Global diffuse distribution in the brain and efficient gene delivery to the dorsal root ganglia by intrathecal injection of adeno‐associated viral vector serotype 1

Abstract

The success of gene therapy for inherited neurodegenerative diseases such as metachromatic leukodystrophy (MLD) depends on the development of efficient gene delivery throughout the brain guarded by the blood-brain barrier and achieves distribution of the deficient enzyme throughout the brain. Direct injection of viral vector into the brain parenchyma is too invasive and may not be sufficient to treat the entire brain. As an alternative approach, we examined the feasibility of intrathecal (IT) injection of adeno-associated viral vector serotype 1 (AAV1). AAV1 vector expressing arylsulfatase A (ASA) and green fluorescence protein (GFP) was intrathecally injected into ASA knockout MLD model mice. Expression of GFP was assessed by fluorescence microscopy and immunohistochemical methods, whereas the concentration of ASA was determined by a quantitative enzyme-linked immunosorbent assay. Broad distribution of GFP expression was seen throughout the brain after IT injection of AAV1 vector. In addition, a large number of nerve fibers in the dorsal spinal cord and many neural cell bodies in the dorsal root ganglia were efficiently transduced. Widespread distribution of ASA activity and a significant reduction of sulfatide content were confirmed in treated MLD model mice. IT injection of AAV1 vector is a useful and non-invasive method for widespread gene delivery to the brain and dorsal root ganglia.