title: Simulation of early calcific aortic valve disease in a 3D platform: A role for myofibroblast differentiation.
abstract: Calcific aortic valve disease (CAVD) is the most prevalent valve disease in the Western world. Recent difficulty in translating experimental results on statins to beneficial clinical effects warrants the need for understanding the role of valvular interstitial cells (VICs) in CAVD. In two-dimensional culture conditions, VICs undergo spontaneous activation similar to pathological differentiation, which intrinsically limits the use of in vitro models to study CAVD. Here, we hypothesized that a three-dimensional (3D) culture system based on naturally derived extracellular matrix polymers, mimicking the microenvironment of native valve tissue, could serve as a physiologically relevant platform to study the osteogenic differentiation of VICs.
  
  
  
  Aortic VICs loaded into 3D hydrogel constructs maintained a quiescent phenotype, similar to healthy human valves. In contrast, osteogenic environment induced an initial myofibroblast differentiation (hallmarked by increased alpha smooth muscle actin [α-SMA] expression), followed by an osteoblastic differentiation, characterized by elevated Runx2 expression, and subsequent calcific nodule formation recapitulating CAVD conditions. Silencing of α-SMA under osteogenic conditions diminished VIC osteoblast-like differentiation and calcification, indicating that a VIC myofibroblast-like phenotype may precede osteogenic differentiation in CAVD.
  
  
  
  Using a 3D hydrogel model, we simulated events that occur during early CAVD in vivo and provided a platform to investigate mechanisms of CAVD. Differentiation of valvular interstitial cells to myofibroblasts was a key mechanistic step in the process of early mineralization. This novel approach can provide important insight into valve pathobiology and serve as a promising tool for drug screening.
authors.affiliation: Center of Excellence in Vascular Biology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA; Center for Biomedical Engineering, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA; Department of Cardiothoracic Surgery, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Jesper
authors.initials: J
authors.lastname: Hjortnaes
authors.affiliation: Center for Interdisciplinary Cardiovascular Sciences, Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Claudia
authors.initials: C
authors.lastname: Goettsch
authors.affiliation: Center for Interdisciplinary Cardiovascular Sciences, Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Hutcheson
authors.affiliation: Center for Biomedical Engineering, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA; Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, USA.
authors.forename: Gulden
authors.initials: G
authors.lastname: Camci-Unal
authors.affiliation: Center of Excellence in Vascular Biology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Lilian
authors.initials: L
authors.lastname: Lax
authors.affiliation: Center of Excellence in Vascular Biology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Katrin
authors.initials: K
authors.lastname: Scherer
authors.affiliation: Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, USA.
authors.forename: Simon
authors.initials: S
authors.lastname: Body
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Frederick J
authors.initials: FJ
authors.lastname: Schoen
authors.affiliation: Department of Cardiothoracic Surgery, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Jolanda
authors.initials: J
authors.lastname: Kluin
authors.affiliation: Center for Biomedical Engineering, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA; Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, USA; Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA. Electronic address: alik@bwh.harvard.edu.
authors.forename: Ali
authors.initials: A
authors.lastname: Khademhosseini
authors.affiliation: Center of Excellence in Vascular Biology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA; Center for Interdisciplinary Cardiovascular Sciences, Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA. Electronic address: eaikawa@partners.org.
authors.forename: Elena
authors.initials: E
authors.lastname: Aikawa
mesh_terms: D000199:Actins / Q000235:genetics; D000818:Animals; D001021:Aortic Valve / Q000378:metabolism / Q000473:pathology*; D001024:Aortic Valve Stenosis / Q000209:etiology* / Q000378:metabolism* / Q000473:pathology; D017209:Apoptosis; D015415:Biomarkers; D002114:Calcinosis / Q000209:etiology* / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D018929:Cell Culture Techniques; D002453:Cell Cycle; D002454:Cell Differentiation; D002470:Cell Survival; D005455:Fluorescent Antibody Technique; D020868:Gene Silencing; D006801:Humans; D020100:Hydrogels; D066298:In Vitro Techniques; D058628:Myofibroblasts / Q000166:cytology / Q000378:metabolism; D010641:Phenotype; D013552:Swine
chemical_list: D000199:Actins; D015415:Biomarkers; D020100:Hydrogels
keywords: Aortic valve stenosis; Calcific aortic valve disease; Hydrogels; Tissue engineering; Valvular interstitial cells