Abstracts

Rationale: The functional network of human induced pluripotent stem cell (hiPSC)-derived neurons is a potentially powerful in vitro model for evaluating disease mechanisms including epilepsy and drug responses. However, the culture time required for the full functional maturation of individual neurons and networks and drug responses are uncertain. Methods: Human iPSC-derived cerebral cortical neurons [Axol Bioscience Inc., UK] were cultured on multi-electrode arrays (MEAs) chip. . Long-term culture of hiPSC-derived neurons were performed by astrocyte co-culture method. We performed long-term culture over 500 days. To evaluate the long-term electrophysiological feature and drug effect of hiPSC-derived neurons, we used a planar MEA measurement system (Alpha Med Scientific, Japan). Spike analyses were performed using Mobius software (Alpha Med Scientific) and MATLAB. Results: We firstly investigated the development of spontaneous electrophysiological activity and pharmacological responses for over 1 year in culture using MEAs. The complete maturation of spontaneous firing, evoked responses, and modulation of activity by glutamatergic and GABAergic receptor antagonists/agonists required 20?"30 weeks. To evaluate the utility of these human iPS-derived neural networks for modeling human disease states and drug screening, we examined chemically evoked epileptiform activity. Electrophysiological seizes were induced by pentylentetrazole (PTZ), the most widely used chemical convulsant in animal models to screen for new anti-epilepsy drugs (AEDs). We also examined the anti-convulsant effects of two common clinical AEDs, phenytoin and sodium valproate (VPA). PTZ induced a rapid increase in synchronized burst firings (SBFs) at 100 M and 1 mM. Phenytoin and VPA also suppressed PTZ-induced epileptiform activity. Conclusions: From these results, we suggest that the human iPSC-derived neuron culture is a useful model system to investigate the effects of common AEDs and an alternative to animal experiments for drug screening. In addition, our assay can be adapted to iPSC-derived neurons from epilepsy patients. Funding: This study was supported by JSPS KAKENHI Grant Number 26560247 and The Naito Foundation.