All-optical electrophysiology in hiPSC-derived neurons with synthetic voltage sensors

Abstract

Voltage imaging and “all-optical electrophysiology” in human induced pluripotent stem cell (hiPSC)-derived neurons have opened unprecedented opportunities for high-throughput phenotyping of activity in neurons possessing unique genetic backgrounds of individual patients. While prior all-optical electrophysiology studies relied on genetically encoded voltage indicators, viral transduction of human neurons with large or multiple expression vectors can impact cell function and often lead to massive cell death. Here, we demonstrate an alternative protocol using a synthetic voltage sensor and genetically encoded optogenetic actuator that generate robust and reproducible results. We demonstrate the functionality of this method by measuring spontaneous and evoked activity in three independent hiPSC-derived neuronal cell lines with distinct genetic backgrounds.

A method for three-dimensional single-cell chronic electrophysiology from developing brain organoids

“…12) Gluing a chamber onto the substrate wafer to completely enclose a 2x2 mesh device array using a bio-compatible adhesive (Kwik-Sil, WPI). (13) Treating the surface of the device with light oxygen plasma (Anatech 106 oxygen plasma barrel asher), followed by adding 3 mL of Ni etchant (type TFB, Transene) into the chamber for 2 to 4 hours to completely release the mesh electronics from the substrate wafer. The device was then ready for subsequent sterilization steps before cell culture.…”

“…The recording technology not only needs to form minimally-invasive and long-term stable electrical interfaces with individual neurons 3D distributed across brain organoids, but also needs to accommodate the rapid volume change occurring during the organoid organogenesis and cortical expansion. Optical imaging coupled with fluorescence dyes 13 or calcium indicators 14 has been used to visualize the neuron activities in 3D. They, however, are limited by the temporal resolution, penetration depth, and long-term signal stability.…”