Decreased Overall Network Activity in iPSC-Derived Cortical Neurons in Individuals with Idiopathic Autism
The early establishment of functional cortical neural networks is an important step in overall brain development, and may be impaired in individuals with autism. Understanding the physiological characteristics of network-level activity and the effect that autism-related genes have on that activity is paramount to developing genotype-phenotype relationships at the cellular level in autism spectrum disorder (ASD).
To use cell based assays to interrogate network-level electrophysiological activity, calcium transients, and other aspects of synaptic function from induced pluripotent stem cell (iPSC)-derived cortical neurons in ASD individuals with putative risk contributing genetic variants (Cukier et al., 2014).
iPSC lines were created from peripheral blood mononuclear cells (PBMCs) of individuals with autism (N=5) and unrelated, sex-matched controls (N=3 lines). iPSCs were derived into neurons with transcriptional lineages resembling cortical neurons (DeRosa et al., 2012). Neurons were plated and differentiated into mixed networks for 0, 14, 28, and 35 days. Developing networks were interrogated with multi-electrode array (MEA) recordings, measurements of calcium transients using Fluo-4, and fixed and stained for relevant morphological markers.
Lines from ASD individuals demonstrated significantly decreased network spiking activity from MEA recordings (p < 0.001, ANOVA) as well as decreased numbers of calcium transients (p < 0.05, t-test). Additionally, ASD lines showed significant differences in measures of neurite morphology (p < 0.001, ANOVA) at early neuronal differentiation times.
The results of this study suggest that in iPSC-derived neurons derived from individuals with ASD, there may be early deficits in network activity and morphology based on a combination of cell based assays, including MEA, Fluo-4 measured calcium transients, and quantification of neurite outgrowth.