y. K., Bers, D. M., Wu, J. C. 2015; 17 (1): 89-100

    Abstract

    ?-adrenergic signaling pathways mediate key aspects of cardiac function. Its dysregulation is associated with a range of cardiac diseases, including dilated cardiomyopathy (DCM). Previously, we established an iPSC model of familial DCM from patients with a mutation in TNNT2, a sarcomeric protein. Here, we found that the ?-adrenergic agonist isoproterenol induced mature ?-adrenergic signaling in iPSC-derived cardiomyocytes (iPSC-CMs) but that this pathway was blunted in DCM iPSC-CMs. Although expression levels of several ?-adrenergic signaling components were unaltered between control and DCM iPSC-CMs, we found that phosphodiesterases (PDEs) 2A and PDE3A were upregulated in DCM iPSC-CMs and that PDE2A was also upregulated in DCM patient tissue. We further discovered increased nuclear localization of mutant TNNT2 and epigenetic modifications of PDE genes in both DCM iPSC-CMs and patient tissue. Notably, pharmacologic inhibition of PDE2A and PDE3A restored cAMP levels and ameliorated the impaired ?-adrenergic signaling of DCM iPSC-CMs, suggesting therapeutic potential.

    View details for DOI 10.1016/j.stem.2015.04.020

    View details for PubMedID 26095046

  • Pravastatin reverses obesity-induced dysfunction of induced pluripotent stem cell-derived endothelial cells via a nitric oxide-dependent mechanism. European heart journal Gu, M., Mordwinkin, N. M., Kooreman, N. G., Lee, J., Wu, H., Hu, S., Churko, J. M., Diecke, S., Burridge, P. W., He, C., Barron, F. E., Ong, S., Gold, J. D., Wu, J. C. 2015; 36 (13): 806-816

    Abstract

    High-fat diet-induced obesity (DIO) is a major contributor to type II diabetes and micro- and macro-vascular complications leading to peripheral vascular disease (PVD). Metabolic abnormalities of induced pluripotent stem cell-derived endothelial cells (iPSC-ECs) from obese individuals could potentially limit their therapeutic efficacy for PVD. The aim of this study was to compare the function of iPSC-ECs from normal and DIO mice using comprehensive in vitro and in vivo assays.Six-week-old C57Bl/6 mice were fed with a normal or high-fat diet. At 24 weeks, iPSCs were generated from tail tip fibroblasts and differentiated into iPSC-ECs using a directed monolayer approach. In vitro functional analysis revealed that iPSC-ECs from DIO mice had significantly decreased capacity to form capillary-like networks, diminished migration, and lower proliferation. Microarray and ELISA confirmed elevated apoptotic, inflammatory, and oxidative stress pathways in DIO iPSC-ECs. Following hindlimb ischaemia, mice receiving intramuscular injections of DIO iPSC-ECs had significantly decreased reperfusion compared with mice injected with control healthy iPSC-ECs. Hindlimb sections revealed increased muscle atrophy and presence of inflammatory cells in mice receiving DIO iPSC-ECs. When pravastatin was co-administered to mice receiving DIO iPSC-ECs, a significant increase in reperfusion was observed; however, this beneficial effect was blunted by co-administration of the nitric oxide synthase inhibitor, N(?)-nitro-l-arginine methyl ester.This is the first study to provide evidence that iPSC-ECs from DIO mice exhibit signs of endothelial dysfunction and have suboptimal efficacy following transplantation in a hindlimb ischaemia model. These findings may have important implications for future treatment of PVD using iPSC-ECs in the obese population.

    View details for DOI 10.1093/eurheartj/ehu411

    View details for PubMedID 25368203

  • Microfluidic Single-Cell Analysis Shows That Porcine Induced Pluripotent Stem Cell-Derived Endothelial Cells Improve Myocardial Function by Paracrine Activation CIRCULATION RESEARCH Gu, M., Nguyen, P. K., Lee, A. S., Xu, D., Hu, S., Plews, J. R., Han, L., Huber, B. C., Lee, W. H., Gong, Y., de Almeida, P. E., Lyons, J., Ikeno, F., Pacharinsak, C., Connolly, A. J., Gambhir, S. S., Robbins, R. C., Longaker, M. T., Wu, J. C. 2012; 111 (7): 882-893

    Abstract

    Induced pluripotent stem cells (iPSCs) hold great promise for the development of patient-specific therapies for cardiovascular disease. However, clinical translation will require preclinical optimization and validation of large-animal iPSC models.To successfully derive endothelial cells from porcine iPSCs and demonstrate their potential utility for the treatment of myocardial ischemia.Porcine adipose stromal cells were reprogrammed to generate porcine iPSCs (piPSCs). Immunohistochemistry, quantitative PCR, microarray hybridization, and angiogenic assays confirmed that piPSC-derived endothelial cells (piPSC-ECs) shared similar morphological and functional properties as endothelial cells isolated from the autologous pig aorta. To demonstrate their therapeutic potential, piPSC-ECs were transplanted into mice with myocardial infarction. Compared with control, animals transplanted with piPSC-ECs showed significant functional improvement measured by echocardiography (fractional shortening at week 4: 27.2±1.3% versus 22.3±1.1%; P<0.001) and MRI (ejection fraction at week 4: 45.8±1.3% versus 42.3±0.9%; P<0.05). Quantitative protein assays and microfluidic single-cell PCR profiling showed that piPSC-ECs released proangiogenic and antiapoptotic factors in the ischemic microenvironment, which promoted neovascularization and cardiomyocyte survival, respectively. Release of paracrine factors varied significantly among subpopulations of transplanted cells, suggesting that transplantation of specific cell populations may result in greater functional recovery.In summary, this is the first study to successfully differentiate piPSCs-ECs from piPSCs and demonstrate that transplantation of piPSC-ECs improved cardiac function after myocardial infarction via paracrine activation. Further development of these large animal iPSC models will yield significant insights into their therapeutic potential and accelerate the clinical translation of autologous iPSC-based therapy.

    View details for DOI 10.1161/CIRCRESAHA.112.269001

    View details for PubMedID 22821929

  • Proteomic Analysis of Endothelial Lipid Rafts Reveals a Novel Role of Statins in Antioxidation JOURNAL OF PROTEOME RESEARCH Gu, M., Fu, Y., Sun, X., Ding, Y., Li, C., Pang, W., Pan, S., Zhu, Y. 2012; 11 (4): 2365-2373

    Abstract

    As inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase, statins have pleiotropic vascular-protective effects, such as anti-inflammatory and antioxidative effects. We investigated the short-term beneficial effects of statins on modulating the translocation of lipid-raft-related proteins in endothelial cells (ECs). Human umbilical vein ECs were treated with atorvastatin for 30 min or 2 h; lipid-raft proteins were isolated and examined by quantitative proteome assay. Functional classification of identified proteins in lipid rafts revealed upregulated antioxidative proteins; downregulated proteins were associated with inflammation and cell adhesion. Among proteins verified by Western blot analysis, endoplasmic reticulum protein 46 (ERp46) showed increased level in lipid rafts with atorvastatin. Further, atorvastatin inhibited the activation of membrane-bound NADPH oxidase in both untreated and angiotensin II-treated ECs, as shown by reduced reactive oxygen species production. Co-immunoprecipitation and immunofluorescence experiments revealed that atorvastatin increased the association of ERp46 and Nox2, an NADPH oxidase isoform, in lipid rafts, thereby inhibiting Nox2 assembly with its regulatory subunits, such as p47phox and p67phox. Our results reveal a novel antioxidative role of atorvastatin by promoting the membrane translocation of ERp46 and its binding with Nox2 to inhibit Nox2 activity in ECs, which may offer another insight into the pleiotropic functions of statins.

    View details for DOI 10.1021/pr300098f

    View details for Web of Science ID 000302388100028

    View details for PubMedID 22428589

  • Generation of Quiescent Cardiac Fibroblasts from Human Induced Pluripotent Stem Cells for In Vitro Modeling of Cardiac Fibrosis. Circulation research Zhang, H., Tian, L., Shen, M., Wu, H., Gu, M., Tu, C., Paik, D. T., Wu, J. C. 2019

    Abstract

    RATIONALE: Activated fibroblasts are the major cell type that secrete excessive extracellular matrix in response to injury, contributing to pathological fibrosis and leading to organ failure. Effective anti-fibrotic therapeutic solutions, however, are not available due to the poorly defined characteristics and unavailability of tissue-specific fibroblasts. Recent advances in single-cell RNA-sequencing (scRNA-seq) fill such gaps of knowledge by enabling delineation of the developmental trajectories and identification of regulatory pathways of tissue-specific fibroblasts among different organs.OBJECTIVE: This study aims to define the transcriptome profiles of tissue-specific fibroblasts using recently reported mouse scRNA-seq atlas, and to develop a robust chemically defined protocol to derive cardiac fibroblasts (CFs) from human induced pluripotent stem cells (iPSCs) for in vitro modeling of cardiac fibrosis and drug screening.METHODS AND RESULTS: By analyzing the single-cell transcriptome profiles of fibroblasts from 10 selected mouse tissues, we identified distinct tissue-specific signature genes, including transcription factors that define the identities of fibroblasts in the heart, lungs, trachea, and bladder. We also determined that CFs in large are of the epicardial lineage. We thus developed a robust chemically-defined protocol that generates CFs from human iPSCs. Functional studies confirmed that iPSC-derived CFs preserved a quiescent phenotype and highly resembled primary CFs at the transcriptional, cellular, and functional levels. We demonstrated that this cell-based platform is sensitive to both pro- and anti-fibrosis drugs. Finally, we showed that crosstalk between cardiomyocytes and CFs via the atrial/brain natriuretic peptide-natriuretic peptide receptor 1 pathway is implicated in suppressing fibrogenesis.CONCLUSIONS: This study uncovers unique gene signatures that define tissue-specific identities of fibroblasts. The bona fide quiescent CFs derived from human iPSCs can serve as a faithful in vitro platform to better understand the underlying mechanisms of cardiac fibrosis and to screen anti-fibrotic drugs.

    View details for DOI 10.1161/CIRCRESAHA.119.315491

    View details for PubMedID 31288631

  • High-throughput Drug Screen to Reverse Phenotype of Pulmonary Artery Hypertension Ipsc Derived Vascular Cells Combined with Bioinformatics Uncovers Promising Therapies Gu, M., Donate, M., Miao, Y., Mao, S., Saito, T., Otsuki, S., Wang, L., Harper, R., Sa, S., Khatri, P., Rabinovitch, M. LIPPINCOTT WILLIAMS & WILKINS. 2018: E70
  • Transcriptomic and epigenomic differences in human induced pluripotent stem cells generated from six reprogramming methods NATURE BIOMEDICAL ENGINEERING Churko, J. M., Lee, J., Ameen, M., Gu, M., Venkatasubramanian, M., Diecke, S., Sallam, K., Im, H., Wang, G., Gold, J. D., Salomonis, N., Snyder, M. P., Wu, J. C. 2017; 1 (10): 826?37
  • Patient-Specific iPSC-Derived Endothelial Cells Uncover Pathways that Protect against Pulmonary Hypertension in BMPR2 Mutation Carriers CELL STEM CELL Gu, M., Shao, N., Sa, S., Li, D., Termglinchan, V., Ameen, M., Karakikes, I., Sosa, G., Grubert, F., Lee, J., Cao, A., Taylor, S., Ma, Y., Zhao, Z., Chappell, J., Hamid, R., Austin, E. D., Gold, J. D., Wu, J. C., Snyder, M. P., Rabinovitch, M. 2017; 20 (4): 490-?
  • Induced Pluripotent Stem Cell Model of Pulmonary Arterial Hypertension Reveals Novel Gene Expression and Patient Specificity AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE Sa, S., Gu, M., Chappe, J., Shao, N., Ameen, M., Elliott, K. A., Li, D., Grubert, F., Li, C. G., Taylor, S., Cao, A., Ma, Y., Fong, R., Nguyen, L., Wu, J. C., Snyder, M. P., Rabinovitch, M. 2017; 195 (7): 930-941
  • Upregulation of HERV-K is Linked to Immunity and Inflammation in Pulmonary Arterial Hypertension. Circulation Saito, T., Miyagawa, K., Chen, S. Y., Tamosiuniene, R., Wang, L., Sharp, O., Samayoa, E., Harada, D., Moonen, J. A., Cao, A., Chen, P. I., Hennigs, J. K., Gu, M., Li, C. G., Leib, R. D., Li, D., Adams, C. M., Del Rosario, P. A., Bill, M. A., Haddad, F., Montoya, J. G., Robinson, W., Fantl, W. J., Nolan, G. P., Zamanian, R. T., Nicolls, M. R., Chiu, C. Y., Ariza, M. E., Rabinovitch, M. 2017

    Abstract

    Background -Immune dysregulation has been linked to occlusive vascular remodeling in pulmonary arterial hypertension (PAH) that is hereditary, idiopathic or associated with other conditions. Circulating autoantibodies, lung perivascular lymphoid tissue and elevated cytokines have been related to PAH pathogenesis but without clear understanding of how these abnormalities are initiated, perpetuated and connected in the progression of disease. We therefore set out to identify specific target antigens in PAH lung immune complexes as a starting point toward resolving these issues to better inform future application of immunomodulatory therapies. Methods -Lung immune complexes were isolated and PAH target antigens were identified by liquid chromatography tandem mass spectrometry (LCMS), confirmed by ELISA, and localized by confocal microscopy. One PAH antigen linked to immunity and inflammation was pursued and a link to PAH pathophysiology was investigated by next generation sequencing, functional studies in cultured monocytes and endothelial cells (EC) and hemodynamic and lung studies in a rat. Results -SAM domain and HD1 domain-containing protein (SAMHD1), an innate immune factor that suppresses HIV replication was identified and confirmed as highly expressed in immune complexes from 16 hereditary and idiopathic PAH vs. 12 control lungs. Elevated SAMHD1 was localized to endothelial cells (EC), perivascular dendritic cells and macrophages and SAMHD1 antibodies were prevalent in tertiary lymphoid tissue. An unbiased screen using metagenomic sequencing related SAMHD1 to increased expression of human endogenous retrovirus K (HERV-K) in PAH vs. control lungs (n=4 each). HERV-K envelope and deoxyuridine triphosphate nucleotidohydrolase (dUTPase) mRNAs were elevated in PAH vs. control lungs (n=10) and proteins were localized to macrophages. HERV-K dUTPase induced SAMHD1 and pro-inflammatory cytokines (e.g., IL6, IL1? and TNF?) in circulating monocytes and pulmonary arterial (PA) EC, and activated B cells. Vulnerability of PAEC to apoptosis was increased by HERV-K dUTPase in an IL6 independent manner. Furthermore, three weekly injections of HERV-K dUTPase induced hemodynamic and vascular changes of pulmonary hypertension in rats (n=8), and elevated IL6. Conclusions -Our study reveals that upregulation of the endogenous retrovirus HERV-K could both initiate and sustain activation of the immune system and cause vascular changes associated with PAH.

    View details for PubMedID 28935667

  • Transcriptomic and epigenomic differences in human induced pluripotent stem cells generated from six reprogramming methods. Nature biomedical engineering Churko, J. M., Lee, J., Ameen, M., Gu, M., Venkatasubramanian, M., Diecke, S., Sallam, K., Im, H., Wang, G., Gold, J. D., Salomonis, N., Snyder, M. P., Wu, J. C. 2017; 1 (10): 826?37

    Abstract

    Many reprogramming methods can generate human induced pluripotent stem cells (hiPSCs) that closely resemble human embryonic stem cells (hESCs). This has led to assessments of how similar hiPSCs are to hESCs, by evaluating differences in gene expression, epigenetic marks and differentiation potential. However, all previous studies were performed using hiPSCs acquired from different laboratories, passage numbers, culturing conditions, genetic backgrounds and reprogramming methods, all of which may contribute to the reported differences. Here, by using high-throughput sequencing under standardized cell culturing conditions and passage number, we compare the epigenetic signatures (H3K4me3, H3K27me3 and HDAC2 ChIP-seq profiles) and transcriptome differences (by RNA-seq) of hiPSCs generated from the same primary fibroblast population by using six different reprogramming methods. We found that the reprogramming method impacts the resulting transcriptome and that all hiPSC lines could terminally differentiate, regardless of the reprogramming method. Moreover, by comparing the differences between the hiPSC and hESC lines, we observed a significant proportion of differentially expressed genes that could be attributed to polycomb repressive complex targets.

    View details for PubMedID 30263871

  • Patient-Specific and Genome-Edited Induced Pluripotent Stem Cell-Derived Cardiomyocytes Elucidate Single-Cell Phenotype of Brugada Syndrome. Journal of the American College of Cardiology Liang, P., Sallam, K., Wu, H., Li, Y., Itzhaki, I., Garg, P., Zhang, Y., Vermglinchan, V., Lan, F., Gu, M., Gong, T., Zhuge, Y., He, C., Ebert, A. D., Sanchez-Freire, V., Churko, J., Hu, S., Sharma, A., Lam, C. K., Scheinman, M. M., Bers, D. M., Wu, J. C. 2016; 68 (19): 2086-2096

    Abstract

    Brugada syndrome (BrS), a disorder associated with characteristic electrocardiogram precordial ST-segment elevation, predisposes afflicted patients to ventricular fibrillation and sudden cardiac death. Despite marked achievements in outlining the organ level pathophysiology of the disorder, the understanding of human cellular phenotype has lagged due to a lack of adequate human cellular models of the disorder.The objective of this study was to examine single cell mechanism of Brugada syndrome using induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs).This study recruited 2 patients with type 1 BrS carrying 2 different sodium voltage-gated channel alpha subunit 5 variants as well as 2 healthy control subjects. We generated iPSCs from their skin fibroblasts by using integration-free Sendai virus. We used directed differentiation to create purified populations of iPSC-CMs.BrS iPSC-CMs showed reductions in inward sodium current density and reduced maximal upstroke velocity of action potential compared with healthy control iPSC-CMs. Furthermore, BrS iPSC-CMs demonstrated increased burden of triggered activity, abnormal calcium (Ca(2+)) transients, and beating interval variation. Correction of the causative variant by genome editing was performed, and resultant iPSC-CMs showed resolution of triggered activity and abnormal Ca(2+) transients. Gene expression profiling of iPSC-CMs showed clustering of BrS compared with control subjects. Furthermore, BrS iPSC-CM gene expression correlated with gene expression from BrS human cardiac tissue gene expression.Patient-specific iPSC-CMs were able to recapitulate single-cell phenotype features of BrS, including blunted inward sodium current, increased triggered activity, and abnormal Ca(2+) handling. This novel human cellular model creates future opportunities to further elucidate the cellular disease mechanism and identify novel therapeutic targets.

    View details for DOI 10.1016/j.jacc.2016.07.779

    View details for PubMedID 27810048

  • In Pulmonary Arterial Hypertension, Reduced BMPR2 Promotes Endothelial-to-Mesenchymal Transition via HMGA1 and Its Target Slug CIRCULATION Hopper, R. K., Moonen, J. A., Diebold, I., Cao, A., Rhodes, C. J., Tojais, N. F., Hennigs, J. K., Gu, M., Wang, L., Rabinovitch, M. 2016; 133 (18): 1783-?

    Abstract

    -We previously reported high-throughput RNA sequencing analyses that identified heightened expression of the chromatin architectural factor High Mobility Group AT-hook 1 (HMGA1) in pulmonary arterial (PA) endothelial cells (ECs) from idiopathic PA hypertension (IPAH) patients compared to controls. Since HMGA1 promotes epithelial to mesenchymal transition in cancer, we hypothesized that increased HMGA1 could induce transition of PAECs to a smooth muscle (SM)-like mesenchymal phenotype (EndMT), explaining both dysregulation of PAEC function and possible cellular contribution to the occlusive remodeling that characterizes advanced IPAH.-We documented increased HMGA1 in PAECs cultured from IPAH vs. donor control lungs. Confocal microscopy of lung explants localized the increase in HMGA1 consistently to PA endothelium, and identified many cells double-positive for HMGA1 and smooth muscle 22 alpha (SM22?) in occlusive and plexogenic lesions. Since decreased expression and function of bone morphogenetic protein receptor (BMPR)2 is observed in PAH, we reduced BMPR2 by siRNA in control PAECs and documented an increase in HMGA1 protein. Consistent with transition of PAECs by HMGA1, we detected reduced PECAM-1 (CD31) and increased EndMT markers, ?SMA, SM22?, calponin, phospho-vimentin and Slug. The transition was associated with spindle SM-like morphology, and the increase in ?SMA was largely reversed by joint knockdown of BMPR2 and HMGA1 or Slug. Pulmonary ECs from mice with EC-specific loss of BMPR2 showed similar gene and protein changes.-Increased HMGA1 in PAECs resulting from dysfunctional BMPR2 signaling can transition endothelium to SM-like cells associated with PAH.

    View details for DOI 10.1161/CIRCULATIONAHA.115.020617

    View details for Web of Science ID 000375604400008

    View details for PubMedID 27045138

  • RNA Sequencing Analysis Detection of a Novel Pathway of Endothelial Dysfunction in Pulmonary Arterial Hypertension AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE Rhodes, C. J., Im, H., Cao, A., Hennigs, J. K., Wang, L., Sa, S., Chen, P., Nickel, N. P., Miyagawa, K., Hopper, R. K., Tojais, N. F., Li, C. G., Gu, M., Spiekerkoetter, E., Xian, Z., Chen, R., Zhao, M., Kaschwich, M., del Rosario, P. A., Bernstein, D., Zamanian, R. T., Wu, J. C., Snyder, M. P., Rabinovitch, M. 2015; 192 (3): 356-366

    Abstract

    Pulmonary arterial hypertension is characterized by endothelial dysregulation, but global changes in gene expression have not been related to perturbations in function.RNA sequencing was utilized to discriminate changes in transcriptomes of endothelial cells cultured from lungs of patients with idiopathic pulmonary arterial hypertension vs. controls and to assess the functional significance of major differentially expressed transcripts.The endothelial transcriptomes from seven control and six idiopathic pulmonary arterial hypertension patients' lungs were analyzed. Differentially expressed genes were related to BMPR2 signaling. Those downregulated were assessed for function in cultured cells, and in a transgenic mouse.Fold-differences in ten genes were significant (p<0.05), four increased and six decreased in patients vs.No patient was mutant for BMPR2. However, knockdown of BMPR2 by siRNA in control pulmonary arterial endothelial cells recapitulated six/ten patient-related gene changes, including decreased collagen IV (COL4A1, COL4A2) and ephrinA1 (EFNA1). Reduction of BMPR2 regulated transcripts was related to decreased ?-catenin. Reducing COL4A1, COL4A2 and EFNA1 by siRNA inhibited pulmonary endothelial adhesion, migration and tube formation. In mice null for the EFNA1 receptor, EphA2, vs. controls, VEGF receptor blockade and hypoxia caused more severe pulmonary hypertension, judged by elevated right ventricular systolic pressure, right ventricular hypertrophy and loss of small arteries.The novel relationship between BMPR2 dysfunction and reduced expression of endothelial COL4 and EFNA1 may underlie vulnerability to injury in pulmonary arterial hypertension.

    View details for DOI 10.1164/rccm.201408-1528OC

    View details for PubMedID 26030479

  • Elafin Reverses Pulmonary Hypertension via Caveolin-1-Dependent Bone Morphogenetic Protein Signaling AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE Nickel, N. P., Spiekerkoetter, E., Gu, M., Li, C. G., Li, H., Kaschwich, M., Diebold, I., Hennigs, J. K., Kim, K., Miyagawa, K., Wang, L., Cao, A., Sa, S., Jiang, X., Stockstill, R. W., Nicolls, M. R., Zamanian, R. T., Bland, R. D., Rabinovitch, M. 2015; 191 (11): 1273-1286

    Abstract

    Pulmonary arterial hypertension is characterized by endothelial cell dysfunction, impaired BMPR2 signaling, and increased elastase activity. Synthetic elastase inhibitors reverse experimental pulmonary hypertension but cause hepatotoxicity in clinical studies. The endogenous elastase inhibitor elafin attenuates the development of hypoxic pulmonary hypertension in mice, but its potential to improve endothelial cell function and BMPR2 signaling, and to reverse severe experimental pulmonary hypertension or vascular pathology in the human disease was unknown.To assess elafin-mediated regression of pulmonary vascular pathology in rats with pulmonary hypertension induced by VEGF receptor blockade and hypoxia (Sugen/Hypoxia), and in lung explants from pulmonary hypertension patients. To determine if elafin amplifies BMPR2 signaling in pulmonary artery endothelial cells from controls and patients, and to elucidate the underlying mechanism. Methods, Measurements and Main Results: In Sugen/Hypoxia rats, elafin reduced elastase activity and reversed pulmonary hypertension, judged by regression of right ventricular systolic pressure and hypertrophy and pulmonary artery occlusive changes. Elafin improved endothelial function by increasing apelin, a product of BMPR2 signaling. Elafin induced apoptosis in human pulmonary arterial smooth muscle cells and in lung organ culture elafin decreased neointimal lesions. In normal and patient pulmonary artery endothelial cells, elafin enhanced survival and promoted angiogenesis by increasing pSMAD dependent and independent BMPR2 signaling. This was linked mechanistically to augmented interaction of BMPR2 with caveolin-1 via elafin-mediated stabilization of caveolin-1 on endothelial surfaces.Elafin reverses obliterative changes in rat and human pulmonary arteries via elastase inhibition and caveolin-1 dependent amplification of BMPR2 signaling.

    View details for DOI 10.1164/rccm.201412-2291OC

    View details for Web of Science ID 000356105000014

    View details for PubMedID 25853696

  • Genome Editing of Isogenic Human Induced Pluripotent Stem Cells Recapitulates Long QT Phenotype for Drug Testing. Journal of the American College of Cardiology Wang, Y., Liang, P., Lan, F., Wu, H., Lisowski, L., Gu, M., Hu, S., Kay, M. A., Urnov, F. D., Shinnawi, R., Gold, J. D., Gepstein, L., Wu, J. C. 2014; 64 (5): 451-459

    Abstract

    Human induced pluripotent stem cells (iPSCs) play an important role in disease modeling and drug testing. However, the current methods are time-consuming and lack an isogenic control.This study sought to establish an efficient technology to generate human PSC-based disease models with isogenic control.The ion channel genes KCNQ1 and KCNH2 with dominant negative mutations causing long QT syndrome types 1 and 2, respectively, were stably integrated into a safe harbor AAVS1 locus using zinc finger nuclease technology.Patch-clamp recording revealed that the edited iPSC-derived cardiomyocytes (iPSC-CMs) displayed characteristic long QT syndrome phenotype and significant prolongation of the action potential duration compared with the unedited control cells. Finally, addition of nifedipine (L-type calcium channel blocker) or pinacidil (KATP-channel opener) shortened the action potential duration of iPSC-CMs, confirming the validity of isogenic iPSC lines for drug testing in the future.Our study demonstrates that iPSC-CM-based disease models can be rapidly generated by overexpression of dominant negative gene mutants.

    View details for DOI 10.1016/j.jacc.2014.04.057

    View details for PubMedID 25082577

  • Large animal induced pluripotent stem cells as pre-clinical models for studying human disease JOURNAL OF CELLULAR AND MOLECULAR MEDICINE Plews, J. R., Gu, M., Longaker, M. T., Wu, J. C. 2012; 16 (6): 1196-1202

    Abstract

    The path to induced pluripotency Discovery of a pan-species pluripotency network Animal iPSCs and disease modelling Issues with large animal iPSCs Conclusions The derivation of human embryonic stem cells and subsequently human induced pluripotent stem cells (iPSCs) has energized regenerative medicine research and enabled seemingly limitless applications. Although small animal models, such as mouse models, have played an important role in the progression of the field, typically, they are poor representations of the human disease phenotype. As an alternative, large animal models should be explored as a potentially better approach for clinical translation of cellular therapies. However, only fragmented information regarding the derivation, characterization and clinical usefulness of pluripotent large animal cells is currently available. Here, we briefly review the latest advances regarding the derivation and use of large animal iPSCs.

    View details for DOI 10.1111/j.1582-4934.2012.01521.x

    View details for Web of Science ID 000304468600005

    View details for PubMedID 22212700

    View details for PubMedCentralID PMC3340484

  • A Novel Mechanism of gamma/delta T-Lymphocyte and Endothelial Activation by Shear Stress The Role of Ecto-ATP Synthase beta Chain CIRCULATION RESEARCH Fu, Y., Hou, Y., Fu, C., Gu, M., Li, C., Kong, W., Wang, X., Shyy, J. Y., Zhu, Y. 2011; 108 (4): 410-417

    Abstract

    Endothelial cells (ECs) have distinct mechanotransduction mechanisms responding to laminar versus disturbed flow patterns. Endothelial dysfunction, affected by imposed flow, is one of the earliest events leading to atherogenesis. The involvement of ?/? T lymphocytes in endothelial dysfunction under flow is largely unknown.To investigate whether shear stress regulates membrane translocation of ATP synthase ? chain (ATPS?) in ECs, leading to the increased ?/? T-lymphocyte adhesion and the related functions.We applied different flow patterns to cultured ECs. Laminar flow decreased the level of membrane-bound ATPS? (ecto-ATPS?) and depleted membrane cholesterol, whereas oscillatory flow increased the level of ecto-ATPS? and membrane cholesterol. Incubating ECs with cholesterol or depleting cellular cholesterol with ?-cyclodextrin mimicked the effect of oscillatory or laminar flow, respectively. Knockdown caveolin-1 by small interfering RNA prevented ATPS? translocation in response to laminar flow. Importantly, oscillatory flow or cholesterol treatment elevated the number of ?/? T cells binding to ECs, which was blocked by anti-ATPS? antibody. Furthermore, the incubation of ?/? T cells with ECs increased tumor necrosis fact ? and interferon-? secretion from T cells and vascular cell adhesion molecule-1 expression in ECs. In vivo, ?/? T-cell adhesion and ATPS? membrane translocation was elevated in the aortic inner curvature and disturbed flow areas in partially ligated carotid arteries of ApoE(-/-) mice fed a high-fat diet.This study provides evidence that disturbed flow and hypercholesterolemia synergistically promote ?/? T-lymphocyte activation by the membrane translocation of ATPS? in ECs and in vivo in mice, which is a novel mechanism of endothelial activation.

    View details for DOI 10.1161/CIRCRESAHA.110.230151

    View details for Web of Science ID 000287484200007

    View details for PubMedID 21193741

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