Decellularized porcine corneal posterior lamellae as carrier matrix for cultivating human umbilical vein endothelial cells in vitro

AIM：To investigate the feasibility of corneal posterior lamellar reconstruction with human umbilical vein endothelial cells (HUVECs) and porcine cornea acellular matrix in vitro, and to observe the physiological function of the transplantation in vivo. METHODS：HUVECs were isolated, cultured, and labeled with fluorescent dye CM-DiI. Porcine corneas were treated with 100% glycerinum, cut to a thinner structure step by step, and dried on the super-clean bench. Transmission electron microscope were used to observe the histological changes of the porcine cornea acellular matrix. Labeled HUVECs were seeded onto the porcine cornea acellular matrix, and examined by scanning electron microscopy. When the HUVECs and Descemets membrane fusion formed a monolayer, the corneal transplantation in rabbits was performed. Twenty-four New Zealand white rabbits were randomly divided into experimental group and control group (n=12 each), and their left eyes served as recipients. RESULTS：Cultured HUVECs exhibited polygonal shape. More than 90% HUVECs were labeled with CM-DiI and the cell membrane was positive with red fluorescence, which was detectable at least up to 3 generations. The histological examination indicated that porcine cornea cells were clearly extracted, and the collagen fibers were well arranged. A continuous monolayer of HUVECs on the porcine cornea acellular matrix was observed under scanning electron microscopy. The reconstructed corneal posterior lamellae were similar to the normal cornea. The observation of transplantation showed that the cornea in experimental group was substantially transparent. However, that in control group was oedematous and adiaphanous. CONCLUSION：Corneal posterior lamellae can be reconstructed in vitro by cultivating HUVECs on porcine cornea acellular matrix. After xenogeneic transplantation, the graft survives in vivo and expresses normal corneal endothelial cell biological functions. Deep lamellar corneal endothelial transplantation is an effective keratoplasty.     

Effect of heterogenic corneal stroma transplantation on peripheral T cells of rats

AIM: To Compare immunogenicity of three kinds of heterogenic corneal stroma. METHODS: 36 SD rats were randomized into 4 groups, each group consisting of 9 rats. Group 1 was control group. Three kinds of heterogenic corneal stroma: porcine, rabbit and chicken corneal stroma were heterotopically transplanted to subcutaneous layer of 27 (group 2-4) SD rats, respectively. The expression of CD4⁺, CD8⁺, CD25⁺, CD71⁺ on peripheral T cells was identified and analyzed by dual fluorescence flow cytometry at 7, 14, 28 days after operation. RESULTS: Compared with control group, the expression of CD4⁺, CD8⁺, CD25⁺, CD71⁺ was no significant change in porcine corneal stroma group(P＞0.05), the expression of CD4⁺ was increased in rabbit corneal stroma (P＜0.05), CD4⁺, CD4⁺ CD71⁺ markedly higher in the chicken corneal stroma (P＜0.01) at 7 days after operation. CONCLUSION: The immunogenicity of porcine stroma is the lowest in three kinds of heterogenic corneal stroma (chicken, rabbit and porcine).     

Effect of antioxidant and NFκB on the induction of iNOS gene in rat pulmonary microvascular endothelial cells in vitro

AIM:To investigate the role of nuclear factor κB (NF_κB) in the induction of iNOS gene by TNFα and LPS in endothelial cells and the effect of antioxidant on the induction of iNOS. METHODS:Nitrite was determined based on Griess reaction. iNOS mRNA was analyzed using Northern blot. NF_κB in the cell nucleole was detected with electrophoretic mobility shift assay.RESULTS: (1)NO production and iNOS mRNA expression induced by LPS and TNFα was blocked by pyrrolidine dithiocarbamate(PDTC) or N-acetylcysteine(NAC). (2)LPS and TNFα triggered the activation and translocation of NF_κB, and PDTC or NAC inhibited the activation of NF_κB induced by LPS and TNFα. CONCLUSIONS:(1)The induction of iNOS gene by TNFα and LPS is dependent on the activation of NF_κB.(2)Antioxidants may inhibit the induction of iNOS gene through the inhibition of NF_κB activation.     

Mixed culture of human iPSCs with rabbit corneal endothelial cells induces differentiation of iPSCs

AIM:To investigate the morphology and protein expression of human induced pluripotent stem cells(iPSCs) in the mixed-culture environment with rabbit corneal endothelial cells(CECs) and to provide the experimental basis and the mechanism of iPSC differentiation into CECs. METHODS:Primary rabbit CECs were isolated with trypsin and subcultured. The human iPSCs were cultured and amplified by a feeder-free method and their characteristics were evaluated by Western blotting. iPSCs labeled with quantum dots of appropriate concentration were used to establish mixed-culture model with rabbit CECs. The morphology of iPSCs was evaluated by atomic force microscopy(AFM) and inverted microscopy. The protein expression of CD31, CD34, CD133 and aquaporin 1(AQP1) in iPSCs was tested by the method of immunofluorescence. RESULTS:The rabbit CECs were hexagonal and showed a typical cobblestone appearance. iPSCs grew in the cloning form, and 3 pluripotent proteins Oct4, Nanog and Sox2 were expressed positively. 1/4 suspension of iPSCs labeled with 10 nmol/L quantum dots and 60% confluence of rabbit CECs made best mixed culture for each other. Under AFM and inverted microscope, the volume of iPSC became bigger and the nuclear-cytoplasm ratio was decreased after 7 days of mixed culture. Some granular protrusions of the membrane were observed and the surface roughness of the cell membrane increased. The protein expression of CD31, CD34, CD133 and AQP1 in iPSCs was negative, while AQP1 was detected after mixed culture for 2 weeks. CONCLUSION:iPSCs morphologically change to endothelial-like cells after mixed culture with rabbit CECs and express the marker protein AQP1 of CECs at the same time.     

Injuring effect of DMSO-soluble particles from cigarette smoke on human umbilical vein endothelial cell line EA. hy 926 in vitro

AIM: To investigate the injuring effect of DMSO-soluble particles from cigarette smoke(DSP) on human umbilical vein endothelial cells. METHODS: Human umbilical vein endothelial cell line EA. hy 926 was used as target cells in the study. The growth and viability of the cells treated with various dosages (1, 2, 4 or 4 mL/L) of DSP and low dose (2 mL/L) of DSP at different time points were evaluated by MTT colorimetric assay and celllular protein assay in 96-well plates. Transmission electron microscopy study was carried out to observe the ultrastructure of human umbilical vein endothelial cells under DSP treatment.RESULTS: DSP inhibited the proliferation of human umbilical vein endothelial cell line EA. hy 926. Under DSP treatment, the reducing cellular protein and increasing cell death(mainly necrosis) were observed in time-dependent and dosage-dependent manners.CONCLUSIONS: These results indicated that the toxic effect of DSP caused functional disturbance and structural damage of human endothelial cells.     

Effect of cilazapril on pulmonary vascular endothelial dysfunction in hypoxic rats

AIM:To study the effect of cilazapril on pulmonary vascular endothelial dysfunction in hypoxic rats. METHODS:The structure and function of endothelium in hypoxic rats were studied by biochemical analysis, radioimmunoassay, transmission electron microscope and correlated with hemodynamic. RESULTS:1) The change and damage of ultrastructure in endothelial cell (EC) were obsevered in hypoxic rats. 2) The contents of plasma nitric oxide (NO) and superoxide dismutase (SOD) activity in blood as well as endothelial nitric oxide synthase (eNOS) activity in the lung tissue were significantly lower in the hypoxic rat than those in contral animals. The concentrations of plasma endothelin-1(ET-1) and angiotensin converting enzyme(ACE) as well as malondialdehyde(MDA) were significantly higher in the hypoxic rat than these in contral animals. The relaxing and contracting factors had a significant positive/negative correlation with mean pulmonary artery pressure (mPAP). 3) Cilazapril significantly decreased the level of ET-1 and ACE and significantly increased the level of NO and activity of eNOS and SOD. At the same time, cilazapril extenuated hypoxia-induced injuries of EC. CONCLUSION:The results indicate that damaging structure and dysfunction of EC existes in hypoxic rats. The cilazapril effectively preventes and treates the chronic hypoxic PH by relieving the injury and improving secretion in EC.     

Effects of peroxynitrite on the endothelial cells

Endothelial cells produce both superoxide and nitric oxide. Nitric oxide and superoxide are known to react rapi dly to formthe stable peroxynitrite anion. Peroxynitrite mediates the oxidation of protein, lipid, deoxyribose and inhibits mitochondrial electron transport. Peroxynitrite may break DNA strands and activate poly(ADP-ribose) synthetase. If the reactionis excessive, it results in a depletion of intracellular NAD⁺ and ATP. There is ultimately cell death.     

Fenofibrate increases endothelial nitric oxide synthase expression in bovine aortic endothelial cells

AIM: We hypothesize that peroxisome proliferator-activated receptor α(PPARα) agonists act directly on nitric oxide (NO) production in vascular endothelium. Thus, the purpose of this study is to investigate the effects of fenofibrate on endothelial NO synthase(eNOS) activity and its expression in cultured vascular endothelial cells. METHODS: Bovine aortic endothelial cells (BAECs) were treated with the PPARα activator fenofibrate. The eNOS activity and the expression of eNOS protein and its mRNA were determined. RESULTS: Our data show that fenofibrate increased eNOS activity in a dose-and time-dependent manner. At the concentration of 10 μmol/L or more, fenofibrate treatment caused a significant increase in eNOS activity. The maximal increase in eNOS activity(2.32±0.47 fold of the control) was observed with 50 μmol/L fenofibrate treatment for 48 h. Fenofibrate failed to increase eNOS activity at 1 and 12 h. RT-PCR analysis demonstrated that eNOS mRNA relative to β-actin mRNA significantly increased at concentrations of 5 μmol/L or more. It reached 2.08±0.33 fold of the control with 50 μmol/L fenofibrate. Significant increase in eNOS mRNA levels was observed after 6 h, and lasted for 48 h. The peak increase in eNOS mRNA levels(2.13±0.30 fold of the control,P<0.01) was observed with 50 μmol/L fenofibrate treatment for 12 h. Longer incubation of cells with 50 μmol/L fenofibrate caused no further increase. The treatment of BAECs with fenofibrate for 48 h demonstrated a concentration-dependent increase in eNOS protein levels as measured by Western blot analysis. Densitometric analysis indicated that there was a significant increase in eNOS to β-actin ratios after fenofibrate treatment at concentrations of 10,50 and 100 μmol/L(1.80±0.45, 2.70±0.42 and 2.20±0.32 fold of the control, respectively, P<0.01). The significant increase in eNOS protein levels was observed 12 h after treatment and lasted for 48 h. CONCLUSION: PPARα activator fenofibrate, enhances endothelial NO production by directly upregulating eNOS expression and activity.     

Protective effects of pioglitazone on endothelial function in rats with hypercholesterolemia

AIM: To investigate the effects of pioglitazone,a PPARγ agonist,on endothelial cell (EC) dysfunction in hypercholesterolemic rats.METHODS: 36 healthy male Wistar rats were assigned to one of the following groups randomly (six rats in each group): control,hypercholesterolemia (HC),and HC treated with pioglitazone 1.5 mg·kg^-1·d^-1,3 mg·kg^-1·d^-1,10 mg·kg^-1·d^-1 and 20 mg·kg^-1·d^-1 (HC＋PIO),respectively.EC function was determined by comparing vasorelaxation to ACh,an EC dependent vasodilator,and acidified NaNO₂,an EC-independent vasodilator.Maximal positive and negative values of the instantaneous first derivative of LVP (+dp/dt_max and dp/dt_max) were determined by MS2000 system.RESULTS: (1) Hypercholesterolemia caused a significant endothelial diastolic dysfunction (maximal relaxation to ACh: 50.51%±2.45% vs 99.78%±3.01% in control,P<0.01).(2) Treatment with pioglitazone relieved EC-dependent vasodilatation in a dose dependent manner,and 10 mg·kg^-1·d^-1 is the best dose.(3) Pioglitazone not only improved EC function,but also reduced cardiac functional injury induced by hypercholesterolemia.CONCLUSION: EC dysfunction induced by hypercholesterolemia can be directly extenuated by pioglitazone,which may effectively prevent from subsequent atherosclerosis and ischemic heart disease.     

Effect of cGMP-dependent protein kinase on endothelial cytoskeleton changes

AIM: To study the effect of cGMP-dependent protein kinase (PKG) on the pathogenesis of burn shock. METHODS: Confluent endothelial cells were disintegrated and centrifugated to obtain cell lysates after being treated with 10% burn serum or PKG activator 8-Br-cGMP. PKG activity of lysates was measured with radioactive isotope label method in a reaction system of phosphorylation of specific substrate H2B by PKG, and the shape and the distribution of intracellular filamentous actin were detected by specific fluorescence staining. For the control study, the PKG specific inhibitor KT5823 were used to pretreat the endothelial cells before the administration of burn serum or PKG activator 8-Br-cGMP. RESULTS: Exposures to burn serum and 8-Br-cGMP led to a rapid time-dependent increase in endothelial PKG activity and the polar distribution of intracellular filamentous actin, and preincubation with KT5823 abolished those effects. CONCLUSIONS: The results suggest that burn serum induces PKG activation and the stress variety of filamentous actin in the vascular endothelial cells, which probably contributes to the endothelial hyperpermeability after burn shock.     

Effects of low and high shear stress on tight junctionsof endothelial cells

AIM:To investigate the effect of high and low shear stress on endothelial permeability and tight junctions(TJs). METHODS:Rabbit abdominal aortas in normal and high fat diet groups were stenosed to 60.7%±7.0% of original cross areas, they were sacrificed after 7 days, and the arteries were stained with Evans blue and Sudan Ⅳ. TJs were investigated with freeze fracture. RESULTS:The non-stenosis aortas were negative, there are 1 mm-wide constant and circular positive areas proximal and distal to the stenosis and scattered, dotted and patched positive areas within 8 mm distal to stenosis. Freeze fracture reveals that in the hyperpermeable regions, the percentages of zonular type of TJs and the numbers of strands of TJs of zonular and macular types in the distal regions are significantly lower than those in the proximal regions (P＜0.01). CONCLUSION: The high and low shear stress induces the increase of endothelial permeability and TJs changes. The regions exposed to low shear stress form readily atherosclerosis.     

Influence of complement bypass-activation on IL-8 expression in endothelial cells

AIM:To study the induction of IL-8 expression by bypass-activated complement in human umbilical vein endothelial cells (HUVECs) and regulatory effect of nuclear factor-kappa B on the expression of IL-8. METHODS:In vitro, zymosan-activated human serum(ZAHS) directly challenged the HUVECs monolayers. Following techniques were used in the experiment: ① RIA for measurement of IL-8,ISH for measurement of their mRNA.② EMSA for measurement of nuclear factor-kappa B(NF-κB). RESULTS:①After HUVECs monolayers were stimulated with ZAHS, the level of IL-8 increased significantly at 4 h. ②The NF-κB activity began upregulated within 30 min after ZAHS stimulation, maximal NF-κB activity was observed at 120 min. Pretreatment of endothelial monolayers with PDTC (20 μmol/L) significantly inhibited the secretion of IL-8 (P＜0.05). CONCLUSION:Bypass-activated complement directly challenged HUVECs to secret IL-8. Cytoplasma to nuclear translocation of NF-κB was necessary for this response.     

Effect of cornus officinalis glycosides ophthalmic solution on the corneal allograft rejection

AIM:To observe the effect of cornus of ficinalis glycosides(COG) ophthalmic solution on the corneal allograft rejection by topical instillation.METHODS:The corneal transplantation model on the closed colony rats was established. The rejection time of all animals was recorded and compared by slit-lamp microscope. The pathologic changes were measured by immunohistochemistry and scanning electron microscope.RESULTS:The histopathological and immunohistochemistry findings showed that the lymphocytes, neovascularity and the expression of ICAM-1 in COG-treated group were significantly fewer than that in control group at 15 d after operation.CONCLUSION:COG ophthalmic solution prevents and suppresses the corneal allograft rejection.     

Effect of lipopolysaccharide on apoptosis of human umbilical vein endothelial cells

AIM: To explore the mechanism of lipopolysaccharide (LPS) on vascular endothelial cell(VEC) damage. METHODS: By using cytometry techniques, we studied the effects of LPS on apoptosis of human umbilical vein endothelial cells (HUVECs) in vitro. RESULTS: LPS was able to induce apoptosis of HUVECs in a time-dose-dependent fashion.CONCLUSION:Apoptosis might play a role in LPS-induced damage of vascular endothelial cells.     

Effect of pulmonary vascular endothelial cells on the development of acute lung injury in rats

AIM: Effect of endothelial cell on the development of acute lung injury and the prevention of dexamethasone in acute lung injury were observed.METHODS:Rats were divided into three groups:1.Control group.2.LPS group:Venous injection with LPS(5mg/kg body weight),execute respectively at 1 h,2 h,6 h and 24 h after LPS injection. 3.dexamethasone group:intraperitoneal injection with dexamethasone ,1 h before LPS injection,execute after 2 hours after LPS injection.RESULTS: Serum NO,TNF-α levels,lung iNOS activity and lung ICAM-1mRNA expression were increased( P <0.05, P <0.01, vs control group),but serum ACE was decreased( P <0.01).Dexamethasone could improve all the changes above mentioned.CONCLUSION:Endothelial cell played a vital role in the development of acute lung injury and dexamethasone could prevent acute lung injury.     

Influence of different flow pattern on VCAM-1, NF-κB expression in vascular endothelial cells

AIM:The objective of this study was to examine the influence of different flow pattern, particularly low shear stress flow regimens, on VCAM-1 and NF-κB in vascular endothelial cells. METHODS:HUVEC covered sheets were placed within rectangular parallel plate flow chambers. Cells were subjected to 4, 18 h of either laminar or oscillatory shear stress. The expression of VCAM-1 and NF-κB activity were analyzed by immunohistochemistry. VCAM-1 mRNA was also detected using in situ hybridization. RESULTS:VCAM-1 mRNA and VCAM-1 expression were not upregulated by laminar shear stress. However, oscillatory shear stress significantly upregulated VCAM-1 mRNA and VCAM-1 expression. Translocation of NF-κB P65 was remarkably increased.CONCLUSION:In same low shear stress, the different expression of VCAM-1 mRNA and VCAM-1 were induced by HUVEC exposed to laminar or oscillatory flow patterns.     

Protective effect of heat-stress preconditioning on anoxic endothelial cells and its mechanism

AIM:To observe the protective effect of heat stress preconditioning on endothelial cells under anoxia and explore its mechanism. METHODS:The endothelial cells were divided into 4 groups: (1) anoxia; (2) heat stress; (3) heat stress preconditioning + hypoxia; (4) control. LDH activity was measrued by using Automatic Biochemistry Analysis-Meter. Cell death rate was determined by trypan blue, NO production was tested by measuring NO₂^-/NO₃^- content in cellular culture medium by using Griess assay. RESULTS:LDH release and cell death rate of the anoxia endothelial cells significantly increased compared with control; 39℃ heat stress preconditioning reduced those increment by 29.47%, 33.67% respectively. 41℃ heat stress preconditioning has no protection against the anoxia-induced injury in endothelial cells. The NO production in anoxic endothelial cells decreased markedly. 39℃ heat stress preconditioning induced the increase in NO production in endothelial cells, but 41℃ heat stress preconditioning made the NOS activity decrease. The NO production was correlated negatively with LDH release and cell death rate in anoxic endothelial cells. CONCLUSION:The heat stress preconditioning within the limits can protect the endothelial cells from anoxia injury. The increase in NO in endothelial cells may play an important role in the mechanism of the protective effect.     

Advances in materials of keratoprosthesis and tissue engineering cornea

Although allograft corneal transplantation has made great progress, keratoprothesis implantation is the only one hope, for both the patients who has fleshy pannus corneal vitiligo and the patients with the failure corneal transplantation surgery whose far sight is only light perceptions to recover their eye sight. To gain success and reduce complications, a lot of work has been done in keratoprosthesis materials and type, but heterogeneity and bio-compatibility are not solved totally. Because of development in the cell culture and tissue engineering, cornea ex vivo culture has gain a critical success. From cell option to carrier using, reconstructed three dimensional culture and epithelium equivalent mimicked human corneas in key morphology and function and were used in basic and clinical investigation. This article reviews the development of materials of keratoprosthesis and tissue engineering cornea.     

Effects of testosterone on endothelial function and intimal proliferation after balloon injury in male rabbit abdominal aorta

AIM: To investigate the effects of testosterone on endothelial function and intimal proliferation after balloon injury in male rabbit abdominal aorta. METHODS: 24 male New Zealand white rabbits were divided randomly into three groups: control group (n=8, sham castration), hypotestosteronemia group (n=8,castration) and testosterone replacement group (n=8,castration +testosterone undecanoate intramuscular injection,14mg/kg). Abdominal aorta was injured with 3 mm PTCA balloon after testosterone undecanoate had been injected for three days. Two weeks later, blood samples were obtained for detection of plasma testosterone, lipids, metabolic product of nitric oxide (NO₂^-／NO₃^-), superoxide dismutase(SOD) and malondialdehyde (MDA),and all the abdominal aorta were excised to be analyzed by computer. RESULTS: The intimal area of hypotestosteronemia group were significantly larger than that of other two groups(P＜0.01). plasma NO₂^-／NO₃^- and SOD levels were significantly decreased, while the total cholesterol(TC),triglycerides(TG), low density lipoprotein(LDL) and plasma MDA were significantly increased. No difference was observed between control group and testosterone replacement group in all parameters. CONCLUSION: Testosterone, at physiological level,had the effects of inhibiting the intimal proliferation and of protecting the endothelial function after balloon injury in male rabbit abdominal aorta.