(T1031) MODELING HEREDITARY SENSORY AND AUTONOMIC NEUROPATHY TYPE IV (HSAN IV) USING HUMAN DRG ORGANOIDS DERIVED FROM PATIENT INDUCED PLURIPOTENT STEM CELLS
PhD student The University of Hong Kong, Hong Kong
Abstract: Hereditary Sensory and Autonomic Neuropathy Type IV (HSAN IV) is a rare autosomal genetic disorder characterized by Congenital Insensitivity to Pain with Anhidrosis. It is caused by mutations in the Neurotrophic Receptor Tyrosine Kinase 1 (NTRK1) gene. While previous animal studies have revealed the significance of NTRK1 in nociceptive neuron formation in the dorsal root ganglia (DRG), its role in congenital sensory neuropathy and the underlying disease mechanisms in the human context are less explored.
In this study, we successfully established human DRG organoids and remodelled HSAN IV disease using induced pluripotent stem cells (iPSCs) lines derived from an HSAN IV patient’s urine. The patient carries homozygous mutations, including a G deletion in one allele at exon 7 leading to early stop code, and a G to A alteration in the other allele at exon 16 that converts glutamic acid to lysine. To eliminate the genetic variations, we also generated isogenic control by correcting the patient’s mutation using CRISPR-based gene editing.
By analysing different developmental stages of DRG organoids, we found that DRG organoids derived from HSAN IV patients underwent a lineage switching between sensory neurons and glial cells without affecting the neural crest stem cell population. During early neurogenesis, a marked reduction of sensory neurons expressing ISLET+ and BRN3A+ cells was detected. Additionally, DRG organoids derived from the patient exhibited few mature sensory markers, TRKA, TRKC, TRPV, and CGRP, and defective axonal outgrowth and extension Notably, gliogenesis was initiated prematurely, with a significant upregulation of FABP7.
These findings suggest that NTRK1 mutations disrupt the balance of neuronal and glial differentiation in human DRG during development, which may contribute to sensory neuropathy in adults. Future studies will focus on uncovering the molecular mechanisms mediated by NTRK1 and identifying therapeutic targets to restore proper neuronal-glial differentiation signals in human DRG.
