Abstract 16694: Human Cardiac Fibroblasts Speed Up Calcium Transient Decline and Prolong Action Potential Duration in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes by a Mechanism That Requires Direct Physical Interaction
Introduction: Cardiac fibroblasts can influence cardiomyocyte structure and function through direct physical interaction and/or by the secretion of soluble factors. Here we assess the relative importance of these different modalities of interaction with human pathological fibroblasts.
Methods: Ventricular fibroblasts were isolated from the explanted hearts of dilated cardiomyopathy (DCM) patients (n=3) and cultured with human induced pluripotent stem cell-derived cardiomyocytes (iPS-CMs) at a ratio of 2:1 for 24 hours in three groups: iPS-CMs with fibroblast conditioned medium (CMed), co-cultured in transwells to allow bi-directional paracrine communication but prevent physical contact (CC), and iPS-CMs in direct contact with fibroblasts (DC). iPS-CMs alone were used as control. iPS-CMs were field stimulated at 1 Hz and calcium transients and action potentials were recorded optically using the fluorescent dyes fluo-4 AM and di-8-ANNEPS respectively. Data is presented as percentage change from control.
Results: When the cells were cultured in direct contact calcium transient duration was significantly reduced compared with control while the other modalities had no effect (-6±1.8%, n=9, p<0.05). Calcium transient time to peak was prolonged by CMed and CC (+14.3±3.8% and +16.0±2.9% respectively, n=9, p<0.01) but was unchanged by DC.
Action potential upstroke velocity was significantly reduced by all culture groups (CMed -23.7±4.6% n=22, p<0.05 vs control, -37.5±4.8% n=10 and -46.38±2.6% n=16 CC and DC respectively, p<0.001 vs control) with the greatest reduction seen in DC (p<0.001 vs CMed and CC). Only culture in contact prolonged APD compared to control (+18.8±2.5%, n=22, p<0.001 vs control).
Conclusion: DCM fibroblasts influence iPS-CM electrophysiology through different modalities of interaction; however physical contact with fibroblasts has significant effects on cardiomyocytes not seen with soluble mediators alone. Whether these effects are mediated through physical intercellular connections, mechanical stretch or by altering paracrine signalling is unclear. With enhanced fibroblast activity a feature of almost all cardiac disease, further investigation of this interaction may identify potential therapeutic targets.
Author Disclosures: C. Kane: None. N. Hellen: None. T. Trantidou: None. J. Gorelik: None. C.M. Terracciano: None.
- © 2014 by American Heart Association, Inc.