Nadine S. Dejneka

Adeno-associated viruses containing bFGF or BDNF are neuroprotective against excitotoxicity

Purpose. Brain-derived neurotrophic factor (BDNF) and basic fibroblast growth factor (bFGF) hold much promise for the protection of retinal ganglion cells against excitotoxic cell death. We tested the possibility of delivering these growth factors to retinal ganglion cells via an adeno-associated viral (AAV) vector and tested their efficacy in two models of excitotoxicity. Methods. Rat retinas were infected with AAV vectors encoding bFGF or BDNF. A control vector containing green fluorescent protein (GFP) was injected in the contralateral eye. Eyes were subjected to either an intravitreal injection of N-methyl-D-aspartate (NMDA) or optic nerve crush, and ganglion cell survival was evaluated. Results. AAV.CMV.bFGF and AAV.CBA.BDNF were neuroprotective against NMDA injection 1 month post-treatment. Additionally, AAV.CMV.bFGF was protective against optic nerve crush. Conclusion. AAV-mediated delivery of bFGF and BDNF can promote retinal cell survival following excitotoxic insult.

Gene Therapy and Animal Models for Retinal Disease

Those plagued by retinal diseases are often robbed of their vision, as often, effective treatments do not exist. Knowledge of the pathophysiology of retinal diseases stems from research on available animal models. Gene therapy may be useful for both genetic and acquired retinal diseases. This review will focus on retinal diseases for which gene therapy has demonstrated promise. The diseases are presented in order of the age at which they are generally first symptomatic and include retinopathy of prematurity, Leber congenital amaurosis, mucopolysaccharidoses, retinoblastoma, retinitis pigmentosa, diabetic retinopathy, glaucoma and age-related macular degeneration. We will describe the animal models used to study these disorders and emphasize the progress that has been made in using gene therapy for the treatment of retinal disease.

Pharmacologically regulated gene expression in the retina following transduction with viral vectors

The availability of inducible expression systems makes regulatable control of therapeutic proteins an attainable goal in gene therapy. We delivered tetracycline-inducible transgenes to the subretinal space using recombinant adenoviruses. Upon administration of doxycycline, we demonstrated reversible expression of green fluorescent protein in the retinal pigment epithelium as well as modulation of human growth hormone produced in the retina and secreted in the blood stream. This mode of delivery and regulation offers a unique way to evaluate gene function in the eye and represents a novel method for introducing therapeutic proteins into the retina.

Strain-dependent anterior segment neovascularization following intravitreal gene transfer of basic fibroblast growth factor (bFGF).

A promising strategy for delaying death of photoreceptor cells in retinal degenerative disease is to support survival of these cells through intraocular delivery of growth/neurotrophic factors. One factor that has received great attention is basic fibroblast growth factor (bFGF; fgf‐2), a known stimulator of angiogenesis. We evaluated the potential for neovascularization induced by adenovirus‐mediated intravitreal delivery of bFGF.

Gene therapy for Leber congenital amaurosis.

Recent success in delivering vision to a canine model of a severe, early-onset blinding disease, Leber congenital amaurosis (LCA) (Acland et al 2001) demonstrates that adeno-associated virus serotype 2 (AAV2) is capable of delivering a corrective gene to the target retinal cells. Results of these studies indicate long-term rescue of vision as assessed by psychophysical, behavioural and molecular biological studies. Preliminary results of studies in progress are described and the implications of these results with respect to developing human clinical trials for LCA and for other retinal degenerative diseases are discussed.

Müller Cell Transduction by AAV2 in Normal and Degenerative Retinas

Gene therapy for retinal diseases has gained increasing attention in recent years (see review, Bennett and Maguire, 2000). Among various gene delivery systems, viral vectors such as adenovirus (Ad), adeno-associated virus (AAV) and lentivirus appear to be the most efficient vehicles for gene transfer. In comparison to the Ad and lentivirus, AAV offers several advantages, including nonpathogenicity, minimal immuogenicity, and stable transgene expression in a wide host range (Flotte and Carter, 1995; Bennett et al., 1999; Anand et al., 2000

Generation of Transgenic Mice for Studies of Ocular Development and Disease

Over the past decade, there has been spectacular growth in our understanding of the molecular genetics of eye development and ocular disease. Although this is primarily caused by developments in recombinant DNA technology, it is also caused in large part by advances in, and the spread of, transgenic mouse technology. Whereas 10 years ago few laboratories had the equipment and skill to generate transgenic mice, now most investigators have access to a transgenic core facility. Transgenic mouse studies have fueled our understanding of ocular development, have delineated regulatory elements involved in gene expression in cells of the eye, and have unraveled pathogenic mechanisms involved in eye disease.