Title:
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An in vitro model for the study of transient receptor potential channels on human sensory neurons
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Sensory neurons are responsible for detecting noxious chemical, mechanical and thermal stimuli
and relaying the information to the central nervous system. They also contribute to local
neurogenic inflammation via the release of neuropeptides. Sensory neurons express a variety of
ion channels, including the transient receptor potential (TRP) channels. TRP channels are one of
the main families of ion channels responsible for nociception and are desirable targets for
analgesic and anti-inflammatory therapies. TRP channel studies on human sensory neurons has
been hampered by the fact that peripheral neurons lack theis cell bodies, which are housed in
neuronal ganglia and are inaccessible via peripheral tissue biopsy.
To overcome this limitation we have differentiated human dental pulp stem cells towards a
neuronal phenotype, termed peripheral neuronal equivalebts (PNEs), which have their cell bodies
present. Microfluorimetric and electrophysiological techniques have demonstrated the functional
expression of TRP channels on PNEs, specifically TRPA 1 and TRPV1. Therefore PNEs represent
a novel source of functional human sensory neurons suitable for in vitro TRP channel studies.
In vivo, neuronal TRP channels become hypersensitised in inflammatory and infectious
environments however the exact mechanism through which this occurs is unknown. PNEs
pre-treated with pro-inflammatory cytokines generated larger responses to TRP channel agonists
when compared to untreated PNEs however no alterations in TRP channel gene expression were
observed. PNEs infected with human rhinovirus also show no change in TRP channel gene
expression suggesting that TRP channel sensitisation, rather than upregulation, contributes to
nerve hypersensitivity.
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