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Palumbo F, Gunjak M, Lee PJ, Günther S, Hilgendorff A, Vadász I, Herold S, Seeger W, Mühlfeld C, Morty RE. Impact of different tissue dissociation protocols on endothelial cell recovery from developing mouse lungs. Cytometry A 2024; 105:521-535. [PMID: 38668123 DOI: 10.1002/cyto.a.24843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 03/11/2024] [Accepted: 04/08/2024] [Indexed: 07/19/2024]
Abstract
Flow cytometry and fluorescence-activated cell sorting are widely used to study endothelial cells, for which the generation of viable single-cell suspensions is an essential first step. Two enzymatic approaches, collagenase A and dispase, are widely employed for endothelial cell isolation. In this study, the utility of both enzymatic approaches, alone and in combination, for endothelial cell isolation from juvenile and adult mouse lungs was assessed, considering the number, viability, and subtype composition of recovered endothelial cell pools. Collagenase A yielded an 8-12-fold superior recovery of viable endothelial cells from lung tissue from developing mouse pups, compared to dispase, although dispase proved superior in efficiency for epithelial cell recovery. Single-cell RNA-Seq revealed that the collagenase A approach yielded a diverse endothelial cell subtype composition of recovered endothelial cell pools, with broad representation of arterial, capillary, venous, and lymphatic lung endothelial cells; while the dispase approach yielded a recovered endothelial cell pool highly enriched for one subset of general capillary endothelial cells, but poor representation of other endothelial cells subtypes. These data indicate that tissue dissociation markedly influences the recovery of endothelial cells, and the endothelial subtype composition of recovered endothelial cell pools, as assessed by single-cell RNA-Seq.
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Affiliation(s)
- Francesco Palumbo
- Flow Cytometry Core Facility, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Department of Lung Development and Remodelling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, member of the German Center for Lung Research (DZL), Bad Nauheim, Germany
- Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), member of the German Center for Lung Research (DZL), Justus Liebig University Giessen, Giessen, Germany
| | - Miša Gunjak
- Department of Lung Development and Remodelling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, member of the German Center for Lung Research (DZL), Bad Nauheim, Germany
- Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), member of the German Center for Lung Research (DZL), Justus Liebig University Giessen, Giessen, Germany
- Department of Translational Pulmonology and the Translational Lung Research Center Heidelberg (TLRC), Heidelberg University Hospital, member of the German Center for Lung Research (DZL), Heidelberg, Germany
| | - Patty J Lee
- Division of Pulmonary, Critical Care and Sleep Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Stefan Günther
- Deep Sequencing Platform, Max Planck Institute for Heart and Lung Research, Bad Nauheim, member of the German Center for Lung Research (DZL), Bad Nauheim, Germany
| | - Anne Hilgendorff
- Institute for Lung Health and Immunity and Comprehensive Pneumology Center (CPC), Helmholtz Zentrum München, member of the German Center for Lung Research (DZL), Munich, Germany
- Center for Comprehensive Developmental Care (CDeCLMU) at the Social Pediatric Center, Dr. von Hauner Children's Hospital, Ludwig-Maximilian-University, Munich, Germany
| | - István Vadász
- Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), member of the German Center for Lung Research (DZL), Justus Liebig University Giessen, Giessen, Germany
- Institute for Lung Health, Justus Liebig University Giessen, Giessen, Germany
- Cardio-Pulmonary Institute, Justus Liebig University Giessen, Giessen, Germany
| | - Susanne Herold
- Institute for Lung Health, Justus Liebig University Giessen, Giessen, Germany
- Cardio-Pulmonary Institute, Justus Liebig University Giessen, Giessen, Germany
- Department of Internal Medicine (Infectious Disease and Hospital Hygiene), University of Giessen and Marburg Lung Center (UGMLC), member of the German Center for Lung Research (DZL), Justus Liebig University Giessen, Giessen, Germany
| | - Werner Seeger
- Department of Lung Development and Remodelling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, member of the German Center for Lung Research (DZL), Bad Nauheim, Germany
- Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), member of the German Center for Lung Research (DZL), Justus Liebig University Giessen, Giessen, Germany
- Institute for Lung Health, Justus Liebig University Giessen, Giessen, Germany
- Cardio-Pulmonary Institute, Justus Liebig University Giessen, Giessen, Germany
| | - Christian Mühlfeld
- Institute of Functional and Applied Anatomy and Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Hannover Medical School, member of the German Center for Lung Research (DZL), Hannover, Germany
| | - Rory E Morty
- Department of Translational Pulmonology and the Translational Lung Research Center Heidelberg (TLRC), Heidelberg University Hospital, member of the German Center for Lung Research (DZL), Heidelberg, Germany
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Ellis LV, Bywaters JD, Chen J. Endothelial deletion of p53 generates transitional endothelial cells and improves lung development during neonatal hyperoxia. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.07.593014. [PMID: 38766251 PMCID: PMC11100739 DOI: 10.1101/2024.05.07.593014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Bronchopulmonary dysplasia (BPD), a prevalent and chronic lung disease affecting premature newborns, results in vascular rarefaction and alveolar simplification. Although the vasculature has been recognized as a main player in this disease, the recently found capillary heterogeneity and cellular dynamics of endothelial subpopulations in BPD remain unclear. Here, we show Cap2 cells are damaged during neonatal hyperoxic injury, leading to their replacement by Cap1 cells which, in turn, significantly decline. Single-cell RNA-seq identifies the activation of numerous p53 target genes in endothelial cells, including Cdkn1a (p21). While global deletion of p53 results in worsened vasculature, endothelial-specific deletion of p53 reverses the vascular phenotype and improves alveolar simplification during hyperoxia. This recovery is associated with the emergence of a transitional EC state, enriched for oxidative stress response genes and growth factors. These findings implicate the p53 pathway in EC type transition during injury-repair and highlights the endothelial contributions to BPD.
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Affiliation(s)
- Lisandra Vila Ellis
- Department of Cell & Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
- Department of Pulmonary Medicine, the University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Jonathan D Bywaters
- Department of Cell & Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
- Department of Pulmonary Medicine, the University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Jichao Chen
- Department of Pulmonary Medicine, the University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
- Department of Pediatrics, Perinatal Institute Division of Pulmonary Biology, University of Cincinnati and Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA
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Zanini F, Che X, Suresh NE, Knutsen C, Klavina P, Xie Y, Domingo-Gonzalez R, Liu M, Kum A, Jones RC, Quake SR, Alvira CM, Cornfield DN. Hyperoxia prevents the dynamic neonatal increases in lung mesenchymal cell diversity. Sci Rep 2024; 14:2033. [PMID: 38263350 PMCID: PMC10805790 DOI: 10.1038/s41598-023-50717-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 12/23/2023] [Indexed: 01/25/2024] Open
Abstract
Rapid expansion of the pulmonary microvasculature through angiogenesis drives alveolarization, the final stage of lung development that occurs postnatally and dramatically increases lung gas-exchange surface area. Disruption of pulmonary angiogenesis induces long-term structural and physiologic lung abnormalities, including bronchopulmonary dysplasia, a disease characterized by compromised alveolarization. Although endothelial cells are primary determinants of pulmonary angiogenesis, mesenchymal cells (MC) play a critical and dual role in angiogenesis and alveolarization. Therefore, we performed single cell transcriptomics and in-situ imaging of the developing lung to profile mesenchymal cells during alveolarization and in the context of lung injury. Specific mesenchymal cell subtypes were present at birth with increasing diversity during alveolarization even while expressing a distinct transcriptomic profile from more mature correlates. Hyperoxia arrested the transcriptomic progression of the MC, revealed differential cell subtype vulnerability with pericytes and myofibroblasts most affected, altered cell to cell communication, and led to the emergence of Acta1 expressing cells. These insights hold the promise of targeted treatment for neonatal lung disease, which remains a major cause of infant morbidity and mortality across the world.
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Affiliation(s)
- Fabio Zanini
- School of Clinical Medicine, University of New South Wales, Sydney, Australia.
- Cellular Genomics Futures Institute, University of New South Wales, Sydney, NSW, Australia.
- Evolution & Ecology Research Centre, University of New South Wales, Sydney, NSW, Australia.
| | - Xibing Che
- Center for Excellence in Pulmonary Biology, Stanford University School of Medicine, Stanford, CA, USA
- Division of Pulmonary, Asthma and Sleep Medicine, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA
| | - Nina E Suresh
- Center for Excellence in Pulmonary Biology, Stanford University School of Medicine, Stanford, CA, USA
- Division of Pulmonary, Asthma and Sleep Medicine, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA
| | - Carsten Knutsen
- Center for Excellence in Pulmonary Biology, Stanford University School of Medicine, Stanford, CA, USA
- Division of Critical Care Medicine, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA
| | - Paula Klavina
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland
| | - Yike Xie
- School of Clinical Medicine, University of New South Wales, Sydney, Australia
| | - Racquel Domingo-Gonzalez
- Center for Excellence in Pulmonary Biology, Stanford University School of Medicine, Stanford, CA, USA
- Division of Critical Care Medicine, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA
| | - Min Liu
- Center for Excellence in Pulmonary Biology, Stanford University School of Medicine, Stanford, CA, USA
- Division of Critical Care Medicine, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA
| | - Alexander Kum
- Center for Excellence in Pulmonary Biology, Stanford University School of Medicine, Stanford, CA, USA
- Division of Critical Care Medicine, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA
| | - Robert C Jones
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Stephen R Quake
- Department of Bioengineering, Stanford University, Stanford, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
- Department of Applied Physics, Stanford University, Stanford, CA, USA
| | - Cristina M Alvira
- Center for Excellence in Pulmonary Biology, Stanford University School of Medicine, Stanford, CA, USA
- Division of Critical Care Medicine, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA
| | - David N Cornfield
- Center for Excellence in Pulmonary Biology, Stanford University School of Medicine, Stanford, CA, USA.
- Division of Pulmonary, Asthma and Sleep Medicine, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
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Cantu A, Gutierrez MC, Dong X, Leek C, Anguera M, Lingappan K. Modulation of recovery from neonatal hyperoxic lung injury by sex as a biological variable. Redox Biol 2023; 68:102933. [PMID: 38661305 PMCID: PMC10628633 DOI: 10.1016/j.redox.2023.102933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 10/07/2023] [Accepted: 10/11/2023] [Indexed: 04/26/2024] Open
Abstract
Recovery from lung injury during the neonatal period requires the orchestration of many biological pathways. The modulation of such pathways can drive the developing lung towards proper repair or persistent maldevelopment that can lead to a disease phenotype. Sex as a biological variable can regulate these pathways differently in the male and female lung exposed to neonatal hyperoxia. In this study, we assessed the contribution of cellular diversity in the male and female neonatal lung following injury. Our objective was to investigate sex and cell-type specific transcriptional changes that drive repair or persistent injury in the neonatal lung and delineate the alterations in the immune-endothelial cell communication networks using single cell RNA sequencing (sc-RNAseq) in a murine model of hyperoxic injury. We generated transcriptional profiles of >55,000 cells isolated from the lungs of postnatal day 1 (PND 1; pre-exposure), PND 7, and PND 21neonatal male and female C57BL/6 mice exposed to 95 % FiO2 between PND 1-5 (saccular stage of lung development). We show the presence of sex-based differences in the transcriptional states of lung endothelial and immune cells at PND 1 and PND 21. Furthermore, we demonstrate that biological sex significantly influences the response to injury, with a greater number of differentially expressed genes showing sex-specific patterns than those shared between male and female lungs. Pseudotime trajectory analysis highlighted genes needed for lung development that were altered by hyperoxia. Finally, we show intercellular communication between endothelial and immune cells at saccular and alveolar stages of lung development with sex-based biases in the crosstalk and identify novel ligand-receptor pairs. Our findings provide valuable insights into the cell diversity, transcriptional state, developmental trajectory, and cell-cell communication underlying neonatal lung injury, with implications for understanding lung development and possible therapeutic interventions while highlighting the crucial role of sex as a biological variable.
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Affiliation(s)
- Abiud Cantu
- Department of Neonatology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | | | - Xiaoyu Dong
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Connor Leek
- Department of Neonatology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Montserrat Anguera
- Department of Biomedical Sciences, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA, USA
| | - Krithika Lingappan
- Department of Neonatology, Children's Hospital of Philadelphia, Philadelphia, PA, USA.
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Rao S, Liu M, Iosef C, Knutsen C, Alvira CM. Endothelial-specific loss of IKKβ disrupts pulmonary endothelial angiogenesis and impairs postnatal lung growth. Am J Physiol Lung Cell Mol Physiol 2023; 325:L299-L313. [PMID: 37310763 PMCID: PMC10625829 DOI: 10.1152/ajplung.00034.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 06/08/2023] [Accepted: 06/09/2023] [Indexed: 06/14/2023] Open
Abstract
Pulmonary angiogenesis drives alveolarization, but the transcriptional regulators directing pulmonary angiogenesis remain poorly defined. Global, pharmacological inhibition of nuclear factor-kappa B (NF-κB) impairs pulmonary angiogenesis and alveolarization. However, establishing a definitive role for NF-κB in pulmonary vascular development has been hindered by embryonic lethality induced by constitutive deletion of NF-κB family members. We created a mouse model allowing inducible deletion of the NF-κB activator, IKKβ, in endothelial cells (ECs) and assessed the effect on lung structure, endothelial angiogenic function, and the lung transcriptome. Embryonic deletion of IKKβ permitted lung vascular development but resulted in a disorganized vascular plexus, while postnatal deletion significantly decreased radial alveolar counts, vascular density, and proliferation of both endothelial and nonendothelial lung cells. Loss of IKKβ impaired survival, proliferation, migration, and angiogenesis in primary lung ECs in vitro, in association with decreased expression of VEGFR2 and activation of downstream effectors. Loss of endothelial IKKβ in vivo induced broad changes in the lung transcriptome with downregulation of genes related to mitotic cell cycle, extracellular matrix (ECM)-receptor interaction, and vascular development, and the upregulation of genes related to inflammation. Computational deconvolution suggested that loss of endothelial IKKβ decreased general capillary, aerocyte capillary, and alveolar type I cell abundance. Taken together, these data definitively establish an essential role for endogenous endothelial IKKβ signaling during alveolarization. A deeper understanding of the mechanisms directing this developmental, physiological activation of IKKβ in the lung vasculature may provide novel targets for the development of strategies to enhance beneficial proangiogenic signaling in lung development and disease.NEW & NOTEWORTHY This study highlights the cell-specific complexity of nuclear factor kappa B signaling in the developing lung by demonstrating that inducible loss of IKKβ in endothelial cells impairs alveolarization, disrupts EC angiogenic function, and broadly represses genes important for vascular development.
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Affiliation(s)
- Shailaja Rao
- Department of Pediatrics, Stanford University School of Medicine, Palo Alto, California, United States
- Stanford Center for Excellence in Pulmonary Biology, Palo Alto, California, United States
| | - Min Liu
- Department of Pediatrics, Stanford University School of Medicine, Palo Alto, California, United States
- Stanford Center for Excellence in Pulmonary Biology, Palo Alto, California, United States
| | - Cristiana Iosef
- Department of Pediatrics, Stanford University School of Medicine, Palo Alto, California, United States
- Stanford Center for Excellence in Pulmonary Biology, Palo Alto, California, United States
| | - Carsten Knutsen
- Department of Pediatrics, Stanford University School of Medicine, Palo Alto, California, United States
- Stanford Center for Excellence in Pulmonary Biology, Palo Alto, California, United States
| | - Cristina M Alvira
- Department of Pediatrics, Stanford University School of Medicine, Palo Alto, California, United States
- Stanford Center for Excellence in Pulmonary Biology, Palo Alto, California, United States
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Cantu A, Gutierrez MC, Dong X, Leek C, Anguera M, Lingappan K. Modulation of Recovery from Neonatal Hyperoxic Lung Injury by Sex as a Biological Variable. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.09.552532. [PMID: 37609288 PMCID: PMC10441379 DOI: 10.1101/2023.08.09.552532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Recovery from lung injury during the neonatal period requires the orchestration of many biological pathways. The modulation of such pathways can drive the developing lung towards proper repair or persistent maldevelopment that can lead to a disease phenotype. Sex as a biological variable can regulate these pathways differently in the male and female lung exposed to neonatal hyperoxia. In this study, we assessed the contribution of cellular diversity in the male and female neonatal lung following injury. Our objective was to investigate sex and cell-type specific transcriptional changes that drive repair or persistent injury in the neonatal lung and delineate the alterations in the immune-endothelial cell communication networks using single cell RNA sequencing (sc-RNAseq) in a murine model of hyperoxic injury. We generated transcriptional profiles of >55,000 cells isolated from the lungs of postnatal day 1 (PND 1) and postnatal day 21 (PND 21) neonatal male and female C57BL/6 mice exposed to 95% FiO 2 between PND 1-5 (saccular stage of lung development). We show the presence of sex-based differences in the transcriptional states of lung endothelial and immune cells at PND 1 and PND 21. Furthermore, we demonstrate that biological sex significantly influences the response to injury, with a greater number of differentially expressed genes showing sex-specific patterns than those shared between male and female lungs. Pseudotime trajectory analysis highlighted genes needed for lung development that were altered by hyperoxia. Finally, we show intercellular communication between endothelial and immune cells at saccular and alveolar stages of lung development with sex-based biases in the crosstalk and identify novel ligand-receptor pairs. Our findings provide valuable insights into the cell diversity, transcriptional state, developmental trajectory, and cell-cell communication underlying neonatal lung injury, with implications for understanding lung development and possible therapeutic interventions while highlighting the crucial role of sex as a biological variable.
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Cantu A, Cantu Gutierrez M, Zhang Y, Dong X, Lingappan K. Endothelial to mesenchymal transition in neonatal hyperoxic lung injury: role of sex as a biological variable. Physiol Genomics 2023; 55:345-354. [PMID: 37395632 PMCID: PMC10625841 DOI: 10.1152/physiolgenomics.00037.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 06/12/2023] [Accepted: 06/27/2023] [Indexed: 07/04/2023] Open
Abstract
Bronchopulmonary dysplasia (BPD) is characterized by an arrest in alveolarization, abnormal vascular development, and variable interstitial fibroproliferation in the premature lung. Endothelial to mesenchymal transition (EndoMT) may be a source of pathological fibrosis in many organ systems. Whether EndoMT contributes to the pathogenesis of BPD is not known. We tested the hypothesis that pulmonary endothelial cells will show increased expression of EndoMT markers upon exposure to hyperoxia and that sex as a biological variable will modulate differences in expression. Wild-type (WT) and Cdh5-PAC CreERT2 (endothelial reporter) neonatal male and female mice (C57BL6) were exposed to hyperoxia (0.95 [Formula: see text]) either during the saccular stage of lung development (95% [Formula: see text]; postnatal day 1-5 [PND1-5]) or through the saccular and early alveolar stages of lung development (75% [Formula: see text]; PND1-14). Expression of EndoMT markers was measured in whole lung and endothelial cell mRNA. Sorted lung endothelial cells (from room air- and hyperoxia-exposed lungs) were subjected to bulk RNA-Seq. We show that exposure of the neonatal lung to hyperoxia leads to upregulation of key markers of EndoMT. Furthermore, using lung sc-RNA-Seq data from neonatal lung we were able to show that all endothelial cell subpopulations including the lung capillary endothelial cells show upregulation of EndoMT-related genes. Markers related to EndoMT are upregulated in the neonatal lung upon exposure to hyperoxia and show sex-specific differences. Mechanisms mediating EndoMT in the injured neonatal lung can modulate the response of the neonatal lung to hyperoxic injury and need further investigation.NEW & NOTEWORTHY We show that neonatal hyperoxia exposure increased EndoMT markers in the lung endothelial cells and this biological process exhibits sex-specific differences.
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Affiliation(s)
- Abiud Cantu
- Division of Neonatology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States
| | - Manuel Cantu Gutierrez
- Division of Neonatology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States
| | - Yuhao Zhang
- Division of Neonatology, Department of Pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas, United States
| | - Xiaoyu Dong
- Division of Neonatology, Department of Pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas, United States
| | - Krithika Lingappan
- Division of Neonatology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States
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