Abstract 13795: Gene Expression Profiles in Engineered Cardiac Tissues Respond to Mechanical Loading and Inhibition of Tyrosine Kinase
Engineered cardiac tissues (ECTs) rapidly mature in vitro to form functional cardiac muscle and respond to mechanical load with increased proliferation and maturation. Little is known regarding the changes in regulatory transcript expression that occur during ECT maturation and in response to mechanical or pharmacologic interventions. We tested the hypothesis that global ECT gene expression patterns can be reproducibly quantified and are altered by mechanical load and by tyrosine kinase inhibition, similar to in vivo myocardium. ECTs generated from day 14.5 rat embryo ventricular cells were treated after 5 days in culture for 48 hours with mechanical stretch (5%, 0.5 Hz) and/or the p38 mitogen-activated protein kinase inhibitor BIRB796 (BIRB). RNA was isolated from 3 sets of experiments and assayed using an Agilent rat 4x44k V3 microarray and Pathway Analysis software for changes in transcript expression, regulatory molecules, and networks. Microarray transcript expression data were validated by QPCR for selected regulatory molecules. At the threshold of a 1.5 fold change in expression, mechanical stretch altered 1,559 transcripts, versus 1,411 for BIRB, and 1,846 for stretch plus BIRB. Somewhat surprisingly, expression was significantly altered for very few of the MAPK pathway members. Increased transcript expression following stretch, e.g Amphiregulin, FOS-like antigen, Interleukin-1 receptor-like 1, MAP3K6, etc., was reversed by BIRB796 and then partially restored by co-treatment by stretch and BIRB. However, some transcripts, e.g. MYH3, were increased by BIRB and not by stretch while others, e.g. FGF8 and Myosin Binding Protein C1, were additively reduced by stretch and BIRB. As anticipated, top altered pathways included Cellular Development, Cellular Growth & Proliferation; Tissue Development; Cell Death, and Cell Signaling. We found multiple shared cardiac transcription factor binding sites in the upstream promoters of transcripts altered by stretch and/or BIRB. Thus, ECTs display a broad spectrum of altered gene expression in response to mechanical load and/or tyrosine kinase inhibition, reflecting the complex regulation of proliferation and differentiation that occurs during ECT maturation and adaptation.
- © 2013 by American Heart Association, Inc.