Redirecting N-acetylaspartate metabolism in the central nervous system normalizes myelination and rescues Canavan disease
Dominic J. Gessler, … , Reuben Matalon, Guangping Gao
Dominic J. Gessler, … , Reuben Matalon, Guangping Gao
Published February 9, 2017
Citation Information: JCI Insight. 2017;2(3):e90807. https://doi.org/10.1172/jci.insight.90807.
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Research Article Metabolism Therapeutics

Redirecting N-acetylaspartate metabolism in the central nervous system normalizes myelination and rescues Canavan disease

Abstract

Canavan disease (CD) is a debilitating and lethal leukodystrophy caused by mutations in the aspartoacylase (ASPA) gene and the resulting defect in N-acetylaspartate (NAA) metabolism in the CNS and peripheral tissues. Recombinant adeno-associated virus (rAAV) has the ability to cross the blood-brain barrier and widely transduce the CNS. We developed a rAAV-based and optimized gene replacement therapy, which achieves early, complete, and sustained rescue of the lethal disease phenotype in CD mice. Our treatment results in a super-mouse phenotype, increasing motor performance of treated CD mice beyond that of WT control mice. We demonstrate that this rescue is oligodendrocyte independent, and that gene correction in astrocytes is sufficient, suggesting that the establishment of an astrocyte-based alternative metabolic sink for NAA is a key mechanism for efficacious disease rescue and the super-mouse phenotype. Importantly, the use of clinically translatable high-field imaging tools enables the noninvasive monitoring and prediction of therapeutic outcomes for CD and might enable further investigation of NAA-related cognitive function.

Authors

Dominic J. Gessler, Danning Li, Hongxia Xu, Qin Su, Julio Sanmiguel, Serafettin Tuncer, Constance Moore, Jean King, Reuben Matalon, Guangping Gao

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Figure 4

Astrocyte-restricted hASPA expression rescues motor function, neuropathology, and biomarker expression in Canavan disease knockout (CD KO) mice.

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Astrocyte-restricted hASPA expression rescues motor function, neuropatho...
Mice were treated intravenously at P1 with 4 × 1011 genome copies of 3rd generation gene therapy containing either a ubiquitous or a partial human glial fibrillary acid protein (phGFAP) promoter. (A and B) Brain sections with astrocyte-restricted EGFP expression that colocalizes with GFAP-positive (red in A) cells but not with myelin basic protein–positive (MBP, red in B) cells (n = 3); high magnification of the same images provided in Supplemental Figure 7, C and D. Scale bars: 50 μm. (C) Weights of WT mice vs. mice treated with ubiquitous or astrocyte-restricted human aspartoacylase (hASPA) expression (n = 8–10) by day (inset) and by week. (D) Motor function (accelerated rotarod, balance beam, and inverted screen) and cognitive (T maze; E) tests of mice with astrocyte-restricted hASPA expression (n = 6–8). UT, untreated. (F) MRI shows T2 signal pattern of ubiquitous vs. astrocyte-restricted hASPA expression in comparison to WT and untreated (KO) mice (P25; n = 3). (G) Magnetic resonance spectrometry of brain shows brain N-acetylaspartate (NAA) levels and (H) Western blotting shows brain ASPA expression (P25; n = 3). (I) Luxol fast blue staining of myelin shows a reduction of myelin fibers (white arrows) and the presence of vacuoles (black arrows) in the cerebellar white matter of CD KO mice vs. mice treated with ubiquitous or astrocyte-restricted hASPA expression (P25; n = 3; original magnification, ×10). GFAP, GFAP promoter–driven hASPA; ML, molecular layer; PK, Purkinje cell layer; GR, granular layer; WM, white matter. Statistical analysis was performed using 2-way ANOVA with multiple comparison correction for C and 1-way ANOVA with multiple comparison correction was used for D, E, G, and H. Data are presented as the mean ± SD. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. ns, not significant.