A human population-based organotypic in vitro model for cardiotoxicity screening

Abstract

Assessing inter-individual variability in responses to xenobiotics remains a substantial challenge, both in drug development with respect to pharmaceuticals and in public health with respect to environmental chemicals. Although approaches exist to characterize pharmacokinetic variability, there are no methods to routinely address pharmacodynamic variability. In this study, we aimed to demonstrate the feasibility of characterizing inter-individual variability in a human in vitro model. Specifically, we hypothesized that genetic variability across a population of iPSC-derived cardiomyocytes translates into reproducible variability in both baseline phenotypes and drug responses. We measured baseline and drug-related effects in iPSC-derived cardiomyocytes from 27 healthy donors on kinetic Ca2+ flux and high-content live cell imaging. Cells were treated in concentration-response with cardiotoxic drugs: isoproterenol (β-adrenergic receptor agonist/positive inotrope), propranolol (β-adrenergic receptor antagonist/negative inotrope), and cisapride (hERG channel inhibitor/QT prolongation). Cells from four of the 27 donors were further evaluated in terms of baseline and treatment-related gene expression. Reproducibility of phenotypic responses was evaluated across batches and time. iPSC-derived cardiomyocytes exhibited reproducible donor-specific differences in baseline function and drug-induced effects. We demonstrate the feasibility of using a panel of population-based organotypic cells from healthy donors as an animal replacement experimental model. This model can be used to rapidly screen drugs and chemicals for inter-individual variability in cardiotoxicity. This approach demonstrates the feasibility of quantifying inter-individual variability in xenobiotic responses and can be expanded to other cell types for which in vitro populations can be derived from iPSCs.

Thorough QT/QTc in a Dish: An In Vitro Human Model That Accurately Predicts Clinical Concentration‐QTc Relationships

“…Measured free fractions in plasma ( f plasma ) and in cardiomyocyte media ( f media ) are summarized in Table 1 The 27 donors exhibited reproducible interindividual variation both at baseline 19 and with treatment with all 10 positive QT drugs. All 10 positive QT drugs exhibited visible increases in the decay-rise ratio at one or more tested concentrations in multiple donors.…”

“…For plasma, results were compared to f plasma reported in the literature (see Table S2); for cardiomyocyte media, results were compared to f media calculated using the mass-balance model of Armitage et al 25 (see Tables S3 and S4). iPSC-derived cardiomyocytes, cell culture, and Ca 2+ flux assay In vitro testing of cardiomyocytes was performed as previously reported. 19 The donor population consisted of 12 women and 15 men, of which 85% were of white (n = 23) and 15% African American (n = 4) ancestry. Catalogue numbers and demographic information on each cell line were previously reported.…”

“…Catalogue numbers and demographic information on each cell line were previously reported. 19 The iPSC cardiomyocytes were cultured under identical conditions in multiple batches using an established protocol. 34,35 The Ca 2+ flux assay was used to evaluate functional performance of cardiomyocytes.…”

“…16 The ability to generate cells from individual donors that replicate patient-specific congenital 17 and disease-specific 18 phenotypes is an exciting development that promises to enable personalized drug safety evaluation, an approach that has recently been tested in dozens of human induced pluripotent stem cell (iPSC)-derived cardiomyocytes. 18,19 Thus, iPSC-based cardiomyocytes are known to be useful in identifying both congenital and drug-induced cardiotoxicity hazards, 17,20,21 particularly at the individual patient level. 22,23 However, even within the Comprehensive in vitro Proarrhythmia Assay (CiPA) initiative-a global effort among regulators, industry, and academia to develop a mechanistic, model-informed approach to cardiac safety that includes iPSCderived cardiomyocytes as a key component-clinical testing for QT prolongation through in vivo electrocardiogram monitoring in phase I clinical trials remains a key component.…”

“…We have previously shown that iPSC-derived cardiomyocytes from a moderate-sized sample of healthy subjects (n = 27) are a highly reproducible in vitro population model. 19 Notably, this sample size is greater than those recommended to control false negatives in C-QTc modeling-based TQT studies. 14 We, therefore, hypothesized that the C-QTc modeling of iPSC-derived cardiomyocytes from a diverse sample of human subjects can serve as a "TQT study in a dish."…”