Vitreous function and intervention of it with vitrectomy and other modalities.

The vitreous body, the largest intraocular component, plays a key role in eye development, refraction, cell barrier function, oxygen metabolism and the pathogenesis of assorted diseases. Age, refraction and systemic diseases can cause vitreous metabolic abnormalities. With the continuous development of vitrectomy techniques and equipment, vitreous injections and vitrectomies have increased over the recent decades. However, the normal oxygen tension gradient in the vitreous helps to protect the lens and anterior chamber angle from oxidative stress damage, whereas the increased vitreous oxygen tension around lens and the trabecular meshwork after vitrectomy. It may lead to postoperative nuclear cataract and increase the risk for glaucoma. As a conventional procedure, scleral buckling holds several advantages over vitrectomy in selected cases. This review raises concerns regarding the function of the vitreous and encourages conducting vitreous interventions prudently if it is possible.

Vitreous function and intervention of it with vitrectomy and other modalities.

The vitreous body, the largest intraocular component, plays a key role in eye development, refraction, cell barrier function, oxygen metabolism and the pathogenesis of assorted diseases. Age, refraction and systemic diseases can cause vitreous metabolic abnormalities. With the continuous development of vitrectomy techniques and equipment, vitreous injections and vitrectomies have increased over the recent decades. However, the normal oxygen tension gradient in the vitreous helps to protect the lens and anterior chamber angle from oxidative stress damage, whereas the increased vitreous oxygen tension around lens and the trabecular meshwork after vitrectomy may lead to postoperative nuclear cataract and a high incidence of open angle glaucoma. As a conventional procedure, scleral buckling holds several advantages over vitrectomy in selected cases. This review raises concerns regarding the function of the vitreous, and encourages conducting vitreous interventions prudently.

Intravitreal anti-VEGF agents, oral glucocorticoids, and laser photocoagulation combination therapy for macular edema secondary to retinal vein occlusion: preliminary report.

AIM: To evaluate the efficacy and safety of combined anti-vascular endothelial growth factor (VEGF) agents, oral glucocorticoid, and laser photocoagulation therapy for macular edema (ME) secondary to retinal vein occlusion (RVO). METHODS: This study included 16 eyes of 16 patients with RVO-associated ME. Patients were initially treated with oral prednisone and an intravitreal anti-VEGF agent. Two weeks later, patients underwent standard laser photocoagulation. Best-corrected visual acuity (BCVA), central retinal thickness (CRT), and retinal vessel oxygenation were examined over 12mo. RESULTS: Patients received 1.43±0.81 anti-VEGF injections. Mean baseline and 12-month logMAR BCVA were 0.96±0.51 (20/178) and 0.31±0.88 (20/40), respectively, in eyes with central retinal vein occlusion (CRVO) (P<0.00), and 1.02±0.45 (20/209) and 0.60±0.49 (20/80), respectively, in eyes with branch retinal vein occlusion (BRVO) (P<0.00). At 12mo, CRT had significantly decreased in eyes with CRVO (P<0.00) and BRVO (P<0.00). Venous oxygen saturation had significantly increased in eyes with CRVO (P<0.00) and BRVO (P<0.00). No examined parameters were significantly different between the 2 RVO groups. No serious adverse effects occurred. CONCLUSION: Anti-VEGF, glucocorticoid, and photocoagulation combination therapy improves visual outcome, prolongs therapeutic effect, and reduces the number of intravitreal injections in eyes with RVO-associated ME.

Study of retinal vessel oxygen saturation in ischemic and non-ischemic branch retinal vein occlusion.

AIM: To explore how oxygen saturation in retinal blood vessels is altered in ischemic and non-ischemic branch retinal vein occlusion (BRVO). METHODS: Fifty BRVO eyes were divided into ischemic (n=26) and non-ischemic (n=24) groups, based on fundus fluorescein angiography. Healthy individuals (n=52 and n=48, respectively) were also recruited as controls for the two groups. The mean oxygen saturations of the occluded vessels and central vessels were measured by oximetry in the BRVO and control groups. RESULTS: In the ischemic BRVO group, the occluded arterioles oxygen saturation (SaO2-A, 106.0%±14.3%), instead of the occluded venule oxygen saturation (SaO2-V, 60.8%±9.4%), showed increases when compared with those in the same quadrant vessels (SaO2-A, 86.1%±16.5%) in the contralateral eyes (P<0.05). The oxygen saturations of the central vessels showed similar trends with those of the occluded vessels. In the non-ischemic BRVO group, the occluded and central SaO2-V and SaO2-A showed no significant changes. In both the ischemic and non-ischemic BRVOs, the central SaO2-A was significantly increased when compared to healthy individuals. CONCLUSION: Obvious changes in the occluded and central SaO2-A were found in the ischemic BRVO group, indicating that disorders of oxygen metabolism in the arterioles may participate in the pathogenesis of ischemic BRVO.

Micellar delivery of dasatinib for the inhibition of pathologic cellular processes of the retinal pigment epithelium.

The objective of this study was to fabricate dasatinib-loaded nanoparticles and evaluate their efficacy in inhibiting cellular processes of the retinal pigment epithelium (RPE) related to proliferative vitreoretinopathy (PVR), for which there are no approved pharmacological approaches. We successfully encapsulated dasatinib, a poorly soluble multi-targeted tyrosine kinase inhibitor which has great potential for the treatment of PVR, into nanoparticles prepared from micellation of PEG-b-PCL. The size of the nanomicelles was approximately 55nm with a narrow distribution. They increased the solubility of dasatinib by 475× and provided a sustained drug release. ARPE-19, an immortal RPE cell line, was used to assess the in vitro efficacy of micellar dasatinib because the RPE is believed to play a key role in the pathogenesis of PVR. Three cell-based assays, namely, proliferation, adhesion and migration, which represent three important PVR-related cellular changes of the RPE, were conducted and the cytotoxicity of micelles was also evaluated. Both blank and dasatinib-loaded micelles were non-cytotoxic towards ARPE-19 cells. Micellar dasatinib significantly inhibited cell proliferation, adhesion and migration compared to the free drug; this might be attributable to enhanced solubility. PEG-b-PCL micelles were taken up into the ARPE-19 cells by an energy-dependent clatharin and caveolae-mediated endocytosis. Our results indicated that cellular uptake and the anti-proliferation effect of drugloaded micelles were linearly correlated. Drug loading appears to be a critical parameter for cellular uptake which in turn impacts the in vitro bioactivities of polymeric micelles. Our results clearly demonstrated that dasatinib-encapsulated micelles offer considerable promise in the management of PVR.

Vitreous substitutes: challenges and directions.

The natural vitreous body has a fine structure and complex functions. The imitation of the natural vitreous body by vitreous substitutes is a challenging work for both researchers and ophthalmologists. Gases, silicone oil, heavy silicone oil and hydrogels, particularly the former two vitreous substitutes are clinically widely used with certain complications. Those, however, are not real artificial vitreous due to lack of structure and function like the natural vitreous body. This article reviews the situations, challenges, and future directions in the development of vitreous substitutes, particularly the experimental and clinical use of a new artificial foldable capsular vitreous body.

Stanniocalcin-1 promotes tumor angiogenesis through up-regulation of VEGF in gastric cancer cells.

BACKGROUND: Stanniocalcin-1(STC-1) is up-regulated in several cancers including gastric cancer. Evidences suggest that STC-1 is associated with carcinogenesis and angiogenic process. However, it is unclear on the exact role for STC-1 in inducing angiogenesis and tumorigeneisis. METHOD: BGC/STC cells (high-expression of STC-1) and BGC/shSTC cells (low- expression of STC-1) were constructed to investigate the effect of STC-1 on the xenograft tumor growth and angiogenesis in vitro and in vivo. ELISA assay was used to detect the expression of vascular endothelial growth factor (VEGF) in the supernatants. Neutralizing antibody was used to inhibit VEGF expression in supernatants. The expression of phosphorylated -PKCßII, phosphorylated -ERK1/2 and phosphorylated -P38 in the BGC treated with STC-1protein was detected by western blot. RESULTS: STC-1 could promote angiogenesis in vitro and in vivo, and the angiogenesis was consistent with VEGF expression in vitro. Inhibition of VEGF expression in supernatants with neutralizing antibody markedly abolished angiogenesis induced by STC-1 in vitro. The process of STC-1-regulated VEGF expression was mediated via PKCßII and ERK1/2. CONCLUSIONS: STC-1 promotes the expression of VEGF depended on the activation of PKCßII and ERK1/2 pathways. VEGF subsequently enhances tumor angiogenesis which in turn promotes the gastric tumor growth.

[The effect of protein kinase C alpha on expression of developmental genes during differentiation of mouse embryonic stem cells into neuron-like cells in vitro].

OBJECTIVE: To study the effect of protein kinase C alpha on the expression of developmental genes pax-6, slit-2 and netrin-1 during differentiation of mouse embryonic stem cells into neuron-like cells in vitro, in an attempt to elucidate their roles in signaling. METHODS: ES-BALB/c cells were induced to form embryoid bodies in the ES conditioned medium for 4 days, and were plated separately on coated glass coverslip into 6-well culture dishes for immunohistochemical study and into 100 mm dishes for RT-PCR assay. These cultures were collected after 1, 3, 5, 7 and 14 days in the presence of 5 x 10(-7) mol/L retinoic acid (RA). The neuron-like cells were stained with antibody to NSE and NF-200. mRNA level of the development related genes (pax-6, slit-2 and netrin-1) in undifferentiated and differentiated ES cells was assessed by RT-PCR assay. Effects of PMA and D-sphingosine on the developmental genes were also observed. RESULTS: Most of the neuron-like cells stained with the antibodies to NSE and NF-200. RT-PCR assay showed that levels of PKC alpha, pax-6 and netrin-1, but not slit-2 transcripts decreased dramatically upon induction on the 1st day, but then raised slowly and resumed to normal level on 14th day. PMA upregulated the levels of PKC alpha, pax-6 and netrin-1; while D-sphingosine downregulated their levels. CONCLUSIONS: The results of the present experiments demonstrate that the developmental genes pax-6 and netrin-1 play a very important role during differentiation of mouse ES cells into neuron-like cells through PKC alpha signaling pathway.

[A preliminary study on gene mutation and its function in a large family (GZ.1 pedigree) with open-angle glaucoma].

OBJECTIVE: To determine the causative mutation of myocilin gene and to investigate its pathogenic function in a large Chinese pedigree (GZ.1) with familial open-angle glaucoma. METHODS: Genome-wide scanning was performed and the Lod scores were calculated. Candidate gene was amplified and screened for mutations using direct sequencing. To elucidate its expression, distribution and cytotoxicity of mutant myocilin, human trabecular cells (HTM) cells were transfected with pcDNA-wild-type and mutant myocilin vectors using liposomes. RESULTS: Mutation analysis of the myocilin gene showed a C-to-T transition at the 1, 109 th nucleotide in exon 3 resulting in a change of amino acid from proline to leucine (Pro370Leu). This mutation cosegregated with all affected individuals (16/16) and never presented in unaffected individuals (0/8). In transfected HTM cells, the mutant myocilin protein was not correctly processed in ER and accumulated as aggresome-like structures in the cytoplasma instead of being secreted. In addition, the expression of mutant protein also led to apoptosis of trabecular cells and the occurrence of. CONCLUSION: The mutation of Pro370Leu in myocilin gene could cause the accumulation of misfolding myocilin protein in HTM cells, which might lead to glaucoma in GZ.1 pedigree.