Shaping human nociceptor excitability via activation of sodium channel Nav1.9.Building a basis for innovative pain therapies.

目前疼痛相关钠通道研究中最令人困惑的问题之一是Nav1.9亚型的功能获得性突变如何导致遗传性疼痛综合征或疼痛感知丧失。通过本文提出的实验，我们的目标是通过使用膜片钳、药理学和多电极阵列记录对具有引起遗传性疼痛综合征或慢性疼痛不敏感性的Nav1.9突变的患者的诱导多能干细胞衍生的人伤害感受器进行解密这两个看似矛盾的结果。这种方法使我们能够评估Nav1.9活性在其天然患者特异性遗传背景中对神经元兴奋性的影响。迄今为止，Nav1.7亚型中的疼痛相关突变表明，降低其阈值是导致临床症状的原因。由于Nav1.7和Nav1.9的生物物理特性有显著差异，我们认为这两个通道遵循不同的机制来支持疼痛phenotypes.Based从细胞系和啮齿类动物神经元的结果，我们假设，在人类神经元Nav1.9是相关的动作电位的完整性和它的过度活跃可能会引起过度兴奋，或最终，去极化阻滞。因此，Nav1.9活性的选择性强增强可能为开发新的治疗策略提供基础。我们的目标是通过使用多电极阵列系统的细胞外电极来间接激活和抑制Nav通道并刺激干细胞衍生的伤害感受器。因此，我们将模拟药物治疗或目前用于治疗方案的皮肤电极的应用。因此，本文提出的实验将有助于了解复杂的伤害性感受器兴奋性、Nav1.9和Nav1.7之间的相互作用，并支持新的、创新的疼痛疗法的开发。

One of the most puzzling questions in present pain-related sodium channel research is how gain-of-function mutations in the subtype Nav1.9 can lead either to inherited pain syndromes or to loss-of-pain-perception. With the here proposed experiments we aim to decipher these two seemingly contradictory outcomes by using patch-clamp, pharmacology and multi-electrode array recordings on induced pluripotent stem cell derived human nociceptors of patients with Nav1.9 mutations causing an inherited pain syndrome or chronic insensitivity to pain. This approach enables us to assess the effects of Nav1.9 activity on neuronal excitability in its natural patient specific genetic background. To date, pain-linked mutations in the subtype Nav1.7 suggested that lowering its threshold is responsible for the clinical symptoms. As Nav1.7 and Nav1.9 differ significantly in their biophysical properties, we suggest that both channels follow distinct mechanisms to support pain phenotypes.Based on results from cell lines and rodent neurons we hypothesize that in human neurons Nav1.9 is relevant for action potential integrity and its hyperactivity may induce hyperexcitability or, finally, depolarization block. Selective strong enhancement of Nav1.9 activity may thus provide the basis for the development of new treatment strategies. We aim to pharmacologically activate and inhibit Nav channels and to stimulate stem cell derived nociceptors via extracellular electrodes using a multi-electrode array system. We will thus mimic either drug treatment or the application of skin electrodes which are currently used in therapeutic regimes. Thus, the here proposed experiments will help to understand complex nociceptor excitability, the interplay between Nav1.9 and Nav1.7, and to support the development of new, innovative pain therapy.