33. Ex Vivo Gene Therapy for Lysosomal Storage Disease in the CNS: Patient iPSC-Derived Neural Stem Cells Correct Pathology in the MPS VII Mouse Brain

Abstract

Neural stem cells (NSCs) derived from induced pluripotent stem cells (iPSCs) may offer an immunologically compatible delivery vehicle for therapeutic proteins in the brain. We evaluated a complete process of ex vivo gene therapy using patient-derived cells in a well-characterized mouse model of the lysosomal storage disease, MPS VII. Fibroblasts from a patient with MPS VII were reprogrammed into iPSCs, and differentiated into multi-potent NSCs. Patient-derived NSCs were able to engraft across the rostrocaudal axis following transplantation in neonatal NOD/SCID mice but were present in very low densities, similar to that seen with primary NSCs. We used a PiggyBac-based transposon vector to deliver a functional version of the missing GUSB gene to patient NSCs, which then expressed normal levels of enzymatically active GUSB. Genetically corrected iPSC-NSCs transplanted post-symptomatically into the striatum of adult MPS VII mice reversed neuropathology in a zone surrounding the grafts, while control contralateral grafts did not. The patient-derived iPSC-NSCs had similar engraftment properties as iPSC-NSCs from a normal human subject, and both lines engrafted similarly in normal and MPS VII NOD-SCID mouse brains. The results demonstrate the potential for ex vivo gene therapy in the brain using human NSCs from autologous, non-neural tissues.