29: Multielectrode array analysis of hiPSC nociceptors for drug discovery

Topic: Basic Science
Subtopic: Non-specific to any diagnosis (including studies in healthy animals), Electrophysiology, Drug development

Background and Aims: The development of new analgesics has been slowed by limited translational value of preclinical pain models. Human donor–derived primary dorsal root ganglia (DRG) cultures provide a human-relevant system to interrogate neuronal excitability but are technically challenging to work with and constrained by availability. Differentiated human induced pluripotent stem cell sensory neurons (hiPSC-SNs) present a promising alternative to bridge the translational gap. We used moderate throughput multielectrode array (MEA) electrophysiology to assess how Merck’s selective Nav1.7, Nav1.8 and HCN channel inhibitors modulate hiPSC-SN excitability, offering a practical functional readout more amenable to analgesic drug discovery than traditional patch clamp techniques.

Methods: hiPSC-SNs (RealDRG, Anatomic) were seeded on 48 well MEA plates. Recordings using Maestro Pro MEA (Axion) captured data simultaneously across all 768 electrodes. Active electrode yield (AEY) was calculated as the number of active electrodes out of the total possible (16) per well. Mean firing rate (MFR) was calculated on a per-well basis in Hz (total spikes per well / acquisition time). Dosing studies occurred between DIV21 and DIV28, a timepoint when Nav1.7, Nav1.8, HCN1, and HCN2 have been shown to be expressed. Compounds were added directly into respective wells, and responses were normalized to pre-compound baseline.

Results: Spontaneous firing of hiPSC-SN cultures was observed starting at days-in-vitro 7 (DIV7), with MFR increasing until three weeks in vitro. Nav1.7 inhibition with SSCI-1 significantly reduced spontaneous firing in hiPSC nociceptors, with a calculated IC50 of firing inhibition approximately 1x the in vitro patch clamp IC50. In contrast, a selective Nav1.8 inhibitor, MSD199, did not demonstrate a significant decrease in MFR at concentrations approaching 100x patch clamp IC50, suggesting a Nav1.8-independence of firing. Finally, testing with a pan-HCN inhibitor Org-34167, robust inhibition of neuronal firing was observed at concentrations 1-2x HCN1 and HCN2 IC50, respectively.

Conclusions: MEA analysis demonstrated that hiPSC-SNs exhibit action potential firing that is sensitive to modulation of ion channels important for sensory neuron excitability. These findings thus support the use of hiPSC-SN models to quantify sensory neuron excitability and to screen candidate analgesics. However, the absence of effect with selective Nav1.8 inhibition highlights the importance of verifying target expression and interpreting results carefully in hiPSC-SN models. Ongoing assay development includes evaluating G-protein coupled targets and co-culture systems such as sensory -neuron/microglia or sensory neurons-macrophages to further study pain mechanisms and pharmacology.

References: N/a

Presenting Author: Dillon McDevitt
Submitting Author: Dillon McDevitt

Senior Author: Parul S. Pall

IASP 2026 Global Year theme of Neuropathic Pain: No

• Michelle K. Clements - Merck and Co., Inc.
• Darrell A. Henze - Merck and Co., Inc.
• Parul S. Pall - Merck and Co., Inc.