The TTX-resistant sodium channel Nav1.8 is expressed in peripheral sensory nociceptors and is implicated in a range of inflammatory and visceral pain conditions such as irritable bowel syndrome (IBS)1. Nav1.8 channel function in sensory neurons changes after injury or inflammation, with a redistribution from the soma to axons and upregulated activity through inflammatory mediators and signalling pathways. This is thought to underlie increased neuronal excitability and a greater role of Nav1.8 currents in persistent, repetitive and ectopic action potential firing in inflammatory and visceral pain. Several gain-of-function mutations in Nav1.8 have also been detected in human patients suffering from small fibre neuropathy (SFN), offering similar genetic target validation and clinical population for personalised medicine approaches seen with Nav1.7 mutations in primary erythmelalgia, paroxysmal extreme pain and SFN patients.
Optical voltage imaging of human iPSC-derived cardiomyocytes was used to assess electrophysiological effects of compounds beyond hERG inhibition. Action potential waveform analysis revealed compound-specific and concentration-dependent changes, enabling mechanistic differentiation of multichannel activity and demonstrating a human-relevant approach for translational cardiac safety assessment.
The presence of sensory neuron markers, excitability properties consistent with sensory neurons, and evidence of nociceptor ion channels (using both RNASeq and electrophysiology) provides strong evidence that iCell Sensory Neurons have a robust sensory neuron phenotype suitable for supporting pain discovery programs.