Category: Megalencephalic leukoencephalopathy with subcortical cysts (MLC)

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare genetic disorder characterized by an abnormal head, loss of motor functions, epilepsy and mild mental decline. The disease is caused by mutations in two genes named MLC1 and GLIALCAM. There are no therapies for MLC patients, only palliative treatment. Interestingly, some patients with GLIALCAM mutations show a remitting phenotype, suggesting that it may be possible to improve the phenotype of MLC patients, even at later stages of the disease.

We present here a gene therapy preclinical therapeutic approach for MLC patients using two animal models of the disease, the Mlc1 and the GlialCAM knock-out mice. Therapeutic genes will be delivered by one-time treatment to the CNS, overcoming the difficulty of crossing the blood-brain barrier. We hope that the results of this project will be able to provide the first therapeutic tools for patients affected with MLC and may have also implications to treat other diseases affecting the myelin.

Project financed by ELA up to: 57 600 €

MLC is a rare form of leukodystrophy mainly linked to mutations in the MLC1 gene. Patients with this disease suffer from macrocephaly and motor and cognitive symptoms associated with a progressive myelin degeneration. Why the absence of MLC1 leads to these defects is an open question. MLC1 is a molecule produced by astrocytes, which are the major glial cells of the brain and is enriched at their interface with the blood vessels. Since astrocytes control vascular functions in the brain, we proposed that brain vascular pathological mechanims could be involved in MLC, a question that has never been adressed. Using a mouse model deficient for MLC1, we started to uncover a gliovascular pathology in MLC. Our results suggest that it might be the first pathological sign of MLC. We now propose to further explore these vascular alterations with the underlying idea that knowing their causative mechanisms could provide therapeutic options for MLC patients.

Project financed by ELA up to: 67 500 €

Hematopoietic stem cell gene therapy (HSC GT) is an experimental treatment based on the transplantation of autologous hematopoietic precursor cells genetically modified to express high levels of ARSA enzyme. This treatment benefits late infantile and early juvenile MLD children if treated in the pre-symptomatic/early symptomatic stage of the disease but is less effective in MLD children treated in the progressive phase of disease, who experience severe neurological deterioration. In order to recognize the reasons behind this different clinical outcome we need a better understanding of the therapeutic mechanisms of correction of MLD neural cells by the progeny of transplanted hematopoietic cells that engraft in the brain.

In this project the investigators aim to fill this gap of knowledge taking advantage of unique and clinically relevant in vitro human disease models, i.e. neural and blood cells derived from healthy donors, untreated and gene therapy treated MLD patients. We expect to clarify how and to which extent the ARSA enzyme is transported from metabolically competent donor blood cells to MLD neurons and glia. Also, they will provide hints on the contribution of complementary mechanisms of correction that could be exploited to enhance the benefit of HSC GT and broaden its accessibility to larger cohorts of MLD patients who presently not meet the inclusion criteria of these experimental treatments.

Project financed by ELA up to: 60 000 €

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare genetic disorder characterized by an abnormal head, loss of motor functions, epilepsy and mild mental decline. The disease is caused by mutations in two genes named MLC1 and GLIALCAM. There are no therapies for MLC patients, only palliative treatment. We recently demonstrated the efficiency of gene therapy in correcting MLC-typical myelin vacuolation. Now we aim to demonstrate that gene therapy is also able to correct the motor impairment present in the MLC knock-out mouse models. Thus, we propose to administer the therapeutic AAV vectors to the affected cells in the brain of these mice, and to look for longitudinal, non-invasive tests to assess for in vivo indicators of disease correction in the animal models that could finally be translated to clinical trials for MLC patients.

Project financed by ELA up to: 44 414 €

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare disease mainly related to mutations in the MLC1 gene. Patients suffer from macrocephaly and motor and cognitive defects associated with progressive myelin degeneration. We have recently shown that MLC originates from early defects in the gliovascular unit, a specialized interface in the brain between blood vessels and astrocytic glial cells, including a defect in vessel contractility that impairs blood flow in the brain. We believe that these alterations are at the origin of MLC. Our project is now to develop an approach to restore the functions of the altered gliovascular unit in a mouse model of MLC and to test whether this strategy can reverse leukodystrophy, which would pave the way for therapeutic intervention in patients.

Project financed by ELA up to: 94 000 €