Sherket B. Peterson’s research while affiliated with University of North Carolina at Chapel Hill and other places

The proteoglycan decorin putatively inhibits cell adhesion and cell migration on various extracellular matrix substrates through interactions with beta(1) integrins. This study, therefore, examined the adhesive, migration, and proliferative characteristics of decorin knockout (Dcn(-/-)) murine embryonic fibroblasts compared to wild-type controls on collagen-coated, fibronectin-coated, and uncoated tissue culture plates. The Dcn(-/-) cells showed significantly greater proliferation than wild-type controls on all substrates. The Dcn(-/-) cells also showed significantly greater adhesion to both collagen and fibronectin; both cell types showed greater adhesion to collagen. The addition of exogenous decorin had a differential effect on adhesion to collagen between cell types, but not on fibronectin. For collagen, blocking either alpha(2) or beta(1) integrin subunits significantly reduced adhesion for Dcn(-/-) cells; whereas for fibronectin, blocking either the alpha(5) or beta(1) integrin subunits reduced adhesion for both cell types. Decorin and the alpha(5)beta(1) integrin may have lesser roles in adhesion to fibronectin than previously presumed. Finally, compared to wild-type cells, Dcn(-/-) cells showed greater migration on both uncoated and collagen substrates. This study demonstrates that decorin affects the biology of various integrins that participate in cell proliferation, adhesion, and migration on various substrates.

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.

Decorin (DCN), a class I member of the small leucine-rich proteoglycan (SLRP) family, is composed of a protein core of approximately 40kDa [1, 2] substituted with a single glycosaminoglycan (GAG) chain of chondroiton/dermatan sulfate on the N-terminal site [3]. DCN has been reported to interact with collagen [4,5] via its core protein, influence collagen fibrillogenesis [6], and inhibit the growth rates of various cell types when added exogenously to cell cultures [5,6]. There has recently been growing interest and studies in DCN related research using the knockout (KO) mice model which provides an excellent example of inherited disorders that stem from deficiencies in decorin expression [7]. Skin and tendon tissues from DCN KO mice have been characterized as being extremely fragile with significantly reduced strength and stiffness [8, 9]. The DCN KO tissues also show potential functional biglycan compensation [9] and at the microscopic level collagen fibrils with highly irregular diameters, abnormal lateral fusion, and loose packing [6] in contrast to wild type (WT) mice. Despite the intensive investigation of the DCN KO mice, the complexity of the animal model makes it difficult to assess the actual influence of decorin. In an attempt to take a more simplistic approach 2D cell phenotypic characterization studies were performed in addition to studying cell growth, contraction, and matrix organization in 3-D models to show the very distinct biochemical responses to type I collagen when compared to WT control cells.

Left Atrium (LA) size has prognostic importance in a variety of cardiac conditions [1] and is known to be enlarged with decreased contractile function in patients with congestive heart failure (CHF) [2]. Nearly 5 million Americans have CHF [3] and a majority of these patients display diastolic dysfunction, which is an abnormality in the left ventricle (LV) myocardial relaxation and/or compliance that alters the ease with which the blood is accepted into the LV from the LA during diastole [4]. Due to abnormal LV filling, the LA experiences intense stress and elevated pressures. In fact, the left atrium is exposed directly to the LV diastolic pressure through the open mitral valve (MV) and because of its thin wall structure it tends to dilate with increasing pressure [5]. This augmented LA size and increased contractility and booster function are some of the mechanisms compensating for decreased early filling in patients with reduced LV compliance [6]. Over time, the LA compensatory contribution decreases, this may lead to intrinsic left atrium dysfunction [7]. This in turn results in a progressive decline in health unless the hearts’ inadequate blood flow is augmented by a left ventricular assist device (LVAD). Although LVAD implantation rest the heart, restores function to the ventricle [8], and improve overall function [9], its effects on the left atrium remain unclear. The purpose of the present study was to use 2D and Doppler echocardiography to define the parameters for assessing LVAD unloading and determine its effect on LA diameter, area, volume, and pressure in patients prior to and following LVAD implantation.