Therapeutic Efficacy of Bone Marrow Transplant, Intracranial AAV-mediated Gene Therapy, or Both in the Mouse Model of MPS IIIB

Sanfilippo syndrome type B (MPS IIIB) is a lysosomal storage disease resulting from a deficiency of N-acetyl-glucosaminidase (NAGLU) activity. In an attempt to correct the disease in the murine model of MPS IIIB, neonatal mice were treated with intracranial AAV2/5-NAGLU (AAV), syngeneic bone marrow transplant (BMT), or both (AAV/BMT). All treatments resulted in some improvement in clinical phenotype. Adeno-associated viral (AAV) treatment resulted in improvements in lifespan, motor function, hearing, time to activity onset, and daytime activity level, but no reduction of lysosomal storage. BMT resulted in improved hearing by 9 months, and improved circadian measures, but had no effect on lifespan, motor function, or central nervous system (CNS) lysosomal storage. AAV/BMT treatment resulted in improvements in hearing, time to activity onset, motor function, and reduced CNS lysosomal storage, but had no effect on lifespan. Combination therapy compared to either therapy alone resulted in synergistic effects on hearing and CNS lysosomal inclusions but antagonistic effects on motor function and lifespan. AAV alone is more efficacious than BMT or AAV/BMT treatment for lifespan. BMT was the least efficacious treatment by all measures. CNS-directed AAV treatment alone appears to be the preferred treatment, combining the most efficacy with the least toxicity of the approaches assessed.