Abstract 16189: Developing a Realistic in vitro Arrhythmia Model: Fibroblast Content Determines Conduction Velocity and Refractory Properties on 3-D Engineered Tissue Constructs
Background: We have used cardiac monolayers as in-vitro model for electrophysiology studies in fibrillation. However their 2-D structure cannot sustain scrolls, which have been shown as an important mechanism that maintains fibrillation. Recent developments in construction techniques of 3-D engineered tissue constructs (ETCs) have allowed precise control of cardiac myocytes and fibroblast content, which would be used to simulate native cardiac environments.
Objectives: We hypothesised that 1) conduction velocity (CV), maximum capture rate (MCR) and effective refractory period (ERP) would be determined by the amount of implanted fibroblast (FB) and that 2) varying these parameters would allow the development of a realistic 3-D in-vitro arrhythmia model.
Methods: 79 ETCs were engineered by seeding neonatal rat cardiomyocytes into collagen scaffolds. They were field stimulated at 1 Hz starting 72 hours after seeding. 38 ETCs were seeded globally with varying percentage of fibroblast, while 10 where seeded with a localized patch of fibroblast. The remaining ETCs were used as control. Optical mapping was performed at day 6 with local electrical stimulation. MCR was defined as the highest rate of basic stimulation train with local capture while ERP was measured using S1-S2 protocol. CV was computed from local activation times found on optical data using custom software.
Results: Measurements showed that 24/79 ETCs had spontaneous electrical activity. 58 ETCs captured to 1 Hz programmed stimulation. A negative correlation was found between MCR and global amount of fibroblast (p = 0.02) and between ERP and MCR (p = 0.09), while CV had a positive correlation with MCR (p=0.006). Action potential alternans and re-entry were also observed in 3 ETCs during pacing.
Conclusion: These results show that 1) conduction velocity and refractoriness are determined by fibroblast content; 2) Variable fibroblast content can be used to develop a realistic in-vitro model of arrhythmias.
- © 2011 by American Heart Association, Inc.