Optimized Conditions for MEA Assay with Human iPSC-Derived Spinal Motor Neurons, Glutamatergic Neurons and Mixed Cortical Neurons

Human induced pluripotent stem cells (hiPSC) derived neurons are now considered a more relevant model system for neurological and psychiatric diseases in vitro. They can be used as a platform for neurological disease modeling, drug discovery and toxicity screening. Neural electrical activity is one of the essential parameters for assessing the functionality of the nervous system. Micro-electrode array (MEA) systems provide a non-invasive and label-free means to assess electrophysiological activity from thousands of neurons in the same plate over time. More and more researchers are using micro-electrode array (MEA) with hiPSC-derived neurons to characterize neuronal phenotypes and perform drug screening. But achieving stable and consistent MEA recordings within the shortest possible culture time remains a challenge. In order to generate a robust protocol for MEA recording on hiPSC- derived neurons, we evaluated several conditions, which could affect culture performance (1.neuron seeding density; 2.seeding medium; 3.astrocyt eco-culture). These conditions were evaluated with BrainXell’s hiPSC-derived spinal motor neurons, cortical glutamatergic neurons and mixed cortical neurons. Our data demonstrate that different neuron types have different optimal seeding densities that can generate the most consistent and robust neuronal activity. Inclusion of BrainPhys neuronal medium as the cultures mature also contributes to consistent, synchronized signals, and astrocyte co-culture accelerates the network maturation. With our current protocol, cortical glutamatergic neurons started to show consistent synchronized signal as early as day 12 after seeding, and spinal motor neurons and mixed cortical neurons started to show on day 18. The synchronized network activity lasted for at least two weeks. The presented data demonstrate the suitable application of hiPSC-derived neurons coupled with MEA technology as a non invasive human neuronal test system that can be used for drug discovery and toxicity screening.