DUAL CARDIOMYOCYTE CLUSTER DETECTION OF THE DIFFERENT TYPES OF ARRHYTHMOGENIC POTENTIAL OF DRUGS

Single cardiomyocytes present unstable beating patterns, which can be partially compensated in a clustered syncytium. Here we present a novel biosensor composed of two clusters of cardiomyocytes for advanced detection of cardiac arrhythmias and
subsequent drug testing.  hESC's clusters were differentiated into CMs syncytium. Two such clusters were seeded
on adherent plates in the vicinity and spontaneously formed electrically connected syncytium resembling the human myocardium and its conductive system. Contraction of twin clustered spontaneously synchronized within 4 days. The Atomic Force Microscope (AFM) vertical deflection enabled measurement and calculation of absolute
cardiomyocyte contraction force, while lateral force measurement can distinguish synchronized and independent contraction behavior of twin clusters. Caffeine induces arrhythmia as a model drug. Subsequent beating patterns were monitored by AFM
lateral force recording and calcium fluorescence imaging as a reference method for describing non-synchronized contractions of cardiomyocytes.
Caffeine increased the beat rate of the syncytium. This was reflected by both the change in vertical and lateral deflection. A significant increase in standard deviation was observed immediately after caffeine injection for both the lateral and the vertical
deflection. Further, caffeine affected the synchronization of vertical and lateral displacement of the AFM cantilever, Interpreted as defects in signal spreading through the bridge resulting in the irregular beat of the two clusters.

Acknowledgments
Ministry of Health of the Czech Republic, grant NU20-06-00156 has financially supported this work. CIISB,
Instruct-CZ Centre of Instruct-ERIC EU consortium, funded by MEYS CR infrastructure project
LM2018127, is gratefully acknowledged for the financial support of the measurements at the CF
Nanobiotechnology.