Gene transfer by viral vectors into blood vessels in a rat model of retinopathy of prematurity

Retinopathy of prematurity: inflammation, choroidal degeneration, and novel promising therapeutic strategies

Retinopathy of prematurity (ROP) is an important cause of childhood blindness globally, and the incidence is rising. The disease is characterized by initial arrested retinal vascularization followed by neovascularization and ensuing retinal detachment causing permanent visual loss. Although neovascularization can be effectively treated via retinal laser ablation, it is unknown which children are at risk of entering this vision-threatening phase of the disease. Laser ablation may itself induce visual field deficits, and there is therefore a need to identify targets for novel and less destructive treatments of ROP. Inflammation is considered a key contributor to the pathogenesis of ROP. A large proportion of preterm infants with ROP will have residual visual loss linked to loss of photoreceptor (PR) and the integrity of the retinal pigment epithelium (RPE) in the macular region. Recent studies using animal models of ROP suggest that choroidal degeneration may be associated with a loss of integrity of the outer retina, a phenomenon so far largely undescribed in ROP pathogenesis. In this review, we highlight inflammatory and neuron-derived factors related to ROP progression, as well, potential targets for new treatment strategies. We also introduce choroidal degeneration as a significant cause of residual visual loss following ROP. We propose that ROP should no longer be considered an inner retinal vasculopathy only, but also a disease of choroidal degeneration affecting both retinal pigment epithelium and photoreceptor integrity.

Treatment of retinopathy of prematurity: a review of conventional and promising new therapeutic options

Retinopathy of prematurity (ROP), a retinal vascular disease of premature infants, continues to be a major cause of preventable childhood blindness all over the world. The incidence of ROP varies among countries, being influenced by the quality of the level of neonatal intensive care. Here, we discuss the potential treatments that are now available or will soon or probably be available for ROP. Although ablation of the avascular retina with laser photocoagulation remains the current gold standard and well established therapy for ROP, some new therapeutic options including angiostatic therapies are being explored based on our knowledge of the pathophysiology of the ROP and complications and efficacy of laser treatment. However, prevention of the development of severe ROP and screening for ROP seem to be the best strategy in avoiding visual impairment caused by ROP in premature infants. New therapeutic interventions including vascular endothelial growth factor antibody administration, gene therapy and supplemental therapies should be supported with evidence-based data for the treatment of ROP.

Intraocular and systemic levels of vascular endothelial growth factor in advanced cases of retinopathy of prematurity

PURPOSE

To measure vitreous, aqueous, subretinal fluid and plasma levels of vascular endothelial growth factor in late stages of retinopathy of prematurity.

METHODS

Interventional study. We enrolled patients with clinical diagnoses of bilateral stage V retinopathy of prematurity, confirmed by b-scan ultrasound and programmed for vitrectomy. During surgery we took samples from blood, aqueous, vitreous, and subretinal fluids. The vascular endothelial growth factor concentration in each sample was measured by ELISA reaction. A control sample of aqueous, vitreous and blood was taken from patients with congenital cataract programmed for phacoemulsification. For statistical analysis, a Mann-Whitney and a Wilcoxon W test was done with a significant P value of 0.05.

RESULTS

We took samples of 16 consecutive patients who met the inclusion criteria. The vascular endothelial growth factor levels in the study group were: aqueous, 76.81 ± 61.89 pg/mL; vitreous, 118.53 ± 65.87 pg/mL; subretinal fluid, 1636.58 ± 356.47 pg/mL; and plasma, 74.64 ± 43.94 pg/mL. There was a statistical difference between the study and the control group (P < 0.001) in the aqueous and vitreous samples.

CONCLUSION

Stage 5 retinopathy of prematurity has elevated intraocular levels of vascular endothelial growth factor, which remains high despite severe retinal lesion. There was no statistical difference in plasma levels of the molecule between the control and study group.

Retinopathy of prematurity

PURPOSE OF REVIEW

This review highlights recent advances in basic science and clinical research on retinopathy of prematurity (ROP).

RECENT FINDINGS

The modern concept of ROP pathophysiology is discussed, as are studies investigating anti-angiogenic agents for treatment. Results of the largest clinical trials are summarized. Current screening criteria, potential modifications to them, and telephotoscreening are discussed.

SUMMARY

ROP is a challenging and involving area of pediatric ophthalmology.

Gene therapy for genetic and acquired retinal diseases

We present an overview of the current status of basic science and translational research being applied to gene therapy for eye disease, focusing on diseases of the retina. We discuss the viral and nonviral methods being used to transfer genes to the retina and retinal pigment epithelium, and the advantages and disadvantages of each approach. We review the various genetic and somatic treatment strategies that are being used for genetically determined and acquired diseases of the retina, including gene replacement, gene silencing by ribozymes and antisense oligonucleotides, suicide gene therapy, antiapoptosis, and growth factor therapies. The rationales for the specific therapeutic approaches to each disease are discussed. Schematics of gene transfer methods and therapeutic approaches are presented together with a glossary of gene transfer terminology.