Mucopolysaccharidoses (MPS) are a related group of 11 debilitating genetic disorders affecting children. They result from a reduction or total deficiency of an enzyme required for the removal of carbohydrate structures called glycosaminoglycans (gags). Gag degradation occurs inside the cell in specific organelles termed lysosomes and in the absence of the appropriate enzyme, undegraded gag accumulates in the cell. This leads to a range of clinical symptoms and multiple tissue failure. Symptoms c ....Mucopolysaccharidoses (MPS) are a related group of 11 debilitating genetic disorders affecting children. They result from a reduction or total deficiency of an enzyme required for the removal of carbohydrate structures called glycosaminoglycans (gags). Gag degradation occurs inside the cell in specific organelles termed lysosomes and in the absence of the appropriate enzyme, undegraded gag accumulates in the cell. This leads to a range of clinical symptoms and multiple tissue failure. Symptoms common to more than one MPS type include mental deterioration, blindness, abdominal organ enlargement and bone growth problems leading to short stature and bone loss. My laboratory has had a long-term interest in developing treatment for MPS and our research led to the clinical implementation of enzyme replacement therapy (ERT) for MPS VI in 2005. While providing the first effective, multi-tissue treatment for MPS, our research showed that several tissues were not responsive to ERT. These are the brain, cartilage and cornea, thus children on ERT regimens will still suffer from mental retardation, arthritis and blindness. With the goal of treating these particular tissues we have developed a new approach to MPS therapy called substrate deprivation therapy (SDT). Instead of adding back the missing enzyme, SDT acts by decreasing gag production which in turn reduces the level of accumulated gag in cells. SDT results in the correction of MPS cells in culture and reduces several key clinical symptoms in the mouse model of MPS IIIA. In this proposal we will extend our research to evaluate the effect of SDT on brain and bone-joint pathology. Evaluation of efficacy will take place in the MPS VII mouse which exhibits both brain and bone disease and in a new model of MPS IVA developed specifically for this study which exhibits a joint pathology unique amongst the MPS disorders.Read moreRead less
Skeletal disease is a major problem for children with mucopolysaccharidoses (MPS). Patients suffer from early onset osteoporosis and osteoarthritis, severely affecting their quality of life. We will evaluate a lentiviral gene therapy vector developed in-house for its capacity to transduce bone, cartilage, synovial and ligament cells in a mouse model of MPS VI. Our goal is to generate high level, sustained expression of the deficient MPS enzyme and alter the course of skeletal disease in MPS.
Evaluation And Comparison Of Lentiviral And AAV Vector Mediated Gene Therapy For The Mucopolysaccharidoses
Funder
National Health and Medical Research Council
Funding Amount
$521,320.00
Summary
The mucopolysaccharidoses are a group of inherited diseases that have profound consequences for affected individuals. They have pleiotropic effects and usually result in premature death. Although intravenous enzyme replacement therapy has been developed for a number of these disorders, this approach to therapy is invasive, very expensive, of limited efficacy, and is completely ineffective in treating brain pathology. The principal reason for this is the protected nature of the brain which preven ....The mucopolysaccharidoses are a group of inherited diseases that have profound consequences for affected individuals. They have pleiotropic effects and usually result in premature death. Although intravenous enzyme replacement therapy has been developed for a number of these disorders, this approach to therapy is invasive, very expensive, of limited efficacy, and is completely ineffective in treating brain pathology. The principal reason for this is the protected nature of the brain which prevents enzymes that are administered intravenously from entering. Therefore, alternative therapies must be considered in order to provide more effective therapy for the mucopolysaccharidoses, especially those that have significant brain pathology. Gene therapy is one such alternative therapy but this still faces the problem of introducing the therapeutic agent (in this case the gene encoding the requisite enzyme) into the brain. This project aims to provide a comparitive evaluation of two gene therapy vectors for their efficacy in treating all aspects of the pathology found in the mucopolysaccharidoses. Both vectors have the properties of being able to efficiently deliver genes to different cell types and result in the stable genetic modification of the target cell, making them ideal for long-term treatment. However, for effective gene therapy, significant and widely distributed gene delivery to the brain, as well as to other tissues, will be required. This project aims to compare the efficacy of these vectors in two different animal models of the mucopolysaccharidoses that exhibit a wide range of the clinical problems associated with these diseases, importantly including brain pathology.Read moreRead less