Efficiency and safety of genipin collagen crosslinking on rabbit cornea stroma model in vivo / 中华实验眼科杂志

Objective To evaluate the efficiency and safety of genipin collagen crosslinking (G-CXL) on rabbit corneas in vivo.Methods Forty healthy New Zealand white rabbits were randomly divided into 0.20％ G-CXL,0.25％ G-CXL,standard UVA-CXL and normal control group.And the right eyes were treated in different grouping.No procedures were performed in the normal control group.The corneal curvature (Km) and central corneal thickness (CCT) of right eyes were evaluated before,7 days and 14 days after crosslinking treatment.Cornea strips were harvested from the right eyes and tensile strain measurements were performed 7 days and 14 days after crosslinking treatment.The structure of corneal stroma was observed under light microscope (LM) and transmission electron microscope (TEM).Results No statistically significant differences in Km were observed among different groups or different timepoints (Fgroup =0.301,P=0.825;Ftime =1.287,P=0.284).Significant difference in CCTs was noticed among different time pionts (Ftime =3.786,P =0.029).Compared with preoperative,the CCTs of all the groups were significantly increased 7 days after crosslinking (all at P＜0.05).No significant difference in CCT was found among the groups (Fgroup =0.557,P=0.646).Seven days after crosslinking treatment,the Young's modulus at 10％ strain was (1 1.96±5.74),(21.24±6.77),(18.76±3.34) and (11.56±4.37) MPa in 0.20％ G-CXL group,0.25％ G-CXL group,UVA-CXL group and normal control group,respectively;the stress at 10％ strain was (0.68 ±0.24),(1.20 ± 0.25),(1.0l ± 0.30) and (0.69 ± 0.26) MPa,respectively;the Young's modulus and stress in 0.25％ G-CXL group was significantly increased when compared with those in 0.20％ G-CXL and normal control group (both at P＜0.05).No significant difference in Young's modulus and stress was observed between 0.25％ G-CXL group and UVA-CXL group (all at P＞0.05).Forteen days after crosslinking treatment,Young's modulus at 10％strain was (16.65±3.19),(19.12±2.39),(22.83 ±4.38) and (12.70±2.72)MPa in 0.20％ G-CXL group,0.25％ G-CXL group,UVA-CXL group and normal control group,respectively;stress at 10％ strain was (0.83 ±0.12),(0.97±0.04),(1.23±0.30) and (0.65±0.20) MPa,respectively;the Young's modulus and stress in UVA-CXL group was significantly increased,when compared with 0.20％ G-CXL group and normal control group (all at P＜0.05).Statistical significance of stress was observed between 0.25％ G-CXL group and UVA-CXL group (P =0.046).There is no significant difference in Young's modulus between 0.25％ G-CXL and UVA-CXL group (P =0.090).LM showed the reduction of keratocytes existed in superficial stroma of 0.20％ and 0.25 ％ G-CXL groups,while the reduction of keratocyte was found in anterior and intermediate stroma of UVA-CXL group.In 0.20％ and 0.25％ G-CXL groups,the ultrastructure of keratocytes was normal except vacuole in some keratocytes.Keratocytes apoptosis was noticed in UVA-CXL group and keratocytes was normal in deep stroma under TEM.Conclusions 0.25％ has a similar biomechanics effect when compared to UVA-CXL.Moreover,histological observation proves a better safety of G-CXL in comparison of UVA-CXL.

Research progress of stem cells in corneal wound healing / 中华实验眼科杂志

As the outermost part,cornea plays a critical role in protecting the eyeball and functions as main component of the dioptric media. Trauma,inflammation,malnutrition,inherited diseases,tumors,contact lens problems and complications of refractive surgeries may cause corneal injury. However,there are still no perfect treatments for severe corneal damage. Progresses have been made in the research field of corneal stem cells in recent years. Epithelial stem cells play an important role in corneal wound healing, whereas the contribution of stromal and endothelial stem cells is less studied. Moreover, corneal cells differentiated from alternative cell sources have a brilliant prospect in transplantation. This article reviewed the recent research progress of stem cells in the corneal epithelial,stromal and endothelial wound healing.

Effects of low-dose of TGF-β1 on maintaining bovine corneal stromal cell growth and retarding extra cellular matrix fibrosis in a three-dimensional culture model / 中华实验眼科杂志

Background Transforming growth factor-β1(TGF-β1) plays an important role in corneal woundhealing.The effects of TGF-β1 on the synthesis of extra cellular matrix (ECM) vary upon different concentrations.Previous studies focused on the effects of high concentration of TGF-β1 on keratocytes under the two-dimensional culture condition,and the effect of low concentration of TGF-β1 on the synthesis of ECM in keratocytes remains unclear.Objective This study was to investigate the growth of Pellet,a three-dimensional model of corneal stroma cells in vitro,and its ECM synthesis under a low concentration of TGF-β1.Methods Bovine corneal stromal cells were isolated from fresh bovine eyeballs by two-step digestion by collagenase and cultured using DMEM/F12 medium with 10％ fetal bovine serum (FBS).Pellets derived fresh bovine keratocytes with culture medium containing 0.25 ng/ml TGF-β1 +5％ FBS and 0.50 ng/ml TGF-β1 +5％ FBS were established,respectively.The morphology of Pellets was observed under the natural light at 48 hours,1 week,2 weeks and 3 weeks after culture.In 3 weeks after culture,the cell structures was observed by hematoxylin-eosin staining,and Calcein-AM/propidium (Calcein-AM/PI) staining was used to assay the cell viability.Real-time flurorescence quantitative PCR and immunofluorescence technology were applied to analyze the expressions of α-smooth muscle actin (α-SMA),fibronectin (FN),type Ⅰ collagen (Col Ⅰ) and type Ⅲ collagen (Col Ⅲ) mRNA and proteins.RT-PCR was employed to detect the expressions of lumican (LUM) mRNA and keratocan (KERA) mRNA in the cells.Results Cells in Pellet clustered throughout the culture duration.Hematoxylin-eosin staining showed the mass red-dyed collagen fibers in both 0.25 ng/ml TGF-β1 +5％ FBS group and 0.50 ng/ml TGF-β1 +5％ FBS group,and most cells possessed complete structures.The death rate of the cells was (33.60±1.65)％ in the 0.25 ng/ml TGF-β1 +5％ FBS group and (30.90±0.78) ％ in the 0.50 ng/ml TGF-β1 +5％ FBS group,showing an insignificant difference between them (t =0.144,P=0.887).The expressions of α-SMA,FN and Col Ⅲ proteins in 0.25 ng/ml TGF-β1 +5％ FBS group were lower than those in the 0.50 ng/ml TGF-β1 + 5 ％ FBS group (tα-SMA =4.622,P =0.010;tFN =2.973,P =0.040;tCol Ⅲ =7.845,P＜0.001),but the expression of Col Ⅰ in 0.25 ng/ml TGF-β1 +5％ FBS group was higher than that in 0.50 ng/ml TGF-β1+5％ FBS group (tColⅠ =4.022,P=0.016).The ratio of Col Ⅲ/Col Ⅰ in 0.25 ng/ml TGF-β1+5％ FBS group was lower than that in the 0.50 ng/ml TGF-β1 +5％ FBS group in both mRNA and protein level (tmRNA =-3.039,P =0.038;tprotein =3.215,P =0.032).The expression of LUM mRNA and KERA mRNA were detected in Pellet at different time points.The expression of LUM mRNA in 0.25 ng/ml TGF-β1 +5％ FBS group increased over time.While in 0.50 ng/ml TGF-β1 +5％ FBS group,the expression of LUM mRNA peaked at 1 week but declined at 2 weeks.The expression of KERA mRNA in two groups were all peaked at 1 week but declined at 2 weeks.Conclusions Low-dose TGF-β1 in Pellet can maintain the normal growth of keratocytes and synthesize ECM.The expression of ECM tends to the normal condition after reducing the concentration of TGF-β1,implying a scarless expression.

Decreased keratocyte density and central corneal thickness in primary open‑angle glaucoma patients undergoing treatment with topical prostaglandin analogues.

Purpose: To evaluate whether prostaglandin (PG) analogue use is associated with alterations in keratocyte density and central corneal thickness (CCT) in subjects with primary open‑angle glaucoma (POAG). Materials and Methods: Thirty‑five POAG patients treated with PG analogues for >2 years and 35 control subjects without glaucoma were included in this cross‑sectional study. All subjects were underwent CCT measurements using ultrasound pachymetry. Keratocyte densities of each stromal layer were determined by in vivo confocal microscopy. Student’s t‑test and Chi‑square test were used for statistical evaluations. Correlations between keratocyte densities and CCT were analyzed using Pearson’s correlation analysis. Results: Keratocyte densities in each stromal layer were significantly lower in glaucoma patients receiving PG analogues as compared to those of controls (P < 0.001). The mean CCT was also lower in glaucoma patients (515.2 ± 18.8 μ) than control subjects (549.6 ± 21.1 μ, P < 0.001). A positive correlation between keratocyte densities in each stromal layer and CCT was observed in POAG patients. Conclusions: Long‑term administration of topical PG analogues may adversely influence keratocyte densities and CCT. Further prospective studies are required clarify the relationship between PG analogues and their effects on the cornea.

Two Cases of Corneal Toxicity in Acanthamoeba Keratitis by Combined Topical Anti-Acanthamoeba Keratitis Eye Solution

PURPOSE: To present a case of corneal toxicity caused by therapeutic duplication during treatment of acanthamoeba keratitis as a complication of contact lens use. CASE SUMMARY: A 12-year-old girl with a history of wearing orthokeratology contact lenses and a 14-year-old girl with a history of wearing cosmetic contact lenses presented with ocular pain, injection, and decreased visual acuity. They were diagnosed as having acanthamoeba keratitis based on slit lamp examination, confocal microscopy and culture. After the patients were treated with polyhexamethylene biguanide (PHMB) and chlorhexidine, corneal epithelial defect and erosion occurred. Use of chlorhexidine was stopped, and PHMB was used to treat patients and recovery of the corneal epithelium with improvement in symptoms of acanthamoeba keratitis was found. CONCLUSIONS: Using PHMB and chlorhexidine together in treating acanthamoeba keratitis increases the risk of corneal toxicity. Therefore, these drugs should be avoided in combination.

Long-Term Effect of Preservative-Free Sodium Hyaluronate Eye Drop on Human Corneal Epithelial Cell

PURPOSE: To investigate the biological effects of preservative-free artificial tear drops on cultured human corneal epithelial cells in vitro. METHODS: The effects of the preservative-free artificial tear drops (Kynex(R) 0.1%, Kynex II(R) 0.18% [Alcon, Seoul, Korea] and Hyaluni eye drops(R) 0.15%, 0.3% [Taejun, Seoul, Korea]) on the human corneal epithelial cells were evaluated. An methyl thiazolyl tetrazolium (MTT)-based colorimetric assay was performed to assess the cellular metabolic activity and a lactate dehydrogenase (LDH) leakage assay was used to determine cellular toxicity. The eye drop ingredients were analyzed for electrolyte composition, pH, and osmolarity. We performed a scratch assay and cellular morphology test using electronic microscopy. RESULTS: The metabolic activity of corneal epithelial cells was higher than controls at 24 hours after exposure and then decreased at 48 and 72 hours after exposure (p < 0.05). The LDH titers of the 4 eye drops were higher compared with controls (p < 0.05). Sodium hyaluronate 0.18% contained lower concentrations of Na+ or Cl- and showed lower osmolarity values compared with the other eye drops. The cellular migration based on the scratch assay was more delayed and cellular damage such as loss of microvilli, rough endothelial reticulum (RER), and mitochondria dilatation was greater than controls based on electron microscopy. CONCLUSIONS: Long-term exposure to preservative-free sodium hyaluronate eye drops may induce decreased metabolic activity and cellular damage. Thus, preservative-free artificial tears should be used carefully to prevent cellular toxicity.

Effect of Cysteamine on Human Peripheral Blood Mononuclear Cells-Chemically Injured Keratocytes Reaction

PURPOSE: To investigate the effect of cysteamine on mixed peripheral blood mononuclear cells (PBMCs)-chemically injured keratocytes reaction (mixed lymphocyte-keratocyte reaction; MLKR). METHODS: PBMC stimulation assay was performed after keratocytes were chemically injured with 0.05 N NaOH for 60 seconds. MLKR was treated with various concentrations of cysteamine (0-10 mM). Intracellular reactive oxygen species (ROS) formation was measured using the oxidation-sensitive fluorescent probe, 2'7'-dichlorofluorescein diacetate (DCF-DA). Proliferation rate of PBMCs stimulated by NaOH-treated keratocytes and secretion profiles of matrix metalloprotease-9 (MMP-9), transforming growth factor-beta1 (TGF-beta1), interleukin-6 (IL-6), and macrophage migration inhibitory factor (MIF) were determined using the bromodeoxyuridine proliferation assay and enzyme-linked immunosorbent assay, respectively. RESULTS: Proliferation rate of PMBCs was suppressed by cysteamine in a dose-dependent manner (p = 0.019). Fluorescence of DCF-DA decreased depending on cysteamine concentration (p < 0.001). MMP-9, IL-6 and TGF-beta1 levels were suppressed by cysteamine in a dose-dependent manner (p < 0.05), whereas MIF levels increased with cysteamine concentration of 0.5-10 mM (p = 0.008). CONCLUSIONS: These study results indicate that cysteamine induced the ROS-mediated inhibition of inflammatory cytokine release and proliferation of PBMCs stimulated by chemically injured keratocytes. Thus, cysteamine can be used in the treatment of chemical corneal burns.

Establishment of a three-dimensional corneal stroma extracellular matrix fibrosis model induced by transforming growth factor-β1 in vitro / 中华实验眼科杂志

Background Extracellular matrix (ECM) fibrosis leads to corneal scaring during the process of cornea wound healing.Transforming growth factor-β1 (TGF-β1) is known to mediate overproduce of ECM components.Our previous study developed a three-dimensional model for corneal stromal cells culture in vitro.Objective The hypothesis of this study was to apply TGF-β1 in the three-dimensional culture system to establish a corneal stroma ECM fibrosis model.Methods Fresh bovine corneas were extracted for the culture of bovine keratocytes in constructed three-dimension culture system.The Pellets were cultured in the DMEM/F12+ 10％ fetal bovine serum (FBS) medium with 0.5 ng/ml or 1.0 ng/ml TGF-β1 or without TGF-β1,respectively.Calcein AM/(propidium iodide) PI staining was employed to assay the cell viability 2 weeks after culture.The expressions of α-smooth muscle actin (α-SMA),type Ⅰ collagen (Col Ⅰ) and Col Ⅲ mRNA and protein in the cells were detected by real-time PCR and Western blot respectively 48 hours,1 week and 2 weeks after cultured.The results were statistically analyzed.Results Cultured for 48 hours in the Pellet system,corneal stromal cells clustered and was identified alive by Calcein-AM/PI staining in 2 weeks.The relative expression levels of α-SMA,Col Ⅰ and Col m mRNA were elevated in both the 0.5 ng/ml and 1.0 ng/ml TGF-β1 supplement groups in comparison with the only DMEM/F12+10％ FBS group,with marked difference among the three groups (Fgroup =696.745,P＜0.001;Fgroup =35.166,P＜0.001;Fgroup =33.677,P＜0.001),and the expression levels increased with the lapse of culture time (Ftime =5.863,P＜0.05;Ftime =298.614,P＜0.001;Ftime =607.472,P＜0.001).The synthetic rate of Col Ⅲ mRNA was obviously faster than that of Col Ⅰ mRNA.Western blot showed that only a trace of α-SMA,Col Ⅰ and Col Ⅲ were detected 48 hours and 1 week after culture.The expression levels of α-SMA,Col Ⅰ and Col Ⅲ in Pellet system in 0.5 ng/ml TGF-β1 medium were 0.395±0.208,1.060±0.175 and 0.629±0.382,and in 1.0 ng/ml TGF-β1 medium were 0.758±0.228,1.201 ±0.187 and 0.753±0.468,respectively 2 weeks after culture,significant differences were shown among the three groups (α-SMA:F=10.691,P＜0.05;Col Ⅰ:F=14.094,P＜0.05;Col Ⅲ:F=10.995,P＜0.05).Conclusions Addition of TGF-β1 and serum enhance the assembly and fibrosis of ECM,showing the higher expressions of specific fibrotic markers in bovine keratocytes Pellet.This culture systerm can be used as a candidate three-dimensional model for corneal stroma ECM fibrosis.

Microarray Analysis for Genes Associated with Angiogenesis in Diabetic OLETF Keratocytes

The purpose of this study was to identify the differences in angiogenesis gene expression between normal and diabetic keratocytes stimulated with interleukin-1alpha (IL-1alpha) and tumor necrosis factor-alpha (TNF-alpha). Primarily cultured normal and diabetic keratocytes were treated with 20 ng/mL of IL-1a and TNF-alpha for 6 hr. cDNA was hybridized to an oligonucleotide microarray. Microarray analysis was used to identify differentially expressed genes that were further evaluated by real-time polymerase chain reaction (RT-PCR). Diabetes keratocytes overexpressed vital components of angiogenesis including Agtr1, and under-expressed components related to the blood vessel maturation, including Dcn. Cytokine-treated diabetic keratocytes differentially expressed components of angiogenesis. OLETF keratocytes after treatment with IL-1alpha and TNF-alpha showed the newly expressed 15 and 14 genes, respectively. Newly and commonly under-expressed five genes followed by treatment with both IL-1alpha and TNF-alpha were also evident. RT-PCR showed results similar to the microarray results. Agtr1 and Itga1 showed an increased expression in diabetic keratocytes compared with normal corneal keratocytes, especially after TNF-alpha treatment. Il6 appeared strong expression after interleukin-1alpha treatment, but showed down expression after TNF-alpha treatment. Further studies to analyze and confirm the significance of the identified angiogenetic genes of diabetes are needed.

Inhibitory effect of curcumin on corneal keratocytes fibrosis / 中华实验眼科杂志

Background The injury or surgery of cornea cause the proliferation of corneal stromal cells and scar formation.Recent research showed that cureumin can obviously reduce the degree of fibrosis of tissue.But if curcumm play inhibitory effect on corneal keratocytes fibrosis is rarely reported.Objecttve This studv was to investigate the effect of curcumin on the transformation of corneal keratocytes into fibroblasts in vitro and further explore the antifibrotic effect of curcumin on corneal keratocytes.Methods The murine corneal keratocytes from 150 BALB/c mice were isolated and primary culture in DMEM culture medium containing 10% fetal bovine serum and then divided into blank control group(inducer group,CG),low-dose group(CG+7.5 mg/L curcumin),mediumdose group(CG+10.0 mg/L curcumin),high-dose group(CG+12.5 mg/L curcumin),non-inducer group.Seven days following intervention,the expression of cell markers such as keratocan,aldehyde dehydrogenase(ALDH),decorin and fibronectin-1 in keratocytes were analyzed by RT-PCR.The effect of curcumin on cultured murine corneal keratocytes proliferation was evaluated by MTS technique.The expression of fibronectin-1 in murine cornea was investigated by immunofluorescence assay.Results The primarily cultured keratocytes showed tlIe fusiform-like shape with the abundant cytoplasm and big nuclei.In the presence of curcumin,the mRNA levels of keratocan and ALDH were down-regulated and those of CD90 and decorin were up-regulated,showing the significantly differences with the increase of dose(P<0.05),but the expression pf fibronectin-i was not obviously changed with the alteration of dose of curcumin. MTS showed that the inhibitory rates of curcumin on keratocytes in 10.0 mg/L and 2. 5 mg/L groups were enhanced in comparison with 7.5 mg/L group, showing statistically significant difference among three groups( F = 956.00, P<0.05). The expression of fibronectin-1 was found in the corneal keratocytes with the red fluorescence in stroma. Conclusion Curcumin can inhibit the fibrosis of corneal keratoeytes in a dose-dependent manner. These results offer a preliminary theoretical basis for the application of curcumin in controlling corneal scar formation during wound healing.

Effect of Mitomycin C, Dexamethasone, and Cyclosporine A 0.05% on the Proliferation of Human Corneal Keratocytes

PURPOSE: To investigate the biologic effect of mitomycin C, dexamethasone and cyclosporine A 0.05% on cultured human keratocytes in vitro. METHODS: Human corneal keratocytes were exposed to a concentration of mitomycin C (0.05%), dexamethasone (0.05%) and cyclosporine A (0.05%) for a period of 3, 5, and 10 minutes. MTT-based colorimetric assay was performed to assess the metabolic activity of cellular proliferation and the concentration of type I procollagen COOH-terminal peptide (PIP) and laminin were measured. Cell damage was determined by using the lactate dehydrogenase (LDH) assay. Apoptotic response was evaluated utilizing flow cytometric analysis with Annexin V and propiodium iodide. RESULTS: The inhibitory effect of cellular proliferation and cytotoxicity in cultured human keratocytes showed a time-dependent response in all drugs. The production of PIP and laminin showed a time-dependent response in cultured cells. Apoptosis was observed in flow cytometry after being treated with mitomycin C, dexamethasone and cyclosporine A. Cyclosporin A resulted in less apoptosis of keratocytes than mitomycin C and dexamethasone. CONCLUSIONS: The apoptotic response of mitomycin C, dexamethasone and cyclosporine A is associated with the inhibitory effect of human corneal keratocyte proliferation. To decrease corneal opacity, mitomycin C and dexamethasone were more effective than cyclosporine A in the present study. Additionally, a high concentration of cyclosporine A greater than 0.05% is necessary to lower corneal opacity.

Pay attention to the effect of keratocyte / 中华实验眼科杂志

Keratocytes situated between the collagen lamellae in the corneal stroma,are mitotically quiescent cells.The cells can secrete collagens and keratan sulfate proteoglycans which contribute to the transparency of the cornea.Upon injury,keratocytes are stimulated to corrent apoptosis and transite into repair phenotypes,fibroblast and myofibroblast.These repair phenotypes can either promote regeneration or induce fibrotic scar,and the latter is detrimental to the otherwise transparent cornea.Moreover,a population of keratocytes can be induced to appear the stem cell-like characteristics.Therefore,keratocytes are no longer bystanders,but active participants in numerous functions.

Effects of Intrastromal Air Injection Compared to Hydro-injection on Keratocyte Apoptosis

PURPOSE: To evaluate the effects of intrastromal air injection and intrastromal balanced salt solution (BSS) injection on corneal keratocyte apoptosis. METHODS: Twelve right eyes of New Zealand White rabbits were divided into an air-injected group (n=6) and a hydro-injected group (n=6). Contralateral eyes served as a control. Air or Balanced salt solution (BSS(R), Alcon, USA) was injected into the deep corneal stroma at the paracentral area to propagate into nearly the entire cornea. To reduce the intraocular pressure, anterior chamber paracentesis was performed. The animals were sacrificed 4 hours (n=6) and 24 hours (n=6) after surgery. Central cornea buttons were retrieved to stain with Hematoxylin & Eosin and TUNEL (Apoptag(R), Chemicon). The mean number of apoptotic keratocytes was counted in 24.67+/-4.04 consecutive high power field (HPF). RESULTS: The mean number of TUNEL-positive cells at 4 hours was 12.85+/-7.25/HPF and 0.25+/-0.44/HPF in air-injected and hydro-injected eyes, respectively. It was reduced to 6.25+/-4.02/HPF and 0.15+/-0.37/HPF in air-injected and hydro-injected eyes after 24 hours. The air-injected group showed significantly more TUNEL-positive cells compared with the hydro-injected or control group until 24 hours (p=0.001, p=0.001, Mann-Whitney U test). CONCLUSIONS: Intrastromal air injection induces significant apoptosis of keratocytes suggesting some damages in the peripheral cornea when used in deep lamellar keratoplasty.

Microarray for Genes Associated with Signal Transduction in Diabetic OLETF Keratocytes

PURPOSE: The purpose of this study was to identify differences in signal transduction gene expression between normal and diabetic keratocytes stimulated with interleukin-1alpha (IL-1alpha) and tumor necrosis factor-alpha (TNF-alpha). METHODS: Normal and diabetic keratocytes were primarily cultured and treated with 20 ng/ml IL-1alpha and TNF-alpha for 6 h. cDNA was hybridized to an oligonucleotide microarray. Genes identified by the microarray were further evaluated by real-time PCR. RESULTS: Diabetic keratocytes over-expressed components of the MAPK and Notch pathways, and under-expressed components of the insulin, calcium, and TGF-beta pathways. Cytokine treated diabetic keratocytes differentially expressed components of the TGF-beta and MAPK pathways. After IL-1alpha and TNF-alpha treatment, nine genes were under-expressed, falling in the insulin, TGF-beta, and Toll-like receptor pathways. Real-time PCR showed a significant decrease in the IL-6 and TGF-beta2 genes and a significant increase in the Ppm1a gene. CONCLUSIONS: There were some differences in gene expression between normal and diabetic keratocytes related to signal transduction pathways, such as the insulin, MAPK, calcium, and TGF-beta pathways. In addition, IL-1alpha and TNF-alpha stimulating the insulin, TGF-beta, and Toll-like receptor signaling pathways may have different effects in diabetic keratocytes.

Effect of Amoebicidal Agents on the Human Corneal Keratocytes in Vitro

PURPOSE: To evaluate the effect of polyhexamethylene biguanide (PHMB) and chlorhexidine on Acanthamoeba cysts and cultured human keratocytes. METHODS: Each well of two-fold diluted PHMB and chlorhexidine were treated on the Acanthamoeba cyst suspension of 5 x 10(4) cysts/ml for 8, 24, and 48 hours to measure the minimal cysticidal concentration (MCC) of each disinfectant and was exposed to the human corneal keratocytes of 5 x 10(4) cells/ml for same hours to measure the survival rate of keratocytes. Inverted phase-contrast micrograph and electron microscopy for observing the morphologic changes were evaluated. RESULTS: MCC of PHMB was 9.42 microgram/ml, 5.62 microgram/ml, and 2.37 microgram/ml, and chlorhexidine was 24.32 microgram/ml, 10.02 microgram/ml, and 7.02 microgram/ml respecitvely in 8, 24, and 48 hours. The survival rate of keratocytes at MCC was 91.7%, 64.6%, and 49.7% in PHMB of which significant decreases were found at 24 and 48 hours, and 95.7%, 90.6%, and 78.1% in chlorhexidine of which significant decrease was only found at 48 hours. The higher the concentration of disinfectants, cysts and keratocytes demonstrated more damaged appearance. CONCLUSIONS: The amoebicidal efficacy of PHMB and chlorhexidine was similar. However, in consideration of toxic effect on keratocytes by disinfectants, chlorhexidine is suggested to be more clinically useful than PHMB.

Gene Microarray Related with Apoptosis in Diabetic OLETF Keratocytes

PURPOSE: This study was to identified differentiated genes concerned with apoptosis that are up-regulated or down-regulated in OLETF corneal keratocytes stimulated with interleukin-1alpha. METHODS: Otsuka Long Evans Tokushima Fatty (OLETF) corneal keratocytes were primarily cultured and treated with 20 ng/ml of IL-1a for 6 hours. Hybridization was carried out using Oligonucleotide microarray. A sample of normal keratocytes was labeled with Cy 3, and a diabetic keratocytes sample was labeled with Cy 5. RESULTS Diabetes showed 20 down-regulated genes and 24 up-regulated genes compared with normal keratocytes. Also, IL-1alpha-treated diabetic keratocytes expressed 31 down-regulated and 33 up-regulated genes. Compared with diabetic keratocytes, the newly expressed genes in OLETF treated with IL-1alpha were Bcl, Lam, Timp, Mmp, Socs, Bmp, Ccl, Lcn, C7, etc. CONCLUSIONS: There were some genes related with apoptosis that expressed differently between normal and diabetic keratocytes of OLETF. Also, IL-1alpha may stimulate differing effects of apoptosis on diabetic corneal keratocytes. Studies analyzing the apoptotic significance of these differences identified in diabetic keratocytes are needed.

Gene Microarray Related with Apoptosis in Diabetic OLETF Keratocytes

PURPOSE: This study was to identified differentiated genes concerned with apoptosis that are up-regulated or down-regulated in OLETF corneal keratocytes stimulated with interleukin-1alpha. METHODS: Otsuka Long Evans Tokushima Fatty (OLETF) corneal keratocytes were primarily cultured and treated with 20 ng/ml of IL-1a for 6 hours. Hybridization was carried out using Oligonucleotide microarray. A sample of normal keratocytes was labeled with Cy 3, and a diabetic keratocytes sample was labeled with Cy 5. RESULTS Diabetes showed 20 down-regulated genes and 24 up-regulated genes compared with normal keratocytes. Also, IL-1alpha-treated diabetic keratocytes expressed 31 down-regulated and 33 up-regulated genes. Compared with diabetic keratocytes, the newly expressed genes in OLETF treated with IL-1alpha were Bcl, Lam, Timp, Mmp, Socs, Bmp, Ccl, Lcn, C7, etc. CONCLUSIONS: There were some genes related with apoptosis that expressed differently between normal and diabetic keratocytes of OLETF. Also, IL-1alpha may stimulate differing effects of apoptosis on diabetic corneal keratocytes. Studies analyzing the apoptotic significance of these differences identified in diabetic keratocytes are needed.

Effect of Dexamethasone and Diclofenac on the Proliferation of Human Corneal Keratocytes

PURPOSE: To evaluate the inhibitory effect of dexamethasone and diclofenac on the proliferation of cultured human keratocytes, and to investigate the apoptotic response and the cellular morphologic changes associated with dexamethasone and diclofenac in vitro. METHODS: Human corneal keratocytes were exposed to 0.05, 0.1, 0.2, 0.4, 0.8, 1.6, and 3.2 mM concentration of dexamethasone and diclofenac for 4, 24, and 48 hours. MTT based calorimetric assay, flow cytometric analysis, fluorescent micrograph, inverted phase-contrast micrograph, and electron microscopy were used to evaluate the results. RESULTS: The inhibitory effect of human keratocyte proliferation increased at higher concentrations and longer exposure times of dexamethasone and diclofenac (p<0.05). In flow cytometry, the maximal apoptotic response developed at 0.4 mM concentration of dexamethasone and 1.6 mM concentration of diclofenac after 4 hours. Apoptotic cells were demonstrated in fluorescent micrograph. Dexamethasone-treated cases showed a more damaged appearance, more swollen rather than spindle shaped, with greater detachment from the bottom of the dish and the chromatin of the nuclear remnant condensed along the nuclear periphery with cytoplasmic vesication and cytoplasmic blebs formation, and partial disruption of the nuclear membrane compared with diclofenac. CONCLUSIONS: The apoptotic response of dexamethasone and diclofenac is associated with the inhibitory effect of human corneal keratocyte proliferation. For inhibition of cellular proliferation of human corneal keratocytes, dexamethasone may be more effective at lower concentration and shorter exposure time than diclofenac.

Effect of Tranilast on the Proliferation of Human Corneal Keratocytes in Vitro

PURPOSE: To evaluate the inhibitory effect of tranilast on proliferation of cultured human keratocytes, and to investigate the apoptotic response and the cellular morphologic changes associated with tranilast in vitro. METHODS: Human corneal keratocytes were exposed to tranilast at a concentration of 0.05, 0.1, 0.2, 0.4, 0.8, 1.6, and 3.2 mg/ml for a period of 4, 24, and 48 hours. Evaluations were conducted with MTT-based-calorimetric assay for measuring the metabolic activity, flow cytometric analysis and fluorescent micrograph for assessing the apoptotic response, and inverted phase-contrast micrograph and electron microscopy for observing the morphologic changes. RESULTS: The inhibitory effect of human keratocyte proliferation was found to have a dose and time dependent pattern (p<0.05). In flow cytometry, the maximal apoptotic response developed at 0.8 mg/ml concentration after 4 and 24 hours of exposure time, and apoptotic cells were demonstrated in fluorescent micrograph. At higher concentration of Tratnilast, human corneal keratocytes were more swollen rather than having a spindle shape and being detached from the bottom of the dish. The damaged keratocytes had degenerative and apoptotic changes like the formation of phagolysosomal granule, marginal condensation in the nucleus, and bleb formation of the nuclear membrane. CONCLUSIONS: The apoptotic response of tranilast is concerned with the inhibitory effect of human corneal keratocyte proliferation. Therefore, tranilast shows promise in clinical use for the inhibition of postoperative excimer laser induced corneal opacity or haze with fewer side effects.

Morphological Characteristics and Intercellular Connections of Corneal Keratocytes

PURPOSE: To investigate the morphological characteristics of keratocytes and the interconnection of keratocytes with adjacent keratocytes using the flat preparation method and scanning electron microscopy with a frontal section of the human corneal stroma. METHODS: The thin, corneal collagen lamellae were carefully dissected from the cornea (n=7), which had been stained by the flat preparation method. The remaining tissue was fixed in 3% glutaraldehyde and observed by transmission electron microscopy following the frontal section. RESULTS: The flat preparation revealed the corneal fibroblasts between the lamellae of the collagen fibers and showed that the ramifying cellular processes of the keratocytes were in contact with the cytoplasmic processes or cell bodies of neighboring fibroblasts. Two types of discrete subpopulations of keratocytes were identified: a smaller, cellular type of keratocyte with spindle-shaped nucleus with heterochromatin, and a larger, cellular type with a large indented nucleus with relatively scanty cytoplasm. Collagen fibers ran parallel to each other toward the fenestration of the cytoplasmic wall of the keratocyte. CONCLUSIONS: These flat preparation method results showed that the keratocytes within the corneal stroma are interconnected with the adjacent keratocytes, which indicates the presence of a functional communicating network through the keratocyte circuits within the stroma. A smaller, cellular type of keratocyte with spindle-shaped nucleus was morphologically differentiated from a larger, cellular type with a large, indented nucleus by flat preparation and transmission electron microscopy.