CNS WHITE MATTER TRACTS AS A NOVEL AVENUE FOR GENE THERAPY FOR KRABBE DISEASE

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Gene therapy (GT) represents a promising approach for the treatment of the CNS pathology in Lysosomal Storage Disorders (LSD), as it has the potential to provide a permanent source of the deficient enzyme. Our group has been developing a lentiviral (LV)-mediated intracerebral GT to treat Globoid Cell Leukodystrophy (GLD) that could achieve maximal transgene dispersal in the CNS from a limited number of injection sites. Published data from our group (in Preliminary Data section in this proposal) clearly demonstrate that a single lentiviral vector (LV) injection into a highly interconnected white matter region (external/internal capsule;EC/IC) resulted in rapid and robust expression of functional galactocerebrosidase (GALC) throughout the entire brain and spinal cord in the Twitcher mouse (murine model of Krabbe disease), resulting in global rescue of enzymatic activity, and marked decrease of activated microglia. The stable production and widespread distribution of the GALC enzyme achieved following EC/IC injection in affected neonatal mice suggests that this approach effectively produces physiological levels of the missing enzyme. The logical scientific progression in the maturation of this gene delivery technology is to assess this strategy in large animals models, including nonhuman primates (NHPs). Hypothesis: Administration of lentiviral vector expressing GALC to the EC/IC region of the Krabbe-affected primate brain will result in transduction and robust expression throughout the CNS. We will test this hypothesis through two Specific Aims. #1. Determine if LV-mediated delivery of the GALC gene in to the EC/IC improves the behavioral and neuromotor deficits of Krabbe-affected rhesus macaques. #2. To assess gene transfer efficiency, diffusion, distribution and long-term expression of the GALC enzyme in CNS tissues of injected NHP (Krabbe-affected and normal animals), histopathologic outcomes and immune response associated with the white matter-directed gene delivery strategy. As this research moves toward human clinical trials, the proposed research plan is absolutely essential for testing this novel GT approach in a large animal model recapitulating the disease. The data generated from this pilot proposal will be integral for the preparation of future grant proposals and be of significant value in designing human clinical trials.