Ca2+ Currents in Human Induced Pluripotent Stem Cell Derived Cardiomyocytes Effects of Two Different Culture Conditions
Human induced pluripotent stem cell derived cardiomyocytes (hiPSC CM) provide a unique opportunity to study human heart physiology and pharmacology and repair injured hearts. The suitability of hiPSC CM critically depends on how closely they share physiological properties of human adult cardiomyocytes (CM) Here we investigated whether a 3D engineered heart tissue (EHT) culture format favors maturation and addressed the L type Ca2+ current (ICa,L) as a readout. The results were compared with hiPSC CM cultured in conventional monolayer (ML) and to our previous data from human adult atrial and ventricular CM obtained when identical patch clamp protocols were used. HiPSC CM were two to three fold smaller than adult CM, independently of culture format [capacitance ML 45 1 pF (n 289) EHT 45 1 pF (n 460) atrial CM 87 3 pF (n 196) ventricular CM 126 8 pF (n 50) Only 88% of ML cells showed ICa, but all EHT. Basal ICa density was 10 1 pA/pF (n 207) for ML and 12 1 pA/pF (n 361) for EHT and was larger than in adult CM [7 1 pA/pF (p 0.05, n 196) for atrial CM and 6 1 pA/pF (p 0.05, n 47) for ventricular CM] However, ML and EHT showed robust T type Ca2+ currents (ICa,T) While Bay K 8644, that activates ICa,L directly, increased ICa,Lto the same extent in ML and EHT, b1 and b2 adrenoceptor effects were marginal in ML, but of same size as Bay K 8644 in EHT. The opposite was true for serotonin receptors. Sensitivity to b1 and b2 adrenoceptor stimulation was the same in EHT as in adult CM logEC50: 5.9 and 6.1 for norepinephrine (NE) and epinephrine (Epi) respectively) but very low concentrations of Rp 8 Br cAMPS were sufficient to suppress effects logEC50: 5.3 and 5.3 respectively for NE and Epi) Taken together, hiPSC CM express ICa,L at the same density as human adult CM, but, in contrast, possess robust ICa,T. Increased effects of catecholamines in EHT suggest more efficient maturation.
Front. Pharmacol.