title: Developmental heterogeneity of cardiac fibroblasts does not predict pathological proliferation and activation.
abstract: BACKGROUND
  Fibrosis is mediated partly by extracellular matrix-depositing fibroblasts in the heart. Although these mesenchymal cells are reported to have multiple embryonic origins, the functional consequence of this heterogeneity is unknown.
  
  
  OBJECTIVE
  We sought to validate a panel of surface markers to prospectively identify cardiac fibroblasts. We elucidated the developmental origins of cardiac fibroblasts and characterized their corresponding phenotypes. We also determined proliferation rates of each developmental subset of fibroblasts after pressure overload injury.
  
  
  RESULTS
  We showed that Thy1(+)CD45(-)CD31(-)CD11b(-)Ter119(-) cells constitute the majority of cardiac fibroblasts. We characterized these cells using flow cytometry, epifluorescence and confocal microscopy, and transcriptional profiling (using reverse transcription polymerase chain reaction and RNA-seq). We used lineage tracing, transplantation studies, and parabiosis to show that most adult cardiac fibroblasts derive from the epicardium, a minority arises from endothelial cells, and a small fraction from Pax3-expressing cells. We did not detect generation of cardiac fibroblasts by bone marrow or circulating cells. Interestingly, proliferation rates of fibroblast subsets on injury were identical, and the relative abundance of each lineage remained the same after injury. The anatomic distribution of fibroblast lineages also remained unchanged after pressure overload. Furthermore, RNA-seq analysis demonstrated that Tie2-derived and Tbx18-derived fibroblasts within each operation group exhibit similar gene expression profiles.
  
  
  CONCLUSIONS
  The cellular expansion of cardiac fibroblasts after transaortic constriction surgery was not restricted to any single developmental subset. The parallel proliferation and activation of a heterogeneous population of fibroblasts on pressure overload could suggest that common signaling mechanisms stimulate their pathological response.
authors.affiliation: From the Departments of Pathology and Developmental Biology, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, CA (S.R.A.); Department of Internal Medicine, Division of Cardiology, and Broad Stem Cell Research Center, University of California Los Angeles School of Medicine (S.R., M.T., P.Z., A.S., A.H., P.K., Z.T., R.A.); and Division of Blood and Marrow Transplantation, Department of Medicine (A.M. S.M.) and Department of Biology (K.S.V., K.R.-H.), Stanford University, CA.
authors.forename: Shah R
authors.initials: SR
authors.lastname: Ali
authors.affiliation: From the Departments of Pathology and Developmental Biology, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, CA (S.R.A.); Department of Internal Medicine, Division of Cardiology, and Broad Stem Cell Research Center, University of California Los Angeles School of Medicine (S.R., M.T., P.Z., A.S., A.H., P.K., Z.T., R.A.); and Division of Blood and Marrow Transplantation, Department of Medicine (A.M. S.M.) and Department of Biology (K.S.V., K.R.-H.), Stanford University, CA.
authors.forename: Sara
authors.initials: S
authors.lastname: Ranjbarvaziri
authors.affiliation: From the Departments of Pathology and Developmental Biology, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, CA (S.R.A.); Department of Internal Medicine, Division of Cardiology, and Broad Stem Cell Research Center, University of California Los Angeles School of Medicine (S.R., M.T., P.Z., A.S., A.H., P.K., Z.T., R.A.); and Division of Blood and Marrow Transplantation, Department of Medicine (A.M. S.M.) and Department of Biology (K.S.V., K.R.-H.), Stanford University, CA.
authors.forename: Mahmood
authors.initials: M
authors.lastname: Talkhabi
authors.affiliation: From the Departments of Pathology and Developmental Biology, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, CA (S.R.A.); Department of Internal Medicine, Division of Cardiology, and Broad Stem Cell Research Center, University of California Los Angeles School of Medicine (S.R., M.T., P.Z., A.S., A.H., P.K., Z.T., R.A.); and Division of Blood and Marrow Transplantation, Department of Medicine (A.M. S.M.) and Department of Biology (K.S.V., K.R.-H.), Stanford University, CA.
authors.forename: Peng
authors.initials: P
authors.lastname: Zhao
authors.affiliation: From the Departments of Pathology and Developmental Biology, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, CA (S.R.A.); Department of Internal Medicine, Division of Cardiology, and Broad Stem Cell Research Center, University of California Los Angeles School of Medicine (S.R., M.T., P.Z., A.S., A.H., P.K., Z.T., R.A.); and Division of Blood and Marrow Transplantation, Department of Medicine (A.M. S.M.) and Department of Biology (K.S.V., K.R.-H.), Stanford University, CA.
authors.forename: Ali
authors.initials: A
authors.lastname: Subat
authors.affiliation: From the Departments of Pathology and Developmental Biology, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, CA (S.R.A.); Department of Internal Medicine, Division of Cardiology, and Broad Stem Cell Research Center, University of California Los Angeles School of Medicine (S.R., M.T., P.Z., A.S., A.H., P.K., Z.T., R.A.); and Division of Blood and Marrow Transplantation, Department of Medicine (A.M. S.M.) and Department of Biology (K.S.V., K.R.-H.), Stanford University, CA.
authors.forename: Armin
authors.initials: A
authors.lastname: Hojjat
authors.affiliation: From the Departments of Pathology and Developmental Biology, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, CA (S.R.A.); Department of Internal Medicine, Division of Cardiology, and Broad Stem Cell Research Center, University of California Los Angeles School of Medicine (S.R., M.T., P.Z., A.S., A.H., P.K., Z.T., R.A.); and Division of Blood and Marrow Transplantation, Department of Medicine (A.M. S.M.) and Department of Biology (K.S.V., K.R.-H.), Stanford University, CA.
authors.forename: Paniz
authors.initials: P
authors.lastname: Kamran
authors.affiliation: From the Departments of Pathology and Developmental Biology, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, CA (S.R.A.); Department of Internal Medicine, Division of Cardiology, and Broad Stem Cell Research Center, University of California Los Angeles School of Medicine (S.R., M.T., P.Z., A.S., A.H., P.K., Z.T., R.A.); and Division of Blood and Marrow Transplantation, Department of Medicine (A.M. S.M.) and Department of Biology (K.S.V., K.R.-H.), Stanford University, CA.
authors.forename: Antonia M S
authors.initials: AM
authors.lastname: Müller
authors.affiliation: From the Departments of Pathology and Developmental Biology, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, CA (S.R.A.); Department of Internal Medicine, Division of Cardiology, and Broad Stem Cell Research Center, University of California Los Angeles School of Medicine (S.R., M.T., P.Z., A.S., A.H., P.K., Z.T., R.A.); and Division of Blood and Marrow Transplantation, Department of Medicine (A.M. S.M.) and Department of Biology (K.S.V., K.R.-H.), Stanford University, CA.
authors.forename: Katharina S
authors.initials: KS
authors.lastname: Volz
authors.affiliation: From the Departments of Pathology and Developmental Biology, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, CA (S.R.A.); Department of Internal Medicine, Division of Cardiology, and Broad Stem Cell Research Center, University of California Los Angeles School of Medicine (S.R., M.T., P.Z., A.S., A.H., P.K., Z.T., R.A.); and Division of Blood and Marrow Transplantation, Department of Medicine (A.M. S.M.) and Department of Biology (K.S.V., K.R.-H.), Stanford University, CA.
authors.forename: Zhaoyi
authors.initials: Z
authors.lastname: Tang
authors.affiliation: From the Departments of Pathology and Developmental Biology, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, CA (S.R.A.); Department of Internal Medicine, Division of Cardiology, and Broad Stem Cell Research Center, University of California Los Angeles School of Medicine (S.R., M.T., P.Z., A.S., A.H., P.K., Z.T., R.A.); and Division of Blood and Marrow Transplantation, Department of Medicine (A.M. S.M.) and Department of Biology (K.S.V., K.R.-H.), Stanford University, CA.
authors.forename: Kristy
authors.initials: K
authors.lastname: Red-Horse
authors.affiliation: From the Departments of Pathology and Developmental Biology, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, CA (S.R.A.); Department of Internal Medicine, Division of Cardiology, and Broad Stem Cell Research Center, University of California Los Angeles School of Medicine (S.R., M.T., P.Z., A.S., A.H., P.K., Z.T., R.A.); and Division of Blood and Marrow Transplantation, Department of Medicine (A.M. S.M.) and Department of Biology (K.S.V., K.R.-H.), Stanford University, CA. RArdehali@mednet.ucla.edu.
authors.forename: Reza
authors.initials: R
authors.lastname: Ardehali
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism; D002454:Cell Differentiation; D019070:Cell Lineage; D049109:Cell Proliferation; D003427:Cross Circulation; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors / Q000235:genetics / Q000378:metabolism; D010496:Pericardium / Q000166:cytology* / Q000254:growth & development; D042787:Receptor, TIE-2 / Q000235:genetics / Q000378:metabolism; D020825:T-Box Domain Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D015703:Antigens, CD; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D020825:T-Box Domain Proteins; C420983:Tbx18 protein, mouse; C068686:Pax3 protein, mouse; D042787:Receptor, TIE-2; C079086:Tek protein, mouse
keywords: aging; cardiac fibroblasts; fibrosis; growth and development