Disease Modeling and Drug Discovery Symposium

Human iPSC-derived neuronal systems enable longitudinal interrogation of disease-associated phenotypes in relevant cell types and provide robust platforms for modelling neurodegenerative disorders. In frontotemporal dementia (FTD), GRN haploinsufficiency caused by heterozygous loss-of-function mutations is characterized by reduced progranulin levels, yet the emergence and progression of functional neuronal abnormalities remain incompletely defined.  

Using an isogenic GRN-FTD model developed by FUJIFILM Cellular Dynamics, we investigated disease-associated functional changes using high-density microelectrode arrays (HD-MEAs). iCell Induced Excitatory Neurons were co-cultured with iCell Astrocytes 2.0 and compared between an Apparently Healthy Normal (AHN) control and a heterozygous GRN R493X line. Cultures were followed from DIV 6 to DIV 50 on MaxTwo 24-well HD-MEA plates, providing 26,400 electrodes per well for repeated, non-invasive and label-free measurements.

Longitudinal ActivityScan and Network recordings revealed a distinct GRN-associated electrophysiological phenotype. Increased neuronal activity emerged early during maturation, with significantly elevated firing rates by DIV 15 (p < 0.01). Network abnormalities developed progressively, including more frequent, higher-amplitude bursts, shorter inter-burst intervals from DIV 25, and >2-fold prolonged burst durations by DIV 50 (p < 0.001), consistent with a hyperexcitable network state. AxonTracking was then applied to map action potential propagation along individual axonal arbors. Despite increased excitability, GRN cultures showed shorter neurites and reduced axonal branching, revealing a divergence between heightened activity at both cellular and network levels and reduced axonal complexity.

Together, these data identify a multiscale functional signature of GRN deficiency that emerges early and evolves during neuronal maturation. Longitudinal HD-MEA phenotyping provides a scalable approach for resolving disease-associated changes across network and axonal levels and for evaluating modulation of these phenotypes in therapeutic studies.

Human iPSC-derived midbrain organoids provide a 3D system to model dopaminergic development and functional alterations relevant to Parkinson’s disease (PD) and related synucleinopathies. In these disorders, disease-relevant changes may first emerge as alterations in excitability, network organization, pharmacological responsiveness, or axonal output before overt neurodegeneration. Longitudinal, non-invasive functional readouts are therefore needed to follow maturation and perturbation responses in the same cultures over time.

Here, in collaboration with STEMCELL Technologies, we used multi-well high-density microelectrode arrays (HD-MEAs) to establish a multiscale profiling workflow for commercially available human midbrain organoids. Organoids were plated at approximately 77 days of age onto PEDOT-coated MaxTwo 24-well HD-MEA plates containing 26,400 electrodes per well and monitored for approximately one month.  

ActivityScan recordings showed progressive strengthening of spontaneous activity, including increased firing rate, spike amplitude, and active area, consistent with functional maturation and improved tissue-electrode coupling. Network recordings detected high-frequency synchronized bursting already at early timepoints, a functional signature consistent with dopaminergic midbrain-like circuitry; over maturation, bursting became more organized, with increased burst cadence and enhanced neuronal recruitment. To evaluate pharmacological responsiveness, organoids were acutely challenged with 4-aminopyridine and tetrodotoxin, which respectively enhanced and suppressed spontaneous spiking in a rapid and reproducible manner. MaxWell Biosystems’ unique AxonTracking assay further enabled label-free extraction of soma-to-axon propagation patterns at the organoid-electrode interface, providing a subcellular readout of axonal functionality relevant to PD- and synucleinopathy-associated circuit dysfunction.  

Together, these results support the use of human midbrain organoids on HD-MEAs as a scalable, non-invasive platform for longitudinal disease-relevant phenotyping. By linking maturation, network dynamics, compound responsiveness, and axonal propagation in the same 3D model, this workflow supports PD-relevant disease modelling, longitudinal functional phenotyping, and therapeutic-response studies.