AAV9-mediated erythropoietin gene delivery into the brain protects nigral dopaminergic neurons in a rat model of Parkinson's disease

Abstract

We have recently shown that intrastriatal injection of recombinant human erythropoietin (EPO) protects dopaminergic (DA) neurons in the substantia nigra (SN) from 6-hydroxydopamine (6-OHDA) toxicity in a rat model of Parkinson's disease. However, systemic administration of EPO did not protect nigral DA neurons, suggesting that the blood-brain barrier limits the passage of EPO protein into the brain. In the present study, we used an adenoassociated viral (AAV) serotype 9 (AAV9) vector to deliver the human EPO gene into the brain of 6-OHDA-lesioned rats. We observed that expression of the human EPO gene was robust and stable in the striatum and the SN for up to 10 weeks. EPO-immunoreactive (IR) cells were widespread throughout the injected striatum, and EPO-IR neurons and fibers were also found in the ipsilateral SN. Enzyme-linked immunosorbent assay and western blot analyses exhibited dramatic levels of EPO protein in the injected striatum. As a result, nigral DA neurons were protected against 6-OHDA-induced toxicity. Amphetamine-induced rotational asymmetry and spontaneous forelimb use asymmetry were both attenuated. Interestingly, we also observed that intrastriatal injection of AAV9-EPO vectors led to increased numbers of red blood cells in peripheral blood. This highlights the importance of using an inducible gene delivery system for EPO gene delivery.

Structural Insight into the Unique Properties of Adeno-Associated Virus Serotype 9

“…Recently, a single intravenous injection of AAV9 vectors expressing ␣-N-acetylglucosaminidase (NAGLU) in mice with mucopolysaccharidosis IIIB (MPS IIIB; lysosomal storage disease) led to correction of their lysosomal storage pathology in the central and peripheral nervous systems and correction of astrocytosis and neurodegeneration (25). Given these properties, AAV9 is currently under development for treatment of neurodegenerative diseases, such as spinal muscle atrophy, amyotrophic lateral sclerosis, Parkinson's disease, and MPS IIIB (7,25,29,30,45,80) (Table 1). Furthermore, while preexisting antibodies to AAVs have been shown to be detrimental to AAV gene delivery, the prevalence of antibodies to AAV9 is lower in humans than those of other serotypes, for example, AAV1 and AAV2 (8), making this serotype an even more attractive candidate for development as a gene delivery vector.…”

Targeting erythropoietin for chronic neurodegenerative diseases

“…Intrastriatal but not systemic administration of EPO can reduce microglia activation in SN, protect nigral DA against 6-OHDA and improve neurobehavioral outcome in a rats [114]. In addition, adenoassociated viral serotype 9 (AAV9) vector mediated deliver of the human EPO gene into the brain of 6-OHDA-lesioned rats robustly promotes the expression of the human EPO gene in the striatum and the SN, prevents DA neuronal loss, attenuates the rotational and spontaneous forelimb use asymmetry ( Figure 2 and Table 2) [115].…”

Pseudotyped Adeno-Associated Virus 2/9-DeliveredCCL11shRNA Alleviates Lung Inflammation in an Allergen-Sensitized Mouse Model

“…Halbert et al demonstrated the higher level and longer gene expression of both AAV2/5 and AAV2/9 compared with AAV2/2 in lung tissues (Halbert et al, 2001). In addition, AAV9 vector has been applied to the treatment of human disease models and recently has been suggested to be beneficial for liver and brain gene delivery (Chen et al, 2009;Xue et al, 2010).…”