FUNCTIONAL ANALYSIS OF IPSC-DERIVED THREE-DIMENSIONAL MODELS ON TRADITIONAL AND NOVEL MICROELECTRODE ARRAYS

Recent advances in induced pluripotent stem cell (iPSC) technology have allowed researchers to produce 3D models of neural tissue, termed spheroids or organoids, that better recapitulate in vivo cellular diversity and spatial architecture. Here, traditional and novel microelectrode array (MEA) methods were used to characterize the electrical response of 3D neural models to neuroactive compounds. Pre-formed Human iPSC-Derived Midbrain Organoids were plated onto CytoView 6 MEA plates and, on Day 125 post-differentiation, dosed with 4-aminopyrirdine, rotenone, or a DMSO control. Baseline and post-dose (1 hour after drug addition) recordings were taken using the Maestro Pro. Dosing with 4-aminopyrirdine increased the mean firing rate by 1.77 Hz and network burst frequency by 0.21 Hz, as compared to baseline, while dosing with rotenone led to a decrease in both metrics (0.44 Hz decrease for mean firing rate and 0.24 Hz decrease for network burst frequency). Further, novel MEAs were created to facilitate specialized measurement of 3D neural models on the Maestro Pro, including MEAs with high density electrodes (170 µm2 area with a pitch of 50 µm) and MEAs with flexible, electrode-containing cantilevers. High density MEAs were able to measure signal from multiple small (~300 µm dimeter) spheroids made of rat cortical neurons or iPSC-derived neurons. In addition, three-dimensional MEAs utilizing electrodes on flexible cantilevers measured robust drug responses in both iPSC-derived midbrain and dorsal forebrain organoids. In total, this study shows that the Maestro Pro system can be used with traditional and novel MEAs to study complex 3D neural models.