Spontaneous Calcium Oscillations of Networked Human iPSC Derived Cortical Neurons as a Sensitive Model for Neurotoxicity Screening

BrainXell's human neuron culture platforms provide a means to model the human brain in a dish and perform in vitro functional assays. This system enables the screening of disease phenotypes and pharmacological agents that alter neuronal activity. In the case of neurotoxicity, it is critical to use in vitro systems that more closely model the human nervous system and its response to environmental toxins. Such a platform provides greater predictive power to indicate which compounds pose a risk. Toward this goal, we have developed an assay centered on the use of BrainXell’s iPSC derived human cortical neurons and the spontaneous calcium oscillations that occur once mature networks have formed. These oscillations represent the changes in calcium concentration that are closely tied to neuronal activity as action potentials invoke large pre synaptic calcium influx and also cause a notable rise in postsynaptic calcium at excitatory synapses Fluorescent measurements of calcium oscillations can be achieved with calcium sensitive dyes that have high signal to noise ratio, efficient cellular loading, and good intracellular retention, and the oscillations are observed spontaneously when culturing neurons under suitable conditions to form mature networks. Such oscillations are reflective of a population of neurons having synchronous network activity. Using this assay, we assessed 12 potentially seizurogenic and toxic compounds and identified various ways in which they impact the spontaneous calcium oscillations. Compounds that target glutamatergic neurotransmission, GABAergic neurotransmission, and voltage gated potassium channels each had distinct effects on the spontaneous calcium oscillations. Moreover, changes were concentration dependent and were observed at low concentrations known to modulate the targets.