Mitral valvular interstitial cells demonstrate regional, adhesional, and synthetic heterogeneity

Because various regions of the mitral valve contain distinctive extracellular matrix enabling the tissues to withstand diverse mechanical environments, we investigated phenotype and matrix production of porcine valvular interstitial cells (VICs) from different regions.

VICswere isolated from the chordae (MCh), the center of the anterior leaflet (AlCtr), and the posterior leaflet free edge (PlFree), then assayed for metabolic, growth, and adhesion rates; collagen and glycosaminoglycan (GAG) production, and phenotype using biochemical assays, flow cytometry, and immunocytochemistry.

The AlCtr VICs exhibited the fastest metabolism but slowest growth. PlFree cells grew the fastest, but demonstrated the least smooth muscle alpha-actin, vimentin, and internal complexity. AlCtr VICs secreted less collagen into the culture medium but more 4-sulfated GAGs than other cells. Adhesion-based separation resulted in altered secretion of sulfated GAGs by MCh and AlCtr cells but not by the PlFree cells.

VICs isolated from various regions of the mitral valve demonstrate phenotypic differences in culture, corresponding to the ability of the mitral valve to accommodate the physical stresses or altered hemodynamics that occur with injury or disease. Further understanding of VIC and valve mechanobiology could lead to novel medical or tissue engineering approaches to treat valve diseases.