Purification and adipogenic differentiation of human yolk sac mesenchymal stem cells

AIM:To purify human yolk sac mesenchymal stem cells (hYS-MSC) and investigate its adipogenic differentiation potential. METHODS:hYS-MSC were separated from yolk sac and purified via passaged culture. Flow cytometric analysis was used to identify the phenotype of hYS-MSC and the alkaline phosphatase(AKP) expression of hYS-MSC was also tested. Adipogenic differentiation of hYS-MSCs was induced by 10 mg/L insulin, 10^-5mol/L indomethacin and 10^-6mol/L dexamethasone. Oil Red O was used for fat staining. RESULTS:hYS-MSCs were purified at passages 2 or 3. Flow cytometric analysis showed the phenotype of purified YS-MSCs was uniformly positive for CD29, CD44, CD105, and CD166, and negative for reactivity to antigens CD34, CD45, or CD86. hYS-MSCs were weakly but clearly positive in AKP. Adipogenic differentiation of YS-MSCs was induced by 10 mg/L insulin, 10^-5mol/L indomethacin and 10^-6mol/L dexamethasone. Accumulation of lipid-rich vacuoles positive in oil red O staining within the cells were appeared and nuclears were pushed to one side of the cells during the period of induction. CONCLUSION:The phenotype of hYS-MSC is coincident with adult human mesenchymal stem cells. hYS-MSC can be induced to differentiate into adipocytes in vitro.     

Change of yolk antibody titers in hens immunized with SARS-CoV antigen

AIM：To observe the change of yolk antibody titers after immunizing hens with SARS-CoV antigen.METHODS：Yolk antibody diluted with water to 1∶1 600 was determined with ELISA methods.RESULTS：The Cutoff is 0.21±0.05.After immunization,antibody titers in hens reached the peak in first 26-28 day (A450=1.3 when antibody was diluted as 1∶1 600),and hold high titers (A450>0.8).The antibody titers decreased after the time of immunity.The increase and peaking of antibody titers were observed at intervals when repeated immunizations were given.CONCLUSION：Yolk antibody kept high titers when hens were immunized with SARS-CoV antigen.     

Effects of endothelial nitric oxide synthase gene transfection on cytokines and cAMP production in human phagocytic cells

AIM and METHOD: Human endothelial nitric oxide synthase (eNOS) gene was transfected into human phagocytic cell U937 and the effects of gene transfer on cytokines and cAMP production were observed. RESULTS: A functional eNOS was stably expressed in transfected U937 cells, but NO release was undetectable in intact transfectants. However, eNOS gene expression upregulated tumor necrosis factor-α release and downregulated interleukin-10 and cAMP production in either presence or absence of NOS inhibitor N^ω-monomethyl-L-arginine. CONCLUSION: The function of tranfected eNOS gene product showed cellular speciality. The effector molecule that changed the produced pattern of cytokines and cAMP in phagocytic cells seems not likely the nitric oxide.     

Effects of exosomes derived from hypoxia-preconditioned umbilical cord mesenchymal stem cells on function of endothelial cells

AIM To investigate the effect of exosomes derived from hypoxia-preconditioned human umbilical cord mesenchymal stem cells (hUCMSCs) on proliferation, migration and tube formation of human umbilical vein endothelial cells (HUVECs). METHODS hUCMSCs and HUVECs were isolated, cultured and identified. Exosomes derived from hUCMSCs were extracted by ultracentrifugation. The morphological change of exosomes was observed under transmission electron microscope. The particle size and concentration of exosomes were detected by nanoparticle tracking analysis, and the surface specific marker proteins of exosomes were determined by Western blot. hUCMSCs were divided into normoxia group and hypoxia group. The viability of hUCMSCs was measured by CCK-8 assay. HUVECs were divided into control group, normoxic exosome group and hypoxic exosome group. The proliferation of HUVECs was detected by EdU assay. The migration ability was detected by cell scratch assay and Transwell experiment. Tube formation ability was evaluated by tube formation experiment. RESULTS Compared with normoxia group, hypoxia pretreatment enhanced the viability and exosome release of hUCMSCs. Compared with normoxic exosome group, hypoxic exosomes enhanced the proliferation, migration and tube formation of HUVECs. CONCLUSION Exosomes derived from hUCMSCs under hypoxia enhances the proliferation, migration and tube formation of HUVECs.     

Vascular endothelial growth factor on function of endothelial progenitor cells from peripheral blood

AIM: To investigate the effect of vascular endothelial growth factor(VEGF) on the biological function of peripheral endothelial progenitor cells (EPCs) and to find the suitable concentration to promote the growth of EPCs.METHODS: Total mononuclear cells (MNCs) were isolated from peripheral blood by density gradient centrifugation,and then the cells were plated on fibronectin-coated culture dishes.After culture for 4 days,attached cells were incubated with VEGF in a series of concentrations (0,10,20 and 50 μg/L) for 72 h,then attached cells were characterized with immunohistochemistry.EPC proliferation and migration activity were assayed with MTT assay and modified Boyden chamber assay,respectively.EPC adhesion assay was performed by replating MNCs on fibronectin-coated dishes,and then the adherent cells were counted.RESULTS: The EPCs from MNCs were successfully isolated and were differentiated to endothelial cells (ECs).Incubation of isolated human MNCs with VEGF increased the proliferative,migratory and adhesive capacities of EPCs,and this effect was most prominent when the concentration of VEGF was 20 μg/L after 72 hours.At the same concentration of VEGF,the functions of EPCs from patients with masculine coronary arteriography were lower than those of EPCs from patients with negative coronary arteriography.CONCLUSION: Functional activities of EPCs are decreased in patients with masculine coronary arteriography.The results suggest that the low concentration of VEGF may improve functional activities of EPCs.     

Human bone marrow mesenchymal stem cells differentiate toward endothelial lineage in vitro

AIM：To investigate the cytological basis and differentiating conditions of human bone marrow mesenchymal stem cells(hMSCs) differentiated into cells of the endothelial lineage in vitro.METHODS：hMSCs were isolated by density gradient centrifugation and fractionated on a 1 073 g/L Percoll.The combination of VEGF165 and various matrix proteins including fibronectin (FN) and typeⅠ collagen (Col) was used to induce hMSCs in vitro.Cells were characterized by immunohistochemistry,cytochemistry,FACS and ultrastructure to identify and detect the differentiated population and markers.RESULTS：hMSCs was positive for KDR.PAS reaction was positive and ultrastructure of hMSCs showed glycogen-pool in ectoplasm.Glycogen reducing or disappear suggested that stem cells have occurred differentiation.Induction of hMSCs resulted in the increase of KDR,β1 integrin and CD34.CONCLUSION：hMSCs were induced to a transit population (TP) that differentiated toward the endothelial progenitor cells (EPC),but not a really EPC.hMSCs pedigree diagram of differentiation was hMSCs→TP→EPC→endothelial cells (ECs).     

Effect of homocysteine on the apoptosis of cultured human umbilical vein endothelial cells

AIM: To investigate the effect of homocysteine(Hcy) on the apoptosis of endothelial cells (EC). METHODS: First-passaged human umbilical vein endothelial cells (hUVEC) were cultured with M199 containing 3 mmol/L Hcy. hUVEC apoptosis was detected as follow: demonstration of nuclear changes by Hoechst 33258 staining, agarose gel electrophoresis of DNA fragments, detection of apoptotic cells by flow cytometry following Annexin V-PI doubled stain, Western blot for P53 and Bax protein detection and colorimetry detecting caspase-3 activity. RESULTS: Compared with control, homocysteine induced characteristic apoptotic changes in hUVEC. The chromosomal DNA of hUVEC appeared "DNA ladder" by agarose gel electrophoresis. Apoptotic cells were increased significantly (P<0.01, n=3). Hcy promoted the expression of protein Bax, P53 (P<0.01, n=3) and enhanced the activity of caspase 3 (P<0.05, n=3). CONCLUSION: Homocysteine induces apoptosis in cultured hUVEC.     

Effects of statin reloading before percutaneous coronary intervention on circulatory endothelial progenitor cells and inflammatory cytokines

AIM:To investigate the effects of atorvastatin reloading in pre-percutaneous coronary intervention (PCI) period on endothelial progenitor cell (EPC) count and inflammatory cytokine expression in the stable angina pectoris patients who had previously received long-term statin treatment. METHODS:The patients with stable angina pectoris that had received long-term statin therapy and planned to accept PCI were randomized into 3 groups: 80 mg atorvastatin 12 h and 40 mg 2 h before coronary angioplasty (80 mg reloading), pre-operatively with 40 mg/d atorvastatin for 7 d (40 mg reloading), and without atorvastatin reloading (no reloading). CD45-/CD133+/CD34+, CD45-/CD34+/KDR+ and CD45-/CD144+/KDR+ EPCs in 100 μL peripheral blood were determined by flow cytometry 1 h prior to PCI and 1 h, 6 h and 24 h after PCI. The serum concentrations of soluble intercellular adhesion molecule 1 (sICAM-1), C-reactive protein (CRP) and troponin I (TnI) were analyzed immediately prior to and 24 h after PCI. RESULTS: (1) In 80 mg reloading group, the numbers of circulating CD45-/CD133+/CD34+ and CD45-/CD34+/ KDR+ early differentiation stage EPCs 1 h and 6 h after coronary angioplasty was significantly elevated compared with those before PCI (P<0.05). (2) In control group, the serum concentrations of sICAM-1 and CRP 24 h after PCI were significantly elevated (P<0.05) compared with preoperative values. (3) The rise in serum TnI concentration from pre- to post-operation in 80 mg reloading group was lower than that in control group. CONCLUSION: The method of atorvastatin reload before PCI affects the number of EPCs in peri-operative period. High dose of atorvastatin application before PCI triggers early EPC circulation. The serum levels of post-operative inflammatory cytokine sICAM-1 as well as CRP are reduced by atorvastatin reloading before PCI.     

Serum from rats at different ages modulates the functional activities of rat bone marrow-derived endothelial progenitor cells

AIM: To investigate the effects of serum from rats at different ages on the functional activities of rat bone marrow-derived endothelial progenitor cells (EPCs). METHODS: Mononuclear cells were obtained from bone marrow of young (1 to 2 month-old) and aged (19 to 26 month-old) Sprague-Dawley rats by Ficoll density gradient centrifugation and cultured with medium DMEM/F12 (containing 10% fetal bovine serum, endothelial cell growth supplement ECGs 100 mg/L, 1×10⁵ U/L of penicillin and streptomycin, respectively), 48 h later, the suspending cells were translocated to be cultured in new flasks coated with fibronectin, the secondary attached cells were used to perform the further experiments. EPCs were characterized as double positive for Dil-ac-LDL uptake and lectin binding. The cells were further identified by CD31 and vWF expression. Serum from young (1 to 2 month-old) and aged (19 to 26 month-old) rats was collected and used to culture EPCs. The experiments were divided into four groups: A= aged rat EPCs + aged rat serum; B= aged rat EPCs + young rat serum; C= young rat EPCs +aged rat serum and D= young rat EPCs + young rat serum. After cultured in DMEM/F12 supplemented with 10% serum from rats at different age (no fetal bovine serum addition in this medium), the average fluorescence intensities of EPCs stained with Dil-ac-LDL were tested by laser scanning co-focal microscopy. Migration and proliferation were assayed by modified Boyden chamber and MTT, respectively. Cell adhesion was performed by replacing EPCs onto cultured DAPI-labeled confluent smooth muscle cell monolayer and the adherent cells were counted. RESULTS: Young rat serum significantly improved the ability of aged rat EPCs for uptake of Dil-ac-LDL (P<0.01), increased the migration (P<0.01), adhesion (P<0.05) and proliferation activity (P<0.01) of aged rat EPCs, whereas aged rat serum obviously decreased the migration (P<0.05) and adhesion (P<0.05) activity of the young rat EPCs. CONCLUSION: Young rat serum significantly improves the activity of aged rat EPCs. On the contrary, aged rat serum partially inhibits the activity of young rat EPCs.     

Regulatory effect of miRNA enfolded in microparticles on endothelial cells

Endothelial cells are the cells lining the inner surfaces of blood vessels. They build up a single cell layer and play an important role in the regulation of vascular functions and the maintenance of homeostasis. The activation or injury of endothelial cells is associated with multiple diseases, including hypertension, atherosclerosis, cancer, diabetes, etc. Recent studies have found that microparticles are involved in the process of endothelial cell injury, thus playing a part in the development of many diseases. miRNAs enfolded in the microparticles have become importance in recent years. Moreover, recent studies also found that the concentration of the miRNAs enfolded in the microvesicles is higher than that of the miRNAs in the plasma, which means that the microparticles are the main form of miRNAs present in peripheral circulatory system. This article is to review the recent research progress in microparticle-encapsulated miRNAs and their regulatory effect on endothelial cell injury.     

Chlamydia pneumoniae enhanced the expression of ICAM-1 in cultured human umbilical vein endothelial cells

AIM: To investigated the effects of Chlamydia pneumoniae (C.pneumoniae) infection on the expression of intercellular adhesion molecule-1 (ICAM-1) in cultured human umbilical vein endothelial cells (HUVECs). METHODS: After propagated in HEP-2 cells, C. pneumoniae organisms were infected to HUVECs. The infection was assessed by ectromicroscope and PCR. The expression of ICAM-1 on HUVECs was detected by flow cytometry before infection and 12 h, 24 h, 48 h, 72 h after infection. RT-PCR was used to detect the ICAM-1 mRNA expression. RESULTS: C.pneumoniae was able to infect cultured HUVECs. After infection, the expression of ICAM-1 on the surface of cultured HUVECs was increased,, the peak was at the time of about 24-48 h; The light quantative RT-PCR analysis demonstrated that the infection also enhanced the ICAM-1 mRNA expression. CONCLUSION: The ability of C.pneumoniae to grow in HUVECs and to stimulate the expression of ICAM-1 protein and mRNA suggests that C.pneumoniae may playa role in atheriosclerosis.     

Role of nitric oxide in proliferation and secretion effect of vascular endothelial cells induced by vascular endothelial growth factor

AIM: To investigate the role of nitric oxide in proliferation and secretion of vascular endothelial cells induced by vascular endothelial growth factorr (VEGF). METHODS: The in vitro cultured vascular endothelial cells of rabbit aorta were divided into control group, VEGF-treated group and VEGF+L-NAME treated group, the absorbance (A) value of vascular endothelial cells, endothelin-1(ET-1) and von Willebrand factor (vWF) in the supernatant were examined by WST-1 assay, radioimmunoassay and ELISA. RESULTS: The A value in VEGF and VEGF+L-NAME treated group were higher than that in control group (P＜0.01). A value in VEGF group was higher than that in VEGF+L-NAME group the ET-1 and vWF were markedly decreased in VEGF group compared with the control and VEGF+L-NAME treated group (P＜0.05, P＜0.01). These results indicated that VEGF promoted the proliferation and inhibited the secretion of ET-1 and vWF in vascular endothelial cells, and L-NAME inhibited the effect of VEGF. CONCLUSION:Nitric oxide is an important mediator in the process of stimulating proliferation and regulating secretion of vascular endothelial cells by VEGF.     

Effects of component of some Chinese herbs on proliferation of human umbilical vein endothelial cells in vitro

AIM: To observe the effects of some component of Chinese herbs for external use on proliferation of human umbilical vein endothelial cells (HUVEC) and investigate the mechanism of promoting tissue repair. METHODS: The method of MTT was used to examine the effects of Rg1, Rh1, perlolyrine, cinnamyl aldehyde, muscone, astragaluspolysaccharin (APS), velver antler polypeptide (VAP) and soluble extract of boswellia carterii birdw (BCB) on proliferation of HUVEC. RESULTS: APS did not promote proliferation of HUVEC at 9.75 mg/L-2.5 g/L; Rh1 promoted proliferation of HUVEC at 1.94 mg/L-0.5 g/L (P<0.05 or P＜0.01), and Rg1 inhibited proliferation of HUVEC at 31 mg/L (P<0.05); VAP promoted proliferation of HUVEC at 1 mg/L-0.5 g/L with optimal dose of 10 mg/L (P<0.01), Cinnamyl aldehyde promoted proliferation of HUVEC at 2 g/L(P＜0. 05); Muscone and soluble extract of BCB inhibited proliferation of HUVEC at 1 g/L, 0.5-2.5 kg/L(P＜0. 01), respectively; Perlolyrine inhibited proliferation of HUVEC at 0.125 g/L-0.5 g/L(P＜0. 01). CONCLUSION: The external herbs for supplementing Qi and warming Yang can promote HUVEC proliferation and improve angiogenesis during tissue repair. The external herbs for promoting blood circulation and accelerating capillary movement may have influence upon other stages of tissue repair.     

Rat mesenchymal stem cells differentiate into neuron-like cells induced by berberine in vitro

AIM: To investigate whether berberine can induce rat mesenchymal stem cells (MSCs) to differentiate into neuron -like cells in vitro. METHODS: MSCs were separated from young rat femurs marrow and expanded in culture medium. MSCs were induced to differentiate by berberine. The morphological changes of MSCs were evaluated by light microscope.Neuron-spcific enolase (NSE), neurofilament (NF), glial fibrillary acidic protein (GFAP) were detected by immunohistochemistry. RESULTS: Induced by berberine for 8 hours,MSCs exhibited neurotype . The expression of NSE and NF in the neuron-like cells was positive, but the glial astrocyte marker GFAP didn't express. CONCLUSION: Berberine may induce adult rat MSCs to differentiate into neuron-like cells in vitro.     

Overexpression of Jagged1 promotes aged rat-derived endothelial proge-nitor cells differentiating into mature endothelial cells

AIM: To investigate the effect of Jagged1 overexpression on endothelial cell-directional differentiation of aged rat-derived endothelial progenitor cells (EPC).METHODS: Mononuclear cells were obtained from bone marrow of young (1 to 2 months old) or aged (19 to 26 months old) Sprague-Dawley rats and cultured in DMEM/F12 medium supplemented with 10% FBS. EPC were characterized as double positive for DiI-ac-LDL uptake and lectin binding. The experiments were divided into control group, PIRES2-EGFP transfection group, PIRES2-EGFP-Jagged1 transfection group and young rat-derived EPC group in which transfection was not performed. The GFP expression positive cell number was acquired by fluorescence microscopy and the transfection efficiency was calculated. Immunofluorescence, RT-PCR and Western blotting were used to detect the mRNA and protein expression. In vitro vasculogenesis kit was used to test the tube formation ability of EPC.RESULTS: EGFP-Jagged1 transfection induced a significant increase in the expression of Jagged1 in aged rat-derived EPC (P<0.01). Compared with the control, Jagged1 overexpression markedly enhanced the mRNA expression of von Willebrand factor (vWF) and kinase insert domain receptor (KDR) of vascular endothelial grouth factor vWF in aged rat-derived EPC (P<0.01) and improved the EPC-related tube formation (P<0.01). No significant difference between Jagged1 transfection and young rat-derived EPC groups in vWF and KDR mRNA expression and the ability of tube formation was found. CONCLUSION: In endothelial cell-conditioning medium, Jagged1 overexpression significantly promotes aged rat-derived EPC differentiation into mature endothelial cells.     

Gender differences in adult circulating endothelial progenitor cells (EPCs) and effect of estradiol on arousing of EPCs in vitro

AIM: To investigate the gender differences and influence of menstrual cycle on the number and activity of adult circulating endothelial progenitor cells (EPCs), and the effect of estradiol on EPCs. METHODS: Ten men and 10 women were enrolled in the study. Peripheral blood samples of the men were collected only once and peripheral blood samples of the women were collected at each menstrual cycle phase (menstrual, pre-ovulatory and mid-luteal phases). The number of CD34⁺/CD133⁺/kinase insert domain-containing receptor (KDR)⁺ EPCs was determined by flow cytometry analysis and the level of circulating estradiol was measured by radioimmunoassay. Mononuclear cells were isolated from the blood and cultured in vitro. After cultured for 7 days, the number and the adhesive capacity of EPCs were observed. The effect of estradiol on the EPCs were detected by transmembrane migration assay and proliferation assay. RESULTS: The number of circulating EPCs was significantly higher in women than that in men (P<0.01), and it was higher at the pre-ovulatory phase and the mid-luteal phase than that at the menstrual phase (P<0.05). After cultured in vitro, the activity of EPCs did not reveal gender difference. In the cells treated with estradiol at concentration of ≥1×10^-9 mol/L, the capacities of transmembrane migration and proliferation were significantly increased (P<0.05). CONCLUSION: There are the gender differences of adult circulating EPCs between men and women. The number and activity of adult circulating EPCs may be regulated by menstrual cycle. In addition, estrogen plays an important role in the arousing of EPCs.     

Effect of ginsenoside Rh2 on cultured PC-3M cells in vitro

AIM:To explore the influence of ginsenoside Rh₂ on cultured PC-3M cell cycle in vitro. METHODS:DNA content was measured using [³H]-TdR incorporation assay. To analysis the cycle changes of PC-3M cells, flow cytometry was used in the experiment.RESULTS:The results indicated that the rate of [³H]-TdR incorporation was lower in Rh₂-treated cells than the control in a dose-dependent manner. Flow cytometry demonstrated that the pecent of G₁ phase treated with Rh₂ was higher than that of control. CONCLUSION:These results suggested that PC-3M cells cultured with Rh₂ for 24 h were blocked at G₁ phase, and Rh₂ inhibited the growth of PC-3M cells in vitro.     

Intravenous transfusion of endothelial progenitor cells reduces neointima formation

AIM: To investigate the feasibility of transplanting endothelial progenitor cells (EPCs) obtained from spleen in vascular endothelium repairmen after vascular injury. METHODS: EPCs were isolated by using a Ficoll density gradient centrifugation, and were cultured in plate. The endothelial characteristics of EPCs were identified by immunochemical staining and fluorescent labeling. Dil-Ac-LDL labeled spleen-derived EPCs were transplanted into the rats by intravenous injection directly after induction of arterial injury and again 24 hours later. Rats received FITC-labeled lectin intravenously before euthanasia. The distribution of fluorescent labeled EPCs was traced. The morphology of arterial intima and media was studied by optical microscopy and image analysing system. RESULTS: The adherent cells were considered EPCs that showed spindle shape and form blood-siland-like structures during development. The adherent cells had many endothelial characteristics. Fluorescent labeling showed that the intravenously injected EPCs specifically restricted to the vascular injury site, and lectin binding confirmed the endothelial phenotype. The ratio of neointimal/media area in EPCs transplantation group was obviously reduced than that in injury group and M199 group (0.82±0.09 vs 1.52±0.21, 1.48±0.19, P<0.01). The PCNA positive expression cells were evidently decreased compared with injury group and M199 group (19.25±3.96 vs 31.42±5.23, 29.37±3.16, P<0.05). CONCLUSION: EPCs incorporate into the process of injured carotid reendothelialization. EPCs transplantation induces an increase in the circulating EPCs, accelerates the process of endothelial repairmen and reduces neointima formation.