Beginning at early stages, human Alzheimer’s disease (AD) brains manifest hyperexcitability, contributing to subsequent extensive synapse loss, which has been linked to cognitive dysfunction. No current therapy for AD is disease-modifying. Part of the problem with AD drug discovery is that transgenic mouse models have been poor predictors of potential human treatment. While it is undoubtedly important to test drugs in these animal models, additional evidence for drug efficacy in a human context might improve our chances of success. Accordingly, in order to test drugs in a human context, we have developed a platform of physiological assays using patch-clamp electrophysiology, calcium imaging, and multielectrode array (MEA) experiments on human (h)iPSC-derived 2D cortical neuronal cultures and 3D cerebral organoids. We compare hiPSCs bearing familial AD mutations vs. their wild-type (WT) isogenic controls in order to characterize the aberrant electrical activity in such a human context. Here, we show that these AD neuronal cultures and organoids manifest increased spontaneous action potentials, slow oscillatory events (~1 Hz), and hypersynchronous network activity. Importantly, the dual-allosteric NMDAR antagonist NitroSynapsin, but not the FDA-approved drug memantine, abrogated this hyperactivity. We propose a novel model of synaptic plasticity in which aberrant neural networks are rebalanced by NitroSynapsin. We propose that hiPSC models may be useful for screening drugs to treat hyperexcitability and related synaptic damage in AD.
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Custom MATLAB (MathWorks) code used for oscillatory spectral power analysis is available online for public use.
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hiPSCs containing the PS1 ΔE9 mutation and the PS1M146V, APPswe mutations were the kind gifts of L. Goldstein (UC San Diego) and M. Tessier-Lavigne (Rockefeller University and Stanford University), respectively. We thank Scott McKercher for editing the manuscript and Kathryn Spencer for assisting in confocal imaging.
This work was supported in part by NIH grants DP1 DA041722, R01 AG056259, and RF1 AG057409 to SAL. BV was supported by NIH grant R01 GM134363 and the Research Training Grant in Alzheimer’s Disease to the Shiley-Marcos Alzheimer’s Disease Research Center (ADRC) at UCSD.
Conflict of interest
The authors declare that SAL is an inventor on worldwide patents for the use of memantine and NitroSynapsin for neurodegenerative and neurodevelopmental disorders. Per Harvard University guidelines, SAL participates in a royalty-sharing agreement with his former institution Boston Children’s Hospital/Harvard Medical School, which licensed the drug memantine (Namenda®) to Forest Laboratories, Inc./Actavis/Allergan, Inc. NitroSynapsin is licensed to EuMentis Therapeutics, Inc. The other authors declare that they have no conflict of interest.
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Ghatak, S., Dolatabadi, N., Gao, R. et al. NitroSynapsin ameliorates hypersynchronous neural network activity in Alzheimer hiPSC models. Mol Psychiatry (2020). https://doi.org/10.1038/s41380-020-0776-7
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