Background Cardiotoxicity is a leading cause for drug attrition during pharmaceutical development and has resulted in numerous preventable patient deaths. Incidents of adverse cardiac drug reactions are more common in patients with pre-existing heart disease than the general population. Here we generated a library of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) from patients with various hereditary cardiac disorders to model differences in cardiac drug toxicity susceptibility for patients of different genetic backgrounds. Methods and Results Action potential duration (APD) and drug-induced arrhythmia were measured at the single cell level in hiPSC-CMs derived from healthy subjects and patients with hereditary long QT syndrome (LQT), familial hypertrophic cardiomyopathy (HCM), and familial dilated cardiomyopathy (DCM). Disease phenotypes were verified in LQT, HCM, and DCM iPSC-CMs by immunostaining and single cell patch clamp. Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) and the human ether-a-go-go-related gene (hERG) expressing human embryonic kidney (HEK293) cells were used as controls. Single cell PCR confirmed expression of all cardiac ion channels in patient-specific hiPSC-CMs as well as hESC-CMs, but not in HEK293 cells. Disease-specific hiPSC-CMs demonstrated increased susceptibility to known cardiotoxic drugs as measured by APD and quantification of drug-induced arrhythmias such as early after depolarizations (EADs) and delayed after depolarizations (DADs). Conclusions We have recapitulated drug-induced cardiotoxicity profiles for healthy subjects, LQT, HCM, and DCM patients at the single cell level for the first time. Our data indicate that healthy and diseased individuals exhibit different susceptibilities to cardiotoxic drugs and that use of disease-specific hiPSC-CMs may predict adverse drug responses more accurately than standard hERG test or healthy control hiPSC-CM/hESC-CM screening assays.

Background Drug-induced arrhythmia is the most common cause of drug development failure and withdrawal from market. This study tested whether human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) combined with a low-impedance microelectrode array (MEA) system could improve upon industry-standard, preclinical cardiotoxicity screening methods, identify the effects of well-characterized drugs, and elucidate underlying risk factors for drug-induced arrhythmia. Human iPSC-CMs may be advantageous over immortalized cell lines because they possess similar functional characteristics as primary human cardiomyocytes and can be generated in unlimited quantities. Methods and Results Pharmacological responses of beating embryoid bodies (EBs) exposed to a comprehensive panel of drugs at 65 to 95 days post-induction were determined. Responses of hiPSC-CMs to drugs were qualitatively and quantitatively consistent with the reported drug effects in literature. Torsadogenic hERG blockers such as sotalol and quinidine produced statistically and physiologically significant effects, consistent with patch-clamp studies on human embryonic stem cell-derived cardiomyocytes (hESC-CMs). False negative and false positive hERG blockers were identified accurately. Consistent with published studies using animal models, early afterdepolarizations (EADs) and ectopic beats were observed in 33% and 40% of embryoid bodies treated with sotalol and quinidine, respectively, compared to negligible EADs and ectopic beats in untreated controls. Conclusions We found that drug-induced arrhythmias can be recapitulated in hiPSC-CMs and documented with MEA. Our data indicate that the MEA/hiPSC-CM assay is a sensitive, robust, and efficient platform for testing drug effectiveness and for arrhythmia screening. We believe that this system holds great potential for reducing drug development costs and may provide significant advantages over current industry standard assays that use immortalized cell lines or animal models.

Background Brugada Syndrome is a disorder associated with characteristic ECG precordial ST elevation and predisposes afflicted patients to ventricular fibrillation and sudden cardiac death. Despite marked achievements in outlining the organ level pathophysiology of the disorder, the understanding of human cellular phenotype has lagged due to lack of adequate human cellular models of the disorder. Methods and Results We recruited two patients with Type 1 Brugada Syndrome (BrS) carrying two different SCN5A variants and two healthy controls. We generated induced pluripotent stem cells (iPSCs) from their skin fibroblasts by using integration-free Sendai virus. We utilized directed differentiation to create purified populations of iPSC-derived cardiomyocytes (iPSC-CMs). BrS iPSC-CMs showed reductions in inward Na+ current density and reduced maximal upstroke velocity of action potential compared to healthy control iPSC-CMs. Furthermore, BrS iPSC-CMs showed increased burden of triggered activity, abnormal Ca2+ transients, and beating interval variation. Correction of the causative variant by genome editing was performed and resultant iPSC-CMs showed resolution of triggered activity and abnormal Ca2+ transients. Gene expression profiling of iPSC-CMs showed clustering of BrS compared to controls. Furthermore, BrS iPSC-CM gene expression correlated with gene expression from BrS human cardiac tissue gene expression. Conclusions Patient-specific iPSC-CMs are able to recapitulate single cell phenotype features of BrS, including blunted inward sodium current, increased triggered activity and abnormal Ca2+ handling. This novel human cellular model creates future opportunities to further elucidate cellular disease mechanism and identify novel therapeutic targets.