Modelling and investigating the circadian pattern in components of human pain circuitry

Thesis

Human induced pluripotent stem cell (hiPSC)-derived models are useful tools for the study of pain that bridge the gap of fundamental interspecies differences in traditional animal models. However, currently available protocols for hiPSC-derived sensory neurons only generate certain clinically relevant subtypes of pain-detecting nociceptors in vitro, with notably a lack of neuropeptide secretion.

The present project has developed a novel hiPSC-based protocol for nociceptors that exhibit both baseline and chemically evoked secretion of calcitonin gene-related peptide (CGRP). Compared to benchmark protocols described in the literature, our method produced nociceptors with distinct pain-related phenotypes, including differential expression of subtype-specific markers (cMET and TRKA), co-expression of CGRP with somatostatin, and altered electrophysiological responsiveness to noxious heat.

The current project also confirmed the presence of an autonomous, oscillating molecular clock in sensory neurons differentiated in vitro, as an intrinsic feature of neuronal maturation. The molecular clock in nociceptors was associated with temporally dynamic gene transcription, protein abundance, translocation & phosphorylation, sodium channel dynamics, and firing activities.

Together, these findings established an integrated framework for generating functionally diverse nociceptors in vitro, with innate circadian molecular oscillations. The present study enables modelling of both physiological and pathological pain in human sensory ganglia, with close resemblance to ex vivo human nociceptors of electrophysiological, biochemical, and circadian properties.

Authors: Li, X

• DOI: 10.5287/ora-6qpoyoqjd
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: circadian; ipsc; nociceptor; pain
• Subjects: Neurosciences