Spatiotemporal Poincare Plotting for Torsades De Pointes Prediction In Vitro Drug-Screening System Exploiting Human iPS Cells and Other Pluripotent Stem Cells

Abstract

QT prolongation is still a major safety concern for selecting and developing candidate compounds. The current integrated assay systems using hERG-transfected HEK-293/CHO-cells (hERG assay), isolated animal tissues (APD or MAP assay) and conscious and/or anesthetized whole animals (QT or Map assay) may identify QT prolongation, but cannot fully predict the potential lethal arrhythmias such as Torsades de Pointes (TdP) or ventricular fibrillation (VF) by drug candidates. Understanding the importance of spatial and temporal regulation of cellular orientation, community size and shape, variety and interactions are keys to resolving mechanisms of epigenetic processes in highly complex cellular systems like tissues and organs. To investigate the meaning of the spatial distribution of cells, an on-chip cell network cultivation system has been developed, and extra-cellular signals (field potentials: FP) of human embryonic cardiomyocytes in geometrically patterning chambers have been recorded with an on-chip multi-electrode array (MEA) system. A proposed strategy for an on-chip assay for providing further insight into the extrapolation of preclinical data to human clinical settings or for expanding or replacing existing in vitro and in vivo cardio- toxicity models includes the following: 1) abnormal triggering (temporal dispersion) causing lethal arrhythmias is estimated by analyzing the time course field potential dispersion of single cells in loop network using Poincaré plotting; 2) spatial dispersion of cells causing spiral re-entry is modeled by using a wider width of cell network loop which can choose different propagation pathways of cells among neighboring circulations; and 3) human ES/iPS cell-based cardiomyocytes are used for cell network formation. In this presentation, we present the system set-up and possible application of this system for drug discovery and toxicology using spatiotemporal Poincaré plotting measurement.