The analysis of candidate analgesics utilising a model of nociception derived from human induced pluripotent stem cells

Abstract

The sensation of pain is an adaptive mechanism vital for the wellbeing of an organism. However, in the case of chronic pain, this essential mechanism is corrupted, resulting in catastrophic suffering for the individual and devastating socioeconomic burdens for the community. Cur rent methods used to treat pain are largely ineffective, associated with deleterious unintended consequences, and diminishing beneficial outcomes. Despite the obvious need and urgency for improved therapeutics, novel drug development has been severely impacted by the poor recapitulation of animal model findings to human diseases, and the difficulties associated with acquiring human primary neuronal tissue. These shortcomings highlight the necessity for a new stratagem to address the pain problem. This study demonstrated the efficient differentiation of human induced pluripotent stem cells (HiPSCs) into cultures possessing key biomarkers associated with the nociceptor phenotype. HiPSC-derived neurons were capable of generating action potentials in response to noxious stimulation measurable by both patch clamp and microelectrode array. Furthermore, HiPSC nociceptors derived from inherited erythromelalgia patients were shown to be electrically active in the absence of stimulation, indicating functional continuity with genetic pain disorders. Drug screening of 295 compounds through the application of spontaneously active HiPSC-derived nociceptors resulted in the selection of twelve candidates able to inhibit spike activity by greater than 40 %. Compound inhibition of HiPSC-derived nociceptor spiking was shown to be reversible and demonstrated less than 5 % cytotoxicity over 24 hours. Identification of dose-response relationships for candidate compounds allowed for the cal culation of IC50s, which further indicated efficacy and nontoxicity. Investigation into the transcriptomic and electrophysiological profiles of selected compounds alluded to promising mechanisms of action for targeted analgesia. The scale, reproducibility, and effectiveness of this drug screen demonstrate a high throughput approach to human neuronal disease modelling which may enable the discovery of new analgesics for the treatment of both general and neuropathic pain