Disclosed herein are methods of treating Canavan disease in a subject through restoring ASPA enzymatic activities in the subject by expressing exogenous wild type ASPA gene in the brain of the subject. Also disclosed are a process of producing neural precursor cells, including NPCs, glial progenitor cells and oligodendroglial progenitor cells, which express an exogenous wild type ASPA gene and the neural precursor cells produced by this process.