Abstracts

Rationale: Ion channel gene mutations underlie various epilepsies. The induced pluripotent stem cell (iPSC) technique offers a powerful approach to explore the effects of these mutations in patient-derived neurons. Methods: This technique involves reprogramming somatic cells into PSCs, typically by retrovirus-mediated transfection of developmental transcription factors. We applied this technique to fibroblasts from a patient with Dravet Syndrome from a mutation in SCN1A, the gene encoding the alpha1 sodium channel Nav 1.1 subunit. Results: We first characterized the mutation in fibroblasts and found that it alters splicing. Then we transduced the fibroblasts using retroviruses carrying Oct3/4, Sox2, c-Myc and Klf4 genes. After 1 month, embryonic SC (ESC)-like colonies formed and expressed the pluripotency markers Nanog, Oct3/4, SSEA-4 and alkaline phosphatase, but not the fibroblast marker TE-7. Similar to ESCs, differentiation of iPSCs yielded embryoid bodies and cells expressing markers of the three embryonic germ layers. We then generated neural SCs and subsequently neurons that showed low sodium currents in whole-cell recording. Characterization of neuronal subtypes and comparison with control fibroblasts is ongoing. Conclusions: These findings suggest that iPSC method is useful for mechanistic studies of epileptic ion channel mutations, and offers the possibility of screening therapeutic compounds to discover novel, mutation-specific epilepsy therapies.