Discussion

High-throughput measurement of
Ca²⁺ transients in human iPSC-derived cardiomyocytes is expected to be a novel
useful method to evaluate drug compound-induced cardiotoxicity in vitro.

FDSS/μCELL (Hamamatsu) is an
imaging microplate reader for cell-based kinetic assays that measures
fluorescence/luminescence signals of all 96/384 wells in a microplate
simultaneously with up to 9 ms time interval and has been widely used for
measurements of intracellular Ca²⁺ concentration changes in drug discovery
field. Recently, we developed a 96-channel electrode array that is mounted on
the FDSS/μCELL, which can add electric field stimulation (EFS) to all 96 wells
of a microplate simultaneously.

 

Using this instrumental setup,
we measured Ca²⁺ transients in human iPSC-cardiomyocytes with a
calcium-sensitive fluorescent dye with 16 ms time interval under temperature
control (37 °C), under spontaneous beating of cardiomyocytes or while EFS was
added at various frequencies. We also examined effects of some ion channel
blockers on the Ca²⁺ transients in cardiomyocytes under spontaneous beating and
with EFS.