Synthesized TGF-beta s in RPE regulates cellular proliferation

Retinal pigment epithelial (RPE) cells transdifferentiate in culture, a transition which is accompanied by a shift in biological activity. The present study investigates whether transforming growth factor (TGF)-beta has the same effects on morphologically transformed RPE cells that it has on primary RPE cells. It also evaluates the autocrine and paracrine activities of TGF-beta s synthesized by RPE cells as well as the anti-TGF-beta effect of mannose-6-phosphate (M-6-P). RPE cells were subcultured at the sixth passage to induce morphological change. The effect of second passaged RPE-conditioned medium (CM) on DNA synthesis was evaluated by the incorporation of 3H-thymidine in rabbit subconjunctival fibroblasts (SCFs) and primary RPE cells. The presence of TGF-beta in RPE-CM was determined using immunoblotting analysis. And the inhibitory effect of M-6-P on cell proliferation mediated by RPE-CM was also analyzed using 3H-thymidine incorporation into DNA. TGF-beta 1, TGF-beta 2, and TGF-beta 3 inhibited the proliferation of the primary cultures of RPE cells in a dose-dependent manner, but the spindle-shaped sixth passaged RPE cells were not inhibited by these growth factors. The medium conditioned by RPE cells stimulated the proliferation of SCFs and inhibited the proliferation of primary RPE cells, in a manner similar to TGF-beta. When this medium was precipitated with either anti-TGF-beta 1, anti-TGF-beta 2, or anti-TGF-beta 3 antibodies, all three TGF-beta s, with an apparent molecular size of 25 kDa, were detected. Mannose-6-phosphate significantly blocked the effect of RPE-CM on cell proliferation. These findings indicate that RPE cells produce biologically functional TGF-beta s and that M-6-P can block the inhibitory effect of RPE-CM on cell proliferation.     

Characterization of the effects of retinal pigment epithelium-conditioned media on porcine and aged human retina

Background

Retinal pigment epithelium (RPE) cells produce neurotrophic factors that rescue photoreceptors from degeneration. Previously, we showed that conditioned medium (CM) from fetal vs adult RPE cells resulted in significantly better porcine retinal preservation, and possessed significantly higher levels of hepatocyte growth factor (HGF) and pigment epithelium-derived factor (PEDF). This study aimed to further describe the effects of human fetal RPE-CM on porcine and aged human retina, and to characterize its effects biochemically.

Methods

RPE-CM was harvested from passage-2 fetal RPE, 7 days after passage, 24-hours after exposure to basal medium. After culture in RPE-CM, porcine retinal morphology was assessed with confocal microscopy. The effects of RPE-CM on porcine and aged human retina survival were assessed by cytotoxicity and apoptosis biochemical assays. To characterize RPE-CM biochemically, effects of heating, digesting with proteinase-K, dilution, concentration, and fractionation were tested. Recombinant proteins and neutralizing antibodies were used to identify proteins that might contribute to the salutary effects of RPE-CM on porcine retina.

Results

Culturing porcine retina in RPE-CM significantly preserved outer nuclear layer width and the number of nuclei in cross-section, and significantly decreased photoreceptor axon retraction. RPE-CM decreased porcine retinal death by 17–34 % (p?<?0.05) compared to basal medium. Human retina from age-related macular degeneration (AMD) and non-AMD donors responded similarly after culture in RPE-CM. Heating, proteinase-K digestion, and dilution significantly diminished RPE-CM-mediated preservation of porcine retina, whereas concentrating RPE-CM significantly enhanced its preservation of porcine retina. Molecular cut filtration identified retina-preserving activity in the 3–100 kDa filtrate. PEDF or HGF at 90 % receptor occupancy significantly improved retinal preservation over 48 h of culture compared to basal medium. Neutralizing PEDF in RPE-CM decreased its ability to reduce retinal apoptosis by 23–27 % (p?<?0.05).

Conclusion

RPE-CM reduced biochemically and histologically measured degeneration in porcine retinae. This effect was concentration-dependent, and can be attributed to a protein component(s) in a 3–100 kDa molecular cut fraction. Human retina (including non-AMD and AMD Caucasian and non-AMD African-American) responds to culture in RPE-CM similarly to porcine retina. Receptor occupancy calculations and retinal viability data indicate that PEDF may be one of the components that contribute to retina preservation by RPE-CM.     

RPE conditioned medium stimulates photoreceptor cell survival, neurite outgrowth and differentiation in vitro.

In the present study we have investigated retinal pigment epithelium-photoreceptor cell interactions in vitro, and their contributions to photoreceptor cell survival and differentiation. Preparations enriched for intact photoreceptor cells from neonatal rat retina were grown in either serum-free medium supplemented with RPE-conditioned medium (RPE-CM) or in serum-free medium alone. A variety of substrate conditions were tested for the best neurite outgrowth. Cultures were monitored for 7 days by light and electron microscopy, as well as by opsin, vimentin and carbonic anhydrase-C immunocytochemistry. RPE-CM was found to stimulate both proliferation of flat cells and photoreceptor differentiation. The number of photoreceptors bearing neurites and their neurite length measurements showed significant differences between the RPE-CM group and the control group within 20 hr in culture. Elimination of contaminating flat cells by the addition of an antimitotic drug prevented photoreceptor cell morphological maturation; however, these cells survived as round cell bodies without processes for at least 10 days in the presence of RPE-CM and expressed opsin during this period. Conditioned medium from the flat-cell monolayers did not support photoreceptor differentiation or their survival. However, the presence of flat cells was a requisite to achieve any neurite outgrowth even in the presence of RPE-CM. In the absence of RPE-CM, neither photoreceptors nor flat cells survived or proliferated. Heat and trypsin treatment of the RPE-CM abolished all its growth-supporting activities which indicates its proteinaceous nature. This represents the first time in vitro that an RPE-derived factor(s) has been shown to be responsible for photoreceptor cell survival and differentiation.     

富血小板血浆促猫角膜内皮细胞增殖的研究

目的 观察富血小板血浆对体外培养猫角膜内皮细胞增殖的影响.方法 采用揭膜法与消化法相结合获取猫角膜原代内皮细胞,培养基采用DMEM培养基(含体积分数10％胎牛血清).采用二次离心法提取富血小板血浆.在完全培养基中加入体积分数分别为5％、10％、20％的富血小板血浆培养角膜内皮细胞,以未加入富血小板血浆的完全培养基为对照.CCK-8试剂盒检测细胞增殖情况,扫描电镜观察细胞形态变化.结果 富血小板血浆体外培养角膜内皮细胞时间越长,其促增殖作用越明显,与对照组比较差异均有显著统计学意义意义(均为P ＜0.01),且随着富血小板血浆含量的增加,角膜内皮细胞增殖越明显,呈剂量依赖性.扫描电镜检测表明,与对照组相比,PRP作用组角膜内皮细胞表面可见丰富的微绒毛,且随着富血小板血浆含量的增加,微绒毛越丰富.结论 富血小板血浆能明显促进体外培养猫角膜内皮细胞增殖.     

Proliferation of CECs requires dual signaling through both MAPK/ERK and PI 3-K/Akt pathways

PURPOSE: To analyze the intracellular signaling involved in the proliferation of choroidal endothelial cells (CECs) in vitro. METHODS: Bovine CECs were cultured in endothelial growth medium (EGM) containing 2% fetal calf serum (FCS), 10 microg/ml bovine brain extract (BBE), and 10 ng/ml epidermal growth factor (EGF) in fibronectin-coated plates. Cells were treated with various specific pharmacologic inhibitors of the mitogen-activated protein kinase (MAPK) and of the phosphatidylinositol 3-kinase (PI 3-K) pathways to analyze signaling involved in CEC proliferation. Activation of the MAPK and PI 3-K was detected by Western blot analysis, using specific antiphosphosignaling protein antibodies. RESULTS: FCS, EGF, and BBE were all necessary to induce optimal CEC proliferation. Individually, these three components were not mitogenic. EGM-stimulated CEC proliferation involved the activation of the Raf/mitogen extracellular signal-regulated kinase (MEK)/extracellular signal-regulated kinase (ERK)/p90(RSK) cascade. Inhibition of Ras resulted in a 92% reduction of CEC proliferation, whereas inhibition of ERK1/2 activity reduced it by only 46%. The PI 3-K/p70(S6K)/Akt pathway was also stimulated during CEC proliferation, and inhibition of PI 3-K activity resulted in a 94% reduction in CEC proliferation. Inhibition of PI 3-K/p70(S6K) activities also unexpectedly inhibited ERK activity, whereas the converse was not observed, suggesting that PI 3-K acted upstream from ERK and controlled this pathway for CEC proliferation. CONCLUSIONS: CEC proliferation involves both ERK and PI 3-K. That PI 3-K signaling is a key component in cell proliferation can be demonstrated by controlling ERK activity. These data on the molecular mechanism and signaling of CEC proliferation may have major implications for developing more selective methods for antiangiogenic and antitumoral therapy.     

Maxadilan 对兔角膜上皮细胞的促增殖作用

目的探讨垂体腺苷酸环化酶激活肽(pituitary adenylate cyclase activating polypeptide,PACAP)的PAC1受体特异激动剂Maxadilan对角膜上皮细胞的促增殖作用。方法分离新西兰大白兔角膜上皮细胞,并在含体积分数10%胎牛血清的DMEM培养基中培养。利用逆转录聚合酶链反应(RT-PCR)检测兔角膜上皮细胞PACAP的PAC1受体;细胞增殖实验采用CCK-8法检测,角膜上皮细胞培养基中分别加入0.01μmol.L-1、0.03μmol.L-1、0.05μmol.L-1、0.10μmol.L-1、0.15μmol.L-1Maxadilan作为实验组,未加入Maxadilan作为对照组,检测不同浓度的Maxadilan对角膜上皮细胞增殖的影响;流式细胞仪分析0.10μmol.L-1Maxadilan对细胞周期的影响。结果 RT-PCR检测显示兔角膜上皮细胞含有PACAP的PAC1受体;CCK-8法检测显示0.05μmol.L-1、0.10μmol.L-1、0.15μmol.L-1Maxadilan实验组分别比对照组细胞增多29.1%、41.5%、32.5%,与对照组相比差异有统计学意义(P分别为0.001、0.000、0.000);流式细胞仪分析显示0.10欁μmol.L-1Maxadilan组细胞增殖指数平均值为35.98%,与对照组细胞细胞增殖指数平均值29.48%相比,差异有统计学意义(P=0.014)。结论角膜上皮细胞存在PACAP的PAC1受体,Maxadilan对角膜上皮细胞有促增殖作用。     

全反视黄酸对豚鼠视网膜色素上皮细胞分泌TGF-β2及细胞内第二信使IP3和cAMP的影响

目的 观察全反视黄酸(ATRA)对培养的豚鼠视网膜色素上皮(RPE)细胞增殖以及分泌转化生长因子β2(TGF-β2)的影响,并观察细胞内第二信使cAMP和IP3的含量变化.方法 培养原代豚鼠RPE细胞,传2代后用于实验.实验分3组进行.第1组用不同浓度ATRA(5×10-6、10×10-6、40×10-6 mol/L)作用于豚鼠RPE细胞,24 h后用MTY法检测细胞增殖情况.第2组加入10×10-6 mol/L的ATRA.分别于2、4、6、8、16 h后收集培养液,用ELISA方法检测RPE细胞TGF-β2的分泌量.第3组以10×10-6 mol/L的ATRA作用于豚鼠RPE细胞,分别于0 min、5 min、30 min、2 h,6 h后收集细胞裂解液,行放射免疫和ELISA方法检测细胞内cAMP和IP3的含量变化.每组均以等量溶剂DMSO作为对照.对不同浓度ATRA组间MTT结果行方差分析,其余实验组与对照组间比较行配对t检验.结果 5×10-6、10×10-6、40×10-6 mol/L ATRA作用RPE细胞24 h后,OD值分别为0.099±0.008、0.117±0.008、0.0871±0.011.与对照组(0.103±0.017)比较,40×10-6 mol/L ATRA作用时OD值显著降低,差异有统计学意义(P<0.05),其他浓度组与对照组相比差异无统计学意义(P>0.05).10×10-6 mol/L的ATRA作用RPE细胞后,TGF-β2的分泌量在作用2、4、6 h时较对照组明显升高,差异均有统计学意义(P<0.05).8 h时无明显变化,16 h时降低(P<0.05).10×10-6 mol/L的ATRA作用于豚鼠RPE细胞后,IP3的含量在各时间点均较对照显著下降,且随时间的延长下降越明显;cAMP的含量只有在作用30 min和2 h时升高,其他时同变化不明显.结论 浓度为40×10-6 mol/L的ATRA对豚鼠RPE细胞的增殖有抑制作用.10×10-6 mol/L的ATRA作用RPE细胞后,TGF-β2的分泌量在6 h内增加,之后随时间延长而降低.ATRA对RPE细胞的作用可能与IP3的下降有关.     

茶碱对培养的牛眼小梁细胞骨架及细胞间黏附的影响

目的 观察茶碱对培养的牛眼小梁细胞的增殖、细胞骨架、细胞间黏附的影响，探讨其降眼压机制。方法 组织块法培养牛眼小梁细胞。不同浓度的茶碱(1、10、50mmol／L)分别作用4h、8h，免疫细胞化学法观察小梁细胞微丝及微管的改变，MTT法观察小梁细胞的增殖。ELISA法检测不同浓度的茶碱作用4h后连接素(β-catenin)的相对表达量。结果 茶碱作用8h抑制细胞增殖。茶碱明显改变细胞形态、微管及微丝染色浓集，变化程度与药物浓度及作用时间有关。茶碱降低连接素的表达量。结论 茶碱抑制小梁细胞增殖，改变细胞骨架，降低细胞间黏附，提示茶碱可能通过影响细胞骨架及细胞间黏附减少房水流出阻力从而降低眼压。     

全反视黄酸对豚鼠视网膜色素上皮细胞分2泌TGF-β2及细胞内第二信使IP3和cAMP的影响

目的观察全反视黄酸（ATRA）对培养的豚鼠视网膜色素上皮（RPE）细胞增殖以及分泌转化生长因子p2（TGF—β2）的影响，并观察细胞内第二信使cAMP和IP3的含量变化。方法培养原代豚鼠RPE细胞，传2代后用于实验。实验分3组进行。第1组用不同浓度ATRA（5×10^-6、10×10^6、40×10^-6mol／L）作用于豚鼠RPE细胞，24h后用MTT法检测细胞增殖情况。第2组加入10×10^-6mol／L的ATRA．分别于2、4、6、8、16h后收集培养液，用ELISA方法检测RPE细胞TGF—β2的分泌量。第3组以10×10^-6mol／L的ATRA作用于豚鼠RPE细胞．分别于0min、5min、30min、2h、6h后收集细胞裂解液。行放射免疫和ELISA方法检测细胞内cAMP和IP3的含量变化。每组均以等量溶剂DMSO作为对照。对不同浓度ATRA组间MTT结果行方差分析，其余实验组与对照组间比较行配对t检验。结果5×10^-6、10×100、40×100mol／LATRA作用RPE细胞24h后，DD值分别为0．099±0．008、0．117±0．008、0．087±0．011。与对照组（0．103±0．017）比较，40×10^-6mol／LATRA作用时OD值显著降低，差异有统计学意2（P〈0．05），其他浓度组与对照组相比差异无统计学意义（p〉0．05）。10×10^-6／mol／L的ATRA作用RPE细胞后，TGF—β2的分泌量在作用2、4、6h时较对照组明显升高，差异均有统计学意义（P〈0．05）．8h时无明显变化，16h时降低（P〈O．05）。10×10^-4mol／L的ATRA作用于豚鼠RPE细胞后，IP3的含量在各时间点均较对照组显著下降，且随时间的延长下降越明显；cAMP的含量只有在作用30min和2h时升高．其他时间变化不明显。结论浓度为40×10^-6mol／L的ATRA对豚鼠RPE细胞的增殖有抑制作用。10×10^-6mol／L的ATRA作用RPE细胞后．TGF-β2的分泌量在6h内增加，之后随时间延长而降低。ATRA对RPE细胞的作用可能与IP3的下降有关。     

Retinal pigment epithelial cells produce a latent fibrinolytic inhibitor that is antigenically and biochemically related to type 1 plasminogen activator inhibitor produced by vascular endothelial cells

Conditioned media from retinal pigment epithelial (RPE) cells in culture contain active and latent plasminogen activator inhibitors (PAIs). Latent activity is unmasked by denaturants and accounts for the vast majority of total inhibitor activity. Activation by denaturants is an unusual characteristic previously described for PAI-1, the inhibitor produced by vascular endothelial cells. This property is not shared by PAI-2 or protease nexin. Reverse fibrin autography demonstrates that the PAI activity in RPE-conditioned media (RPE-CM) comigrates with purified endothelial cell-derived PAI-1 and has an apparent Mr of 50,000. Immunoblotting with a monospecific antiserum directed against endothelial cell-derived PAI-1 demonstrates a cross-reacting protein in RPE-CM at 50 kDa, and this same antiserum is able to immunoprecipitate a 50 kDa protein from [35S]methionine-labeled RPE-CM. These data suggest that RPE cells produce a PAI that is biochemically and immunologically related to PAI-1.     

全反视黄酸对豚鼠视网膜色素上皮细胞分泌TGF-β2及细胞内第二信使IP3和cAMP的影响

目的 观察全反视黄酸(ATRA)对培养的豚鼠视网膜色素上皮(RPE)细胞增殖以及分泌转化生长因子β2(TGF-β2)的影响,并观察细胞内第二信使cAMP和IP3的含量变化.方法 培养原代豚鼠RPE细胞,传2代后用于实验.实验分3组进行.第1组用不同浓度ATRA(5×10-6、10×10-6、40×10-6 mol/L)作用于豚鼠RPE细胞,24 h后用MTY法检测细胞增殖情况.第2组加入10×10-6 mol/L的ATRA.分别于2、4、6、8、16 h后收集培养液,用ELISA方法检测RPE细胞TGF-β2的分泌量.第3组以10×10-6 mol/L的ATRA作用于豚鼠RPE细胞,分别于0 min、5 min、30 min、2 h,6 h后收集细胞裂解液,行放射免疫和ELISA方法检测细胞内cAMP和IP3的含量变化.每组均以等量溶剂DMSO作为对照.对不同浓度ATRA组间MTT结果行方差分析,其余实验组与对照组间比较行配对t检验.结果 5×10-6、10×10-6、40×10-6 mol/L ATRA作用RPE细胞24 h后,OD值分别为0.099±0.008、0.117±0.008、0.0871±0.011.与对照组(0.103±0.017)比较,40×10-6 mol/L ATRA作用时OD值显著降低,差异有统计学意义(P<0.05),其他浓度组与对照组相比差异无统计学意义(P>0.05).10×10-6 mol/L的ATRA作用RPE细胞后,TGF-β2的分泌量在作用2、4、6 h时较对照组明显升高,差异均有统计学意义(P<0.05).8 h时无明显变化,16 h时降低(P<0.05).10×10-6 mol/L的ATRA作用于豚鼠RPE细胞后,IP3的含量在各时间点均较对照显著下降,且随时间的延长下降越明显;cAMP的含量只有在作用30 min和2 h时升高,其他时同变化不明显.结论 浓度为40×10-6 mol/L的ATRA对豚鼠RPE细胞的增殖有抑制作用.10×10-6 mol/L的ATRA作用RPE细胞后,TGF-β2的分泌量在6 h内增加,之后随时间延长而降低.ATRA对RPE细胞的作用可能与IP3的下降有关.     

Retinal pigment epithelial cells produce PDGF-like proteins and secrete them into their media

Human retinal pigment epithelial cells at confluence were used to condition serum-free Dulbecco's modified Eagle's medium. Conditioned media were exhaustively dialyzed against 0.5 N acetic acid, lyophilized, and subjected to Western blot analysis, using as primary antibody an IgG fraction prepared from goat antiserum directed against human platelet-derived growth factor. Native platelet-derived growth factor was resolved as a band with Mr of 30 kDa under non-reducing conditions, while bands with Mr of 36-38 kDa and 18.5 kDa were resolved from retinal pigment epithelial cell-conditioned media. Acid extracts of retinal pigment epithelial cells also contained bands at 36-38 kDa and media conditioned for 48 hr exhibited much denser bands than media conditioned for 24 hr. No bands were detected when non-immune goat IgG fractions were substituted for primary antibody and when conditioned media were prepared from several human fibroblast lines in the same manner as those prepared from retinal pigment epithelial cells, no detectable bands or only a faint shadow at 36 kDa were seen. Retinal pigment epithelial cell-conditioned media prepared in the presence of [35S]methionine were loaded on an anti-platelet-derived growth factor IgG affinity column, eluted, and subjected to SDS-polyacrylamide gel electrophoresis. Bands with Mr slightly less than 36 kDa and 18 kDa were visualized by autoradiography, demonstrating that the platelet-derived growth factor-like proteins in retinal pigment epithelial cell-conditioned media are newly synthesized. Two fractions eluted from the column also markedly stimulated fibroblast chemotaxis and incorporation of [3H]thymidine, both of which were neutralized by soluble anti-platelet-derived growth factor IgG. These data suggest that retinal pigment epithelial cells in culture produce platelet-derived growth factor-like proteins and secrete them into their media where they are capable of stimulating fibroblast chemotaxis and proliferation.     

TGF beta secretion modulates the density-dependent growth of pig retinal pigment epithelium in vitro

BACKGROUND: We aimed to identify the cytokine(s) responsible for the density-dependent growth regulation of pig retinal pigment epithelium (RPE) in vitro. METHODS: Confluent monolayers of primary pig RPE were established on bovine corneal endothelial extracellular matrix-coated tissue culture well inserts wrapped with dialysis membranes with different molecular weight cutoffs (0.5-50 kDa). These confluent RPE monolayers were then cocultured with first passage porcine RPE plated at a density of 1 cell/mm2, so that the newly plated RPE was bathed with different molecular weight fractions of the confluent cell media. Growth rates of the newly plated RPE were determined 72 h after plating and the molecular weight fraction of the confluent cell medium that inhibits the RPE proliferation was determined. First passage pig RPE (1 cell/mm2) were cocultured with confluent monolayers of primary pig RPE on inserts in the presence of different amounts of TGF-beta neutralizing antibody (0.1-100 microg/ml). Growth rates of the newly plated RPE were calculated 72 h after plating to determine the antibody concentration that would maximize the growth rate of the newly plated RPE in the presence of an adjacent confluent RPE monolayer. RESULTS: The growth rate of the newly plated RPE decreased when RPE were bathed with the 10- to 25-kDa fractions of medium from an adjacent confluent RPE monolayer. This growth inhibition reached statistical significance with the 25- to 50-kDa fractions (p < 0.05), and was abolished by adding pan-specific neutralizing antibody against TGF-beta (0.1-5 microg/ml). Blocking greater amounts of TGF-beta in the medium with higher doses of antibody (>10 microg/ml) also inhibited the growth of the newly plated RPE, in the presence or absence of a neighboring confluent cell layer. CONCLUSION: The TGF-beta family of cytokines mediates the density-dependent growth suppression of RPE in vitro. Neutralizing the effect of these cytokines by adding anti-TGF-beta antibodies can result in more rapid growth of the RPE in vivo.     

Carboxyamido-triazol (CAI) inhibiert Unterschritte der choroidalen Neovaskularisation an choroidalen Endothelzellen und retinalen Pigmentepithelzellen in vitro

BACKGROUND: Retinal pigment epithelial cells (RPE cells) and choroidal endothelial cells (CECs) are important cell types in the process of choroidal neovascularization in exudative age-related macular degeneration (AMD). In this study, we evaluated the antiproliferative and antimigratory abilities of carboxyamido-triazole (CAI), a drug modulating calcium-dependent signal transduction on RPE cells and CECs. METHODS: Human fetal RPE cells and bovine CECs were exposed to CAI in a concentration range of 0.1 to 10 microM. Cell proliferation was stimulated with 10% serum or 10 ng/ml bFGF. The effect of CAIs on cell proliferation was estimated. Furthermore, we evaluated CAI's effects on CEC and RPE cell migration induced by fibronectin. RESULTS: CAI had a stronger inhibitory effect on serum-induced CEC proliferation than on RPE cell proliferation. A much stronger effect was seen on the proliferation of bFGF-stimulated RPE cells and CECs. Furthermore, the fibronectin-stimulated migration of RPE cells and CECs was inhibited by CAI. In this assay, a stronger inhibitory effect was seen on RPE cells than on CECs. CONCLUSION; CAI inhibits important substeps of choroidal neovascularization on RPR cells and CECs. Therefore, CAI may be of value for the treatment of choroidal neovascularization in exudative AMD.     

Characterization of early retinal progenitor microenvironment: presence of activities selective for the differentiation of retinal ganglion cells and maintenance of progenitors

The maintenance and differentiation of retinal progenitors take place in the context of the microenvironment in which they reside at a given time during retinal histogenesis. To understand the nature of the microenvironment in the developing retina, we have examined the influence of activities present during the early stage of retinal histogenesis on enriched retinal progenitors, using the neurosphere model. Early and late retinal progenitors, enriched as neurospheres from embryonic day 14 (E14) and E18 rat retina, respectively, were cultured in embryonic day 3 (E3) chick retinal conditioned medium, simulating the microenvironment present during early retinal histogenesis. Examination of the differentiation and proliferation of retinal progenitors revealed that the early microenvironment contains at least three regulatory activities, which are partitioned in different size fractions of the conditioned medium with different heat sensitivity. First, it is characterized by activities, present in heat stable <30 kDa fraction, that promote the differentiation of retinal ganglion cells (RGCs), the early born neurons. Second, it contains activities, present in heat-sensitive >30 kDa fraction, that regulate the number of early born neurons and maintain the pool of retinal progenitors. Third, it possesses activities, present in heat-sensitive <30 kDa fraction, that prevent the premature differentiation of early retinal progenitors into the late born neurons. Thus, our observations demonstrate the regulatory influence of microenvironment on the maintenance and differentiation of retinal progenitors and establish neurospheres as a viable model system for the examination of such influences.     

Inhibitory effects of verapamil isomers on the proliferation of choroidal endothelial cells

Purpose To evaluate the effects of verapamil isomers on in vitro proliferation of bovine choroidal endothelial cells (CECs). Materials and methods CECs were isolated from bovine eyes and cultured in endothelial growth medium (EGM). For the proliferation assays, CECs were exposed to verapamil isomers (0.1–100 μM) in EGM with 2% fetal bovine serum or basic fibroblast growth factor (bFGF) (10 ng/ml). After 72 h of incubation with the desired drug, the cellular proliferation was determined by an MTT assay and a BrdU assay. In addition, the drug toxicity on CECs stimulated with EGM was evaluated by cell counting with trypan blue. Results All verapamil isomers inhibited the bFGF- or medium-stimulated growth significantly in a concentration range of 10–40 μM without toxicity. No significant differences were seen between the inhibitory effects of the various isomers. Cell toxicity was detected at a concentration of 100 μM verapamil isomers on EGM-stimulated CECs. Conclusion The results demonstrate the efficacy of all verapamil isomers in inhibiting CEC proliferation involved in the process of choroidal neovascularization. d-(+)-Verapamil may be recommended for further in vivo evaluation in an animal model of exudative AMD; it has fewer systemic and local side effects because calcium channels are not blocked.     

血管紧张素Ⅱ对体外培养的牛眼小梁细胞^3H胸腺核苷酸掺入率及胶原合成的影响

目的观测血管紧张素Ⅱ(AngiotensinⅡ,AngⅡ)对体外培养的牛眼小梁细胞(bovine trabecularmeshwork cells,TM cell)3H胸腺核苷酸(3H-thymidine,3H-TdR)掺入率及胶原合成的影响,探讨原发性青光眼的发病机制.方法(1)牛眼小梁细胞的体外培养应用免疫组化方法(neuronal specific enolas,NSE,Ⅷ因子相关抗原染色)、细胞鉴定、光学及电子透射显微镜对细胞进行形态学及生长特性的观察;(2)AngⅡ(1×10-7mol@L-1及1×10-8mol@L-1)以及其Ⅰ型受体(angiotensin receptor type I,AT1)拮抗剂孵育TM细胞,采用检测3H-TdR掺入率的方法了解细胞增殖状态,并用化学方法检测培养液中羟脯氨酸含量,间接推导胶原含量.结果牛眼小梁细胞培养成功,以上皮型为主.AngⅡ明显地增加了牛眼小梁细胞的3H-TdR摄入率,同时培养液中的羟脯氨酸含量亦相应增高.结论体外培养牛眼小梁细胞技术是研究小梁细胞特性的重要实验技术.AngⅡ可以诱导体外培养的牛眼小梁细胞的细胞增殖率升高,同时促使胶原合成增强.AT1受体拮抗剂可以部分阻断此促增殖效应.眼科学报2001;17209-212.     

胶质细胞培养液对视网膜色素上皮细胞生长的影响

目的 观察体外培养的视网膜色素上皮细胞条件培养液对视网膜神经胶质细胞生长的影响。方法 用不同稀释度的视网膜条件培养液培养视网膜神经胶质细胞，细胞计数法观察细胞数量的变化；MTT法测定对细胞增生活性（吸光度A值）的影响；流式细胞仪观察细胞周期的变化。结果 随着视网膜条件培养液浓度的增加，视网膜胶质细胞的数量明显增加，吸光度A值升高，进入S期的细胞明显增加，显示体外培养视网膜色素上皮细胞促进视网膜神经胶质细胞增生。结论 视网膜色素上皮细胞和视网膜神经胶质细胞细胞间的相互作用对于PVR等的产生和发展是非常重要的。     

Factors modulating the effect of retinoids on cultured retinal pigment epithelial cell proliferation.

The effect of several naturally-occurring retinoids and 13-cis-retinoic acid on the proliferation of cultured bovine retinal pigment epithelial (RPE) cells was investigated. None of the retinoids tested were toxic to the cultures and all, except retinylpalmitate, inhibited cell proliferation when given for more than 3 days. The relative potencies of the retinoids were; all-trans-retinoic acid greater than 13-cis-retinoic acid greater than all-trans-retinol approximately equal to all-trans-retinaldehyde. Uptake of retinoic acid by cultured RPE cells was 10-fold less than the uptake of retinol. Although retinoic acid-treated cultures showed strong density-dependent growth inhibition, cellular proliferation was inhibited more in sparse cultures than in dense ones. Retinoic acid did not significantly inhibit the proliferation of first passage bovine or rabbit RPE cells, but partially inhibited the proliferation of first passage human RPE cells. The sensitivity of all these cultures to growth inhibition by retinoic acid increased in subsequent subcultures, yet there was no effect of passage number on retinoic acid uptake. This study demonstrates that RPE cell proliferation can be inhibited by retinoic acid but the sensitivity of these cells to the retinoid's effects are modulated by incubation time, in vitro aging, and cell density.     

慢病毒载体介导TLR2基因干扰大鼠角膜上皮细胞和基质细胞的实验研究

目的　观察慢病毒载体（ｌｅｎｔｉｖｉｒａｌｖｅｃｔｏｒ,ＬＶ）介导ＴＬＲ２基因干扰大鼠角膜上皮细胞（ｃｏｒｎｅａｌｅｐｉｔｈｅｌｉａｌｃｅｌｌ,ＣＥＣ）和基质细胞（ｃｏｒｎｅａｌｓｔｒｏｍａｌｃｅｌｌ,ＣＳＣ）的有效性和安全性。方法　分别培养大鼠ＣＥＣ和ＣＳＣ,转染组用携带绿色荧光蛋白（ｅｎｈａｎｃｅｄｇｒｅｅｎｆｌｕｏｒｅｓｃｅｎｔｐｒｏｔｅｉｎ,ｅＧＦＰ）和ＴＬＲ２小干扰ＲＮＡ（ｓｍａｌｌｉｎｔｅｒｆｅｒｅｎｃｅＲＮＡ,ｓｉＲＮＡ）的ＬＶ转染,空白对照组加入空白培养液,阴性对照组加入不携带目的基因的ＬＶ。转染组按最佳感染复数（ｍｕｌｔｉｐｌｉｃｉｔｙｏｆｉｎｆｅｃｔｉｏｎ,ＭＯＩ）分别为１０、５０、１００、２００加入ＬＶ-ＴＬＲ２-ｓｉＲＮＡ-ｅＧＦＰ,选择ｅＧＦＰ表达最强的ＭＯＩ进行后续实验,观察细胞形态,ＣＣＫ８检测细胞增殖情况。流式细胞仪检测两种角膜细胞的转染效率,ＲＴ-ＰＣＲ检测转染后ＴＬＲ２ｍＲＮＡ的表达情况。结果　ＭＯＩ＝２００时转染ＣＥＣ和ＣＳＣ荧光表达最高,和空白对照组相比细胞形态未发生明显改变;ＣＣＫ８结果显示转染组与空白对照组、阴性对照组的ＩＯＤ值差异均无统计学意义（均为Ｐ＞０．０５）;流式细胞仪检测ＣＥＣ和ＣＳＣ转染效率分别为７７．６００％ ±１．１００％和７６．３００％ ±１．３８７％,和阴性对照组相比差异均有显著统计学意义（均为Ｐ＜０．００１）。ＲＴ-ＰＣＲ检测转染后ＣＥＣ和ＣＳＣＴＬＲ２ｍＲＮＡ相对表达量均较对照组明显下降,差异均有显著统计学意义（均为Ｐ＜０．００１）。结论　ＬＶ-ＴＬＲ２-ｓｉＲＮＡ-ｅＧＦＰ可在体外稳定有效转染ＣＥＣ和ＣＳＣ,且对细胞安全性无影响,可有效下调ＴＬＲ２ｍＲＮＡ的表达。