Poster 1: Cell and Tissue Studies

Sampurna Saikia, Yasuhiko Ago, Shunji Tomatsu

University of Delaware

Background: Mucopolysaccharidosis IVA or MPS IVA is one of the most important genetic disorders grouped in Lysosomal storage diseases, because of accumulation of the undegraded substrate in absence of the enzyme N-acetylegalactyosamine-6-sulphate sulphates. Different phenotypic symptoms like skeletal abnormalities, short stature, knock knees, cloudy eyes, vision loss, course facial features are the outcome of the disease onset. Although gene therapy has been established for promising outcome for one-time permanent treatment, as the continual enzyme is expected to produce after injection with transduced cells, high immune responses against the gene therapy treatment are an overriding phenomenon to consider, which eventually decrease the treatment efficacy. Therefore, a new strategy is required to induce immune tolerance to specific proteins and viral vectors using mouse models. In this study we hypothesized that oral delivery of peptides for GALNS will induce the tolerance in mice for MPS IVA, which will eventually increase the efficiency of gene therapy treatments by improving bone and cartilage lesions. Methods: Neonatal male mice will be treated with three epitope peptides and GALNS enzyme within 48 hours of birth for every alternate day continuing for 20 days in two doses at the rate of 2.5µg/g body weight and 5µg/g body weight followed by tail vein injection with 5×1013 GC/kg CAG-GALNS AA9 vectors to the peptide and GALNS experimental treatment group at the age of 30 days. Collection of plasma samples from treated mice bi-weekly after each gene therapy treatments for GALNS activity was carried out until euthanization of the mice at age of 24 weeks to collect various tissues. We target to evaluate the vector biodistribution, antibody and enzymatic activity along with GAG levels in plasma and various tissues followed by pathology and bone morphology. Results: ELISA for anti-GALNS antibody by using purified GALNS as primary antibody for standards, showed a various range of anybody concentrations in different groups of treated animals including the control group. Similarly, enzymatic activities among the treated mice groups varied widely with the highest enzymatic activity shown for the group treated with GALNS 2.5µg/g body weight. The therapeutic efficacy of the gene therapy treatment will be evaluated by conducting GAG assay, KS levels in plasma and tissues, bone pathology and vector copy number analysis.

Research Area: Rehabilitation & Treatment