SLAS 2023 Conference

The SLAS 2023 International Conference and Exhibition took place from February 25 to March 1, 2023, at the San Diego Convention Center in San Diego, California. This premier event brought together scientists, researchers, engineers, and industry professionals to explore advancements in laboratory automation and screening technologies. The conference featured nine educational tracks, over 150 scientific talks, and numerous networking opportunities

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Poster

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A Novel, High-Throughput Electrophysiology Platform for Compound Screening with a Peripheral Nerve Microphysiological System

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Introduction:

Microphysiological systems (MPS) have the potential to better inform preclinical stages of drug development by enabling toxicity screening with systems that mimic in vivo physiology. These systems are attracting attention from the pharmaceutical industry in the hope they will curb attrition rates, lower costs, and reduce reliance on animal models. AxoSim has developed an innovative MPS, the NerveSim® platform, for screening neurotoxic compounds using an embedded electrode array (EEA) to record compound action potentials (CAPs) from peripheral nerve cultures. Bridging the gap between in vitro and in vivo, the NerveSim® platform measures multiple clinically relevant electrophysiological metrics using custom, automated hardware and software.

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Methods:

The NerveSim® EEA platform is a custom 24-well tissue culture plate with an integrated circuit board to allow high-throughput electrophysiological recordings. Each well contains a cell-restrictive outer layer and a growth-permissive inner gel that together guide axonal growth into a 3D nerve-like bundle. At the bottom of the inner gel are a series of 10 microelectrodes (1 mm spacing) that can be used for recording or stimulation. Dissociated rat dorsal root ganglion (DRG) spheroids were placed into the inner gel and cultured for four weeks to ensure growth along the EEA. A baseline electrophysiological recording was obtained at four weeks before the cultures were exposed to three doses of the chemotherapeutic Paclitaxel (PTX; 10 to 500 nM) for seven days. At the conclusion of dosing, we recorded electrophysiology again to observe any deviations from baseline caused by the drug treatment.

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Results:

Using a proprietary system, multiple NerveSim® EEA cultures were stimulated in parallel at multiple distal sites with both a stimulation current ramp (1 to 71 µA) and a stimulation frequency ramp (0.5 to 2 Hz) while recording the CAPs at the DRG body and axons. From these data, we collected the conduction velocity (CV), peak response amplitude (AMP), and threshold stimulus strength (TSS), which are all clinically relevant electrophysiological metrics. Dosing with higher concentrations of PTX (>10 nM) resulted in slower CV, lower AMP, and higher TSS compared to the vehicular control, consistent with peripheral neuropathy. Higher PTX concentrations had reduced or nonexistent responses when stimulating at distal location, confirming the axonal degeneration expected with high dose PTX. The stimulation current ramp allowed differentiation of the responses of C fiber subtypes based on the presence of activity dependent slowing (ADS). Fluorescent microscopy confirmed that robust axonal growth was present for lower doses (<500 nM), suggesting that this system can detect subtle pathological changes in electrophysiology that occur before the loss of cell viability.

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Conclusion:

The existing in vitro methods for screening neurological drugs provide poor fidelity at replicating in vivo physiology and function. To bridge this gap, AxoSim’s NerveSim® EEA platform integrates a novel 3D tissue culture model that mimics in vivo peripheral nerves with a custom, automated system for high-throughput population level electrophysiology. Combined with immunohistochemistry to correlate functional electrophysiological data with the morphology, the EEA platform is a unique preclinical screening model specifically designed for investigating peripheral neuropathy, neuroprotection, and neuroregeneration.

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