RETINAL TOXICITY OF INTRAVITREAL GENISTEIN IN A RABBIT MODEL

Experimental Models of Glaucoma: A Powerful Translational Tool for the Future Development of New Therapies for Glaucoma in Humans-A Review of the Literature

Glaucoma is a common complex disease that leads to irreversible blindness worldwide. Even though preclinical studies showed that lowering intraocular pressure (IOP) could prevent retinal ganglion cells loss, clinical evidence suggests that lessening IOP does not prevent glaucoma progression in all patients. Glaucoma is also becoming more prevalent in the elderly population, showing that age is a recognized major risk factor. Indeed, recent findings suggest that age-related tissue alterations contribute to the development of glaucoma and have encouraged exploration for new treatment approaches. In this review, we provide information on the most frequently used experimental models of glaucoma and describe their advantages and limitations. Additionally, we describe diverse animal models of glaucoma that can be potentially used in translational medicine and aid an efficient shift to the clinic. Experimental animal models have helped to understand the mechanisms of formation and evacuation of aqueous humor, and the maintenance of homeostasis of intra-ocular pressure. However, the transfer of pre-clinical results obtained from animal studies into clinical trials may be difficult since the type of study does not only depend on the type of therapy to be performed, but also on a series of factors observed both in the experimental period and the period of transfer to clinical application. Conclusions: Knowing the exact characteristics of each glaucoma experimental model could help to diminish inconveniences related to the process of the translation of results into clinical application in humans.

Sustained-release genistein from nanostructured lipid carrier suppresses human lens epithelial cell growth

AIM

To design and investigate the efficacy of a modified nanostructured lipid carrier loaded with genistein (Gen-NLC) to inhibit human lens epithelial cells (HLECs) proliferation.

METHODS

Gen-NLC was made by melt emulsification method. The morphology, particle size (PS), zeta potentials (ZP), encapsulation efficiency (EE) and in vitro release were characterized. The inhibition effect of nanostructured lipid carrier (NLC), genistein (Gen) and Gen-NLC on HLECs proliferation was evaluated by cell counting kit-8 (CCK-8) assay, gene and protein expression of the proliferation marker Ki67 were evaluated with real-time quantitative polymerase chain reaction (RT-qPCR) and immunofluorescence analyses.

RESULTS

The mean PS of Gen-NLC was 80.12±1.55 nm with a mean polydispersity index of 0.11±0.02. The mean ZP was -7.14±0.38 mV and the EE of Gen in the nanoparticles was 92.3%±0.73%. Transmission electron microscopy showed that Gen-NLC displayed spherical-shaped particles covered by an outer-layer structure. In vitro release experiments demonstrated a prolonged drug release for 72h. The CCK-8 assay results showed the NLC had no inhibitory effect on HLECs and Gen-NLC displayed a much more prominent inhibitory effect on cellular growth compared to Gen of the same concentration. The mRNA and protein expression of Ki67 in LECs decreased significantly in Gen-NLC group.

CONCLUSION

Sustained drug release by Gen-NLCs may impede HLEC growth.

Ocular biocompatibility evaluation of hydroxyl-functionalized graphene

We have presented our recent efforts on genotoxicity and intraocular biocompatibility of hydroxylated graphene (G-OH) prepared by ball milling. We have previously demonstrated that the as-synthesized G-OH could be considered as an excellent alternative for graphene oxide which had been applied widely. Following our last report on G-OH, we carried out detailed studies on genotoxicity and in vivo biocompatibility of G-OH in this work. Less than 5% enhanced caspase-3 level was observed for cells exposed to more than 50 μg/mL G-OH over 72 h, suggesting G-OH caused cell apoptosis was slight. The G-OH induced DNA damage was also found to be mild since expression of p53 and ROS regeneration level was quite low even at high concentration of G-OH over a long time. Cell viability was found to be higher than 90% with 50 μg/mL G-OH and 80% with 100 μg/mL G-OH using flow cytometry. Comet results suggested that less than 5% tail could be found with 100 μg/mL G-OH. TEM results confirmed that G-OH could penetrate into and out of the cytoplasm by means of endocytosis and exocytosis without causing damage on cell membranes. In vivo biocompatibility of G-OH was studied by intravitreal injection of G-OH into rabbits. The ocular fundus photography results showed that G-OH could be diffused in the vitreous body gradually without any damage caused. Injection of G-OH had caused few damages on eyesight related functions such as intraocular pressure, electroretinogram and histological structures of the retina.

Retinal toxicity of intravitreal trastuzumab in a rabbit model: preliminary results of an experimental study

PURPOSE

To evaluate the retinal toxicity of intravitreal trastuzumab in a rabbit model.

METHODS

Fourteen New Zealand albino rabbits, weighing between 2.5 and 3 kg were used for this study. In the first group (n=6), 0.1 mL trastuzumab 10 mg/mL was injected into the vitreous. In the second group (n=6), the same volume of sterile balanced saline solution was injected intravitreally (sham injection). Additionally, 0.1 mL of 2 other concentrations of trastuzumab (7.5 and 5 mg/mL, respectively), was injected into the vitreous of 2 rabbits. Slit-lamp and funduscopic examinations were performed and the animals were observed for 2 weeks for signs of inflammation, infection, and toxicity. An electroretinogram (ERG) was performed at baseline and 14 days after the injection. The animals were killed on day 14 and a histological examination was performed in the enucleated eyes.

RESULTS

The clinical examination was unremarkable on either sham or intravitreal injection of trastuzumab. Conversely, the ERG was greatly affected and in 2 cases extinguished 14 days after trastuzumab injection. Consistent with electrophysiological abnormalities of the retina, signs of retinal edema in experimented eyes, suggesting morphologic retinal damage, were observed. In contrast, in the sham injected eyes, the ERG was normal without histopathologic retinal changes.

CONCLUSIONS

Intravitreal trastuzumab seems to be toxic to the retina in albino rabbits even at a concentration of 5 mg/mL. Further studies are needed to evaluate the safety of intravitreal trastuzumab in models of choroidal neovascularization, as well as to obtain experience concerning the intravitreal toxicity of trastuzumab in primates too and not only in rabbits.