Congenital insensitivity to pain (CIP) can be induced by the p.L811P de novo mutation in the gene coding for the voltage-gated sodium channel Nav1.9. The patients are devoid of any pain perception, resulting in severe self-inflicted wounds. Experiments on dorsal root ganglia (DRGs) from knock-in mice and a rat neuroblastoma cell line showed that the loss of pain phenotype is linked to a gain-of-function mutation of Nav1.9 (Leipold et al. 2013). Although a hyperpolarizing shift in channel activation and slowed deactivation was seen in DRGs and rat neuroblastoma cells, a hyperpolarizing shift in the channel’s inactivation was solely observed in the murine DRGs. Patient-specific induced pluripotent stem cell (iPSC) derived nociceptors offer the possibility to study human sensory neurons of this patient, promising to clarify in part conflicting data and could provide insight into the physiological function of the voltage-gated sodium channel Nav1.9. Therefore we reprogrammed patient fibroblasts carrying the p.L811P mutation in the Nav1.9 gene scn11a by induced expression of the Yamanaka factors. We subsequently differentiated the acquired induced pluripotent stem cells (iPSCs) of healthy controls and the patient into nociceptors using a small molecule approach. We are currently testing various differentiation protocols to enhance the expression of Nav1.9 in these human nociceptors. We perform a detailed analysis of nociceptor excitability by whole-cell patch clamp electrophysiology and non-invasive multi electrode array recordings. We focus on resting membrane potential, action potential characteristics as well as spontaneous and evoked excitability at different temperatures. These experiments are currently ongoing and the results will be presented at the meeting. Nav1.9 is known to be an important contributor to pain signaling and has not only been found to lead to congenital insensitivity to pain but is also connected to hereditary pain syndromes such as familial episodic pain, painful peripheral neuropathy and erythromelalgia. This study will help to elucidate the role of Nav1.9 in action potential generation and modulation in nociceptors and potentially help to develop new pain treatments with fewer side effects.
Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCB282
Poster Communications: Loss of pain due to a gain-of-function mutation: iPSC-derived human nociceptors as a disease model of a Nav1.9-linked pain syndrome
A. Foerster1, S. Sontag2, J. E. Meents1, M. Hampl1, H. M. Schüler3, I. Kurth3, M. Zenke2, A. Lampert1
1. Institute of Physiology, University Hospital Aachen, Aachen, Germany. 2. Institute for Biomedical Engineering, Cell Biology, University Hospital Aachen, Aachen, Germany. 3. Institute of Human Genetics, University Hospital Aachen, Aachen, Germany.
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Where applicable, experiments conform with Society ethical requirements.