Efficient transduction of vascular smooth muscle cells with a translational AAV2.5 vector: a new perspective for in-stent restenosis gene therapy.

Coronary artery disease represents the leading cause of mortality in the developed world. Percutaneous coronary intervention involving stent placement remains disadvantaged by restenosis or thrombosis. Vascular gene therapy-based methods may be approached, but lack a vascular gene delivery vector. We report a safe and efficient long-term transduction of rat carotid vessels after balloon injury intervention with a translational optimized AAV2.5 vector. Compared with other known adeno-associated virus (AAV) serotypes, AAV2.5 demonstrated the highest transduction efficiency of human coronary artery vascular smooth muscle cells (VSMCs) in vitro. Local delivery of AAV2.5-driven transgenes in injured carotid arteries resulted in transduction as soon as day 2 after surgery and persisted for at least 30 days. In contrast to adenovirus 5 vector, inflammation was not detected in AAV2.5-transduced vessels. The functional effects of AAV2.5-mediated gene transfer on neointimal thickening were assessed using the sarco/endoplasmic reticulum Ca(2+) ATPase isoform 2a (SERCA2a) human gene, known to inhibit VSMC proliferation. At 30 days, human SERCA2a messenger RNA was detected in transduced arteries. Morphometric analysis revealed a significant decrease in neointimal hyperplasia in AAV2.5-SERCA2a-transduced arteries: 28.36±11.30 (n=8) vs 77.96±24.60 (n=10) µm(2), in AAV2.5-green fluorescent protein-infected, P<0.05. In conclusion, AAV2.5 vector can be considered as a promising safe and effective vector for vascular gene therapy.

Natural history of Canavan disease revealed by proton magnetic resonance spectroscopy (1H-MRS) and diffusion-weighted MRI.

Canavan disease is a childhood leukodystrophy caused by mutations in the gene for human aspartoacylase ( ASPA), which leads to an abnormal accumulation of the substrate molecule N-acetyl-aspartate (NAA) in the brain. This study was designed to model the natural history of Canavan disease using MRI and proton magnetic resonance spectroscopy ( (1)H-MRS). NAA and various indices of brain structure (morphology, quantitative T1, fractional anisotropy, apparent diffusion coefficient) were measured in white and gray matter regions during the progression of Canavan disease. A mixed-effects statistical model was used to fit all outcome measures. Longitudinal data from 28 Canavan patients were directly compared in each brain region with reference data obtained from normal, age-matched pediatric subjects. The resultant model can be used to non-invasively monitor the natural history of Canavan disease or related leukodystrophies in future studies involving drug, gene therapy, or stem cell treatments.

Immune responses to AAV in a phase I study for Canavan disease.

BACKGROUND: Canavan disease is a rare leukodystrophy with no current treatment. rAAV-ASPA has been developed for gene delivery to the central nervous system (CNS) for Canavan disease. This study represents the first use of a viral vector in an attempt to ameliorate a neurodegenerative disorder. METHODS: Subjects received intracranial infusions via six cranial burr holes. Adeno-associated virus, serotype 2 (AAV2), mediated intraparenchymal delivery of the human aspartoacylase cDNA at a maximum dose of 1 x 10(12) vector genomes per subject. The immune response and safety profiles were monitored in the follow-up of ten subjects. RESULTS: Following rAAV2 administration, we found no evidence of AAV2 neutralizing antibody titers in serum for the majority of subjects tested (7/10). In a subset (3/10) of subjects, low to moderately high levels of AAV2 neutralizing antibody with respect to baseline were detected. In all subjects, there were minimal systemic signs of inflammation or immune stimulation. In subjects with catheter access to the brain lateral ventricle, cerebrospinal fluid was examined and there was a complete absence of neutralizing antibody titers with no overt signs of brain inflammation. CONCLUSIONS: rAAV2 vector administration to the human CNS appears well tolerated. The low levels of immune response to AAV2 detected in 3/10 subjects in this study suggest at this dose and with intraparenchymal administration this approach is relatively safe. Long-term monitoring of subjects and expansion to phase II/III will be necessary in order to make definitive statements on safety and efficacy.

Effects of AAV-2-mediated aspartoacylase gene transfer in the tremor rat model of Canavan disease.

The tremor rat is a spontaneous epilepsy model with a seizure phenotype caused by a deletion in the aspartoacylase (ASPA) gene. The absence of ASPA expression in these animals results in undetectable levels of enzyme activity and the accumulation of the substrate N-acetyl-aspartate (NAA) in brain, leading to generalized myelin vacuolation and severe motor and cognitive impairment. In support of human gene therapy for CD, recombinant adeno-associated viral vector (AAV-2) expressing ASPA was stereotactically delivered to the tremor rat brain and effects on the mutant phenotype were measured. AAV-ASPA gene transfer resulted in elevated aspartoacylase bioactivity compared to untreated mutant animals and elicited a significant decrease in the pathologically elevated whole-brain NAA levels. Assessment of motor function via quantitative rotorod testing demonstrated that rats injected with AAV-ASPA significantly improved on tests of balance and coordinated locomotion compared to animals receiving control vectors. This study provides evidence that AAV-2-mediated aspartoacylase gene transfer to the brain improves biochemical and behavioral deficits in tremor rat mutants (tm/tm) and supports the rationale of human gene transfer for Canavan disease.