Lucy E. Walmsley

VEGF delivery with retrogradely transported lentivector prolongs survival in a mouse ALS model

Amyotrophic lateral sclerosis (ALS) causes adult-onset, progressive motor neuron degeneration in the brain and spinal cord, resulting in paralysis and death three to five years after onset in most patients. ALS is still incurable, in part because its complex aetiology remains insufficiently understood. Recent reports have indicated that reduced levels of vascular endothelial growth factor (VEGF), which is essential in angiogenesis and has also been implicated in neuroprotection, predispose mice and humans to ALS. However, the therapeutic potential of VEGF for the treatment of ALS has not previously been assessed. Here we report that a single injection of a VEGF-expressing lentiviral vector into various muscles delayed onset and slowed progression of ALS in mice engineered to overexpress the gene coding for the mutated G93A form of the superoxide dismutase-1 (SOD1G93A) (refs 7–10), even when treatment was only initiated at the onset of paralysis. VEGF treatment increased the life expectancy of ALS mice by 30 per cent without causing toxic side effects, thereby achieving one of the most effective therapies reported in the field so far.

Lentivector-mediated SMN replacement in a mouse model of spinal muscular atrophy

Spinal muscular atrophy (SMA) is a frequent recessive autosomal disorder. It is caused by mutations or deletion of the telomeric copy of the survival motor neuron (SMN) gene, leading to depletion in SMN protein levels. The treatment rationale for SMA is to halt or delay the degeneration of motor neurons, but to date there are no effective drug treatments for this disease. We have previously demonstrated that pseudotyping of the nonprimate equine infectious anemia virus (using the lentivector gene transfer system) with the glycoprotein of the Evelyn-Rokitnicki-Abelseth strain of the rabies virus confers retrograde axonal transport on these vectors. Here, we report that lentivector expressing human SMN was successfully used to restore SMN protein levels in SMA type 1 fibroblasts. Multiple single injections of a lentiviral vector expressing SMN in various muscles of SMA mice restored SMN to motor neurons, reduced motor neuron death, and increased the life expectancy by an average of 3 and 5 days (20% and 38%) compared with LacZ and untreated animals, respectively. Further extension of survival by SMN expression constructs will likely require a knowledge of when and/or where high levels of SMN are needed.

Trophic activity of Rabies G protein-pseudotyped equine infectious anemia viral vector mediated IGF-I motor neuron gene transfer in vitro

The present study examines gene delivery to cultured motor neurons (MNs) with the Rabies G protein (RabG)-pseudotyped lentiviral equine infectious anemia virus (RabG.EIAV) vector. RabG.EIAV-mediated beta-galactosidase (RabG.EIAV-LacZ) gene expression in cultured MNs plateaus 120 h after infection. The rate and percent of gene expression observed are titer-dependent (P < 0.001). The rat IGF-I cDNA sequence was then cloned into a RabG.EIAV vector (RabG.EIAV-IGF-I) and was shown to induce IGF-I expression in HEK 293 cells. MNs infected with RabG.EIAV-IGF-I demonstrate enhanced survival compared to MNs infected with RabG.EIAV-LacZ virus (P < 0.01). In addition, IGF-I expression in cultured MNs induced profound MN axonal elongation compared to control virus (P < 0.01). The enhanced motor neuron tropism of RabG.EIAV previously demonstrated in vivo, together with the trophic effects of RabG.EIAV-IGF-I MN gene expression may lend this vector to therapeutic application in motor neuron disease.

532. Cervical Spinal Cord Delivery of a Lentiviral Vector in SOD-1 Transgenic Mice

Objective: Recent work has suggested that injection of lentiviral vectors might constitute means of therapeutic gene delivery to diseased motor neurons in ALS. However, as implied by the name, Amyotrophic Lateral Sclerosis, this disorder results in sclerosis of the spinal cord. In addition, axonal transport is altered in these animals. The present study attempts to characterize the behavioral impact as well as the distribution of gene expression in the CNS following direct spinal cord injection of the rabies G protein pseudotyped lentiviral vector, EIAV.LacZ, in control and SOD-1 transgenic mice.

735. EIAV-IGF-I Gene Transfer to Motor Neurons Enhances Axonal Length In Vitro

Background: Insulin-like growth factor (IGF)-I has various effects on proliferation, differentiation, and survival of neurons in the central nervous system. Neurodegenerative disease processes occurring in amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA) and diabetic neuropathy ultimately result in motor neuron (MN) death. Equine infectious anemia virus (EIAV)-based gene transfer vectors have been reported to sustain long-term gene expression in the nervous system. Pseudotyping of EIAV vectors with the rabies-G envelope protein (RabG.EIAV) has rendered EIAV vectors capable of retrograde axonal transport and access to the central nervous system after peripheral injection. This provides an attractive remote nervous system-targeting approach.