As part of the FDA approval process for novel therapeutic drugs, safety screening demonstrating that the candidate drug does not have deleterious effects on the human cardiac action potential is required. Healthy human heart cells are not available for such preclinical drug testing. There is currently no consensus on the best experimental approach to provide the most efficient, economical, and faithful determination if the drug is likely to lengthen the cardiac action potential (Long QT) and result in the potentially fatal arrhythmia known as Torsade de Pointes. The FDA is actively seeking new reliable models for preclinical drug testing. The FDA, HESI, and Pharma recognize that human cardiac myocytes derived from induced pluripotent stem cells (iPSCDCMs) offer a great opportunity to improve drug safety screening. Human iPSCDCMs cells are in plentiful supply, and are able to withstand comprehensive electrophysiology to determine the drug-cell interactions. Although most ionic currents in these cells closely resemble those from freshly isolated heart cells, one important channel is missing: The inward rectifier current, IK1. As a result of this missing current, the cells do not have a physiological resting potential, are spontaneously active, and have an anomalous response to drugs. Viral transfection of Kir2.1, the molecular basis of IK1, has proved difficult, resulting in foreshortened action potentials, or complete lack of ability to stimulate action potentials at all. We have developed a novel technology, which restores IK1 using electronic expression. Using a mathematical model, IK1 is almost instantaneously calculated, based on the membrane potential of the cell. The calculated current is then applied to the cell electronically through an electrode, resulting in a virtual IK1, which interacts with the other membrane currents. Synthetic IK1 is easily adjusted to be appropriate for cell type and cell capacitance. We met all our Phase I optimization goals. The Phase II goal is validate our device against the FDA CiPA assay, develop new ionic current waveforms, automate cell type identification, field test the device, and develop a high throughput version of the Cybercyte. Finally, we will prepare the device for commercialization. Our technology will have a significant impact on human health, as well as a strong economic impact. Our device enables easy identification of atrial and ventricular iPSCDCMs, thus increasing reliability of results, and reducing the number of experiments required for statistical significance. Our approach uses Human cells, which also reduces the likelihood of false positives/false negatives. This improved, high througput preclinical safety testing will more accurately identify drugs with adverse side effects earlier in the development process. This improved accuracy will avoid wasted expenditures on unsuccessful candidate compounds and will reduce the abandonment of potentially beneficial drugs.
Drug safety screening is required for all new drug candidates to determine if they have the potential to prolong the cardiac action potential and lead to the potentially fatal Torsade de Pointes. We will develop and validate our novel device (including a high throughput version) as a commercial system which enables human induced pluripotent stem cell derived cardiac myocytes to be used as a faithful model of the human heart, and produce more physiologically and clinically relevant data compared with the current screening, which is performed on non-human cells, and has severe limitations in its predictive ability. Our device is a major step forward in drug safety screening, as it will improve accuracy and reduce the costs associated with drug development.
