title: Manipulation of valve composition to elucidate the role of collagen in aortic valve calcification.
abstract: BACKGROUND
  Extracellular matrix (ECM) disarray is found in calcific aortic valvular disease (CAVD), yet much remains to be learned about the role of individual ECM components in valvular interstitial cell (VIC) function and dysfunction. Previous clinical analyses have shown that calcification is associated with decreased collagen content, while previous in vitro work has suggested that the presence of collagen attenuates the responsiveness of VICs to pro-calcific stimuli. The current study uses whole leaflet cultures to examine the contributions of endogenous collagen in regulating the phenotype and calcification of VICs.
  
  
  METHODS
  A "top-down" approach was used to characterize changes in VIC phenotype in response to collagen alterations in the native 3D environment. Collagen-deficient leaflets were created via enzymatic treatment and cultured statically for six days in vitro. After culture, leaflets were harvested for analysis of DNA, proliferation, apoptosis, ECM composition, calcification, and gene/protein expression.
  
  
  RESULTS
  In general, disruption of collagen was associated with increased expression of disease markers by VICs in whole organ leaflet culture. Compared to intact control leaflets, collagen-deficient leaflets demonstrated increased VIC proliferation and apoptosis, increased expression of disease-related markers such as alpha-smooth muscle actin, alkaline phosphatase, and osteocalcin, and an increase in calcification as evidenced by positive von Kossa staining.
  
  
  CONCLUSIONS
  These results indicate that disruption of the endogenous collagen structure in aortic valves is sufficient to stimulate pathological consequences in valve leaflet cultures, thereby highlighting the importance of collagen and the valve extracellular matrix in general in maintaining homeostasis of the valve phenotype.
authors.forename: Karien J
authors.initials: KJ
authors.lastname: Rodriguez
authors.forename: Laura M
authors.initials: LM
authors.lastname: Piechura
authors.forename: Ana M
authors.initials: AM
authors.lastname: Porras
authors.affiliation: Department of Biomedical Engineering, University of Wisconsin-Madison, 1550 Engineering Drive, #2152, Madison, WI 53706, USA. kmasters@wisc.edu.
authors.forename: Kristyn S
authors.initials: KS
authors.lastname: Masters
mesh_terms: D000818:Animals; D001021:Aortic Valve / Q000378:metabolism* / Q000473:pathology; D017209:Apoptosis; D015415:Biomarkers / Q000378:metabolism; D002114:Calcinosis / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D049109:Cell Proliferation; D003094:Collagen / Q000378:metabolism*; D004261:DNA Replication; D005786:Gene Expression Regulation; D006349:Heart Valve Diseases / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D010641:Phenotype; D013552:Swine; D013997:Time Factors; D046509:Tissue Culture Techniques
chemical_list: D015415:Biomarkers; D003094:Collagen