MLD Research

Metachromatic Leukodystrophy (MLD), the most common form of Leukodystrophy, is a rare inherited neurometabolic disorder affecting the white matter of the brain (Leukoencephalopathy).
 It is characterized by the accumulation of a fatty substance known as sulfatide (a sphingolipid) in the brain and other areas of the body (i.e., liver, gall bladder, kidneys, and/or spleen).
 The fatty protective covering on the nerve fibers (myelin) is lost from areas of the central nervous system (CNS) due to the buildup of sulfatide.
 Symptoms of Metachromatic Leukodystrophy may include convulsions, seizures, personality changes, spasticity, progressive dementia, motor disturbances progressing to paralysis, and/or visual impairment leading to blindness.
 Metachromatic Leukodystrophy is inherited as an autosomal recessive trait.  There are three types of the disease that have similar symptoms.
 However, they are distinguished by the age of onset: infantile, juvenile, and adult forms of Metachromatic Leukodystrophy.
 MLD is a rare disease, affecting about one in 60,000 people.

Three Types of MLD:
Late Infantile – Onset of symptoms between 6 mo. and 2 yrs.
Juvenile – Onset of symptoms after age four until sixteen.
Adult – Onset of symptoms late teens.

MLD Research Canada

DR. TONY RUPAR

  • B.Sc., Ph.D., Western Ontario, Fellow of the Canadian College of Medical Genetics
  • Associate Professor, Biochemistry and Paediatrics
  • Chairman, Division of Clinical Biochemistry
  • Chair, Human Molecular Genetics Program, Child Health Research Institute
  • Director, Biochemical Genetics Laboratory, CPRI
  • Director, Bethanys Hope Leukodystrophy Research Laboratory

Bethanys HopeWhat is MLD?

Bethanys Hope
Dr. Rupar’s Info Sheet

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DR. STEPHANIE NEWMAN
Stephanie Newman has recently completed her PhD from the University of Oxford, UK. The University of Oxford is rated as the best University in the world and has a long term reputation of excellence. From a world-renowned research institution Dr. Newman has established a specific research focus in inborn errors of metabolism with a particular focus on rare lysosomal storage disorder Niemann Pick Disease Type C (NPC).

Dr. Newman has uncovered a specific innate immune abnormality in NPC where results determined NPC macrophage cells display reduced phagocytosis of several targets. Phagocytosis is a physiologically ancient process by which cell engulf and degrade invading particles and microbes. Defective phagocytosis can initiate abnormal immunological and inflammatory responses that we suggest contribute to NPC phenotype. Abnormal phagocytosis also impacts the ability to fight off infection, therefore showing obvious clinical interest in NPC.

Recently Dr. Newman has returned to London, Ontario to begin her Post-Doctoral training under the direction of Dr. Tony Rupar, where she will assist in moving the MLD clinical trial forward, bringing new ideas for MLD therapies. Dr. Newman is an enthusiastic and optimistic member of Team 2018. She will bring her wide range of skills, international collaborators, and a personal, well established background in rare disease to the Bethanys Hope Leukodystrophy Research Laboratory, where she will assist in associated MLD clinical trial research in London, Ontario. Her career goals are to remain in the field of rare disease research, continuing to focus on discovery of new therapeutics.

Research Update - June 2018

The research laboratory has focused on understanding the disease process and developing treatments for MLD. Cultured fibroblast cell lines from patients with MLD and the mouse model of MLD have been extensively studied. Successes with both the cell lines and the mouse model have informed experiments designed to accumulate further preclinical safety data.

In MLD, mutations in the ARSA gene cause the loss of the activity of the enzyme arylsulfatase A (ARSA) resulting in the accumulation of a lipid, sulfatide, in the central and peripheral nervous systems. This causes a progressive neurodegeneration. The mouse model of MLD also accumulates sulfatide in the brain especially the cerebellum.

The blood brain barrier protects the brain but is a major impediment to treating MLD and other lysosomal storage diseases with a neurological component. We have developed a strategy to treat the MLD mouse using adult mice with a mature blood brain barrier. This mimics the clinical situation where almost all patients with MLD are diagnosed at an age when the blood brain barrier is formed. The therapy is to surgically access the lateral ventricle of the brain. The lateral ventricle is filled with cerebral spinal fluid (CSF) and contains the choroid plexus that produces the CSF. The measure of success for the treatment is the reduction of the concentration of
sulfatide in the cerebellar region of the brain to levels seen in wild type mice.

The treatment is gene therapy using a lentivirus – based gene therapy vector (LV-hARSA) that contains DNA that codes for a functional ARSA. Surgical delivery of LV-hARSA into the lateral ventricle of adult MLD mice results in the widespread transduction of cells within the choroid plexus and ependymal cells throughout the CNS and stable expression for months.

Ependymal cells line the CSF containing compartments in the brain. A single dose of LV-hARSA delivered into the lateral ventricle of adult MLD mice reduces cerebellar sulfatide concentrations by 18% to the same level as seen in wild type mice. More than 100 mice and rats have been treated and tolerated both the surgical procedure and LVhARSA without adverse events.

The gene therapy vector, LH-hARSA, introduces a correct ARSA gene sequence into the chromosomes of the choroid plexus and ependymal cells that are transduced. Detailed studies to identify the location of the integrated ARSA gene within those chromosomes have been completed as part of a safety assessment and demonstrated a clinically favorable integration site profile. Further safety studies have been successfully completed using both the mouse model of MLD and cultured
cells obtained from patients with MLD. These studies have not identified vector – caused toxicity.

Research is ongoing to assess the potential of cell therapy in the mouse model of MLD using mesenchymal stem cells. Mesenchymal stem cells expressing green fluorescent protein introduced with a foamy virus vector are seen to have migrated from the lateral ventricle (left) to distant areas of the mouse brain.

Looking Forward:
A pre – clinical trial application meeting with Health Canada to discuss a potential clinical trial using intra-cerebroventricular delivery has informed the direction of future research to prepare for a clinical trial application. Other ongoing research is targeted at developing strategies to impact peripheral nerve disease.

Bethanys HopeResearch Summary

TEAM 2018 PROGRESS BAR!