Published papers

Background: Macular hole results from a tractional force at the vitreo-retinal interface which is developed by modification and subsequent degeneration of the posterior precortical vitreous and the internal limiting membrane (ILM). Meanwhile, the wet type of age-related macular degeneration (AMD) is caused by the submacular formation of choroidal neovascularization (CNV). Although exudative changes derived from CNV may cause epiretinal membrane (ERM) formation, which can also cause tractional force at the vitreo-retinal interface, there have been few reports of AMD-associated macular hole development in which the full thickness of the retinal tissue is completely torn by the tractional force. Moreover, intraoperative finding of macular hole associated with AMD with a possible involvement of subretinal lesion has not been described. Case presentation: A 78-year-old man diagnosed with wet AMD with subretinal fluid and mild cataract received 8 treatments with intravitreal pegaptanib. After AMD remission, he developed a secondary macular hole in the same eye. He underwent a pars plana vitrectomy that successfully closed the macular hole. Intraoperatively, it was found that the patient's vitreous was formed and that the ERM and ILM were adherent, suggesting the involvement of a tractional force at the vitreo-retinal interface due to an inflammatory reaction related to AMD and/or intravitreally injected chemical compounds, resulting in macular hole development. Changes in the condition of his AMD and the RPE were observed on a fluorescein angiogram (FA) and an indocyanine green angiogram (IA) that preceded macular hole development, suggesting that subretinal changes may also have been involved in the pathogenesis. Conclusion: These clinical data, including the intraoperative findings and the temporal changes in the angiograms, suggest that an inflammatory reaction at the vitreo-retinal interface and subretinal lesion related to AMD contribute to the macular hole development in AMD patients treated with intravitreal injection.

Current therapeutic antiangiogenic biologics used for the treatment of pathological ocular angiogenesis could have serious side effects due to their interference with normal blood vessel physiology. Here, we report the generation of novel antivascular endothelial growth factor-A (VEGF) biologics, termed VEGF Sticky-traps, with unique properties that allow for local inhibition of angiogenesis without detectable systemic side effects. Using genetic and pharmacological approaches, we demonstrated that Sticky-traps could locally inhibit angiogenesis to at least the same extent as the original VEGF-trap that also gains whole-body access. Sticky-traps did not cause systemic effects, as shown by uncompromised wound healing and normal tracheal vessel density. Moreover, if injected intravitreally, recombinant Sticky-trap remained localized to various regions of the eye, such as the inner-limiting membrane and ciliary body, for prolonged time periods, without gaining access either to the photoreceptors/choriocapillaris area or the circulation. These unique pharmacological characteristics of Sticky-trap could allow for safe treatment of pathological angiogenesis in patients with diabetic retinopathy and retinopathy of pre-maturity.

Autologous retinal pigment epithelium (RPE) grafts derived from induced pluripotent stem cells (iPSCs) may be used to cure blinding diseases in which RPE dysfunction results in photoreceptor degeneration. Four-, two-, and one-factor-derived iPSCs (4F-, 2F-, and 1F-iPSC5, respectively) were differentiated into fully functional cuboidal pigmented cells in polarized monolayers that express RPE-specific markers. 1F-iPSC-RPE (1F-iPS-RPE) strongly resembles primary human fetal RPE (hfRPE) based on proteomic and untargeted metabolomic analyses, and using novel in vivo imaging technology coupled with electroretinography, we demonstrated that 1F-iPS-RPE mediate anatomical and functional rescue of photoreceptors after transplantation in an animal model of RPE-mediated retinal degeneration. 1F-iPS-RPE cells were injected subretinally as a suspension and formed a monolayer dispersed between host RPE cells. Furthermore, 1F-iPS-RPE do not simply provide trophic support to rescue photoreceptors as previously speculated but actually phagocytose photoreceptor outer segments in vivo and maintain visual cycling. Thus, 1F-iPS-RPE grafts may be superior to conventional iPS-RPE for clinical use because 1F-iPS-RPE closely resemble hfRPE, mediate anatomical and functional photoreceptor rescue in vivo, and are generated using a reduced number of potentially oncogenic reprogramming factors. STEM CELLS TRANSLATIONAL MEDICINE 2012;1:96-109

PURPOSE. To investigate the role of reactive oxygen species (ROS) as the prime initiators of the angiogenic response after alkali injury of the cornea and observe the effects of antioxidants in preventing angiogenesis. METHODS. The corneal epithelia of SOD-1-deficient mice or wild-type (WT) mice were removed after application of 0.15 N NaOH to establish the animal model of alkali burn. ROS production was semiquantitatively measured by dihydroethidium (DHE) fluorescence. Angiogenesis was visualized by CD31 immunohistochemistry. The effects of the specific NF-kappa B inhibitor DHMEQ, the antioxidant N-acetyl-L-cysteine (NAC), and hydrogen (H(2)) solution were observed. RESULTS. ROS production in the cornea was enhanced immediately after alkali injury, as shown by increased DHE fluorescence (P < 0.01). NF-kappa B activation and the upregulation of vascular endothelial growth factor (VEGF) and monocyte chemoattractant protein-1 (MCP-1) were significantly enhanced (P < 0.01), leading to a significantly larger area of angiogenesis. Angiogenesis in SOD-1(-/-) mice corneas were significantly higher in WT mice (P < 0.01), confirming the role of ROS. Pretreatment with the specific NF-kappa B inhibitor DHMEQ or the antioxidant NAC significantly reduced corneal angiogenesis by downregulating the NF-kappa B pathway (P < 0.01) in both WT and SOD-1(-/-) mice. Furthermore, we showed that irrigation of the cornea with hydrogen (H 2) solution significantly reduced angiogenesis after alkali-burn injury (P < 0.01). CONCLUSIONS. Immediate antioxidant therapy with H(2)-enriched irrigation solution is a new potent treatment of angiogenesis in cornea to prevent blindness caused by alkali burn. (Invest Ophthalmol Vis Sci. 2011;52:427-433) DOI:10.1167/iovs.106167

PURPOSE. CD44 is a cell-surface adhesion molecule and receptor for hyaluronan (HA), one of the major extracellular matrix components. The purpose of the present study was to clarify a role of HA and CD44 in the development of choroidal neovascularization (CNV). METHODS. Laser photocoagulation was used to induce CNV in C57BL/6 mice or CD44-deficient mice. The mRNA expression of CD44 and HA synthase (HAS)-2 in the retinal pigment epithelium (RPE)-choroid complex was evaluated by DNA microarray and real-time RT-PCR analyses 3 days after laser treatment. HA synthesis and CD44 expression were examined by immunohistochemistry 1 week after photocoagulation. Mice with laser-induced CNV were systemically administered the HA synthesis inhibitor 4-methylumbelliferone (MU) or an antiCD44-neutralizing antibody. The response of CNV was analyzed by volumetric measurements 1 week after photocoagulation. Macrophage infiltration into CNV lesions was evaluated by real-time RT-PCR for F4/80 3 days after laser-induced injury. RESULTS. The induction of CNV led to a significant increase in expression of CD44 and HAS2 mRNA. HA and CD44 were immunopositive in the CNV lesions. Compared with vehicle treatment, the systemic application of MU significantly attenuated CNV volume in a dose-dependent fashion, together with macrophage infiltration into the lesions. Consistently, antibody-based blockade of CD44 resulted in a significant reduction of CNV volume, compared with the isotype control. In contrast, genetic ablation of CD44 significantly augmented CNV formation together with HA accumulation and macrophage infiltration, compared with wild-type mice. CONCLUSIONS. These results indicate a significant role of HA and its receptor CD44 in the development of CNV. (Invest Ophthalmol Vis Sci. 2009;50:4410-4415) DOI: 10.1167/iovs.08-3044

PURPOSE. To investigate the role of eicosapentaenoic acid (EPA), the major omega-3 polyunsaturated fatty acid (PUFA), in the development of choroidal neovascularization (CNV), together with underlying molecular mechanisms. METHODS. Six-week-old C57BL/ 6 mice were fed with laboratory chow with 5% EPA or the omega-6 PUFA linoleic acid ( LA) for 4 weeks. Laser photocoagulation was performed to induce CNV, and the volume of CNV tissue was evaluated by volumetric measurements. The expression and production of intercellular adhesion molecule (ICAM)-1, monocyte chemotactic protein (MCP)-1, vascular endothelial growth factor ( VEGF) and interleukin (IL)-6 in the retinal pigment epithelium (RPE)-choroid in vivo, and stimulated b-End3 endothelial cells and RAW264.7 macrophages in vitro were evaluated by RT-PCR and ELISA. Fatty acid composition in the serum and the RPE-choroid was analyzed by gas chromatography and high-performance liquid chromatography, respectively. Serum levels of C-reactive protein (CRP), IL-6, VEGF, MCP-1, and soluble ICAM-1 were examined by ELISA. RESULTS. The CNV volume in EPA-fed animals was significantly suppressed compared with that in control mice, whereas the LA-rich diet did not affect CNV. The mRNA expression and protein levels of ICAM- 1, MCP-1, VEGF, and IL- 6 after CNV induction were significantly reduced in EPA-supplemented mice. In vitro, EPA application led to significant inhibition of mRNA and protein levels of ICAM- 1 and MCP-1 in endothelial cells and VEGF and IL- 6 in macrophages. EPA- fed mice exhibited significantly higher levels of EPA and lower levels of the omega-6 PUFA arachidonic acid in the serum and the RPE-choroid than control animals. EPA supplementation also led to significant reduction of serum levels of IL- 6 and CRP after CNV induction. CONCLUSIONS. The present study demonstrates for the first time that an EPA- rich diet results in significant suppression of CNV and CNV-related inflammatory molecules in vivo and in vitro. These results suggest that frequent consumption of omega-3 PUFAs may prevent CNV and lower the risk of blindness due to age-related macular degeneration.

Interleukin (IL)-6, a potent proinflammatory cytokine, is suggested to be a risk factor for choroidal neovascularization (CNV) because of its increased levels in the serum of patients with age-related macular degeneration; however, the role of IL-6 in CNV has not been defined. The present study reveals the critical contribution of IL-6 signaling and its downstream STAT3 pathway to the murine model of laser-induced CNV. CNV induction by laser treatment stimulated IL-6 expression in the retinal pigment epithelium-choroid complex, and antibody-based blockade of M-6 receptor or genetic ablation of M-6 led to significant suppression of CNV. CNV generation was accompanied by STAT3 activation in choroidal endothelial cells and macrophages, and M-6 receptor blockade resulted in selectively inhibited phosphorylation of STAT3 but not extracellular signal-regulated kinase 1/2. Consistently, pharmacological blockade of STAT3 pathway also suppressed CNV. in addition, M-6 receptor neutralization led to significant inhibition of the in vivo and in vitro expression of inflammation-related molecules including monocyte chemotactic protein, intercellular adhesion molecule-1, and vascular endothelial growth factor, and of macrophage infiltration into CNV. These results indicate the significant involvement of H,6 receptor-mediated activation of STAT3 inflammatory pathway in CNV generation, suggesting the possibility of M-6 receptor blockade as a therapeutic strategy to suppress CNV associated with age-related macular degeneration.

PURPOSE: To understand the prognosis of polypoidal choroidal vasculopathy (PCV) by evaluating the responsiveness to intravitreal ranibizumab (IVR) monotherapy according to the presence of a single or multiple polyps. DESIGN: Retrospective case series. METHODS: We included 48 treatment-naive eyes of 48 patients who received IVR monotherapy at the Medical Retina Division Clinic, Keio University Hospital between March 2009 and January 2013 and attended the clinic for at least 12 months. All patients received 3 monthly IVR injections followed by pro re nata injections and were divided into single polyp and multiple polyps groups according to indocyanine green angiography and optical coherence tomography (OCT) findings. The outcome measures included changes in best corrected visual acuity (BCVA) and OCT findings over 2 years after initial IVR. RESULTS: At baseline, the multiple polyps group exhibited a poorer BCVA, larger greatest linear dimension, and higher prevalence of fibrovascular pigment epithelial detachment compared with the single polyp group. Over 2 years, the multiple polyps group showed no improvement in BCVA, although the central retinal thickness (CRT) decreased in both groups. The multiple polyps group exhibited a significantly greater CRT at 1 year and required more injections in the first year compared with the single polyp group; furthermore, it included a higher number of nonresponders judged either by BCVA or fundus findings at 1 year and fundus findings at 2 years. CONCLUSIONS: We propose that the stratification of PCV lesions according to the presence of single or multiple polyps may be valuable to understand the prognosis. (C) 2016 The Authors. Published by Elsevier Inc.

Photoreceptors are the most numerous and metabolically demanding cells in the retina. Their primary nutrient source is the choriocapillaris, and both the choriocapillaris and photoreceptors require trophic and functional support from retinal pigment epithelium (RPE) cells. Defects in RPE, photoreceptors, and the choriocapillaris are characteristic of age-related macular degeneration (AMD), a common vision-threatening disease. RPE dysfunction or death is a primary event in AMD, but the combination(s) of cellular stresses that affect the function and survival of RPE are incompletely understood. Here, using mouse models in which hypoxia can be genetically triggered in RPE, we show that hypoxia-induced metabolic stress alone leads to photoreceptor atrophy. Glucose and lipid metabolism are radically altered in hypoxic RPE cells; these changes impact nutrient availability for the sensory retina and promote progressive photoreceptor degeneration. Understanding the molecular pathways that control these responses may provide important clues about AMD pathogenesis and inform future therapies.

Proliferative diabetic retinopathy (PDR) is the most severe form of diabetic retinopathy and, along with diabetic macular edema, is responsible for the majority of blindness in adults below the age of 65. Therapeutic strategies for PDR are ineffective at curtailing disease progression in all cases; however a deeper understanding of the ocular metabolic landscape in PDR through metabolomic analysis may offer new therapeutic targets. Here, global and targeted mass spectrometry-based metabolomics were used to investigate metabolism. Initial analyses on vitreous humor from patients with PDR (n = 9) and non-diabetic controls (n = 11) revealed an increase of arginine and acylcarnitine metabolism in PDR. The oxygen-induced-retinopathy (OIR) mouse model, which exhibits comparable pathological manifestations to human PDR, revealed similar increases of arginine and other metabolites in the urea cycle, as well as downregulation of purine metabolism. We validated our findings by targeted multiple reaction monitoring and through the analysis of a second set of patient samples [PDR (n = 11) and non-diabetic controls (n = 20)]. These results confirmed a predominant and consistent increase in proline in both the OIR mouse model and vitreous samples from patients with PDR, suggesting that over activity in the arginine-to-proline pathway could be used as a therapeutic target in diabetic retinopathy.

Glycemic control is essential to manage metabolic diseases such as diabetes. Frequent measurements of systemic glucose levels with prompt managements can prevent organ damages. The eye is a glucose highly demanding organ in our body, and the anterior chamber (AC) in the eye has been suggested for a noninvasive blood glucose monitoring site. However, calculating blood glucose levels from measuring glucose levels in AC has been difficult and unclear. In this study, we aimed to examine glucose levels from AC and find a correlation with blood glucose levels. A total of 30 patients with cataracts (men and women, study 1; 7 and 3, study 2; 9 and 11) who visited Keio University Hospital from 2015 to 2018 and agreed to participate in this study were recruited. Glucose levels from AC and the blood were examined by a UV-hexokinase or H2O2-electrode method before/during the cataract surgery. These values were analyzed with regression analyses depending on the groups (blood glucose-ascending and descending groups). In the blood glucose-descending group, glucose levels from AC were strongly correlated with blood glucose levels (a high R2 value, 0.8636). However, the relatively moderate correlation was seen in the blood glucose-ascending group (a low R2 value, 0.5228). Taken together, we showed different correlation ratios on glucose levels between AC and the blood, based on blood glucose dynamics. Stacking data regarding this issue would enable establishing noninvasive blood glucose monitoring from measuring glucose levels in AC more correctly, which will be helpful for proper and prompt managements for glucose-mediated complications.

PURPOSE: To evaluate cytokine and protein levels in the aqueous humor (AqH) of eyes with ocular surface diseases. DESIGN: Prospective consecutive case series. METHODS: This study includes 14 patients (aged 62.4 +/- 13.7 years) with chronic-phase ocular surface diseases (4 with ocular cicatricial pemphigoid, 5 with chemical burns, 2 with a thermal burn, 2 with Stevens-Johnson syndrome, and 1 with exposure keratitis), 14 matched patients without ocular surface disease (controls with corneal scar), and 30 patients who underwent cataract surgery (healthy controls). AqH samples were collected at the beginning of surgery. AqH levels of cytokines (interleukin [IL]-1 alpha, IL-1 beta, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13, IL-17A, monocyte chemotactic protein [MCP]-1, interferon [IFN]-alpha, IFN-gamma, macrophage inflammatory protein [MIP]-1 alpha, MIP-1 beta, P-selectin, E-selectin, soluble-intercellular adhesion molecule [s-ICAM]-1, tumor necrosis factor [TNF]-alpha, granulocyte-macrophage colony-stimulating factor [GMCSF], IFN-gamma-induced protein [IP]-10) were measured using multiplex beads immunoassays. RESULTS: The levels of IL-6, IL-10, IL-17A, GM-CSF, E-selectin, P-selectin, and s-ICAM in AqH were significantly elevated in eyes with ocular surface diseases (in pg/mL: 1696 +/- 804, 4.0 +/- 1.0, 24.3 +/- 9.8, 26.0 +/- 18.3, 5150 +/- 1232, 13122 +/- 7219, and 7914 +/- 2813, respectively), compared to healthy controls (IL-6: 6.36 +/- 0.94, P = .001; IL-10: 1.68 +/- 0.04, P = .0006; IL-17A: 3.7 +/- 0.2, P = .008; GM-CSF: 2.7 +/- 0.3, P = .007; E-selectin: 2093 +/- 37, P = .0001; P-selectin: 3658 +/- 137, P = .0001; sICAM-1: 1397 +/- 119, P = .008). The levels of IL-6, IL-17A, E-selectin, and P-selectin in AqH were significantly higher in eyes with ocular surface diseases compared to those with corneal scar (IL-6: 44.1 +/- 15.0, P = .0077; IL-17A: 4.1 +/- 0.7, P = .034; E-selectin: 2439 +/- 302, P = .039; and P-selectin: 5673 +/- 1553, P = .017). CONCLUSIONS: Multiple AqH cytokine levels were elevated in chronic ocular surface diseases. ((C) 2017 Elsevier Inc. All rights reserved.)

Phototransduction is accomplished in the retina by photoreceptor neurons and retinal pigment epithelium (RPE) cells. Photoreceptors rely heavily on the RPE, and death or dysfunction of RPE is characteristic of age-related macular degeneration (AMD), a very common neurodegenerative disease for which no cure exists. RPE replacement is a promising therapeutic intervention for AMD, and large numbers of RPE cells can be generated from pluripotent stem cells. However, questions persist regarding iPSC-derived RPE (iPS-RPE) viability, immunogenicity, and tumorigenesis potential. We showed previously that iPS-RPE prevent photoreceptor atrophy in dystrophic rats up until 24 weeks after implantation. In this follow-up study, we longitudinally monitored the same implanted iPS-RPE, in the same animals. We observed no gross abnormalities in the eyes, livers, spleens, brains, and blood in aging rats with iPSC-RPE grafts. iPS-RPE cells that integrated into the subretinal space outlived the photoreceptors and survived for as long as 21/2 years while nonintegrating RPE cells were ingested by host macrophages. Both populations could be distinguished using immunohistochemistry and electron microscopy. iPSC-RPE could be isolated from the grafts and maintained in culture; these cells also phagocytosed isolated photoreceptor outer segments. We conclude that iPS-RPE grafts remain viable and do not induce any obvious associated pathological changes.

Docosahexaenoic acid (DHA) and ultra-long-chain polyunsaturated fatty acids (ULC–PUFAs) are uniquely enriched in membrane phospholipids of retinal photoreceptors. Several studies have shown that di-DHA- and ULC–PUFA-containing phospholipids in photoreceptors have an important role in maintaining normal visual function; however, the molecular mechanisms underlying the synthesis and enrichment of these unique lipids in the retina, and their specific roles in retinal function remain unclear. Long-chain acyl-coenzyme A (CoA) synthetase 6 (ACSL6) preferentially converts DHA into DHA–CoA, which is a substrate during DHA-containing lipid biosynthesis. Here, we report that Acsl6 mRNA is expressed in the inner segment of photoreceptor cells and the retinal pigment epithelial cells, and genetic deletion of ACSL6 resulted in the selective depletion of di-DHA– and ULC–PUFA-containing phospholipids, but not mono-DHA-containing phospholipids in the retina. MALDI mass spectrometry imaging (MALDI–MSI) revealed the selective distribution of di-DHA– and ULC–PUFA-containing phospholipids in the photoreceptor outer segment (OS). Electroretinogram of Acsl6−/− mice exhibited photoreceptor cell-derived visual impairment, whereas the expression levels and localization of opsin proteins were unchanged. Acsl6−/− mice exhibited an age-dependent progressive decrease of the thickness of the outer nuclear layers, whereas the inner nuclear layers and OSs were normal. These results demonstrate that ACSL6 facilitates the local enrichment of di-DHA– and ULC–PUFA-containing phospholipids in the retina, which supports normal visual function and retinal homeostasis.

Lutein, a xanthophyll of a carotenoid, is anticipated as a therapeutic product to prevent human eye diseases. However, its biological mechanism is still unclear. Here, we show the molecular mechanism of lutein's effect to reduce photodamage of the retina. We analyzed the light-exposed retinas of Balb/c mice given lutein-supplemented or normal diet. Visual function was measured by electroretinogram, and histological changes were observed. Immunohistochemical and immunoblot analyses were performed to analyze molecular mechanism. The reactive oxygen species induced in the retina was evaluated by fluorescent probes. In the mice after light exposure, reduction of a-wave and b-wave amplitudes in electroretinogram, indicating visual impairment, and thinning of the photoreceptor cell layer owing to apoptosis were both attenuated by lutein diet. Interestingly, gamma-H2AX, a marker for double-strand breaks (DSBs) in DNA, was up-regulated in the photoreceptor cells after light exposure, but this increase was attenuated by lutein diet, suggesting that DSBs caused by photodamage contributed to the photoreceptor cell death and that this change was suppressed by lutein. Moreover, the expression of eyes absent (EYA), which promotes DNA repair and cell survival, was significantly up-regulated with lutein diet in the light-exposed retina. Therefore, lutein induced EYA for DNA repair, which could suppress DNA damage and photoreceptor cell apoptosis. Lutein reduced light-induced oxidative stress in the retina, which might contribute to promote DNA repair. The lutein-supplemented diet attenuated light-induced visual impairment by protecting the photoreceptor cells' DNA. (C) 2012 Elsevier Inc. All rights reserved.

Successful transition from embryonic to adult circulation is critical for survival of mammalian organisms. This shift occurs in the central cardiovascular circulation and in the eye as oxygen tension increases. However, its regulation is not well understood. We have used combinatorial gene deletion and overexpression assays to assess the effect of astrocyte-targeted deletion of von Hippel-Lindau tumor suppressor (Vhl), hypoxia-inducible factor-alpha s (Hif-alpha s), and Vegf on the normal regression of the hyaloidal vessels, the fetal ocular circulation system. Astrocytic Vhl deletion induced accelerated hyaloidal regression and subsequent massive secondary outgrowth. Combinatorial gene deletion involving Vhl, Hif-alpha s, and Vegf genes revealed that HIF-2 alpha/vascular endothelial growth factor signaling induces secondary outgrowth in Vhl mutants. Conversely, HIF-1 alpha regulated macrophage migration inhibitory factor and promoted macrophage infiltration that accelerates hyaloidal vessel regression. The phenotype observed in Vhl mutants strongly resembles human persistent hyperplastic primary vitreous cases and may provide insights into vascular remodeling mechanisms in other systems.

Vascular/parenchymal crosstalk is increasingly recognized as important in the development and maintenance of healthy vascularized tissues. The retina is an excellent model in which to study the role of cell type-specific contributions to the process of blood vessel and neuronal growth. During retinal vascular development, glial cells such as astrocytes provide the template over which endothelial cells migrate to form the retinal vascular network, and hypoxia-regulated vascular endothelial growth factor (VEGF) has been demonstrated to play a critical role in this process as well as pathological neovascularization. To investigate the nature of cell-specific contributions to this process, we deleted VEGF and its upstream regulators, the hypoxia-inducible transcription factors HIF-1 alpha and HIF-2 alpha, and the negative regulator of HIF alpha, von Hippel Lindau protein (VHL), in astrocytes. We found that loss of hypoxic response and VEGF production in astrocytes does not impair normal development of retinal vasculature, indicating that astrocyte-derived VEGF is not essential for this process. In contrast, using a model of oxygen-induced ischemic retinopathy, we show that astrocyte-derived VEGF is essential for hypoxia-induced neovascularization. Thus, we demonstrate that astrocytes in the retina have highly divergent roles during developmental, physiological angiogenesis, and ischemia-driven, pathological neovascularization. (C) 2010 Wiley-Liss, Inc.

Background: Lutein and zeaxanthin are suggested micronutrient supplements to prevent the progression of age-related macular degeneration (AMD), a leading cause of blindness worldwide. To monitor the levels of lutein/zeaxanthin in the macula, macular pigment optical density (MPOD) is measured. A commercially available device (MPSII (R), Elektron Technology, Switzerland), using technology based on heterochromatic flicker photometry, can measure both absolute and estimated values of MPOD. However, whether the estimated value is applicable to Asian individuals and/or AMD patients remains to be determined. Methods: The absolute and estimated values of MPOD were measured using the MPSII (R) device in 77 participants with a best-corrected visual acuity (BCVA) > 0.099 (logMAR score). Results: The studied eyes included 17 young (20-29 years) healthy, 26 aged (> 50 years) healthy, 18 aged and AMD-fellow, and 16 aged AMD eyes. The mean BCVA among the groups were not significantly different. Both absolute and estimated values were measurable in all eyes of young healthy group. However, absolute values were measurable in only 57.7%, 66.7%, and 43.8%, of the aged healthy, AMD-fellow, and AMD groups, respectively, and 56.7% of the eyes included in the 3 aged groups. In contrast, the estimated value was measurable in 84.6%, 88.9% and 93.8% of the groups, respectively, and 88.3% of eyes in the pooled aged group. The estimated value was correlated with absolute value in individuals from all groups by Spearman's correlation coefficient analyses (young healthy: R-2 = 0.885, P = 0. 0001; aged healthy: R-2 = 0.765, P = 0.001; AMD-fellow: R-2 = 0.851, P = 0.0001; and AMD: R-2 = 0.860, P = 0.013). Using the estimated value, significantly lower MPOD values were found in aged AMD-related eyes, which included both AMD-fellow and AMD eyes, compared with aged healthy eyes by Student's t-test (P = 0.02). Conclusions: Absolute, in contrast to estimated, value was measurable in a limited number of aged participants; however, it was correlated with estimated value both in young and aged Asian populations with or without AMD. These results may inform future clinical studies investigating the measurement of MPOD in understanding the role of macular pigments in the pathogenesis of AMD.

Retina is a highly vascularized tissue with a high oxygen and metabolic demand receiving light located in the back of the eye. The development and the maintenance of the retinal vasculature are important to regulate the homeostasis in the tissue. a Subunits of hypoxia-inducible factor (HIF) are key molecules in hypoxia response inducing genes required for cell survival such as vascular endothelial growth factor under hypoxia. Neurons, glia, and vascular endothelium cells interdependently form neurovascular unit in the retina tightly regulated by hypoxia response via HIF expression. A corruption of the precise hypoxia response in the developmental or matured retinal tissue may lead congenital vascular anomalies or adult neovascular ocular diseases. To regulate hypoxia response through HIF activity would be an ideal therapeutic target for these vision-threatening eye diseases.