Objective To study the effect of hypoxia on proliferation of cultured bovine retinal pigment epithelium (RPE) cells and expression of the antiapoptotic protein bcl-2. Methods The bovine RPE cells were cultured under normal and hypoxic chamber respectively. After 24 hours, the proliferation of RPE cells was evaluated by［3-(4,5-dimethylthiazole-2yl)-2,5-diphenyl tetrazolium bromide, MTT］test. At the same time, anti-bcl-2 protein antibody was examined by immuno-histochemistry method. Results The A value in the hypoxia group was higher than that in the normal group after 24 hours (P＜0.05 )in MTT-test. Positive staining for anti-bcl-2 protein antibody was seen in 72.6% cells in hypoxia group and 38.64% in normal group. The positive staining was more obvious near the nucleus, and fine granules scattered in cytoplasm of some cells. Conclusion Hypoxia can stimulate the proliferation of RPE cells and expression of antiapoptotic protein bcl-2. The results indicate that bcl-2 may play an important role in mediating the proliferation activity of RPE cells. (Chin J Ocul Fundus Dis, 2002, 18: 293-295)
Objective To compare the effects of hypoxia-inducible drugs using deferoxamine (DFO) and accordion technique (AT) on activating the hypoxia-inducible factor 1α (HIF-1α)/vascular endothelial growth factor (VEGF) signaling pathway to promote bone regeneration and remodelling during consolidation phase of distraction osteogenesis (DO). Methods Forty-five specific-pathogen-free adult male Sprague-Dawley (SD) rats were randomly divided into the control group, DFO group, and AT group, with 15 rats in each group. All rats underwent osteotomy to establish a right femur DO model. Then, continuous distraction was started for 10 days after 5 days of latency in each group. During the consolidation phase after distraction, no intervention was performed in the control group; DFO was locally perfused into the distraction area in the DFO group starting at the 3rd week of consolidation phase; cyclic stress stimulation was given in the AT group starting at the 3rd week of consolidation phase. The general condition of rats in each group was observed. X-ray films were conducted at the end of the distraction phase and at the 2nd, 4th, and 6th weeks of the consolidation phase to observe the calcification in the distraction area. At the 4th and 6th weeks of the consolidation phase, peripheral blood was taken for ELISA detection (HIF-1α, VEGF, CD31, and Osterix), femoral specimens were harvested for gross observation, histological staining (HE staining), and immunohistochemical staining [HIF-1α, VEGF, osteopontin (OPN), osteocalcin (OCN)]. At the 6th week of the consolidation phase, Micro-CT was used to observe the new bone mineral density (BMD), bone volume/tissue volume (BV/TV), trabecular separation (Tb.Sp), trabecular number (Tb.N), and trabecular thickness (Tb.Th) in the distraction area, and biomechanical test (ultimate load, elastic modulus, energy to failure, and stiffness) to detect bone regeneration in the distraction area. Results The rats in all groups survived until the termination of the experiment. ELISA showed that the contents of HIF-1α, VEGF, CD31, and Osterix in the serum of the AT group were significantly higher than those of the DFO group and control group at the 4th and 6th weeks of the consolidation phase (P<0.05). General observation, X-ray films, Micro-CT, and biomechanical test showed that bone formation in the femoral distraction area was significantly better in the DFO group and AT group than in the control group, and complete recanalization of the medullary cavity was achieved in the AT group, and BMD, BV/TV, Tb.Sp, Tb.N, and Tb.Th, as well as ultimate load, elastic modulus, energy to failure, and stiffness in the distraction area, were better in the AT group than in the DFO group and control group, and the differences were significant (P<0.05). HE staining showed that trabecular bone formation and maturation in the distraction area were better in the AT group than in the DFO group and control group. Immunohistochemical staining showed that at the 4th week of consolidation phase, the expression levels of HIF-1α, VEGF, OCN, and OPN in the distraction area of the AT group were significantly higher than those of the DFO group and control group (P<0.05); however, at 6th week of consolidation phase, the above indicators were lower in the AT group than in the DFO group and control group, but there was no significant difference between groups (P>0.05). Conclusion Both continuous local perfusion of DFO in the distraction area and AT during the consolidation phase can activate the HIF-1α/VEGF signaling pathway. However, AT is more effective than local perfusion of DFO in promoting the process of angiogenesis, osteogenesis, and bone remodelling.
ObjectiveUnder hypoxic conditions, the survival and apoptosis of human amniotic mesenchymal stem cells (hAMSCs) were observed by transient transfection of hypoxia-inducible factor 1α (HIF-1α) gene, to investigate the effect of HIF-1α on hypoxic tolerance of hAMSCs.MethodsThe hAMSCs were isolated and cultured from amniotic membrane tissue from voluntary donors who were treated with cesarean section. And the morphological observation by inverted phase contrast microscope and immunofluorescence detection of the expressions of stem cell markers OCT-4 and NANOG were performed to identify the cultured cells. The third generation hAMSCs were treated with 200 μmol/L CoCl2, and transient transfection of plasmids were added according to the following grouping: group A was hAMSCs blank group; group B was pcDNA3.1 negative control group; group C was short hairpin RNA (shRNA) negative control group; group D was shRNA-HIF-1α interference group; group E was pcDNA3.1-HIF-1α over expression group. Cell survival rate of each group was measured by cell counting kit 8 (CCK-8) at 12, 24, 48 hours after hypoxia treatment. Flow cytometry was used to detect apoptosis rate of each group at 24 hours after hypoxia treatment. The expression levels of HIF-1α, vascular endothelial growth factor (VEGF), B-cell lymphoma 2 (Bcl-2), Bax, and cleaved Caspase-3 (C-Caspase-3) proteins were detected by Western blot at 24 hours after hypoxia treatment.ResultsCCK-8 assay showed that the cell survival rate of group D was significantly lower than those of groups A and C at all time points after hypoxia treatment; while the cell survival rate in group E was significantly increased than those in groups A and B, and the diffrences at 24 hours were significant (P<0.05). In group E, the cell survival rate at 24 hours was significantly higher than those at 12 and 48 hours (P<0.05). The results of flow cytometry showed that the apoptosis rate in group D was significantly higher than those in groups A and C (P<0.05), and the apoptosis rate in group E was significantly lower than those in groups A and B (P<0.05). Western blot showed that the expressions of HIF-1α, VEGF, and Bcl-2 proteins in group D were significantly decreased when compared with those in groups A and C, and the expressions of Bax and C-Caspase-3 proteins were significantly increased (P<0.05). On the contrary, the expressions of HIF-1α, VEGF, and Bcl-2 proteins in group E were significantly higher than those in groups A and B, and the expressions of Bax and C-Caspase-3 proteins were significantly decreased (P<0.05).ConclusionOverexpression of HIF-1α gene can significantly improve hAMSCs tolerance to hypoxia, the mechanism may be related to up-regulation of VEGF and Bcl-2 expressions, and down-regulation of Bax and C-Caspase-3 expressions.
Objective To investigate the effect of hypoxia on expressions of erythropoietin（EPO）mRNA and protein in retinal Muuml;ller cells cultured in vitro. Methods Retina tissues from the new-born Wistar rats were dissected into cell suspension after digested by pancreatin.Muuml;ller cells were separated and purified by mechanical concussion and blowing and striking method.The expression of EPO mRNA and protein under the condition of hypoxia was detected by semi-quantitative reverse transcriptase（RT）-polymerase chain reaction（PCR）and immunocytochemical method. Results Retinal Muuml;ller cells were cultured successfully，95% of which were positively stained by glial fibrillary acidic protein（GFAP）.Positively stained EPO protein was located in the cytoplasm and protuberance.The expression of EPO mRNA and protein was faint in the normal retinal Muuml;ller cells，but increased obviously and time-dependently after hypoxia. Conclusion Expression of EPO mRNA and protein increases in Muuml;ller cells after hypoxia，which may be one of the protective factors for the nerves in anoxic retinopathy. (Chin J Ocul Fundus Dis, 2006, 22: 196-199)
Objective：To investigate the role of 17beta; estradiol on th e expressi on of vascular endothelial growth factor (VEGF) and on the releasing rate of lac tate dehydrogenase (LDH) in cultured anoxiainjured human retinal pigment epit h eliual (RPE) cells. Methods:Established the anoxiainjuried m odel of human RPE c ells with Cobalt Chloride (CoCl2) after RPE cells were pretreated with 17beta;E 2 and tamoxife, 17beta;E2 antagonist. The expression of VEGF mRNA was detecte d by re v erse transcriptionpolymerase chain reaction technique (RTPCR). The cultured RP E cells were divided into four groups: normal control group, anoxiainjured gro u p, 17beta;E2 pretreatment group and 17beta;E2 with tamoxifen pretreatment grou p. The releasing rate of LDH was detected by chromatometry. The expression of VEGF pro tein were detected by cellular immunohistochemistry. Results:T he expression of VEGF and LDH releasing rate were higher in anoxiainjured grou p than that in nor m al control group (P＜0.05), and were lower in 17beta;E2 pretreatment group than th at in anoxiainjured group （P＜0.05）. When the effect of 17beta;E2 was o bstructe d by tamoxifen, the expression of VEGF and LDH releasing rate increased but didn prime;t differ much from which in anoxiainjured group (P＞0.05). Conc lusion:The ex pression of VEGF increases in anoxiainjured human RPE cells. 17beta;E2 can do wnr egulate the expression of VEGF and decrease the releasing rate of LDH, which can be blocked by tamoxifen.
ObjectiveTo investigate the effects of smoking combined with intermittent hypoxia on the pathophysiology of lung tissue and thoracic aorta, and the endothelial injury.MethodsTwenty-four rats (SPF, female, six weeks old) were divided randomly into 4 groups (n=6). The control group was given false smoking and normal oxygen exposure, the smoking-exposed group was exposed in smoking, the intermittent hypoxia group was exposed in intermittent hypoxia environment, and the overlap group was exposed to smoking and intermittent hypoxia. After 8 weeks, body weight, right ventricular hypertrophy index (RVHI), the pathological changes of lung tissue and thoracic aorta were measured, and the level of endothelin-1 (ET-1), endothelial nitric oxide synthase (eNOS), vascular endothelial growth factor (VEGF) and stromal cell-derived factor-1α (SDF-1α) in serum of rats were evaluated.ResultsRVHI of rats in the smoking-exposed group, intermittent hypoxia group, overlap group were higher than that in the control group. In addition, RVHI in the overlap group was higher than that in the smoking-exposed group, intermittent hypoxia group (all P<0.05). The levels of ET-1, VEGF and SDF-1α in the serum of the smoking-exposed group, intermittent hypoxia group and overlap group were higher than those in the control group, while the level of eNOS was lower than that in the control group, (all P<0.05), the most significant difference was between control group and the overlap group. Pathological observation of lung tissue and thoracic aorta showed obvious emphysema in the smoking-exposed group and overlap group, which was more obvious in the overlap group than that in the smoking-exposed group (all P<0.05). Lung interstitial inflammatory infiltration, bronchial wall lymphocyte hyperplasia and pulmonary fibrosis were shown in different degrees in the smoking-exposed group, intermittent hypoxia group and overlap group, and the pulmonary arteriole wall showed thickening, fibrosis and peripheral inflammatory infiltration also were found in these groups. Thoracic aorta in the smoking-exposed group, intermittent hypoxia group and overlap group showed different degrees of endothelial cell injury, middle membrane thickening, and collagen fiber hyperplasia. The pathological features of the overlap group were most obvious compared to the other two groups.ConclusionsSmoking and intermittent hypoxia exposure can lead to different degrees of lung tissue and vascular endothelial injury and decrease of vascular endothelial protective factors in rats, resulting in dysfunction of vascular endothelial cells, which leads to the structural remodeling of pulmonary arterioles and aorta, such as thickening, fibrosis, etc. Combined smoking and intermittent hypoxia exposure can lead to more serious pathological damage.
Objective To study the effect of hypoxia on the prol iferation of hBMSCs and human placental decidua basal is-MSCs (hPDB-MSCs), and to provide the theoretical basis for discovering the new seed cells source for tissue engineering. Methods Density gradient centrifugation method was adopted to isolate and culture hBMSCs and hPDB-MSCs,flow cytometry (FCM) was appl ied to detect cell surface marker. After establ ishing the experimental model of CoC12 chemical hypoxia, MTT method was appl ied to evaluate the prol iferation of hBMSCs and hPDB-MSCs at different time points (6, 12, 24, 48, 72, 96 hours) with various CoC12 concentration (0, 50, 75, 100, 125, 150, 175, 200 μmol/L). Results FCM analysis revealed that hPDB-MSCs and hBMSCs expressed CD9, CD29, CD44, CD105, CD106 and human leucocyte antigen ABC (HLA-ABC), but both were absent for CD34, CD40L and HLA-DR. Compared with hBMSCs, hPDB-MSCs expressed stage-specific embryonic antigen 1 (SSEA-1), SSEA-3, SSEA-4, TRA-1-60 and TRA-1-81 better. The prol iferations of hPDB-MSCs and hBMSCs were inhibited within the first 12 hours under hypoxia condition, but promoted after 12 hours of hypoxia. Compared with the control group, the hBMSCs were remarkably prol iferated 24 hours after hypoxia with CoC12 concentration of 150 μmol/L (P lt; 0.05), while hPDB-MSCs were significantly prol iferated 12 hours after hypoxia with CoC12 concentration of 75 μmol/L (P lt; 0.05). Conclusion Compared with hBMSCs, hPDB-MSCs express more specific surface antigens of embryonic stem cells and are more sensitive to the prol iferation effects of chemical hypoxia, indicating it may be a new seed cells source for tissue engineering.
Objective To observe the expression of vascular endothelial growth factor receptor-1 (VEGFR-1) and VEGFR-2 in hypoxic chorioretinal endothelial cells of monkeys (RF/6A), and to evaluate the effect of minocycline. Methods RF/6A was cultured and divided into four groups: control group, hypoxia group, hypoxia and low dose of minocycline group (0.5 mu;mol/L), hypoxia and medium dose of minocycline group (5 mu;mol/L), and hypoxia and high dose of minocycline group (50 mu;mol/L). Real-time reverse transcriptionpolymerase chain reaction (RT-PCR) and immunohistopathological staining were used to measure the mRNA and protein expression of VEGFR-1 and VEGFR-2, respectively. Results RT-PCR showed that the expression of VEGFR-1 mRNA did not vary significantly between groups (F 24 h=0.17,F 48 h=1.53,F72 h=2.04;P＞0.05). Compared with hypoxia group, the expression of VEGFR-2 mRNA in all minocycline treated groups were significantly downregulated (low minocycline, medium minocycline, high minocycline: t=4.69, 20.16, 17.12; P＜0.001). The immunohistopathological study showed the cells with positive staining of VEGFR-1 can be observed in all groups, and the staining was relatively weak and mainly located in cell membrane and cytoplasm. The optical density value analysis showed that the protein expression of VEGFR-1 did not vary significantly between groups at all time points（F 24 h=0.251,F 48 h=0.340,F72 h=0.589;P＞0.05）. The VEGFR-2 positive staining cells were also observed in all groups, and the staining was relatively high. Brown staining particles of VEGFR-2 were observed in the cell membrane with minor staining particles in cytoplasm. The staining density of VEGFR-2 was significantly higher in hypoxia group than control group. Compared with the hypoxia group, the protein expression of VEGFR-2 in minocycline treated groups was significantly lower（F 24 h=19.147,F 48 h=14.893,F72 h==11.984; P＜0.05). Conclusion The expression of VEGFR-2 is upregulated in RF/6A, and minocycline somewhat shows an inhibition effect.
Objective To investigate relationship between hypoxia microenvironment and occurrence and development of hepatocellular carcinoma (HCC). Method The relevant literatures on researches of the relationship between the hypoxic microenvironment and the HCC were review and analyzed. Results The hypoxia microenvironment played an important role in inducing the drug resistance and angiogenesis of the HCC cells, and it was an important factor of affecting the ability of tumor metabolism, invasion, and migration. The hypoxia microenvironment could up-regulate the expression of hypoxia-inducible factors (HIFs) and promote its transcriptional activity, promote the expression of the vascular endothelial growth factor gene, and regulate the neovascularization in the tumor. Among them, the HIF-1α played a major role in regulating the angiogenesis, immune escape, tumor invasion and metastasis-related gene expression, participating in the glycolysis, regulating lysyl oxidase 2 and thus regulated epithelial-mesenchymal transition, then promoted the invasion and metastasis of the HCC; HIF-2α was a key regulator of the malignant phenotype involving in the cell proliferation, angiogenesis, apoptosis, metabolism, metastasis, and resistance to chemotherapy. The hypoxia microenvironment posed some difficulties for the treatment of HCC, but it was also a potential therapeutic breakthrough. Conclusion Hypoxia microenvironment can promote invasion and metastasis of HCC through various mechanisms, which provides new targets and strategies for clinical treatment of HCC.
ObjectiveTo study the influence of hemin on blood pressure of intermittent hypoxic rats and investigate the mechanism of hypertension caused by intermittent hypoxia.MethodsTwenty-four male SD rats were randomly divided into a hemin group, an intermittent hypoxia group (IH group) and a normal group. Thirty minutes after intraperitoneal injection of hemin, the rats in the hemin group were exposed to intermittent normobaric hypoxic environment (8 h/d). The rats in the IH group were intraperitoneal injected with normal sodium and then exposed to the same environment (8 h/d). The rats in the normal group were intraperitoneal injected with normal sodium and placed in the glass box. The three groups were bred in the same condition. Thirty-five days later, the mean carotid artery pressure (mCAP) of the rats was measured and their plasma carbon monoxide (CO) level was measured by Chalmer’s method. Reverse transcription polymerase chain reaction was performed to detect the levels of heme oxygenase-1 (HO-1) mRNA expression in lung, liver, spleen, kidney and other organs. The expression of HO-1 protein in the organs was detected by immunohistochemistry.ResultsThe mCAP in the IH group was significantly higher than the hemin group and the normal group (P<0.05), and was higher in the hemin group than the normal group (P<0.05). The concentration of plasma CO in the hemin group was higher than the IH group and the normal group (P<0.05). There was no significant difference in plasma CO between the IH group and the normal group (P>0.05). The expression of HO-1 mRNA of lung, liver, spleen and kidney in the hemin group and the IH group was higher than the normal group (P<0.05), and was higher in the hemin group than the IH group (P<0.05). The relationship between mCAP and HO-1 mRNA showed a curvilinear trend. The quadratic curve fitting equation was Y=39.715+446.640X-334.353X2.ConclusionsIntermittent hypoxia can cause hypertension in rats. The HO-1 expression is increased in hypoxic rats, but the plasma CO does not increase significantly. As an inducer of HO-1, hemin can increase the expression of HO-1 and CO in hypoxic rats, then lower their blood pressure to some extent.