Asymmetrically paced engineered heart tissue recapitulates dyssynchronyassociated contractile impairment

J Stenzig, MN Hirt, M Lemme, M Lemoine, G Hoeppner, Y Etzion, T Eschenhagen

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Electrical conduction dyssynchrony is associated with impaired cardiac pump function and poor clinical outcome. Non-physiological action potential propagation can be caused by ectopic electrical pacing or by conduction disorders. The cellular and molecular effects of dyssynchrony are difficult to study in animal models due to multiple secondary effects. Here we set out to test if asymmetrically paced engineered heart tissue (EHT) can be useful to study drug treatment of dyssynchrony in vitro.
EHT in 24-well format was prepared using either 500,000 neonatal rat ventricular heart cells or 1 million human induced pluripotent stem cell (hiPSC) derived cardiomyocytes. Pacing electrode racks for asymmetrical pacing were constructed and evaluated by EHT excitation mapping under different conditions. EHTs were cultured for 3 weeks and contractility was regularly analysed using a camera and pattern recognition software. EHTs were either left
non-paced (spontaneous beating), or paced symmetrically or asymmetrically from day 4-5 on (2 V, 1.2 ms biphasic pulse; 2 Hz). Protein was extracted and analysed by Western-blot for Ca2+/calmodulin-dependent protein kinase II (CaMKII), P38 mitogen-activated protein kinase (p38MAPK, all isoforms), AKT (all isoforms), p-AKT (P-Ser473) and α-actinin-2.
The use of asymmetric pacing electrode racks led to electrical propagation through the EHT rather than simultaneous excitation as observed under symmetric pacing. Both rat and human EHT regularly displayed higher force development in symmetrically paced mode than in asymmetrically paced mode, and as compared to non-paced controls. Conduction velocity did not differ between groups after the culture period. Pacing prolonged both contraction and relaxation kinetics. While total CaMKII and p38MAPK protein per EHT did not differ, the abundance of α-actinin-2 was higher in symmetrically paced EHTs, reflecting more contractile units per cell. P-AKT was significantly less abundant in asymmetrically paced EHTs as had been described before for dyssynchrony.
Our findings argue for asymmetrically paced EHT as a promising in vitro platform to study drug effects on dyssynchrony.
Original languageEnglish GB
StatePublished - 2019


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