title: Endocardial fibroelastosis is caused by aberrant endothelial to mesenchymal transition.
abstract: BACKGROUND
  Endocardial fibroelastosis (EFE) is a unique form of fibrosis, which forms a de novo subendocardial tissue layer encapsulating the myocardium and stunting its growth, and which is typically associated with congenital heart diseases of heterogeneous origin, such as hypoplastic left heart syndrome. Relevance of EFE was only recently highlighted through the establishment of staged biventricular repair surgery in infant patients with hypoplastic left heart syndrome, where surgical removal of EFE tissue has resulted in improvement in the restrictive physiology leading to the growth of the left ventricle in parallel with somatic growth. However, pathomechanisms underlying EFE formation are still scarce, and specific therapeutic targets are not yet known.
  
  
  OBJECTIVE
  Here, we aimed to investigate the cellular origins of EFE tissue and to gain insights into the underlying molecular mechanisms to ultimately develop novel therapeutic strategies.
  
  
  RESULTS
  By utilizing a novel EFE model of heterotopic transplantation of hearts from newborn reporter mice and by analyzing human EFE tissue, we demonstrate for the first time that fibrogenic cells within EFE tissue originate from endocardial endothelial cells via aberrant endothelial to mesenchymal transition. We further demonstrate that such aberrant endothelial to mesenchymal transition involving endocardial endothelial cells is caused by dysregulated transforming growth factor beta/bone morphogenetic proteins signaling and that this imbalance is at least in part caused by aberrant promoter methylation and subsequent transcriptional suppression of bone morphogenetic proteins 5 and 7. Finally, we provide evidence that supplementation of exogenous recombinant bone morphogenetic proteins 7 effectively ameliorates endothelial to mesenchymal transition and experimental EFE in rats.
  
  
  CONCLUSIONS
  In summary, our data point to aberrant endothelial to mesenchymal transition as a common denominator of infant EFE development in heterogeneous, congenital heart diseases, and to bone morphogenetic proteins 7 as an effective treatment for EFE and its restriction of heart growth.
authors.affiliation: From the Department of Cardiology and Pneumology (X.X., F.A., E.M.Z.), Department of Nephrology and Rheumatology (B.T., M.Z.), University Medical Center of Göttingen, Georg-August University, Göttingen, Germany; Department of Cardiac Surgery, Boston Children's Hospital, Harvard Medical School, MA (I.F., I.V., P.J.d N.); Division of Matrix Biology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (T.Z.H., R.K., E.M.Z.); Lab Genetica Molecolare, Papa Giovanni XXIII Hospital, Bergamo, Italy (M.I.); Department of Cancer Biology and the Metastasis Research Center, University of Texas MD Anderson Cancer Center, Houston (R.K.); and DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Germany (E.M.Z.).
authors.forename: Xingbo
authors.initials: X
authors.lastname: Xu
authors.affiliation: From the Department of Cardiology and Pneumology (X.X., F.A., E.M.Z.), Department of Nephrology and Rheumatology (B.T., M.Z.), University Medical Center of Göttingen, Georg-August University, Göttingen, Germany; Department of Cardiac Surgery, Boston Children's Hospital, Harvard Medical School, MA (I.F., I.V., P.J.d N.); Division of Matrix Biology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (T.Z.H., R.K., E.M.Z.); Lab Genetica Molecolare, Papa Giovanni XXIII Hospital, Bergamo, Italy (M.I.); Department of Cancer Biology and the Metastasis Research Center, University of Texas MD Anderson Cancer Center, Houston (R.K.); and DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Germany (E.M.Z.).
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Friehs
authors.affiliation: From the Department of Cardiology and Pneumology (X.X., F.A., E.M.Z.), Department of Nephrology and Rheumatology (B.T., M.Z.), University Medical Center of Göttingen, Georg-August University, Göttingen, Germany; Department of Cardiac Surgery, Boston Children's Hospital, Harvard Medical School, MA (I.F., I.V., P.J.d N.); Division of Matrix Biology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (T.Z.H., R.K., E.M.Z.); Lab Genetica Molecolare, Papa Giovanni XXIII Hospital, Bergamo, Italy (M.I.); Department of Cancer Biology and the Metastasis Research Center, University of Texas MD Anderson Cancer Center, Houston (R.K.); and DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Germany (E.M.Z.).
authors.forename: Tachi
authors.initials: T
authors.lastname: Zhong Hu
authors.affiliation: From the Department of Cardiology and Pneumology (X.X., F.A., E.M.Z.), Department of Nephrology and Rheumatology (B.T., M.Z.), University Medical Center of Göttingen, Georg-August University, Göttingen, Germany; Department of Cardiac Surgery, Boston Children's Hospital, Harvard Medical School, MA (I.F., I.V., P.J.d N.); Division of Matrix Biology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (T.Z.H., R.K., E.M.Z.); Lab Genetica Molecolare, Papa Giovanni XXIII Hospital, Bergamo, Italy (M.I.); Department of Cancer Biology and the Metastasis Research Center, University of Texas MD Anderson Cancer Center, Houston (R.K.); and DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Germany (E.M.Z.).
authors.forename: Ivan
authors.initials: I
authors.lastname: Melnychenko
authors.affiliation: From the Department of Cardiology and Pneumology (X.X., F.A., E.M.Z.), Department of Nephrology and Rheumatology (B.T., M.Z.), University Medical Center of Göttingen, Georg-August University, Göttingen, Germany; Department of Cardiac Surgery, Boston Children's Hospital, Harvard Medical School, MA (I.F., I.V., P.J.d N.); Division of Matrix Biology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (T.Z.H., R.K., E.M.Z.); Lab Genetica Molecolare, Papa Giovanni XXIII Hospital, Bergamo, Italy (M.I.); Department of Cancer Biology and the Metastasis Research Center, University of Texas MD Anderson Cancer Center, Houston (R.K.); and DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Germany (E.M.Z.).
authors.forename: Björn
authors.initials: B
authors.lastname: Tampe
authors.affiliation: From the Department of Cardiology and Pneumology (X.X., F.A., E.M.Z.), Department of Nephrology and Rheumatology (B.T., M.Z.), University Medical Center of Göttingen, Georg-August University, Göttingen, Germany; Department of Cardiac Surgery, Boston Children's Hospital, Harvard Medical School, MA (I.F., I.V., P.J.d N.); Division of Matrix Biology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (T.Z.H., R.K., E.M.Z.); Lab Genetica Molecolare, Papa Giovanni XXIII Hospital, Bergamo, Italy (M.I.); Department of Cancer Biology and the Metastasis Research Center, University of Texas MD Anderson Cancer Center, Houston (R.K.); and DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Germany (E.M.Z.).
authors.forename: Fouzi
authors.initials: F
authors.lastname: Alnour
authors.affiliation: From the Department of Cardiology and Pneumology (X.X., F.A., E.M.Z.), Department of Nephrology and Rheumatology (B.T., M.Z.), University Medical Center of Göttingen, Georg-August University, Göttingen, Germany; Department of Cardiac Surgery, Boston Children's Hospital, Harvard Medical School, MA (I.F., I.V., P.J.d N.); Division of Matrix Biology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (T.Z.H., R.K., E.M.Z.); Lab Genetica Molecolare, Papa Giovanni XXIII Hospital, Bergamo, Italy (M.I.); Department of Cancer Biology and the Metastasis Research Center, University of Texas MD Anderson Cancer Center, Houston (R.K.); and DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Germany (E.M.Z.).
authors.forename: Maria
authors.initials: M
authors.lastname: Iascone
authors.affiliation: From the Department of Cardiology and Pneumology (X.X., F.A., E.M.Z.), Department of Nephrology and Rheumatology (B.T., M.Z.), University Medical Center of Göttingen, Georg-August University, Göttingen, Germany; Department of Cardiac Surgery, Boston Children's Hospital, Harvard Medical School, MA (I.F., I.V., P.J.d N.); Division of Matrix Biology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (T.Z.H., R.K., E.M.Z.); Lab Genetica Molecolare, Papa Giovanni XXIII Hospital, Bergamo, Italy (M.I.); Department of Cancer Biology and the Metastasis Research Center, University of Texas MD Anderson Cancer Center, Houston (R.K.); and DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Germany (E.M.Z.).
authors.forename: Raghu
authors.initials: R
authors.lastname: Kalluri
authors.affiliation: From the Department of Cardiology and Pneumology (X.X., F.A., E.M.Z.), Department of Nephrology and Rheumatology (B.T., M.Z.), University Medical Center of Göttingen, Georg-August University, Göttingen, Germany; Department of Cardiac Surgery, Boston Children's Hospital, Harvard Medical School, MA (I.F., I.V., P.J.d N.); Division of Matrix Biology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (T.Z.H., R.K., E.M.Z.); Lab Genetica Molecolare, Papa Giovanni XXIII Hospital, Bergamo, Italy (M.I.); Department of Cancer Biology and the Metastasis Research Center, University of Texas MD Anderson Cancer Center, Houston (R.K.); and DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Germany (E.M.Z.).
authors.forename: Michael
authors.initials: M
authors.lastname: Zeisberg
authors.affiliation: From the Department of Cardiology and Pneumology (X.X., F.A., E.M.Z.), Department of Nephrology and Rheumatology (B.T., M.Z.), University Medical Center of Göttingen, Georg-August University, Göttingen, Germany; Department of Cardiac Surgery, Boston Children's Hospital, Harvard Medical School, MA (I.F., I.V., P.J.d N.); Division of Matrix Biology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (T.Z.H., R.K., E.M.Z.); Lab Genetica Molecolare, Papa Giovanni XXIII Hospital, Bergamo, Italy (M.I.); Department of Cancer Biology and the Metastasis Research Center, University of Texas MD Anderson Cancer Center, Houston (R.K.); and DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Germany (E.M.Z.).
authors.forename: Pedro J
authors.initials: PJ
authors.lastname: Del Nido
authors.affiliation: From the Department of Cardiology and Pneumology (X.X., F.A., E.M.Z.), Department of Nephrology and Rheumatology (B.T., M.Z.), University Medical Center of Göttingen, Georg-August University, Göttingen, Germany; Department of Cardiac Surgery, Boston Children's Hospital, Harvard Medical School, MA (I.F., I.V., P.J.d N.); Division of Matrix Biology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (T.Z.H., R.K., E.M.Z.); Lab Genetica Molecolare, Papa Giovanni XXIII Hospital, Bergamo, Italy (M.I.); Department of Cancer Biology and the Metastasis Research Center, University of Texas MD Anderson Cancer Center, Houston (R.K.); and DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Germany (E.M.Z.). Elisabeth.zeisberg@med.uni-goettingen.de.
authors.forename: Elisabeth M
authors.initials: EM
authors.lastname: Zeisberg
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D015703:Antigens, CD / Q000235:genetics; D015415:Biomarkers; D055419:Bone Morphogenetic Protein 7 / Q000235:genetics / Q000502:physiology / Q000627:therapeutic use; D015820:Cadherins / Q000235:genetics; D054338:Cell Transdifferentiation / Q000235:genetics / Q000502:physiology*; D002478:Cells, Cultured; D019175:DNA Methylation; D004695:Endocardial Fibroelastosis / Q000188:drug therapy / Q000473:pathology*; D004699:Endocardium / Q000473:pathology*; D004848:Epithelium / Q000473:pathology*; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D016027:Heart Transplantation; D006801:Humans; D018636:Hypoplastic Left Heart Syndrome / Q000473:pathology / Q000601:surgery; D007223:Infant; D007231:Infant, Newborn; D008648:Mesoderm / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D011401:Promoter Regions, Genetic; D051381:Rats; D011917:Rats, Inbred Lew; D011994:Recombinant Proteins / Q000627:therapeutic use; D015398:Signal Transduction / Q000502:physiology; D051785:Smad Proteins / Q000235:genetics / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000502:physiology; D016042:Transplantation, Heterotopic; D000099152:Cadherin 5
chemical_list: D015703:Antigens, CD; D015415:Biomarkers; D055419:Bone Morphogenetic Protein 7; D015820:Cadherins; D011994:Recombinant Proteins; D051785:Smad Proteins; D016212:Transforming Growth Factor beta; D000099152:Cadherin 5; C525819:BMP7 protein, human
keywords: congenital heart disease; endocardial fibroelastosis; endocardium; endothelial cell; fibrosis; hypoplastic left heart syndrome