Research Home University of North Carolina - Chapel Hill, Dr. Haiyan Fu AAV-mediated Gene Therapy for Neurological Disease of MPS III Using a Knock-out Mouse Model With the support of the MPS IIIB community, we have made AAV vectors (means of carrying genes into cells) containing the normal human a-N-acetylglucosaminidase (NaGlu) gene, which is missing in MPS IIIB patient. We have previously shown that our AAV vectors mediated the production of NaGlu (the enzyme missing in MPS IIIB) and corrected the storage of glycosaminoglycan (GAG, previously called mucoploysaccharides) in cultured human and mouse MPS IIIB cells. Using AAV vectors, injected into mouse brain, we have also demonstrated the long-term, but only localized production of the missing enzyme and the localized correction of lysosomal storage in MPS IIIB mouse brain in the area of our injection. In addition, we have observed the correction of GAG storage in liver (50-80%) and in other peripheral tissues (<40%) of mice, by a single intravenous (I.V.) infusion of the AAV vector. The critical issue in developing treatment for the CNS diseases in MPS, is to be able to deliver therapeutic reagents (AAV vector) to the whole brain and not just a localized area. Enzymes and vectors, when given by an I.V. injection, are prevented from entering the brain, due to the presence of a physical barrier called blood-brain barrier (BBB). In the past year, with generous support from Ben’s Dream - the Sanfilippo Research Foundation, we have been focusing our research efforts on developing methods to enhance vector delivery to the brain. 1) We have successfully delivered the AAV vector into CNS by a single I.V. injection, using mannitol to disrupt the BBB. Simultaneously, for the first time, we achieved a global distribution of the vector in the brain of mice, even though the number of brain cells involved was still small. I.V. administration could also deliver AAV vector into multiple somatic tissues. More efforts are needed to increase the efficiency of the procedure. 2) We also injected AAV vector into a spinal fluid space (cistern) of adult mouse brain and achieved broad dispersion of the AAV vector in the CNS, including brain and spinal cord. Both approaches above are non-invasive, compared with direct injection into brain tissue. We anticipate that combining the peripheral (I.V.) and intracisternal delivery of AAV vector will contribute greatly in developing therapies to treat physical and neurological diseases in MPS. This may also benefit therapeutic studies for other lysosomal diseases since they share many similar features. More studies are needed to explore more efficient means for delivery of AAV vectors to the whole brain, in order to pursue our goal of treating CNS disorder in MPS IIIB patients. The studies have been done by Dr. Haiyan Fu in the laboratory of Dr. Joseph Muenzer, with the collaboration of Dr. Richard J. Samulski of Gene Therapy Center, at University of North Carolina at Chapel Hill.