Gene therapy for spinal cord disorders

Abstract

The disclosure pertains to methods and compositions for treating disorders affecting the central nervous system (CNS). These disorders include neurometabolic disorders such as lysosomal storage diseases that affect the central nervous system, e.g., Niemann-Pick A disease. They also include disorders such as Alzheimer's disease. The disclosed methods involve contacting an axonal ending of a neuron with a composition containing high titer AAV carrying a therapeutic transgene so that the AAV vector is axonally transported in a retrograde fashion and transgene product is expressed distally to the administration site.

Description

[0001]This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 60 / 677,057, filed May 2, 2005, and U.S. Provisional Application No. 60 / 685,808, filed May 31, 2005, the contents of which are herein incorporated by reference.FIELD OF THE INVENTION[0002]The present invention relates to compositions and methods for treating disorders affecting the central nervous system (CNS) and in particular, the spinal cord. The invention further relates to compositions comprising viral vectors such as adeno-associated virus (AAV) vectors, and methods of administration thereof.BACKGROUND OF THE INVENTION[0003]A group of metabolic disorders known as lysosomal storage diseases (LSD) includes over forty genetic disorders, many of which involve genetic defects in various lysosomal hydrolases. Representative lysosomal storage diseases and the associated defective enzymes are listed in Table 1.TABLE 1Lysosomal storage diseaseDefective enzymeAspartylglucosaminuriaAspartyl...

AI Technical Summary

Benefits of technology

This approach enables extensive correction of lysosomal storage pathology and cholesterol imbalances across multiple brain regions, improving motor function and reducing neuropathological symptoms in animal models of Niemann-Pick disease and Alzheimer's disease.

Problems solved by technology

A major challenge to treating LSD (as opposed to treating a liver-specific enzymopathy) is the need to reverse lysosomal storage pathology in multiple separate tissues.

However, patients with metabolic disease that affects the CNS (e.g., type 2 or 3 Gaucher disease) do not respond to intravenous ERT because the replacement enzyme is prevented from entering the brain by the blood brain barrier (BBB).

Furthermore, attempts to introduce a replacement enzyme into the brain by direct injection have been unsuccessful in part due to enzyme cytotoxicity at high local concentrations (unpublished observations) and limited parenchymal diffusion rates in the brain (Pardridge, Peptide Drug Delivery to the Brain, Raven Press, 1991).

As Aβ accumulates, it aggregates into extracellular plaques, causing impairment of synaptic function and loss of neurons.

The pathology leads to dementia, loss of coordination, and death.

However, the correction of pathology, such as storage pathology in the context of LSD, is typically confined to the immediate vicinity of the injection site because of limited parenchymal diffusion of the injected vector and the secreted transgene product (Taylor et al.

This significantly increases the risk of brain damage.

In addition, some regions of the brain may be difficult to access surgically.

However, it is not known what specific parameters were responsible for the observed axonal transport, and whether sufficient and effective axonal transport would occur in a diseased neuron that is in a state of cellular dysfunction.

Indeed, lesions observed in LSD neurons have been reported to interfere with or even block axonal transport (reviewed in Walkley (1998) Brain Pathol., 8:175-193), suggesting that disease-compromised neurons would not support trafficking of AAV along their axons.

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