Scalable Measurements of Intrinsic Excitability in Human iPS Cell-Derived Excitatory Neurons Using All-Optical Electrophysiology

Abstract

Induced pluripotent stem (iPS) cells offer the exciting opportunity for modeling neurological disorders in vitro in the context of a human genetic background. While significant progress has been made in advancing the use of iPS cell-based disease models, there remains an unmet need to characterize the electrophysiological profile of individual neurons with sufficient throughput to enable statistically robust assessment of disease phenotypes and pharmacological modulation. Here, we describe the Optopatch platform technology that utilizes optogenetics to both stimulate and record action potentials (APs) from human iPS cell-derived excitatory neurons with similar information content to manual patch clamp electrophysiology, but with ~ 3 orders of magnitude greater throughput. Cortical excitatory neurons were produced using the NGN2 transcriptional programming approach and cultured in the presence of rodent glial cells. Characterization of the neuronal preparations using immunocytochemistry and qRT-PCR assays reveals an enrichment of neuronal and glutamatergic markers as well as select ion channels. We demonstrate the scale of our intrinsic cellular excitability assay using pharmacological assessment with select ion channel modulators quinidine and retigabine, by measuring changes in both spike timing and waveform properties. The Optopatch platform in human iPS cell-derived cortical excitatory neurons has the potential for detailed phenotype and pharmacology evaluation, which can serve as the basis of cellular disease model exploration for drug discovery and phenotypic screening efforts.

Keywords: Electrophysiology; Induced pluripotent stem cells; Optogenetics.