CNS-directed gene/cell therapy of LSDs

Lysosomal storage disorders (LSD) are rare genetic diseases caused by the deficiency of lysosomal enzymes required for important metabolic reactions. Deficiency of arylsufatase A (ARSA) and beta-galactocerebrosidase (GALC) in Metachromatic and Globoid Cell Leukodystrophies (MLD and GLD), respectively, cause a severe lack of myelin, an essential component needed for the insulation and conductivity of electrical signals within the nervous system. The most severe forms of these diseases manifested in the pediatric population leads to progressive brain damage with a fatal outcome for these children shortly after birth. Gene therapy strategies can achieve rapid and robust production and efficient delivery of the deficient enzymes in CNS tissues, either by intracerebral injection of viral vectors delivering the missing gene or by transplantation of gene-corrected cells expressing physiological or supranormal levels of the missing enzyme, as shown by our group and others in relevant animal models. However, none of these approaches alone is sufficient to cure the diseases. In this proposal we will focus on the hypothesis that a combinatorial strategy based on direct intracerebral gene delivery, transplantation of gene-corrected neural and hematopoietic stem cells designed to target different sites of pathology in an appropriate time-window, may represent a possible solution to treat leukodystrophies. To test this hypothesis we will optimize combined protocols, assessing their safety and efficacy in appropriate and relevant murine models. In parallel, since the logical scientific progression in the maturation of these approaches toward clinical trials is their evaluation in large animals models, we will test feasibility and tolerability of the intracerebral injection of vectors in non-human primates, addressing potential safety concerns. In addition, since a better knowledge of the mechanisms underlying these disease is instrumental to develop effective therapies, we will focus on the establishment of disease-specific neural cells obtained from from patient-specific induced pluripotent stem cells (iPSCs), a novel and promiding stem cell type which will offer an unprecedented opportunity to recapitulate the CNS pathology of this diseases in vitro and to further test the efficacy and safety of gene therapy strategies.