Recipient Organization
UNIV OF PENNSYLVANIA
(N/A)
PHILADELPHIA,PA 19104
Performing Department
School Of Veterinary Medicine
Non Technical Summary
The purpose of the grant is to determine if very high levels of circulating enzyme can cross the blood brain barrier and provide relief from the clinical signs seen in the brain in cats with a lysosomal storage disease, mannosidosis. Lysosomal storage diseses, of which there are more than 50, with 60% having mental retardation in children, can be treated by administration of the relevant enzyme. However, enzymes do not usually cross the blood brain barrier. Experiments in mice with several diseases has shown that administration of high levels of enzyme have altered the brain diseae. Cats with mannosidosis have progreesive neurological disease requiring euthanasia by 6 months of age. Using liver-directed gene theapy, this project is designed to see if we can affect the brain disease in a large animal model.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
For many years, the blood brain barrier has been considered a major obstacle to systemic therapy to reach the central nervous system for lysosomal storage diseases. However, recent data have indicated that high serum levels of beta-glucuronidase can alter the central nervous system lesions and behavioral abnormalities in adult mucopolysaccharidosis VII mice. But the question remains, is this observation limited to mice and to mucopolysaccharidosis VII or will it be true for large animals as models for children and for other lysosomal storage diseases This grant proposal is designed to answer these questions. We have shown improvement in central nervous system neuropathological lesions in mucopolysaccharidosis I and VII dogs with constant high serum levels of alpha-L-iduronidase and beta-glucuronidase, respectively, following neonatal, intravenous retroviral gene therapy. However, because the mucopolysaccharidosis dogs lack clinical signs of the central nervous system lesions, improvement in neurological function in the large animals could not be evaluated. This grant application proposes to test the levels of serum activity associated with transit across the blood brain barrier using somatic (liver-based) gene therapy in cats with alpha-mannosidosis. Alpha-mannosidosis cats have significant, well-documented neurological signs of disease, with death by six months of age if untreated, and well-described neuropathological lesions. Alpha-mannosidosis cats have also been shown to respond to bone marrow transplantation and direct brain injection of a viral vector so it will be clear if high serum enzyme activity is successful. Thus, we propose to determine if high constant serum alpha-mannosidase activity will cross the blood brain barrier and abrogate the clinical and neuropathological disease. This is an important proof of principle before proposing gene therapy clinical trials to produce high serum enzyme activity in any of the 60% of lysosomal storage diseases with central nervous system lesions found in children.
Project Methods
Specific Aim 1: a) Treat seven alpha-mannosidosis (AMD) kittens intravenously at 3 days of age with high or low doses of the retroviral (RV) vector to produce varied serum activity of lysosomal alpha-mannosisdase (LAMAN). b) Evaluate the clinical progression of the disease by physical examination, electodiagnostic testing, and magnetic resonance imaging in treated cats and compare the results to untreated affected and normal age-matched controls. c) Evaluate the central nervous system (CNS) and hepatic lesions by enzyme and oligosaccharide analysis, histology, immunohistochemisty, and electron microscopy in tissues from treated cats and compare the results to untreated affected and normal age-matched controls. Specific Aim 2: Treat seven 7 week-old AMD kittens with liver-directede intravenous adeno-associated viral (AAV2/8) vector gene therapy, an age more consistent with the diagnosis of lysosomal storage diseases (LSDs) in children, an age more representative of the age at diagnosis of children (post weaning ~1 year in a child), and when there is clearly no question about the blood brain barrier (BBB) permeability, allowing quantitation of the effect of high constant serum activity on CNS function and lesions. Specific Aim 3: Follow those treated cats that show successful CNS therapy long-term to evaluate continued efficacy and any potential side effects of vector-based gene therapy.