Abstract 16227: Histological Findings of Increased Extra-Cellular Matrix and Altered Cellular Composition Correlates With the Severity of Myxomatous Mitral Valve Degeneration
Objective: Abnormal accumulation of type III collagen, proteoglycans, and valvular interstitial cells (VICs) in mitral valve prolapse may lead to increased morphological severity of myxomatous mitral valve degeneration.
Methods: Twenty-five human posterior mitral valve leaflets (20 prolapsed leaflets with severe mitral regurgitation obtained at surgical repair and 5 normal posterior valve leaflets from autopsy) were studied. H&E stain (for valve morphology), Picro-Sirius Red stain (for type I and III collagen content) and Alcian Blue@ pH 2.5 (for proteoglycan content) were performed. Immunohistochemistry was used to assess cell phenotype using antibodies to fibroblast specific protein 1 (FSP1), smooth muscle alpha-actin (microfilaments) and vimentin (intermediate filaments). Valve layer thickness including atrialis, spongiosa and ventricularis were measured by ocular micrometer. Histological severity was graded by measuring the myxoid area infiltration of the spongiosa layer. Grade 0: no infiltration; 1: mild; 2: moderate; and grade 3 -severe infiltration including venticularis. Polarization microscopy was used to quantify type I and III collagen density and computerized planimetry to measure the proteoglycan density.
Results: See Table and Figure
Conclusion: Increased type III collagen, proteoglycan density and VIC proliferation in the spongiosa layer is associated with increased morphological severity of myxomatous mitral valve degeneration. Genetic and molecular signaling studies are needed to elucidate extracellular infiltration and VIC proliferation in the disease progression of mitral valve degeneration
- © 2011 by American Heart Association, Inc.