Cone-rod homeobox transcriptionally activates TCF7 to promote the proliferation of retinal pigment epithelial and retinoblastoma cells in vitro

AIM:To investigate the proliferation regulatory effect of cone-rod homeobox(CRX)in retinal pigment epithelium(RPE)and retinoblastoma(RB)cells to explore the potential application and side effect(oncogenic potential)of CRXbased gene therapy in RPE-based retinopathies.METHODS:Adult human retinal pigment epithelial(ARPE)-19 and human retinal pigment epithelial(RPE)-1 cells and Y79 RB cell were used in the study.Genetic manipulation was performed by lentivirus-based technology.The cell proliferation was determined by a CellTiter-Glo Reagent.The mRNA and protein levels were determined by quantitative real-time polymerase chain reaction(qPCR)and Western blot assay.The transcriptional activity of the promoter was determined by luciferase reporter gene assay.The bindings between CRX and transcription factor 7(TCF7)promoter as well as TCF7 and the promoters of TCF7 target genes were examined by chromatin immunoprecipitation(ChIP)assay.The transcription of the TCF7 was determined by a modified nuclear run-on assay.RESULTS:CRX overexpression and knockdown significantly increased(n=3,P<0.05 in all the cells)and decreased(n=3,P<0.01 in all the cells)the proliferation of RPE and RB cells.CRX overexpression and knockdown significantly increased and deceased the mRNA levels of Wnt signaling target genes[including MYC proto-oncogene(MYC),JUN,FOS like 1(FOSL1),CCND1,cyclin D2(CCND2),cyclin D3(CCND3),cellular communication network factor 4(CCN4),peroxisome proliferator activated receptor delta(PPARD),and matrix metallopeptidase 7(MMP7)]and the luciferase activity driven by the Wnt signaling transcription factor(TCF7).TCF7 overexpression and knockdown significantly increased and decreased the proliferation of RPE and RB cells and depletion of TCF7 significantly abolished the stimulatory effect of CRX on the proliferation of RPE and RB cells.CRX overexpression and knockdown significantly increased and decreased the mRNA level of TCF7 and the promoter of TCF7 was significantly immunoprecipitated by CRX antibody.CONCLUSION:CRX transcriptionally activates TCF7 to promote the proliferation of RPE and RB cells in vitro.CRX is a potential target for RPE-based regenerative medicine.The potential risk of this strategy,tumorigenic potential,should be considered.

Bone morphogenetic protein-6 suppresses TGF-β_(2)-induced epithelial-mesenchymal transition in retinal pigment epithelium

AIM:To evaluate the effect of bone morphogenetic protein-6(BMP-6)on transforming growth factor(TGF)-β_(2)-induced epithelial-mesenchymal transition(EMT)in retinal pigment epithelium(RPE).METHODS:Adult retinal pigment epithelial cell line(ARPE-19)were randomly divided into control,TGF-β_(2)(5μg/L),and BMP-6 small interfering RNA(siRNA)group.The cell morphology was observed by microscopy,and the cell migration ability were detected by Transwell chamber.The EMT-related indexes and BMP-6 protein levels were detected by Western blotting.Furthermore,a BMP-6 overexpression plasmid was constructed and RPE cells were divided into the control group,TGF-β_(2)+empty plasmid group,BMP-6 overexpression group,and TGF-β_(2)+BMP-6 overexpression group.The EMT-related indexes and extracellular regulated protein kinases(ERK)protein levels were detected.RESULTS:Compared with the control group,the migration of RPE cells in the TGF-β_(2) group was significantly enhanced.TGF-β_(2) increased the protein expression levels ofα-smooth muscle actin(α-SMA),fibronectin and vimentin but significantly decreased the protein levels of E-cadherin and BMP-6(P<0.05)in RPE.Similarly,the migration of RPE cells in the BMP-6 siRNA group was also significantly enhanced.BMP-6 siRNA increased the protein expression levels ofα-SMA,fibronectin and vimentin but significantly decreased the protein expression levels of E-cadherin(P<0.05).Overexpression of BMP-6 inhibited the migration of RPE cells induced by TGF-β_(2) and prevented TGF-β_(2) from affecting EMT-related biomarkers(P<0.05).CONCLUSION:BMP-6 prevents the EMT in RPE cells induced by TGF-β_(2),which may provide a theoretical basis for the prevention and treatment of proliferative vitreoretinopathy.

PI3K/AKT/mTOR signaling pathway inhibitors in proliferation of retinal pigment epithelial cells

AIM: To determine whether the PI3K/AKT/mTOR pathway is activated in proliferative vitreoretinopathy (PVR) in homo-sapiens. METHODS: The retina of controls and patients with PVR were collected and their levels of PI3K, phospho-AKT, phospho-mTOR, phospho-p70S6k and phospho-4EBP-1 were determined by Western blot. The cultured human retinal pigment epithelial cell line D407 was treated with a specific mTOR inhibitor, rapamycin (RAPA) or a PI3K inhibitor, LY294002, of various concentrations and durations. Cell morphology was observed by phase contrast microscopy and the proliferation and apoptosis of treated cells were determined by MTT assay and flow cytometry. RESULTS: Levels of PI3K, phospho-AKT, phospho-mTOR, phospho-P70S6K and phospho-4EBP1 was increased in the retina in PVR (P <0.05). In D407 cells, both RAPA and LY294002 significantly inhibited cell proliferation and cell cycle progression, and promoted apoptosis (P <0.05); morphologically, the cells became smaller. Both RAPA and LY294002 reduced levels of phospho-AKT, phospho-mTOR, phospho-p70S6k and phospho-4EBP1 expression (P <0.05). RAPA, but not LY294002, had no significant effect on PI3K expression. CONCLUSION: PI3K/AKT/mTOR signaling pathway is highly activated in the retinal pigment epithelial cells of PVR. The inhibitors of PI3K/AKT/mTOR signaling pathway, RAPA and LY294002, could inhibited the PI3K/AKT/mTOR signaling pathway by reducing the levels of phosphorylation of mTOR pathway components.

Up-regulation of HIF-1α and VEGF Expression by Elevated Glucose Concentration and Hypoxia in Cultured Human Retinal Pigment Epithelial Cells

Summary： In order to explore the effect of high glucose concentration and high glucose concentration with hypoxia on the production of hypoxia-inducible factor-1α （HIF-1α） and vascular endothelial growth factor （VEGF）, human RPE cells were cultured in 5,56 mmol/L glucose （control group）, 5.56 mmol/L glucose with 150 !a mol/L COCl2 （hypoxic group）, 25 mmol/L glucose （high glucose group） and 25 mmol/L glucose with 150 μmol/L COCl2 （combination group）. RT-PCR was used to detect the expression of HIF-1α and VEGF mRNAs. Western blot analysis was used to measure the levels of HIF-1α and VEGF proteins. Although the small amount of HIF-1α protein was able to be detected in high glucose group but not in control group, there was no significant difference between the expression of HIF-1α mRNA of RPE cells in high glucose group and that of RPE cells in control group. As compared with RPE cells in control group, the mRNA expression and the protein synthesis of VEGF in high glucose group were up-regulated. As compared with RPE cells in hypoxic group, the expression of HIF-1α mRNA of RPE cells in combination group was not different, but the protein synthesis of HIF-1α, the mRNA expression and the protein synthesis of VEGF were more obviously up-regulated. In conclusion, high concentration glucose mainly influence the protein synthesis of HIF-1α of RPE cell, and HIF-1α protein is able to be accumulated in high concentration glucose. Under hypoxia, the HIF-1α protein induced by high concentration glucose is more stable, and the expression of VEGF is obviously increased. It is suggested that high concentration glucose may play a role in retinal neovascularization, especially at ischemia stage of diabetic retinopathy.

4-HNE Induces Apoptosis of Human Retinal Pigment Epithelial Cells by Modifying HSP70

The role of heat shock protein 70 (HSP70) in apoptosis of human retinal pigment epithelial cells (ARPE-19) induced by 4-hydroxy-2-nonenal (4-HNE) was explored. Different concentrations of 4-HNE were used to stimulate ARPE-19 cells, and apoptosis was measured by flow cytometry. The expression of apoptotic-related proteins, HSP70, X-linked inhibitorof- apoptosis (XIAP), Bcl-2, and Bax were quantified by Western blotting. HSP70 and XIAP overexpression plasmids, or their corresponding siRNAs were transfected into ARPE-19 cells using Lipofectamine. 2000. Co-immunoprecipitation and Western blotting were used to detect the effect of 4-HNE on the expression of HSP70 and the binding level between 4-HNE and HSP70. The results showed that 4-HNE induced late apoptosis in ARPE-19 cells, accompanied by elevated levels of 4-HNE-modified IISP70, but it did not affect HSP70 protein expression. 4-HNE-modified HSP70 down-regulated the expression of the apoptosis inhibitory protein XIAP. Overexpression of HSP70 or XIAP inhibited 4-HNE-induced apoptosis of ARPE-19 cells. It was suggested that 4-HNE could promote XIAP degradation by modification of HSP70 to induce late apoptosis of human retinal pigment epithelial cells.

Cholecystokinin octapeptide antagonizes apoptosis in human retinal pigment epithelial cells

Although cholecystokinin octapeptide-8 is important for neurological function, its neuroprotective properties remain unclear. We speculated that cholecystokinin octapeptide-8 can protect human retinal pigment epithelial cells against oxidative injury. In this study, retinal pigment epithelial cells were treated with peroxynitrite to induce oxidative stress. Peroxynitrite triggered apoptosis in these cells, and increased the expression of Fas-associated death domain, Bax, caspase-8 and Bcl-2. These changes were suppressed by treatment with cholecystokinin octapeptide-8. These results suggest that cholecystokinin octapeptide-8 can protect human retinal pigment epithelial cells against apoptosis induced by peroxynitrite.

Peroxynitrite-induced expression of inducible nitric oxide synthase and activated apoptosis via nuclear factor-kappa B pathway in retinal pigment epithelial cells and antagonism of cholecystokinin octapeptide-8 in vitro

AIM: To explore that if peroxynitrite induced the expression of inducible nitric oxide synthase (iNOS)via nuclear factor-kappa B (NF-kappa B)pathway in retinal pigment epithelial (RPE) cells and the antagonism of cholecystokinin octapeptide-8 (Melatonin, CCK-8) in vitro. METHODS: RPE cells were obtained from eyes of C57BL/6 mouse and divided into control, peroxynitrite and CCK-8 groups. Control group was treated with saline, peroxynitrite group was treated with peroxynitrite, and CCK-8 group was treated with CCK-8 after added with peroxynitrite. All changes were observered at 6, 12 and 24 hours after treatment. Gene array analysis, Reverse Transcription Polymerase Chain Reaction (RT-PCR) were used to determine the expression of inducible nitric oxide synthase ( iNOS)mRNA in RPE cells. Western blotting was used to test the apoptosis of RPE cells. Immunofluorescent staining was used to determine the NF-kappa B pathway signal transduction. RESULTS: Compared to the control group, the expression of iNOS mRNA was up-regulated in peroxynitrite group and down-regulated in CCK-8 group with gene array analysis. Apoptosis was increased in peroxynitrite group and decreased in CCK-8 group with western blotting. The NF-kappa B pathway signal transduction was more and more stronger in the peroxynitrite group. But in CCK-8 group, little stronger could be observed at 12 hours, then weak at 24 hours with immunofluorescent staining (P<0.001). CONCLUSION: This study suggested that apoptosis of RPE cells was partly induced by peroxynitrite, which may be the new way of oxidative damage to the RPE cells. The NF-kappa B signal transduction may affect and reinforce apoptosis mediated by peroxynitrite. CCK-8 decreased apoptosis of RPE cells induced by peroxynitrite and is a potential agent for therapy of retinopathy. The mechanism of CCK-8 dealing with RPE cells may be related to its direct inhibition of the formation of iNOS to produce peroxynitrite and antagnism of damage of peroxynitrite to the RPE cells.

Gac fruit extracts ameliorate proliferation and modulate angiogenic markers of human retinal pigment epithelial cells under high glucose conditions

Objective: To investigate the impact of the extracts of Gac fruit parts(peel, pulp, seed, and aril) on the cell viability and angiogenesis markers of human retinal pigment epithelial(ARPE-19) cells under high glucose conditions. Methods: The effect of the extracts of Gac fruit peel, pulp, seed and aril on the ARPE-19 cells was determined using MTT viability assay, Trypan blue dye and morphological changes were observed using light microscopy. Enzyme-linked immunosorbent-based assay was performed to evaluate the effect of Gac fruit parts on the reactive oxygen species(ROS), vascular endothelial growth factor(VEGF) and pigmented epithelium-derived factor(PEDF) secretions. Results: High glucose(HG) at 30 mmol/L increased ARPE-19 cell viability and ROS and VEGF secretions. While, the exposure of ARPE-19 cells in high glucose condition to Gac fruit extracts led to inhibition of cell viability, induced morphological changes, decreased ROS and VEGF secretions, and increased PEDF level. Gac pulp, seed, and aril at 1 000 μg/mL showed significant inhibition activities [(7.5 ± 5.1)%,(2.7 ± 0.5)%,(3.2 ± 1.1)%, respectively] against HG-induced ARPE-19 cell viability. The findings also demonstrated that Gac aril at 250 μg/mL significantly decreased ROS and VEGF levels [(40.6 ± 3.3) pg/mL,(107.4 ± 48.3) pg/mL, respectively] compared to ROS [(71.7 ± 2.9) pg/mL ] and VEGF [(606.9 ± 81.1) pg/mL] in HG untreated cells. Moreover, 250 μg/mL of Gac peel dramatically increased PEDF level [(18.2 ± 0.3) ng/mL] compared to that in HG untreated cells [(0.48 ± 0.39) ng/mL]. Conclusions: This study indicates that the extracts of Gac peel, pulp, seed and aril reduced cell viability, minimized ROS generations and showed angiogenic activities. Therefore, our findings open new insights into the potentiality of Gac fruit against HG-related diabetic retinopathy disease.

Puerarin antagonizes peroxyntrite-induced injury in retinal pigment epithelial cells

A rat model of diabetes mellitus was established by intraperitoneal injection of streptozotocin. Three days later, the rats were intraperitoneally administered 140 mg puerarin/kg daily, for a total of 60 successive days. DNA ladder results showed increased apoptosis over time in retinal pigment epithelial cells from rats with streptozotocin-induced diabetes mellitus. Western blot analysis, Reverse transcription-PCR, immunohistochemistry, and flow cytometry results showed increased expression of 3-nitrotyrosine, a peroxyntrite marker, as well as inducible nitric synthase and Fas/FasL, in retinal pigment epithelial cells. Puerarin reversed these changes, and results demonstrated that puerarin inhibited Fas/FasL expression and alleviated peroxyntrite injury to retinal pigment epithelial cells. These results suggested that puerarin inhibited production of inducible nitric oxide synthase and directly antagonized peroxyntrite injury in retinal pigment epithelial cells.

Control of peroxyntrite -induced production of inducible nitric oxide synthase isoforms and antagonism of cholecystokinin octapeptide-8 in retinal pigment epithelial cells in vivo

AIM: To explore if peroxyntrite (ONOO(-)) induced iNOS vi;7 Fas/ Fas/L pathway in diabetic rats and the effection of cholecystokinin octapeptide-8 (CCK-8) as therapeutic agent for decrease diabetic retinopathy. METHODS: Thirty-six rats were taken as control group, seventy two were given (streptozotocin) STZ (45mg/kg) and then divided into ONOO(-) group and CCK-8 group (peritoneal injection CCK-8). STZ-induced diabetic rats were treated with CCK-8 for 60 days. Western blotting analysis, DNA ladder, RT-PCR, immunohistochemistry and flow cytometry were used for determining the expression of nitrotyrosine (NT, the foot print of ONOO(-)); apoptosis and inducible nitric oxide synthase (iNOS) mRNA as well as Fas/Fasl signal transduction in RPE cells. RESULTS: Both RPE cells in ONOO(-) and CCK-8 group developed apoptosis and expressed NT, iNOS mRNA and Fas/Fasl. But latter delayed the all changes in a time-dependent manner compared with control and ONOO(-) group (P<0.001). iNOS and Fas/Fasl were up-regulated and associated with an increase of expression of ONOO(-) in vivo. CONCLUSION: The study suggested that apoptosis of RPE was partly induced by ONOO(-) may be the new way of oxidative damage to the RPE cells. CCK-8 decreased RPE cells apoptosis partly induced by ONOO(-) and is a potential drug for therapy of diabetic retinopathy. The mechanism of CCK-8 dealing with RPE cells may be related to its direct inhibition of the formation of iNOS to produce ONOO(-) and antagnism of damage of ONOO(-) to RPE cells.

Cross-talk between microRNA-let7c and transforming growth factor-β2 during epithelial-to-mesenchymal transition of retinal pigment epithelial cells

AIM: To explore the roles of microRNA-let7 c(miR-let7 c) and transforming growth factor-β2(TGF-β2) and cellular signaling during epithelial-to-mesenchymal transition(EMT) of retinal pigment epithelial cells. METHODS: Retinal pigment epithelial(ARPE-19) cells were cultured with no serum for 12 h, and then with recombinant human TGF-β2 for different lengths of time. ARPE-19 cells were transfected with 1×106 TU/mL miR-let7 c mimcs(miR-let7 cM), miR-let7 c mimcs negative control(miR-let7cMNC) and miR-let7 c inhibitor(miR-let7 cI) using the transfection reagent. The expression of keratin-18, vimentin, N-cadherin, IKB alpha, p65 were detected by Western blot, quantitative polymerase chain reaction and immunofluorescence. RESULTS: The expression of miR-let7c was dramatically reduced and the nuclear factor-kappa B(NF-κB) signaling pathway was activated after induction by TGF-β2(P<0.05). In turn, overexpressed miR-let7 c significantly inhibited TGF-β2-induced EMT(P<0.05). However, miR-let7 c was unable to inhibit TGF-β2-induced EMT when the NF-κB signaling pathway was inhibited by BAY11-7082(P<0.01). CONCLUSION: The miR-let7 c regulates TGF-β2-induced EMT through the NF-κB signaling pathway in ARPE-19 cells.

A Trojan horse biomimetic delivery system using mesenchymal stem cells for HIF-1α siRNA-loaded nanoparticles on retinal pigment epithelial cells under hypoxia environment

AIM: To demonstrate the feasibility of mesenchymal stem cell(MSC)-mediated nano drug delivery, which was characterized by the “Trojan horse”-like transport of hypoxiainducible factor-1α small interfering RNA(HIF-1α si RNA) between MSCs and retinal pigment epithelial cells(RPE) under hypoxia environment.METHODS: Plasmid and lentivirus targeting the human HIF-1α gene were designed and constructed. HIF-1α si RNA was encapsulated into poly(lactic-co-glycolic acid) nanoparticles(PLGA-NPs) through the water-in-oil-in-water(w/o/w) multiple emulsion technique. The effect of PLGANPs uptake on the expression of HIF-1α m RNA was tested in RPE cells by real-time quantitative polymerase chain reaction(q PCR) and additional transfected conditions were used as control, including lentivirus group, nude plasmid group and blank PLGA group. MSCs were transfected with the NPs and the transfection efficacy was evaluated by flow cytometry. Transwell co-culture system of transfected MSCs and RPE cells was constructed under hypoxia environment. The effects of MSC-loaded HIF-1α si RNA PLGA-NPs on proliferation, apoptosis, and migration of RPE cells were then evaluated. The effect of transfected MSCs on HIF-1α expression of RPE cells was analyzed by using q PCR at the time points 24h, 3d, and 7d.RESULTS: The average diameter of PLGA-NPs loaded with HIF si RNA was 314.1 nm and the zeta potential was-0.36 m V. The transfection efficiency of PLGA-NPs was 67.3%±5.2% into MSCs by using flow cytometry. Compared with the lentivirus group, the PLGA-NPs loaded with HIF-1α si RNA can effectively reduce the expression of HIF-1α m RNA up to 7d in RPE(0.63±0.05 at 7d, P<0.001). In the Transwell co-culture system of transfected MSCs and RPE, the abilities of proliferation(2.34±0.17, 2.40±0.28, 2.47±0.24 at 48h, F=0.23, P=0.80), apoptosis(14.83%±2.43%, 12.94%±2.19%, 12.39%±3.21%;F=0.70, P=0.53) and migration(124.5±7.78, 119.5±5.32, 130±9.89, F=1.33, P=0.33) of the RPE cells had no differences between MSCloaded HIF-1α si RNA PLGA-NPs and other groups. The inhibition of PLGA on the HIF-1α m RNA expression in RPE cells could continue until the 7th day, the level of HIF-1α m RNA was lower than that of other groups(F=171.98, P<0.001). CONCLUSION: The delivery of PLGA-NPs loaded with HIF-1α si RNA carried by MSCs is found to be beneficial temporally for HIF-1α m RNA inhibition in RPE cells under hypoxia environment. The MSC-based bio-mimetic delivery of HIF-1α si RNA nanoparticles is a potential method for therapy against choroidal neovascularization.

Effects of curcumin nanoparticles on proliferation and VEGF expression of human retinal pigment epithelial cells

AIM:To investigate the effects of curcumin(Cur)nanoparticles loaded with chitosan derivatives grafted by deoxycholic acid(Chit-DC)on human retinal pigment epithelial(h RPE)cell proliferation and vascular endothelial growth factor(VEGF)m RNA expression.METHODS:Cur nanoparticles were synthesized with Chit-DC as the carrier and Cur as the supported drug.Cell counting kit-8(CCK-8)method was used to detect the effects of different concentrations of Cur/Chit-DC,Chit-DC,and Cur on the proliferation of h RPE cells for different times.The changes of Cur/Chit-DC and Cur on h RPE cell cycle were determined by flow cytometry.Semi-quantitative reverse transcription-polymerase chain reaction(RT-PCR)was used to detect the m RNA expression levels of VEGF in h RPE cells treated with Cur,Chit-DC and Cur/Chit-DC at 10μg/m L for 24 h.RESULTS:Different concentrations of Chit-DC nanoparticle treated h RPE cells had no significant difference in terms of optical density(OD)values compared with the control group at 24 h and 48 h.Moreover,there was no change in the cell morphology under a light microscope.After 24 h treatment with Cur/Chit-DC and Cur,the percentage of G0-G1 phase cells increased and the percentage of S phase cells decreased in all concentration groups.Cur/Chit-DC and Cur in all concentration groups inhibited the proliferation of h RPE cells in a time and dose dependent manner,and reduced the expression level of VEGF m RNA.CONCLUSION:The Cur/Chit-DC nanoparticles can release Cur continuously and have sustained release function.Both Cur/Chit-DC nanoparticles and Cur could inhibit h RPE cells cultured in vitro,and could reduce the expression level of VEGF m RNA in h RPE cells.

Blocking VEGF signaling augments interleukin-8 secretion via MEK/ERK/1/2 axis in human retinal pigment epithelial cells

AIM:To identify proangiogenic factors engaged in neovascular age-related macular degeneration(AMD)except vascular endothelial growth factor(VEGF)from human retinal pigment epithelial(h RPE)cells and investigate the underlying mechanisms.METHODS:VEGF receptor 2(VEGFR2)in ARPE-19 cells was depleted by si RNA transfection or overexpressed through adenovirus infection.The m RNA and the protein levels of interleukin-8(IL-8)in ARPE-19 cells were measured by quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay respectively.The protein levels of AKT,p-AKT,MEK,p-MEK,ERK1/2,p-ERK1/2,JNK,p-JNK,p38 and p-p38 were detected by Western blotting.A selective chemical inhibitor,LY3214996,was employed to inhibit phosphorylation of ERK1/2.Cell viability was determined by MTT assay.RESULTS:Knockdown of VEGFR2 in ARPE-19 cells robustly augmented IL-8 production at both the m RNA and the protein levels.Silencing VEGFR2 substantially enhanced phosphorylation of MEK and ERK1/2 while exerted no effects on phosphorylation of AKT,JNK and p38.Inhibiting ERK1/2 phosphorylation by LY3214996 reversed changes in VEGFR2 knockdown-induced IL-8 upregulation at the m RNA and the protein levels with no effects on cell viability.VEGFR2 overexpression significantly reduced IL-8 generation at the m RNA and the protein levels.CONCLUSION:Blockade of VEGF signaling augments IL-8 secretion via MEK/ERK1/2 axis and overactivation of VEGF pathway decreases IL-8 production in h RPE cells.Upregulated IL-8 expression after VEGF signaling inhibition in h RPE cells may be responsible for being incompletely responsive to anti-VEGF remedy in neovascular AMD,and IL-8 may serve as an alternative therapeutic target for neovascular AMD.

Influence of IL-1β and TNF-α on Fas Expression of Human Retinal Pigment Epithelial Cells in Vitro

Purpose:To observe Fas expression change of cultured human retinal pigment epithelial (RPE) cells by IL-1β and TNF-α.Methods:With flow cytometry, immunohischemistry, and color imaging system, Fas expressions by exposure to IL-1β and/or TNF-α were measured.Results:The gray degree values of Fas expression were 67.5±6.1 in IL-1β+TNF-α-treated group, 80.1±9.2 in IL-1β-treated group, and 70.4±6.4 in TNF-α-treated group, respectively. There were significant differences (P < 0.005) compared with control group (107.0±10.2). Flow cytometry showed that 15.0% cultured human RPE cells expressed Fas. Fas-positive in IL-1β, TNF-α, and IL-1β+TNF-α-treated groups expressed was 28.1%, 34.5%, and 65.2%, respectively. Conclusion:IL-1β, TNF-α, and combining both of them can up-regulate Fas protein expression, which may contribute to more Fas (+) cells in proliferative vitreoretinopathy (PVR). Minimizing this process by means of inducing apoptosis of Fas (+) proliferative cells of Fas/FasL pathway is a future preventive and therapeutic possibility for PVR. Eye Science 2004;20:39-41.

Effect of EGb761 on light-damaged retinal pigment epithelial cells

AIM: To investigate the protective mechanism of Gingko Biloba extract(EGb761) on the ability of retinal pigment epithelial(RPE) cells to resist light-induced damage in a comparative proteomics study. · METHODS: Human RPE cells(ARPE-19) were randomly distributed to one of three groups: normal control(NC group) and light-damaged model without or with EGb761 group(M and ME groups,respectively). The light-damaged model was formed by exposing to white light(2 200 ±300)lx for 6h. The RPE cells in ME group were conducted with EGb761(100μg/mL) before light exposure. The soluble cellular proteins extracting from each groups were separated by two-dimensional electrophoresis and stained by silver staining. Different proteins in the profiles of the gels were analyzed by Image Master Software. Two-fold expressing protein spots were identified by Matrix-assisted laser desorption/ ionization tandem time-of-flight(MALDI-TOF/TOF) mass spectrometry. ·RESULTS: NC,M and ME groups displayed 1 892±71,2 145 ±23 and 2 216 ±85 protein spots,respectively. We identified 33 proteins with different expression levels between the NC and M groups,25 proteins between the M and ME groups,and 11 proteins between the NC and ME groups. MALDI-TOF/TOF mass spectrometry successfully identified 16 proteins,including metabolic enzymes,cytoskeletal proteins,anti-oxidation proteins,and others. ·CONCLUSION: Differences in some important proteins,such as cathepsin B,heat shock protein,and cytochrome C reductase,indicated that multiple pathways may be induced in light-damaged RPE cells and the protective effect of EGb761.

Immunocytochemical characteristics of cultured human retinal pigment epithelial cells

Objective: To investigate the immunocytochemical characteristics of cultured human retinal pigment epithelial cells (RPEC). Methods: Indirect immunofluorescence mehtods were applied to study the expression of keratin, vimentin, actin, Ⅷ factor and glial fibrillary acidic protein (GFAP), and HAM45 in the 1st-passage and the 3rd- to 6th-passages of RPEC. Results: subcultured human RPEC demonstrated positive staining for keratin and vimentin protein; keratin reactivity was a constant feature of all human RPEC.The first-passage RPEC did not stain with abtibodies to vimentin, or stained very weakly. After passaged for 3 to 6 times, however, RPEC demonstrated intensively positive staining for vimentin. BPEC expressed generally negative staining for actin, Ⅷ factor, GFAP,and HAM45. Conclusion: Cultured RPECs always express keratin other than proteins of actin, Ⅷ factor, GFAP and HAM45. Protein vimentin expression intensity of RPEC increases with more passages. This indicates alternative phenotype of RPEC due to cell cultural conditions.

Induction of Differentiation of Mesenchymal Stem Cells into Retinal Pigment Epithelial Cells for Retinal Regeneration by Using Ciliary Neurotrophic Factor in Diabetic Rats

Diabetic retinopathy(DR)is a common cause of blindness all over the world.Bone marrow mesenchymal stem cells(BMSCs)have been considered as a promising strategy for retinal regeneration in the treatment of DR.However,the poor viability and low levels of BMSCs engraftment limit the therapeutic potential of BMSCs.The present study aimed to examine the direct induction of BMSCs differentiation into the cell types related to retinal regeneration by using soluble cytokine ciliary neurotrophic factor(CNTF).We observed remarkably increased expression of cellular retinaldehyde-binding protein(CRALBP)and retinoid isomerohydrolase(RPE65)in BMSCs treated with CNTF in vitro,indicating the directional differentiation of BMSCs into the retinal pigment epithelium(RPE)cells,which are crucial for retinal healing.In vivo,the diabetic rat model was established by use of streptozotocin(STZ),and animals treated with BMSCs+CNTF exhibited better viability and higher delivery efficiency of the transplanted cells than those treated with BMSCs injection alone.Similar to the in-vitro result,treatment with BMSCs and CNTF combined led to the differentiation of BMSCs into beneficial cells(RPE cells),and accelerated retinal healing characterized by the activation of rod photoreceptor cells and phagocytosis function of RPE cells.In conclusion,CNTF contributes to the differentiation of BMSCs into RPE cells,which may help overcome the current stem cell therapy limitations in the field of retinal regeneration.

OPTIMAL CONDITIONS FOR DETECTING 5-BROMO-DEOXYURIDINE USED AS A MARKER OF TRANSPLANTED RETINAL PIGMENT EPITHELIAL CELLS

Objective To detemine optimal conditions by using 5 bromodeoxyuridine (BrdU) as a marker of transplanted retinal pigment epithelial (RPE) cells in the subretinal space of albino rabbits Methods Pigmented rabbit RPE cells at second to fifth passage were fed with 20 μmol/L BrdU in Eagle’s minimal essential medium (MEM) for five days After extensive wash with phosphate buffered saline (PBS),the cells were detached by trypsin and used for transplantation onto Bruch’s membrane of albino rabbits Eyes were enucleated at various times post transplantation Acetone, 4% paraformaldehyde, periodate lysine paraformaldehyde (PLP),or half strength Karnovsky’s fixatives were individually used to fix the tissue in order to find optimal condition for detecting BrdU marker The fixation was followed by embedding in OCT compound, glycol plastic, or paraffin The transplanted area was then sectioned, pepsin digested, and used for immunohistochemical staining with monoclonal antibody against BrdU and avidin biotin alkaline phosphatase complex (ABC AP) Results Frozen sections of acetone or paraformaldehyde fixed tissue gave strong immunostaining of BrdU but the overall morphology was poor Karnovsky’s fixed tissue offered strong staining but this was buried by strong background When using PLP as a fixative, we obtained strongly positive blue staining with very low background, and also excellent morphologic preservation Conclusion In combination with immunohistochemical detection method, BrdU labeling is an excellent long term marker for RPE transplantation one year after surgery To use BrdU as a marker necessitates the use of pepsin digestion to make the BrdU antigen in the nuclei accessible to antibody But the pepsin digestion may damage other tissues and result in overall poor morphology Among the fixatives tested in this study, PLP fixed tissues offered both strong BrdU staining and good preservation of structural integrity, particularly the fine structure of photoreceptor and RPE cells

Lycium barbarum polysaccharides protected human retinal pigment epithelial cells against oxidative stressinduced apoptosis

AIM: To investigate the protective effect and its mechanism of lycium barbarum polysaccharides(LBP)against oxidative stress-induced apoptosis in human retinal pigment epithelial cells.METHODS: ARPE-19 cells, a human retinal pigment epithelial cell lines, were exposed to different concentrations of H2O2 for 24h, then cell viability was measured by Cell Counting Kit-8(CCK-8) assay to get the properly concentration of H2O2 which can induce half apoptosis of APRE-19. With different concentrations of LBP pretreatment, the ARPE-19 cells were then exposed to appropriate concentration of H2O2, cell apoptosis was detected by flow cytometric analysis. Expression levels of Bcl-2 and Bax were measured by real time quantitative polymerase chain reaction(RT-PCR) technique.RSULTS: LBP significantly reduced the H2O2-induced ARPE-19 cells’ apoptosis. LBP inhibited the H2O2-induced down-regulation of Bcl-2 and up-regulation of Bax.CONCLUSION: LBP could protect ARPE-19 cells from H2O2-induced apoptosis. The Bcl-2 family had relationship with the protective effects of LBP.