Title: Influence of Material Chemistry on Valvular Interstitial Cells In Vitro
Authors:: Matthew N. Rush1,2, Eduardo Esquivel2, and Elizabeth L. Hedberg-Dirk2,3
Affiliations: 1Department of Nanoscience and Microsystems, Center for Microengineered Materials, University of New Mexico, 2Center for Biomedical Engineering, University of New Mexico, 3Department of Chemical and Nuclear Engineering, University of New Mexico
Abstract: The overall goal of our laboratory is to develop material platforms for the tissue engineering of aortic heart valve leaflets. The aim of this work is to examine the primary cells of the heart valve, valvular interstitial cells (VICs), on substrates with well-defined chemistries to determine the influence of substrate chemistry on VIC attachment, proliferation, and differentiation in vitro. We hypothesized that COO- terminated self-assembled monolayers (SAMs) illicit an increase in proliferation and differentiation to an extracellular matrix synthesizing phenotype due to the negatively charged environment present during valvogenesis. To this end, SAMs presenting the physiologically relevant functional groups of CH3 (hydrophobic), OH (hydrophilic), COO- (negative at physiological pH), or NH2+ (positive at physiological pH) were used. Formation of SAMs was achieved through deposition of chromium (15 Å) and gold (300 Å) onto glass slides followed by incubation in an ethanol solution containing 1mM short chain thiols with the desired end functional group. Examination of surface chemistry through goniometry revealed contact angles of 107°+/-0.32°, 23°+/-0.7°, 43°+/-2.50°, & 26°+/-1.22° for CH3, OH, NH2+, & COO- surfaces, respectively. For cell studies, VICs were harvested using a collagenase digestion of the aortic valve leaflets from excised porcine hearts. Evaluation of attachment and proliferation was determined through microscopy and a quantitative colorimetric assay while phenotypic expression was determined through qPCR genetic analysis. This research allows for the understanding of VIC behavior in chemically controlled two-dimensional environments to be translated into the intelligent design of synthetic three-dimensional scaffolds for regeneration of aortic heart leaflet tissue.