An Induced Pluripotent Stem Cell Model for Friedreich's Ataxia (IN8-1.007)

Abstract

Objective: The development of cellular models of neurological diseases to study pathogenesis and test potential therapeutics has been hindered by the inaccessibility of relevant cell types. Induced pluripotent stem (iPS) cells are generated from easily accessible cells and provide a long term source of self-renewing embryonic stem (ES)-like cells that can be differentiated into the cell types of interest. Background Friedreich9s ataxia (FRDA) is an autosomal recessive disease caused by relative deficiency of the mitochondrial protein frataxin. Most patients are homozygous for the hyperexpansion of a GAA repeat in the first intron of the frataxin gene, which causes its downregulation by epigenetic mechanisms. Frataxin deficiency impairs iron-sulfur cluster biogenesis in mitochondria, resulting in multiple enzyme deficiencies, energy deficit, oxidative damage and altered iron metabolism. However, though the defect is in every cell, only specific neuronal populations, cardiomyocytes an beta cells degenerate. Design/Methods: We generated iPS cells from FRDA patients and controls by lentiviral transduction of a specific set of transcription factors (Oct4, Sox2, Lin28 and Nanog) and validated them for pluripotency and genetic integrity. We obtained neurons and cardiomyocytes from these iPS cells and morphologically and functionally characterized them. Results: FRDA-derived iPS cells are frataxin deficient and show GAA repeat instability. They can generate neural precursors (neurospheres), neurons and cardiomyocytes. GAA repeats stabilize during neurogenesis, but remain unstable during cardiomyocyte differentiation. FRDA iPS-derived neurons have the same cell body size as controls, but extend less processes and tend to mature more slowly. After 5-6 weeks of differentiation, significantly more control than FRDA neurons express sodium currents and generate action potentials. FRDA cardiomyocytes progressively develop mitochondrial abnormalities. Studies on calcium signaling, iron metabolism, mitochondrial function and biogenesis are ongoing. Conclusions: iPS cells derived from FRDA patients recapitulate genetic, epigenetic and pathogenic mechanisms occurring in the disease. Supported by: European Community 7th Framework Programme (EFACTS collaborative project). Disclosure: Dr. Pandolfo has received personal compensation for activities with Santhera.Dr. Pandolfo has received (royalty or license fee or contractual rights)payments from Athena Diagnostic. Dr. Pandolfo has received research support from Repligen. Dr. Chintawar has nothing to disclose. Dr. Wattenhofer-Donze has nothing to disclose. Dr. Puccio has nothing to disclose.