Isolation of three different sizes of exosomes in an Asian population with different retinal diseases before and after treatment: preliminary results.

Exosomes are membranous structures measuring between 40-120 nm that are secreted by various cells of the human body into the body fluid system. Exosomes contain proteins, mRNA, miRNA, and signaling molecules, and physiologically they assist in the intercellular transport of proteins and RNA molecules. In this study, we used an immunoaffinity filter paper platform combined with scanning electron microscopy and microfluidic systems to detect the size of exosomes within the aqueous humor. Eight aqueous humor samples showed three distinct sizes of exosomes that were significantly different on scanning electron microscopy(P < 0.01). We further used nanoparticle tracking analysis to assess the size distribution of exosomes within the aqueous humor. We found significantly different distributions of exosomes between patients with three different ocular diseases and patients with normal cataracts as controls. An obvious peak of exomeres(size around 35 nm)was found in the patients with central retinal vein occlusion and vitreous hemorrhage. Flare-ups of large exosomes(size 90-120 nm)were found in the patients with the inflammatory ocular disease pars planitis. No obvious peaks in exomeres or large exosomes were found in the control group. There was a high association between the distribution of exosomes and the pathogenesis of ocular diseases. After intravitreal anti-vascular endothelial growth factor treatment, the aqueous humor from the patients with neovascular diseases showed a significant reduction in exosomes in nanoparticle tracking analysis. These findings suggest that at least three distinct sizes of exosomes exist in the aqueous humor:(1)exomeres:<35 nm;(2)small exosomes:60-80 nm; and (3)large exosomes:90-120 nm. Different sizes of exosomes may have different implications in normal or diseased eyes.

Three different sized exosomes were identified in aqueous humor.The distribution of exosome size was significantly different between the patients with inflammatory and neovascularization retinal diseases.After intravitreal anti-vascular endothelial growth factor treatment, the aqueous humor from patients with neovascular diseases showed a significant reduction in exosomes in nanoparticle tracking analysis.

Photoreceptor and vision protective effects of astragaloside IV in mice model with light-evoked retinal damage.

Cone cell-enriched macular degeneration is a major cause of functional vision deterioration. Astragaloside IV (Asg IV), an active triterpenoid saponin component with properties of anti-oxidative and anti-apoptotic damage, which benefit retinal tissue and capillaries. But, the nutraceutical therapeutic effects on functional vision have not been fully evaluated. In this study, mice were administrated to high-intensity light exposure after either receiving a vehicle or Asg IV (0.05, 0.5, and 50 mg/kg, BID). During this time, their spatial-visual performance, visual acuity (VA), and visual contrast sensitivity function (VCSF) were measured using the behavioral optomotor reflex method. Morphological changes in the retina were determined by histological examination. High energy light-evoked visual damage was confirmed by the loss in structural tissue integrity in the retina accompanied by a decline in both VA and VCSF, whereas the retina tissue exhibited loss of cone cell density and severe cone-specific opsin misplacement. In contrast, prophylactic oral Asg IV (0.5, and 50 mg/kg, BID)-treated exerted protective and improvement effects against light-evoked deterioration of functional vision. Asg IV treatment significantly improved the thresholds of VA and VCSF. In particular, Asg IV (50 mg/kg, BID) modulated and increased the survival of the photoreceptors, especially the cone cells, which targeted and enhanced the high spatial frequency-characterized VCSF. In contrast, the cellular protective effect of Asg IV (50 mg/kg, BID) on photoreceptors was significantly reversed by synchronous injection of a glucocorticoid receptor (GR) antagonist (mifepristone). This study demonstrated the major neuroretina-protective effect and functional vision-improving effect of Asg IV in vivo.

Paper-Based Microfluidic Platforms for Understanding the Role of Exosomes in the Pathogenesis of Major Blindness-Threatening Diseases.

Emerging roles of exosomes in the pathogenesis of major blindness-threatening diseases, such as age-related macular degeneration, glaucoma, and corneal dystrophy, were discovered by aqueous humor analysis. A new diagnostic method using cellulose-based devices and microfluidic chip techniques for the isolation of exosomes from aqueous humor is less cumbersome and saves time. This method will enable more investigations for aqueous humor analysis in the future.

UVB promotes the initiation of uveitic inflammatory injury in vivo and is attenuated by UV-blocking protection.

PURPOSE: Uveitic inflammatory injury can cause irreversible visual loss; however, no single animal model recapitulates all the characteristics of human uveitis. Ultraviolet radiation (UVR) is one of the risk factors for uveitis, but the role of UVR in the pathogenesis of uveitic injury is unclear. The aim of this study was to elucidate whether UVB promotes the initiation of, and subsequently contributes to, uveitic inflammatory injury. METHODS: Mice were assigned to either a blank control group or one of three UVB treatment groups: no protection, protection with Nelfilcon A contact lens (Food and Drug Administration [FDA] class II, about 46.8% UVB transmittance), or protection with Etafilcon A contact lens (FDA class IV, about 0.55% UVB transmittance). The contact lenses acted as blocking barriers against UVR. After the application of UVR, pathologic injuries were determined with slit-lamp microscopy and histologic examination. RESULTS: Compared with the intact status of the controls, the anterior eyes of the UVB groups showed pathologic alterations in physiologic properties and tissue integrity. UVR promoted anterior uveitic inflammatory injury, with expansion of the hyperemic iris vessels, over-production of aqueous humor protein, disruption of the blood-aqueous barrier, and embedding of infiltrative leukocytes inside the iridocorneal angle. However, blockage of UVR in vivo retarded the progression of uveitic inflammatory injury. The highest level of UV protection in the Etafilcon A group resulted in greater inhibition of uveitic inflammatory injury than that in the Nelfilcon A group. CONCLUSIONS: This study demonstrates that UVB initiated and promoted uveitic inflammatory injury. UV protection is needed for the clinical management of anterior uveitis. The Etafilcon A lenses provide better protection of the anterior segment of the eye against UVB damage compared with the Nelfilcon A lenses.

UV-blocking spectacle lens protects against UV-induced decline of visual performance.

PURPOSE: Excessive exposure to sunlight may be a risk factor for ocular diseases and reduced visual performance. This study was designed to examine the ability of an ultraviolet (UV)-blocking spectacle lens to prevent visual acuity decline and ocular surface disorders in a mouse model of UVB-induced photokeratitis. METHODS: Mice were divided into 4 groups (10 mice per group): (1) a blank control group (no exposure to UV radiation), (2) a UVB/no lens group (mice exposed to UVB rays, but without lens protection), (3) a UVB/UV400 group (mice exposed to UVB rays and protected using the CR-39™ spectacle lens [UV400 coating]), and (4) a UVB/photochromic group (mice exposed to UVB rays and protected using the CR-39™ spectacle lens [photochromic coating]). We investigated UVB-induced changes in visual acuity and in corneal smoothness, opacity, and lissamine green staining. We also evaluated the correlation between visual acuity decline and changes to the corneal surface parameters. Tissue sections were prepared and stained immunohistochemically to evaluate the structural integrity of the cornea and conjunctiva. RESULTS: In blank controls, the cornea remained undamaged, whereas in UVB-exposed mice, the corneal surface was disrupted; this disruption significantly correlated with a concomitant decline in visual acuity. Both the UVB/UV400 and UVB/photochromic groups had sharper visual acuity and a healthier corneal surface than the UVB/no lens group. Eyes in both protected groups also showed better corneal and conjunctival structural integrity than unprotected eyes. Furthermore, there were fewer apoptotic cells and less polymorphonuclear leukocyte infiltration in corneas protected by the spectacle lenses. CONCLUSIONS: The model established herein reliably determines the protective effect of UV-blocking ophthalmic biomaterials, because the in vivo protection against UV-induced ocular damage and visual acuity decline was easily defined.