Intravitreal Administration of Retinal Organoids-Derived Exosomes Alleviates Photoreceptor Degeneration in Royal College of Surgeons Rats by Targeting the Mitogen-Activated Protein Kinase Pathway.

Increasing evidence suggests that exosomes are involved in retinal cell degeneration, including their insufficient release; hence, they have become important indicators of retinopathies. The exosomal microRNA (miRNA), in particular, play important roles in regulating ocular and retinal cell functions, including photoreceptor maturation, maintenance, and visual function. Here, we generated retinal organoids (ROs) from human induced pluripotent stem cells that differentiated in a conditioned medium for 60 days, after which exosomes were extracted from ROs (Exo-ROs).

Role of mTORC1 activity during early retinal development and lamination in human-induced pluripotent stem cell-derived retinal organoids.

Retinal organoids derived from human-induced pluripotent stem cells (hiPSC) are powerful tools for studying retinal development as they model spatial and temporal differentiation of retinal cell types. Vertebrate retinal development involves a delicate and coordinated process of retinal progenitor cell (RPC) differentiation, and the mammalian target of rapamycin complex 1 (mTORC1) has been reported to play a significant role in this complex process. Herein, using hiPSC-derived retinal organoids, we identify the time-dependent role of mTORC1 in retinal development, specifically in retinal ganglion cell (RGC) differentiation and the retinal lamination process, during the early stages of retinal organoid (RO) development.

Novel Hypoxia-Inducible Factor 1α (HIF-1α) Inhibitors for Angiogenesis-Related Ocular Diseases: Discovery of a Novel Scaffold via Ring-Truncation Strategy.

Ocular diseases featuring pathologic neovascularization are the leading cause of blindness, and anti-VEGF agents have been conventionally used to treat these diseases. Recently, regulating factors upstream of VEGF, such as HIF-1α, have emerged as a desirable therapeutic approach because the use of anti-VEGF agents is currently being reconsidered due to the VEGF action as a trophic factor. Here, we report a novel scaffold discovered through the complete structure-activity relationship of ring-truncated deguelin analogs in HIF-1α inhibition.

Dry age-related macular degeneration like pathology in aged 5XFAD mice: Ultrastructure and microarray analysis.

Age-related macular degeneration (AMD) is a leading cause of blindness in the elderly. The two types of AMD are: dry and wet AMD. While laser-induced choroidal neovascularization has been used extensively in the studies of wet AMD, there is no established mouse model that fully recapitulates the cardinal features of dry AMD.

Disruption of outer blood-retinal barrier by Toxoplasma gondii-infected monocytes is mediated by paracrinely activated FAK signaling.

Ocular toxoplasmosis is mediated by monocytes infected with Toxoplasma gondii that are disseminated to target organs. Although infected monocytes can easily access to outer blood-retinal barrier due to leaky choroidal vasculatures, not much is known about the effect of T. gondii-infected monocytes on outer blood-retinal barrier.

L1 increases adhesion-mediated proliferation and chemoresistance of retinoblastoma.

Retinoblastoma is the most common intraocular cancer in children, affecting 1/20,000 live births. Currently, children with retinoblastoma were treated with chemotherapy using drugs such as carboplatin, vincristine, and etoposide. Unfortunately, if conventional treatment fails, the affected eyes should be removed to prevent extension into adjacent tissues and metastasis.

Antiangiogenic effect of betaine on pathologic retinal neovascularization via suppression of reactive oxygen species mediated vascular endothelial growth factor signaling.

Reactive oxygen species (ROS) as well as vascular endothelial growth factor (VEGF) play important roles in pathologic retinal neovascularization. We investigated whether betaine inhibits pathologic retinal neovascularization in a mouse model of oxygen induced retinopathy (OIR). Betaine was intravitreally injected in OIR mice at postnatal day (P) 14.

Hypoxia-induced fibroblast growth factor 11 stimulates capillary-like endothelial tube formation.

Low oxygen or hypoxia can be observed in the central region of solid tumors. Hypoxia is a strong stimulus for new blood vessel formation or angiogenesis, which is essential for tumor growth and progression. Fibroblast growth factor 11 (FGF11) is an intracellular non-secretory FGF whose function has not yet been fully characterized.

Real-time estimation of paracellular permeability of cerebral endothelial cells by capacitance sensor array.

Vascular integrity is important in maintaining homeostasis of brain microenvironments. In various brain diseases including Alzheimer's disease, stroke, and multiple sclerosis, increased paracellular permeability due to breakdown of blood-brain barrier is linked with initiation and progression of pathological conditions. We developed a capacitance sensor array to monitor dielectric responses of cerebral endothelial cell monolayer, which could be utilized to evaluate the integrity of brain microvasculature.

Suppression of transient receptor potential canonical channel 4 inhibits vascular endothelial growth factor-induced retinal neovascularization.

Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis and thus contributes to many vasoproliferative retinopathies including retinopathy of prematurity. Based on the importance of canonical transient receptor potential (TRPC) channels in VEGF signaling, we firstly evaluated the expression of TRPC channels in mouse retina by reverse transcriptase-polymerase chain reaction. All seven TRPC channels were expressed in mouse retina.

STAT3 inhibition suppresses proliferation of retinoblastoma through down-regulation of positive feedback loop of STAT3/miR-17-92 clusters.

Retinoblastoma, the most common intraocular malignant tumor in children, is characterized by the loss of both functional alleles of RB1 gene, which however alone cannot maintain malignant characteristics of retinoblastoma cells. Nevertheless, the investigation of other molecular aberrations such as matrix metalloproteinases (MMPs) and miRNAs is still lacking. In this study, we demonstrate that STAT3 is activated in retinoblastoma cells, Ki67-positive areas of in vivo orthotopic tumors in BALB/c nude mice, and human retinoblastoma tissues of the advanced stage.

Hypoxia-mediated retinal neovascularization and vascular leakage in diabetic retina is suppressed by HIF-1α destabilization by SH-1242 and SH-1280, novel hsp90 inhibitors.

In diabetic retinopathy (DR), visual deterioration is related with retinal neovascularization and vascular hyperpermeability. Anti-vascular endothelial growth factor (VEGF) agents are currently utilized to suppress retinal neovascularization and macular edema (ME); however, there are still concerns on the widespread use of them because VEGF is a trophic factor for neuronal and endothelial cells in the retina. As an alternative treatment strategy for DR, it is logical to address hypoxia-related molecules to treat DR because the retina is in relative hypoxia as DR progresses.

Suppression of protein kinase C-ζ attenuates vascular leakage via prevention of tight junction protein decrease in diabetic retinopathy.

To investigate the effect of protein kinase C (PKC)-ζ inhibition on vascular leakage in diabetic retinopathy, streptozotocin-induced diabetic mice were intravitreously injected with siPKC-ζ. According to the fluorescein angiography of the retinal vessels, suppression of PKC-ζ effectively attenuated vascular leakage in diabetic retina. Further evaluation on the retina with western blot analysis and immunohistochemistry revealed accompanying restoration of tight junction proteins on retinal vessels.

Anti-apoptotic effect of clusterin on cisplatin-induced cell death of retinoblastoma cells.

Clusterin is a cytoprotective chaperone protein that is known to protect various retinal cells. It was also reported to be overexpressed in several types of malignant tumors, whose chemoresistance correlates with the expression of clusterin. Herein, we investigated the effect of clusterin on cisplatin-induced cell death of retinoblastoma cells.

Animal models of diabetic retinopathy: doors to investigate pathogenesis and potential therapeutics.

Effective and validated animal models are valuable to investigate the pathogenesis and potential therapeutics for human diseases. There is much concern for diabetic retinopathy (DR) in that it affects substantial number of working population all around the world, resulting in visual deterioration and social deprivation. In this review, we discuss animal models of DR based on different species of animals from zebrafish to monkeys and prerequisites for animal models.

Anti-angiogenic effect of luteolin on retinal neovascularization via blockade of reactive oxygen species production.

Purpose: Oxidative stress-induced vascular endothelial growth factor (VEGF) is thought to play a critical role in the pathogenesis of retinopathy of prematurity (ROP). This study was performed to investigate the anti-angiogenic effect of luteolin against reactive oxygen species (ROS)-induced retinal neovascularization.

Methods: The toxicity of luteolin was evaluated through modified 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay in human retinal microvascular endothelial cells (HRMECs) as well as TUNEL staining in the retina of C57BL/6J mice.

Inhibitory activity of bevacizumab to differentiation of retinoblastoma cells.

Vascular endothelial growth factor (VEGF) is a major regulator in retinal and choroidal angiogenesis, which are common causes of blindness in all age groups. Recently anti-VEGF treatment using anti-VEGF antibody has revolutionarily improved the visual outcome in patients with vaso-proliferative retinopathies. Herein, we demonstrated that bevacizumab as an anti-VEGF antibody could inhibit differentiation of retinoblastoma cells without affection to cellular viability, which would be mediated via blockade of extracellular signal-regulated kinase (ERK) 1/2 activation.

Clusterin protects H9c2 cardiomyocytes from oxidative stress-induced apoptosis via Akt/GSK-3β signaling pathway.

Clusterin is a secretory glycoprotein, which is highly up-regulated in a variety of normal and injury tissues undergoing apoptosis including infarct region of the myocardium. Here, we report that clusterin protects H9c2 cardiomyocytes from H2O2-induced apoptosis by triggering the activation of Akt and GSK-3β. Treatment with H2O2 induces apoptosis of H9c2 cells by promoting caspase cleavage and cytochrome c release from mitochondria.

Inhibition of protein kinase C delta attenuates blood-retinal barrier breakdown in diabetic retinopathy.

Vision loss in diabetic retinopathy is due to macular edema characterized by increased vascular permeability, which involves phosphorylation associated with activation of protein kinase C (PKC) isoforms. Herein, we demonstrated PKC delta inhibition could prevent blood-retinal barrier breakdown in diabetic retinopathy. Increased vascular permeability of diabetic retina was accompanied by a decrease of zonula occludens (ZO)-1 and ZO-2 expression.

Differential roles of matrix metalloproteinase-9 and -2, depending on proliferation or differentiation of retinoblastoma cells.

Purpose: To investigate the differential roles of matrix metalloproteinase (MMP)-9 and MMP-2 in the proliferation or differentiation of retinoblastoma cells.

Methods: Cell proliferation assay with an MMP-9 inhibitor and cell viability assay with an MMP-2 inhibitor were performed in retinoblastoma cells with 5 ng/mL fibroblast growth factor 2 for proliferation, 0.1% bovine serum albumin for differentiation, or reverse transcriptase-polymerase chain reaction (RT-PCR) for MMP-9, MMP-2, and their tissue inhibitors TIMP-1 and TIMP-2.

Osteopontin splice variants differentially modulate the migratory activity of hepatocellular carcinoma cell lines.

Osteopontin (OPN, SPP1) is a secretory extracellular matrix protein that has been implicated in cancer-associated mechanisms such as metastasis, invasion and angiogenesis. Three OPN isoforms (OPN-a, -b and -c) derived from alternative splicing are known to exist, but their functional specificity remains unclear. Here, we found that the expression profile of OPN isoforms in hepatocellular carcinoma (HCC) cell lines and patient tissues were correlated with specific cellular phenotypes and tumorigenicity of HCC.

Neurotrophin receptors TrkA and TrkB in retinoblastoma are differentially expressed depending on cellular differentiation.

Retinoblastoma is the most common primary intraocular malignancy in children. With the progression of retinoblastoma, retinoblastoma cells lose their ability to differentiate. Regardless of many attempts to identify prognostic factors in retinoblastoma, further investigation for prognostic factors of retinoblastoma progression is still required because of the lack of sensitivity and specificity of these prognostic factors in predicting disease progression.

Protective effect of clusterin from oxidative stress-induced apoptosis in human retinal pigment epithelial cells.

Purpose: Oxidative stress to retinal pigment epithelial (RPE) cells is thought to play a critical role in the pathogenesis of age-related macular degeneration (AMD). This study was conducted to investigate whether clusterin protects human RPE cells from ROS-induced apoptosis through a PI3K/Akt survival pathway.

Methods: The preventive effect of clusterin on reactive oxygen species (ROS) production and RPE cell death induced by hydrogen peroxide was determined in ARPE-19 cells.

Angiopoietin-1 reduces vascular endothelial growth factor-induced brain endothelial permeability via upregulation of ZO-2.

Brain microvessels possess barrier structures comprising tight junctions which are critical for the maintenance of central nervous system homeostasis. Brain vascular diseases, such as ischemic stroke damage to blood-brain barrier, increase the vascular permeability, and then lead to vasogenic brain edema. Herein, we examined whether angiopoietin-1 (Ang-1) could regulate zonula occludens-2 (ZO-2) expression and counteract vascular endothelial growth factor (VEGF)-induced vascular permeability.