Abstract 18700: Cardiac Fibroblast Co-Culture Promotes More Adult-Like Electrophysiological Properties in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes
Cardiac fibroblasts can influence cardiomyocyte structure and function through direct physical interaction and/or by the secretion of soluble factors. Here we assessed the effects of fibroblast co-culture on cardiomyocyte electrophysiology.
Ventricular fibroblasts from failing human hearts (DCM, n=4) were seeded onto human induced pluripotent stem cell-derived cardiomyocytes (iPS-CMs) at a ratio of 2:1 and cultured for 24 hours.
iPS-CMs alone were used as control. Ca2+ transients (CaT) and action potential duration (APD) were assessed optically using fluo-4 AM and di-8-ANEPPS. Data are presented as percentage change from control where appropriate.
iPS-CM CaT duration was significantly reduced with fibroblasts (-8.4±2.2% n=12 p<0.01). Sarcoplasmic reticulum (SR) Ca2+ uptake was highly upregulated (2.07±0.12s-1 vs 0.63±0.07s-1 in control n=26, 23 p<0.001), associated with a greater in SR Ca2+ content (F/F0: 3.74±0.11 vs 2.97±0.11 in control n=37, 32 p<0.001) and SERCA2a protein (1.02±0.08 vs 0.55±0.01 n=3 p<0.01). iPS-CMs with fibroblasts displayed a greater dependence on SR uptake for Ca2+ extrusion than other mechanisms (SR/NCX/Slow: 60.7/31.9/7.4% vs 23.3/70.9/5.8% in control).
Gly-Arg-Gly-Asp-Ser (GRGDS) is a fibronectin mimetic peptide known to stimulate integrins in a similar manner to the extracellular matrix (ECM) in vivo. Application of 10mM GRGDS recapitulated fibroblast-induced CaT changes, with a shorter time to peak (133.1±7.1 vs 220.4±7.9 ms; p<0.001) and time to transient decay (241.9±5.6 vs 381.6±19.6 ms; p<0.001). APD was substantially shorter after GRGDS (322.3±4.6 vs 552.8±21 ms in control; p<0.001). Response of GRGDS-treated iPSC-CMs to IKs and IK1 blockade was enhanced vs control (% baseline APD; 30μM chromanol 293B: 153.5±4.6 vs 119.1±1.7%, p<0.001; 100μM BaCl2: 141.0±2.6 vs 122.7±3.7%, p<0.001).
Cardiac fibroblasts promote more adult-like electrophysiological properties in iPSC-CMs and these effects are recapitulated by integrin activation, suggesting a role for fibroblast-derived ECM. Understanding the mechanisms through which this is achieved may provide insight into the development of myocyte electrophysiology, and help develop models which are more representative of adult human physiology.
Author Disclosures: C. Kane: None. C.M. Terracciano: None.
- © 2016 by American Heart Association, Inc.