Partial cure of established disease in an animal model of metachromatic leukodystrophy after intracerebral adeno-associated virus-mediated gene transfer

Abstract

Metachromatic leukodystrophy (MLD) is a lysosomal storage disease caused by genetic deficiency of arylsulfatase A (ARSA) enzyme. Failure in catalyzing the degradation of its major substrate, sulfatide (Sulf), in oligodendrocytes and Schwann cells leads to severe demyelination in the peripheral (PNS) and central nervous system (CNS), and early death of MLD patients. The ARSA knockout mice develop a disease that resembles MLD but is milder, without significant demyelination in the PNS and CNS. We showed that adeno-associated virus serotype 5-mediated gene transfer in the brain of ARSA knockout mice reverses Sulf storage and prevents neuropathological abnormalities and neuromotor disabilities when vector injections are performed at a pre-symptomatic stage of disease. Direct injection of viral particles into the brain of ARSA knockout mice at a symptomatic stage results in sustained expression of ARSA, prevention of Sulf storage and neuropathological abnormalities. Despite these significant corrections, the treated mice continue to develop neuromotor disability. We show that more subtle biochemical abnormalities involving gangliosides and galactocerebroside are in fact not corrected.

Comparative Efficacy and Safety of Multiple Routes of Direct CNS Administration of Adeno-Associated Virus Gene Transfer Vector Serotype rh.10 Expressing the Human Arylsulfatase A cDNA to Nonhuman Primates

“…This beneficial effect is likely mediated by bone marrow-derived stem cells that migrate into the brain and differentiate into microglia that produce normal copies of the ARSA enzyme (Asheuer et al, 2004;Biffi et al, 2006). When performed at an early stage of the disease, hematopoietic cell transplantation can stabilize the cerebral demyelination in patients with late-onset MLD (juvenile and adult forms) (Krivit et al, 1999;Sevin et al, 2007). However, in the more severe infantile and early juvenile form of MLD, hematopoietic cell transplantation does not arrest the rapid progression of cerebral demyelination, even when the procedure is performed early in presymptomatic infants (Bredius et al, 2007).…”

“…For direct CNS gene therapy, AAV vectors have emerged as the most promising clinical vector because of their excellent safety and efficacy profile (Sevin et al, 2007;Sondhi et al, 2008). AAV-based therapies to the CNS have been assessed in Canavan, late infantile neuronal ceroid lipofuscinosis (LINCL), Alzheimer's, and Parkinson's diseases ( Janson et al, 2002;Tuszynski and Blesch, 2004;McPhee et al, 2006;Kaplitt et al, 2007;Worgall et al, 2008;Mandel, 2010;Souweidane et al, 2010;Kells et al, 2012).…”

“…The loss of functional ARSA enzyme leads to an accumulation of 3-O-sulfogalactosyl ceramides (sulfatides) in oligodendrocytes, myelin sheaths, and Schwann cells, triggering widespread demyelination in the CNS and peripheral nervous system (PNS) (Gieselmann et al, 2003;MolanderMelin et al, 2004;Takahashi and Suzuki, 2012;Patil and Maegawa, 2013). Sulfatides also accumulate in neurons, promoting neuronal dysfunction and degeneration (Gieselmann et al, 2003;Molander-Melin et al, 2004;Wittke et al, 2004;Sevin et al, 2007). As glial cells and neurons are highly sensitive to this aberrant storage, these cells are progressively lost, resulting in broad and rapid neurologic decline that manifests as ataxia, inability to walk or stand, seizures, and cognitive decline (von Figura et al, 2001;Rauschka et al, 2006;Gieselmann and Krageloh-Mann, 2010).…”

“…Because the disease affects all regions of the nervous system, treatment must reestablish the missing enzymatic function throughout (Beck, 2007;Gray, 2013). Because the blood-brain barrier prevents effective therapy with systemic administration of ARSA, investigators have explored the use of gene therapy to provide the missing ARSA enzyme in MLD via direct intraparenchymal administration or by the use of genetically modified bone marrow stem cells that differentiate into microglial cells in the CNS (Matzner et al, 2000;Biffi et al, 2004Biffi et al, , 2006Biffi et al, , 2013Sevin et al, 2006Sevin et al, , 2007Colle et al, 2010;Piguet et al, 2012). The CNS manifestations of MLD are ideal for a CNS gene therapy approach because the ARSA enzyme is secreted into the extracellular matrix and incorporated into neighboring and distant cells via the ubiquitous cell surface, mannose 6-phosphate (M6P) receptor (Willingham et al, 1981;Funk et al, 1992;Ghosh et al, 2003).…”

Le virus du Sida au milieu du gué vingt-cinq ans après

“…Ces lentivecteurs (LV) sont devenus incontournables en génétique moléculaire et physiologie, et c'est pourquoi des firmes de Biotechnologie construisent d'énormes banques de LV couvrant tous les gènes humains pour explorer leur fonction. En 2007, les premiers essais de thérapie cellulaire utilisant des LV chez l'homme ont commencé [13] ; qu'en sera-t-il dans une génération ?…”