title: Valvular interstitial cells suppress calcification of valvular endothelial cells.
abstract: BACKGROUND
  Calcific aortic valve disease (CAVD) is the most common heart valve disease in the Western world. We previously proposed that valvular endothelial cells (VECs) replenish injured adult valve leaflets via endothelial-to-mesenchymal transformation (EndMT); however, whether EndMT contributes to valvular calcification is unknown. We hypothesized that aortic VECs undergo osteogenic differentiation via an EndMT process that can be inhibited by valvular interstitial cells (VICs).
  
  
  RESULTS
  VEC clones underwent TGF-β1-mediated EndMT, shown by significantly increased mRNA expression of the EndMT markers α-SMA (5.3 ± 1.2), MMP-2 (13.5 ± 0.6) and Slug (12 ± 2.1) (p < 0.05), (compared to unstimulated controls). To study the effects of VIC on VEC EndMT, clonal populations of VICs were derived from the same valve leaflets, placed in co-culture with VECs, and grown in control/TGF-β1 supplemented media. In the presence of VICs, EndMT was inhibited, shown by decreased mRNA expression of α-SMA (0.1 ± 0.5), MMP-2 (0.1 ± 0.1), and Slug (0.2 ± 0.2) (p < 0.05). When cultured in osteogenic media, VECs demonstrated osteogenic changes confirmed by increase in mRNA expression of osteocalcin (8.6 ± 1.3), osteopontin (3.7 ± 0.3), and Runx2 (5.5 ± 1.5). The VIC presence inhibited VEC osteogenesis, demonstrated by decreased expression of osteocalcin (0.4 ± 0.1) and osteopontin (0.2 ± 0.1) (p < 0.05). Time course analysis suggested that EndMT precedes osteogenesis, shown by an initial increase of α-SMA and MMP-2 (day 7), followed by an increase of osteopontin and osteocalcin (day 14).
  
  
  CONCLUSIONS
  The data indicate that EndMT may precede VEC osteogenesis. This study shows that VICs inhibit VEC EndMT and osteogenesis, indicating the importance of VEC-VIC interactions in valve homeostasis.
authors.affiliation: Center of Excellence in Vascular Biology, Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston.|Department of Cardiothoracic Surgery, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Jesper
authors.initials: J
authors.lastname: Hjortnaes
authors.affiliation: Vascular Biology Program and Department of Surgery, Boston Children's Hospital, Harvard Medical School, Boston.
authors.forename: Kayle
authors.initials: K
authors.lastname: Shapero
authors.affiliation: Center for Interdisciplinary Cardiovascular Sciences, Brigham and Women's Hospital, Harvard Medical School, Boston.
authors.forename: Claudia
authors.initials: C
authors.lastname: Goettsch
authors.affiliation: Center for Interdisciplinary Cardiovascular Sciences, Brigham and Women's Hospital, Harvard Medical School, Boston.
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Hutcheson
authors.affiliation: Center of Excellence in Vascular Biology, Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston.
authors.forename: Joshua
authors.initials: J
authors.lastname: Keegan
authors.affiliation: Department of Cardiothoracic Surgery, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Jolanda
authors.initials: J
authors.lastname: Kluin
authors.affiliation: Department of Thoracic Surgery, Boston Children's Hospital, Harvard Medical School, Boston.
authors.forename: John E
authors.initials: JE
authors.lastname: Mayer
authors.affiliation: Vascular Biology Program and Department of Surgery, Boston Children's Hospital, Harvard Medical School, Boston.
authors.forename: Joyce
authors.initials: J
authors.lastname: Bischoff
authors.affiliation: Center of Excellence in Vascular Biology, Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston.|Center for Interdisciplinary Cardiovascular Sciences, Brigham and Women's Hospital, Harvard Medical School, Boston.
authors.forename: Elena
authors.initials: E
authors.lastname: Aikawa
mesh_terms: D000818:Animals; D001021:Aortic Valve / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D001024:Aortic Valve Stenosis / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D001057:Apolipoproteins E / Q000172:deficiency / Q000235:genetics; D015415:Biomarkers / Q000378:metabolism; D002114:Calcinosis / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D002450:Cell Communication / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D002465:Cell Movement; D002478:Cells, Cultured; D018920:Coculture Techniques; D003470:Culture Media / Q000378:metabolism; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D058750:Epithelial-Mesenchymal Transition; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D018345:Mice, Knockout; D010012:Osteogenesis / Q000187:drug effects / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D012756:Sheep; D013997:Time Factors; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology
chemical_list: D001057:Apolipoproteins E; D015415:Biomarkers; D003470:Culture Media; D012333:RNA, Messenger; D053773:Transforming Growth Factor beta1
keywords: Calcific aortic valve disease; Calcification; Endothelial-to-mesenchymal transformation; Valvular endothelial cells; Valvular interstitial cells