Electronic "expression" of the inward rectifier in cardiocytes derived from human-induced pluripotent stem cells.
BACKGROUND
Human-induced pluripotent stem cell (h-iPSC)-derived cardiac myocytes are a unique model in which human myocyte function and dysfunction are studied, especially those from patients with genetic disorders. They are also considered a major advance for drug safety testing. However, these cells have considerable unexplored potential limitations when applied to quantitative action potential (AP) analysis. One major factor is spontaneous activity and resulting variability and potentially anomalous behavior of AP parameters.


OBJECTIVE
To demonstrate the effect of using an in silico interface on electronically expressed I(K1), a major component lacking in h-iPSC-derived cardiac myocytes.


METHODS
An in silico interface was developed to express synthetic I(K1) in cells under whole-cell voltage clamp.


RESULTS
Electronic I(K1) expression established a physiological resting potential, eliminated spontaneous activity, reduced spontaneous early and delayed afterdepolarizations, and decreased AP variability. The initiated APs had the classic rapid upstroke and spike and dome morphology consistent with data obtained with freshly isolated human myocytes as well as the readily recognizable repolarization attributes of ventricular and atrial cells. The application of 1 µM of BayK-8644 resulted in anomalous AP shortening in h-iPSC-derived cardiac myocytes. When I(K1) was electronically expressed, BayK-8644 prolonged the AP, which is consistent with the existing results on native cardiac myocytes.


CONCLUSIONS
The electronic expression of I(K1) is a simple and robust method to significantly improve the physiological behavior of the AP and electrical profile of h-iPSC-derived cardiac myocytes. Increased stability enables the use of this preparation for a controlled quantitative analysis of AP parameters, for example, drug responsiveness, genetic disorders, and dynamic behavior restitution profiles.
Obstetrics and Gynecology; Physiology and Biophysics. Electronic address: bett@buffalo.edu.
Glenna C L
GC
Bett
Aaron D
AD
Kaplan
Agnieszka
A
Lis
Thomas R
TR
Cimato
Emmanuel S
ES
Tzanakakis
Qinlian
Q
Zhou
Michael J
MJ
Morales
Randall L
RL
Rasmusson
D000200:Action Potentials; D001145:Arrhythmias, Cardiac / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D020746:Calcium Channels, L-Type / Q000096:biosynthesis*; D002478:Cells, Cultured; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000166:cytology / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000378:metabolism; D018408:Patch-Clamp Techniques
D020746:Calcium Channels, L-Type
AP; APD; Arrhythmia; DAD; EAD; Heart; I(Ca); I(K1); I(K1,Synthetic); I(Na); I(f); I(to); Potassium channel; Repolarization; Stem cell; TS; Timothy syndrome; action potential; action potential duration; calcium current; dV/dt(max); delayed afterdepolarization; early afterdepolarization; h-iPSC; human-induced pluripotent stem cell; iPSC; induced pluripotent stem cell; inward rectifier potassium current; maximum rate of change of voltage with time; pacemaker current; sodium current; synthetic I(K1); transient outward potassium current