Development and characterization of a scalable calcium imaging assay using human iPSC-derived neurons

Area of Science:

• Neuroscience
• Drug Discovery
• Cellular Assays

Background:

• Modeling complex human neuronal circuitry for drug discovery is challenging.
• Calcium oscillation assays offer a functional in vitro model of neuronal networks.
• Scalable high-throughput screening (HTS) methods are needed for neuroscience drug discovery.

Purpose of the Study:

• To optimize calcium oscillation assays for scalable drug discovery.
• To investigate the impact of neuron-astrocyte ratios on network activity.
• To characterize the role of GABAergic neurons and bicuculline in neuronal network function.

Main Methods:

• Developed HTS-compatible cell culture methods with defined neuron-to-astrocyte ratios.
• Analyzed network firing patterns, spike frequencies, and amplitudes.
• Utilized a novel pixel-based analysis for automated calcium imaging.
• Investigated the effects of DAPT, GABAergic neurons, and bicuculline on network activity.

Main Results:

• Optimal neuron-to-astrocyte ratios were identified for cellular distribution and network firing.
• Increased neuron density decreased spike frequency but increased spike amplitude.
• DAPT was found to negatively regulate astrocyte viability.
• GABAergic neurons and bicuculline modulated local field activity and synchronized network spikes.

Conclusions:

• Optimized cell culture conditions enhance the utility of calcium oscillation assays for drug discovery.
• Neuron-astrocyte ratios and specific neuronal subtypes significantly influence network dynamics.
• The developed pixel-based analysis enables scalable assessment of local field activity in neuronal networks.