Long-Term Improvement of Neurological Signs and Metabolic Dysfunction in a Mouse Model of Krabbe’s Disease after Global Gene Therapy

Abstract

We report a global adeno-associated virus (AAV)9-based gene therapy protocol to deliver therapeutic galactosylceramidase (GALC), a lysosomal enzyme that is deficient in Krabbe's disease. When globally administered via intrathecal, intracranial, and intravenous injections to newborn mice affected with GALC deficiency (twitcher mice), this approach largely surpassed prior published benchmarks of survival and metabolic correction, showing long-term protection of demyelination, neuroinflammation, and motor function. Bone marrow transplantation, performed in this protocol without immunosuppressive preconditioning, added minimal benefits to the AAV9 gene therapy. Contrasting with other proposed pre-clinical therapies, these results demonstrate that achieving nearly complete correction of GALC's metabolic deficiencies across the entire nervous system via gene therapy can have a significant improvement to behavioral deficits, pathophysiological changes, and survival. These results are an important consideration for determining the safest and most effective manner for adapting gene therapy to treat this leukodystrophy in the clinic.

Conditions for combining gene therapy with bone marrow transplantation in murine Krabbe disease

“…These include bone marrow transplantation (BMT), enzyme replacement therapy, gene therapy via different routes of administration, substrate reduction therapy, chemical chaperone therapy, small molecule therapy including anti-inflammatory drugs and combinations of these approaches. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] These different approaches have resulted in variable degrees of success. Some of these trials only resulted in minimal extension of life, and significant less than 100 days.…”

Failure to clear developmental apoptosis contributes to the pathology of RNASET2-deficient leukoencephalopathy

“…The development of animal models to study leukodystrophies in vivo has been invaluable for testing therapies (Priller et al, 2001;Biffi et al, 2004;Launay et al, 2017;Marshall et al, 2018), however many of those models fail to recapitulate the key aspects of the human disease.…”

Brainstem development requires galactosylceramidase and is critical for the pathogenesis of Krabbe Disease

“…In addition, it was particularly intriguing that the residual GALC was unable to cross-correct affected tissues, as deduced from the severe phenotype. This result may correlate with deteriorative moribund pathology of HSCT-treated twitcher and KD patients despite the increased GALC activity 25,26,27,28 , emphasizing the importance of providing GALC at a specific developmental period.…”