Abstract 188: Manipulation of Excitation-contraction Coupling in Cardiomyocytes Using Conductive Polyaniline Scaffolds

Abstract

The application of tissue engineered patches made of conductive polymer scaffolds combined with cardiomyocytes (CMs) could provide a dual method of improving the damaged myocardium after an infarction: firstly by introducing functional CMs to the area; secondly the conductive polymer could modulate electrical transmission across the scar tissue. Polyaniline (PANI) scaffolds are one such example, however, the consequences of growing CMs on conductive PANI scaffolds with regards to CM electrophysiology are unknown. In this study we assess the hypothesis that conductive PANI scaffolds affect CM calcium transients and action potential morphology in culture. Neonatal rat ventricular myocytes (NRVMs) and neonatal rat fibroblasts were co-cultured on conductive and non-conductive (sodium hydroxide treated) PANI scaffolds and remained viable after four days of culture, covering the surface of the construct. Compared to those cultured on non-conductive PANI scaffolds, NRVM cultured on conductive PANI scaffolds show faster calcium transients, measured using Fluo-4AM and field stimulated at 1 Hz, with a decrease in the time to peak (t p non-conductive=105±6 ms, t p conductive= 85±5 ms, p<0.05, n=6) and time to 50% (t 50 non-conductive=212±12 ms, t 50 conductive= 116±7 ms, p<0.001, n=6) and 90% decay (t 90 non-conductive=404±24 ms, t 90 conductive= 266±15 ms, p<0.001, n=6). Action potential morphology, assessed using FluoVolt membrane potential dye and stimulated at 1 Hz, remain unchanged for conductive and non-conductive PANI scaffolds. The PANI scaffolds are compatible with NRVMs and the cells have good viability after four days in culture. The conductive PANI scaffolds have a significant effect on myocyte calcium cycling but this is not caused by a change in action potential morphology. Further work is required to understand the mechanism behind the change in calcium handling in the CMs on the conductive PANI scaffolds.