Abstract P2098: The Effect Of Cyclic Stretch On Cardiac Fibroblasts

Abstract

Introduction: Cardiac fibrosis is the accumulation of extracellular matrix proteins in the interstitium and contributes to heart failure. The main source of cardiac fibrosis is cardiac fibroblasts (cFBs), which are activated as a result of pressure overload. Activated fibroblasts, also known as myofibroblasts, express α-smooth muscle actin (α-SMA) and have an increased production of collagen. Here, the objective was to study the behavior of induced pluripotent stem cell (iPSC) derived cFBs in response to pro-fibrotic cytokines and mechanical stress. Methods: Confluent iPSC monolayers were differentiated into cFBs using the protocol in Figure 1A. Afterwards, the differentiated cells were exposed to 10 ng/ml transforming growth factor β (TGFβ) and 10% cyclic stretch at 1 Hz for 3 days using the Flexcell FX-6000 system. Results: iPSC-cFBs had a fibroblast-like morphology. Furthermore, the presence of cardiac ( GATA4, TCF21 ) and fibroblast ( VIM, PDGFRα, DDR2 ) markers at gene and protein levels confirmed the cFB identity. TGF-β stimulation resulted in increased mRNA and protein levels of α-SMA. Additionally, stretching reduced collagen 1 mRNA and protein expression (Fig. 1B/C). Furthermore, stretching was able to protect the cells from TGF-β stimulation, significantly reducing α-SMA and collagen 1 protein and mRNA levels. This was associated with decreased mRNA expression of TGF-β downstream targets ( PAI1). Conclusion: Cyclic mechanical stretch reduces cFB activation and can protect against TGF-β stimulation, resulting in reduced collagen production and transdifferentiation into myofibroblasts.