Neuroprotective Effect of siRNA Entrapped in Hyaluronic Acid-Coated Lipoplexes by Intravitreal Administration

Since the possibility of silencing specific genes linked to retinal degeneration has become a reality with the use of small interfering RNAs (siRNAs), this technology has been widely studied to promote the treatment of several ocular diseases. Despite recent advances, the clinical success of gene silencing in the retina is significantly reduced by inherent anatomical and physiological ocular barriers, and new strategies are required to achieve intraocular therapeutic effectiveness. In this study, we developed lipoplexes, prepared with sodium alginate as an adjuvant and strategically coated with hyaluronic acid (HA-LIP), and investigated the potential neuroprotective effect of these systems in a retinal light damage model. Successful functionalization of the lipoplexes with hyaluronic acid was indicated in the dynamic light scattering and transmission electron microscopy results. Moreover, these HA-LIP nanoparticles were able to protect and deliver siRNA molecules targeting caspase-3 into the retina. After retinal degeneration induced by high light exposure, in vitro and in vivo quantitative reverse transcription-PCR (RT-qPCR) assays demonstrated significant inhibition of caspase-3 expression by HA-LIP. Furthermore, these systems were shown to be safe, as no evidence of retinal toxicity was observed by electroretinography, clinical evaluation or histology.

The anti-oxidative Effect of Chrysanthemum Extract on Retinal- light Damage of Mice

Background:Apoptosis of photoreceptor cells and oxidative stress of RPE in age-related macular degeneration (AMD) could be promoted by photopic oxidative stress. In our study we are aim to study the protective effect of chrysanthemum extract on light damaged retina of mice.Methods:In vitro, ARPE-19 cells are incubated and divided into four groups: the control, the light damaged, the low and high dose-chrysanthemum extract groups. The last three groups were dropped in zero, low and high concentration of chrysanthemum extract separately before exposing to light. Cellular viability and Reactive Oxygen Species(ROS) production were measured by MTT and immunofluorescence. In vivo, C57BL/6J mice were divided into four groups as above mentioned. Low and high concentration of chrysanthemum extract were given by continuous intragastric administration before being exposed to white light. Retinal function was evaluated by electroretinogram. Optical coherence tomography and Fluorescein fundus angiography were used to observe the morphology and vessels. HE staining and TUNEL immunofluorescence for presenting morphology and apoptosis of isolated retina.Results:Viability of ARPE-19 cells decreased and ROS production increased after the light damaged. However, treatment with chrysanthemum extract, viability improved and ROS declined. After light injury, dysfunctional retina, destroyed morphology and increased apoptosis rate were observed in mice especially in RPE and photoreceptor layer. Treatment with chrysanthemum extract, retina function improved as well as structure of RPE and photoreceptor layers. Rate of apoptosis decreased via the raised concentration of anti-oxidative enzyme superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px). Conclusions:Preventive administration of chrysanthemum extract reduces the oxidative-stress induced by light damage, which indicating Chrysanthemum have a potential of preventive measure for AMD.

Oxidative Stress, Ocular Disease and Diabetes Retinopathy

Background: Oxidative stress is caused by free radicals or oxidant productions, including lipid peroxidation, protein modification, DNA damage and apoptosis or cell death and results in cellular degeneration and neurodegeneration from damage to macromolecules. Results: Accumulation of the DNA damage (8HOdG) products and the end products of LPO (including aldehyde, diene, triene conjugates and Schiff’s bases) were noted in the research studies. Significantly higher levels of these products in comparison with the controls were observed. Oxidative stress induced changes to ocular cells and tissues. Typical changes include ECM accumulation, cell dysfunction, cell death, advanced senescence, disarrangement or rearrangement of the cytoskeleton and released inflammatory cytokines. It is involved in ocular diseases, including keratoconus, Fuchs endothelial corneal dystrophy, and granular corneal dystrophy type 2, cataract, age-related macular degeneration, primary open-angle glaucoma, retinal light damage, and retinopathy of prematurity. These ocular diseases are the cause of irreversible blindness worldwide. Conclusions: Oxidative stress, inflammation and autophagy are implicated in biochemical and morphological changes in these ocular tissues. The development of therapy is a major target for the management care of these ocular diseases.