ObjectiveTo investigate the impact of L-Phenylalanine on the efficiency of retinal pigment epithelial (RPE) cell derivation from human embryonic stem cells (hESCs) and explore the underlying mechanisms. MethodsH1 hESCs were routinely cultured with mTeSR medium and divided into control and experimental groups. When cells reached over-confluence, spontaneous differentiation was triggered using 10% KSR differentiation medium without bFGF. L-Phenylalanine (0.2 mmol/L) was supplemented in the experimental group from the 3rd week. The expression of RPE markers and Wnt signaling components in the two groups was detected by Real time-RCR, Western blot and Flow cytometry analyses. Purified hESC-RPE cells and PBS were injected into the subretinal space of sodium iodine-induced retinal degeneration rats separately. Retinal function was assessed by ERG 6 weeks after the transplantation. ResultsOn the 7th week, much more pigment cell clumps appeared in the experimental group compared to the control group. Within these areas there were monolayer hexagonal RPE cells full of pigment granules. The experimental group showed significantly higher expression of Pax6, MITF, Tyrosinase, RPE65, Wnt3a, Lef1 and Tcf7 genes than the control group (P < 0.01). Higher expression level of MITF and RPE65 proteins and higher percentage of RPE65 (+) cells (P < 0.01) were detected in the experimental group. 6 weeks after sub-retinal transplantation of hESC-RPE cells, the amplitudes of a-b wave in the transplanted eyes were significantly higher than those in the control eyes (P < 0.01) at the stimulus intensity of 3.0 cd·s/m2. ConclusionsL-Phenylalanine effectively promoted the differentiation of embryonic stem cells into retinal pigment epithelial cells, and its impacts on the Wnt/β-catenin signaling pathway may partially explain the underlying mechanisms. Subretinal transplantation of hESC-RPE remarkably improved the retinal functions of retinal degenerative animal models.
ObjectiveTo observe the macular choroidal and retinal pigment epithelium (RPE) thickness in tilted disc syndrome (TDS). MethodsThis is a descriptive study. Thirty eyes of 22 TDS patients (TDS group) and 30 eyes of 15 normal subjects (control group) were analyzed. Among TDS group, there were 8 males (11 eyes) and 14 females (19 eyes), the average age was (9.00±2.78) years old. The best corrected visual acuity (BCVA) was 0.3-1.0, and the average spherical equivalent degree was (-3.44±2.22) DS. Among the control group, there were 8 males (16 eyes) and 7 females (14 eyes), the average age was (9.33±1.11) years old. The best corrected visual acuity (BCVA)≥1.0, and the average spherical equivalent degree was (-3.18±1.13)DS. The difference of the spherical equivalent degree between two groups was not statistically significant (t=-1.648, P=0.110). Enhanced depth imaging techniques of frequency-domain optical coherence tomography was used to measure the thickness of choroid and RPE at totally 17 sites. There sites included subfoveal, 4 sites each (500, 1000, 1500 and 2000 μm from the fovea) at the horizontal (nasal/temple) and vertical (superior/inferior) directions. ResultsThe subfoveal choroidal thickness was (235.53±51.77) μm and (273.45±60.3) μm in TDS patients and control respectively, the difference was significant(t=-2.612,P=0.011). The difference of the choroidal thickness of the other 8 horizontal sites (F=24.180) and 8 vertical sites (F=23.390) in TDS group was statistically significant (P=0.000). The TDS choroidal thickness of all horizontal sites except nasal 1000 μm site was thinner than corresponding sites of the control group (P<0.05). The TDS choroidal thickness of the subfoveal site and 4 inferior vertical sites was thinner than corresponding sites of the control group (P<0.05). The subfoveal RPE thickness was (32.56±5.00) μm and (36.58±3.60) μm in TDS patients and control respectively, the difference was significant(t=-3.567,P=0.001). The subfoveal RPE thickness was the thickest among other 16 sites in both groups, and the TDS RPE thickness of all sites was thinner than control group, the difference was statistically significant (P<0.05). ConclusionThe choroidal and RPE thickness of TDS patient was thinner than normal subjects.
ObjectiveTo observe the effect of complement receptor 1 (CR1) on barrier of cultured human retinal epithelial cells (hRPE) under complement-activated oxidative stress. MethodsThe third to fifth passage of hRPE cultured on Transwell insert were used to establish a stable hRPE monolayer barrier. The hRPE monolayer barrier was exposed to 500 μmol/L ten-butyl hydroperoxide and 10% normal human serum to establish the hRPE monolayer barrier model of complement-activated oxidative stress in vitro. hRPE monolayer barriers under complement-activated oxidative stress were divided into two groups including model group and CR1 treatment (1 μg/ml) group. Model group and CR1 treatment group were treated with 1 μl phosphate buffer solution (PBS) or CR1 for 4 hours. Normal hRPE monolayer barrier were used as control in transepithelial resistance (TER) measurement experiment. TER was measured to evaluate the barrier function of hRPE. The hRPE-secreted vascular endothelial growth factor (VEGF) and chemokine (C-C Motif) Ligand 2 (CCL2), together with complement bioactive fragments (C3a, C5a) and membrane-attack complex (MAC) in the supernatant were detected by enzyme-linked immune sorbent assay. ResultsStable hRPE monolayer barrier was established 3 weeks after hRPE seeded on Transwell insert. Complement-activated oxidative stress resulted in a sharp decrease of TER to 54.51% compared with normal hRPE barrier. CR1 treatment could significantly improve TER of barrier under complement-activated oxidative stress to 63.48% compared with normal hRPE barrier(t=21.60, P < 0.05). Compared with model group, CR1 treatment could significantly decrease the concentration of VEGF and CCL2 by 11.48% and 23.47% secreted by hRPE under complement-activated oxidative stress (t=3.26, 2.43; P < 0.05). Compared with model group, CR1 treatment could also decreased the concentration of C3a, C5a and MAC by 24.00%, 27.87%, 22.44%.The difference were statistically significant (t=9.86, 2.63, 6.94; P < 0.05). ConclusionsCR1 could protect the barrier function of hRPE cells against complement-activated oxidative stress. The underlying mechanism may involve inhibiting complement activation and down-regulating the expression of VEGF and CCL2.
Retinitis pigmentosa (RP) is a genetic disorder of photoreceptor cell apoptosis and retinal pigment epithelium (RPE) cell atrophy caused by gene mutation. The clinical manifestations are night blindness, peripheral visual field loss and progressive vision loss. RPE cell apoptosis plays an important role in the progression of RP, and exogenous implantation of RPE cells as an alternative therapy has shown certain efficacy in animal experiments and clinical trials. With the diversification of cell sources, the update of surgical techniques and the continuous emergence of biological materials, more possibilities and hopes are provided for cell therapy. To further promote the development of this field in the future, it is still necessary to strengthen the cooperation between medicine, bioengineering and other disciplines in the future to jointly promote the innovation and development of therapeutic methods. It is believed that RPE cell transplantation therapy will show a brighter prospect in the future
ObjectiveTo investigate the role of sonic hedgehog (Shh) signal transduction pathway in the expression of vascular endothelial growth factor (VEGF) under hypoxia in cultured human retinal pigment epithelial (hRPE) cells. MethodsARPE-19 were cultured and divided into normal ARPE-19 (Cont) and hypoxia group (100 μmol/L CoCl2 Cobalt Chloride +ARPE-19); hypoxia group was further divided into CoCl2 group, cyclopamine group (CYA) and dimethyl sulfoxide (DMSO) group. 20μmol/L cyclopamine was added to the CYA group 1 hour before hypoxia, 1‰DMSO was added into DMSO group at the same time. The hRPE cells were cultured under hypoxia for 4, 8, 12, 24 hours. The expression of Shh and VEGF were determined by Real-time fluorescent quantitate PCR (RT-PCR). The amount of VEGF in the hRPE-conditioned supernatant was measured using enzyme linked immunosorbent assay (ELISA) at 4, 8, 12, 24 hours, respectively. ResultsRT-PCR tests showed that the level of Shh and VEGF of hRPE was time dependently increased (Shh: F=45.260, P=0.001; VEGF: F=264.938, P=0.001). The level of Shh and VEGF of hRPE in the group treated with cyclopamine was decreased (P < 0.01). ELISA tests showed that the amount of VEGF in hRPE supernatant was significantly increased in time-dependent manner (F=3 156.676, P=0.001), and it was down-regulated by cyclopamine under hypoxia (P < 0.01). ConclusionShh signal transduction pathway could play a role in the VEGF expression induced by hypoxia in hRPE cells.
ObjectiveTo study how CD73 is shed from the retinal pigment epithelium (RPE) surface.MethodsCD73 shedding was induced by treating RPE with lipopolysaccharides (LPS) and TNF-α. After Phospholipase C (PLC) or pan matrix metalloproteinase (MMP) inhibitors were added, surface amount of CD73 was evaluated by flow cytometry (FACS). Then selective inhibitors or their corresponding siRNAs of MMP-2 and MMP-9 were applied to the treatments of RPE; and their effects on induced CD73 shedding were evaluated by FACS. By site directed mutagenesis, mutations were introduced to Lys547-Phe548 coding sites of CD73 cDNA, which was cloned in a pcDNA mammalian expression vector. Both wt-CD73 and mutated-CD73 were over expressed in CD73-/- RPE and their induced shedding was compared.ResultsLPS and TNF-α induced CD73 shedding from RPE was completely blocked by the addition of pan MMP inhibitor but not PLC inhibitor. Selective MPP-9, but not MMP-2, inhibitor or its siRNA blocked CD73 shedding. In CD73-/- RPE induced CD73 shedding was happened to overexpressed wt-CD73 but not Lys547-Phe548 sites mutant CD73.ConclusionMMP-9 is responsible for shedding CD73 from RPE through hydrolyzing its Lys547 -Phe548 sites.
ObjectiveTo observe the changes of eotaxin-1(CCL11), eotaxin-2(CCL24)and eotaxin-3(CCL26)in ranibizumab treated light-injured human retinal pigment epithelium (RPE) cells ARPE-19 and investigate the effects of vascular endothelial growth factor (VEGF) antagonist to the expressions of eotaxins. MethodsCultured human RPE cells(8th-12th generations)were divided into light-injured group, ranibizumab treated group and normal control group. Cells of the three groups were exposed to the blue light at the intensity of(600±100) Lux for 12 h to establish the light injured model, while cell culture dishes of the normal control group were wrapped with double-layer foil. The cells of ranibizumab treated group were treated with VEGF-A antagonist(ranibizumab)at the final concentration of 0.125 mg/ml for 24 hours directly after the illumination. The mRNA and protein of VEGF-A, eotaxin-1, eotaxin-2, eotaxin-3, NF-κB were determined by Real time-PCR, enzyme-linked immunosorbent assay, Western blot, immunohistochemical staining at 0, 3, 6, 12, 24 hours after light damage. ResultsThe mRNA and protein level of VEGF-A, eotaxin-1, eotaxin-2, eotaxin-3, NF-κB in the light-injuried group increased significantly compared to that in normal control group (P < 0.05). After treating with ranibizumab, the expression of eotaxin-1, eotaxin-2, eotaxin-3, NF-κB were significantly suppressed (P < 0.05). ConclusionThe suppression of over-expression of VEGF in human RPE may down-regulate the expression of eotaxins, via the suppression of NF-κB.
Objective To observe the effect of bone forming protein 4 (BMP4) on the proliferation and migration of human retinal pigment epithelium (RPE) cells under oxidative stress, and to preliminarily explore its effect on epithelial-mesenchymal transition (EMT) of RPE cells. MethodsHuman RPE cells cultured in vitro were divided into normal group, pure 4-hydroxynonenal (HNE) group (4-HNE group), 4-HNE+NC group and 4-HNE+ small interfering BMP (siBMP4) group. The effect of 4-HNE on the proliferation of RPE cells was detected by thiazole blue colorimetry. The effects of 4-HNE and BMP4 on cell migration were determined by cell scratch test. The expression of BMP4 was detected by immunofluorescence staining, Western blot and real-time quantitative polymerase chain reaction. The transfection efficiency of siBMP4 was observed by fluorescence microscopy. Mitochondrial reactive oxygen species (MitoSOX) were detected by flow cytometry. The expression of EMT markers E-cadherin and Fibronection were detected by immunofluorescence assay. t-test was used for comparison between the two groups, and one-way analysis of variance was used for comparison between the three groups. ResultsCompared with normal group, cell proliferation and migration ability of 4-HNE group were significantly enhanced, with statistical significance (t=21.619, 24.469; P＜0.05). The expression of BMP4 in cells was significantly increased, and the difference was statistically significant (t=19.441, P＜0.05). The relative expression levels of BMP4 mRNA and protein were also significantly increased, with statistical significance (t=26.163, 37.163; P＜0.05). After transfection with siBMP4 for 24 h, the transfection efficiency of BMP4 in RPE cells was＞90%. Compared with 4-HNE group and 4-HNE+NC group, the relative expression levels of BMP4 protein (F=27.241), mRNA (F=36.943), cell mobility (F=46.723) and MitoSOX expression levels (F=39.721) in normal group and 4-HNE+siBMP4 group were significantly decreased. The differences were statistically significant (P＜0.05). The epithelial marker E-cadherin increased significantly, while the mesenchymal marker Fibronection decreased significantly, with statistical significance (F= 51.722, 45.153; P＜0.05). ConclusionsBMP4 inhibits RPE proliferation and migration under oxidative stress. BMP4 is involved in inducing EMT in RPE cells.
ObjectiveTo study the role of Rac1 in the epithelial-mesenchymal transition (EMT) process of retinal pigment epithelial cells (RPE) induced by transforming growth factorβ(TGF-β). MethodsHuman ARPE-19 cells were divided into 4 groups including control group, TGF-βgroup, TGF-β+NSC23766 group, NSC23766 group. NSC23766 was added to medium 2 hours before TGF-βtreatment to block the Rac1 receptors.α-smooth muscle actin (α-SMA) expression was measured by immunofluorescence and Western blot. Cell scratch assay, invasion assay and gel contraction experiments were used to measure cell migration, invasion, cell contraction. ResultsThe expression ofα-SM A was higher in TGF-βgroup, compared with the control group, TGF-β+NSC23766 group (F=825.314, P < 0.05). Cell scratch assay showed that the cellular gap was less in GF-βgroup, compared with the control group, TGF-β+NSC23766 group, NSC23766 group (F=177.351, P < 0.05). Cell invasion assay showed that, the number of cells pass through the fiber membrane was the same in TGF-βgroup and other 3 groups (F=0.371, P=0.055). Gel contraction assay showed that TGF-βcan promote the cellular contraction, compare to the control group, TGF-β+NSC23766 group, NSC23766 group, the difference was statistically significant (F=40.473, P < 0.05). ConclusionRac1 play a role in TGF-β-induced behavioral changes of RPE cells; NSC23766 inhibit RPE cellular behavior change by regulating Rac1 activation.
ObjectiveTo observe the effect of exosomes derived from human umbilical cord blood mesenchymal stem cells (hUCMSC) on the expression of vascular endothelial growth factor (VEGF) A in blue light injured human retinal pigment epithelial (RPE) cells. MethodshUCMSC were cultured with exo-free fetal bovine serum for 48 hours, and then the supernatants were collected to isolate and purify exosomes by gradient ultracentrifugation method. Transmission electron microscopy was used to identify the morphology of exosomes. Surface specific maker protein CD63 and CD90 were detected via Western blot. Cultured ARPE-19 cells were divided into normal control group, blue light injured group and hUCMSC exosomes treated group. Cells were exposed to the blue light at the intensity of (2000±500) Lux for 12 hours to establish the light injured models. The cells of hUCMSC exosomes treated group were treated by different concentrations of exosomes for 8, 16, 24 hours. The mRNA and protein of VEGF-A were determined by real time-polymerase chain reaction and Western blot. Immunofluorescence assay were used to detect the expression levels of VEGF-A. ResultshUCMSC exosomes were successfully isolated, they exhibited round or oval shape and their diameter ranged from 50 to 100 nm with membrane structure through electron microscope. hUCMSC exosomes expressed the common surface marker protein CD63 and the surface marker protein CD90 of hUCMSC. The protein and mRNA level of VEGF A in the blue light injured group increased significantly compared to that in normal control group (t=-16.553, -19.456; P < 0.05). After treating with low, middle and high concentration of hUCMSC exosomes for 8, 16 and 24 hours, the protein and mRNA level of VEGF A of injured RPE were significantly decreased (P < 0.05). With the treated time and concentration of hUCMSC exosomes improved, the protein and mRNA level of VEGF A of injured RPE gradually decreased (P < 0.05). Immunofluorescence assay showed the protein level of VEGF-A of injured RPE gradually decreased with the same concentration of hUCMSC exosomes treated over time. ConclusionhUCMSC exosomes can effectively down-regulate the mRNA and protein level of VEGF-A in blue light injured RPE, the effect depends on the concentration and treated time of hUCMSC exosomes.