RESUMEN
Recent studies have suggested that reduced endothelial progenitor subpopulation in lectin-binding and DiLDL-uptaking cell (EPC subpopulation) number and activity was associated with EPC subpopulation senescence that involved telomerase activity and telomere length. Stromal cell-derived factor-1alpha (SDF-1alpha) has been shown to augment a variety of cellular functions of EPC subpopulation and subsequently contribute to ischemic neovascularization. Therefore, we investigated whether SDF-1alpha might be able to prevent senescence of EPC subpopulation and also investigated the effects of SDF-1alpha on the telomerase activity and telomere length. EPC subpopulation were isolated from peripheral blood and characterized. After ex vivo prolonged cultivation, EPC subpopulation became senescent as determined by acidic beta-galactosidase staining. SDF-1alpha dose-dependently inhibited the onset of EPC subpopulation senescence. Moreover, SDF-1alpha increased proliferation and colony-forming activity of EPC subpopulation. SDF-1alpha also increased telomerase activity and telomere length, which was accompanied with upregulation of the catalytic subunit, telomerase reverse transcriptase (TERT). Whereas these effects of SDF-1alpha on telomerase activity and expression of hTERT mRNA were significantly attenuated by CXCR4-specific peptide antagonist (AMD3100) and phosphoinositide 3-kinase (PI3K) inhibitor (LY294002). In conclusions, SDF-1alpha delays the onset of EPC subpopulation senescence, which may be related to the activation of telomerase and elongation of telomere length. The inhibition of EPC subpopulation senescence and induction of EPC subpopulation proliferation by SDF-1alpha in vitro may importantly improve the functional activity of EPC subpopulation for potential cell therapy.
Asunto(s)
Senescencia Celular/efectos de los fármacos , Quimiocina CXCL12/farmacología , Células Endoteliales/enzimología , Lectinas/metabolismo , Células Madre/citología , Telomerasa/metabolismo , Telómero/metabolismo , Adulto , Proliferación Celular/efectos de los fármacos , Ensayo de Unidades Formadoras de Colonias , Células Endoteliales/citología , Células Endoteliales/efectos de los fármacos , Activación Enzimática/efectos de los fármacos , Femenino , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Masculino , Fosfatidilinositol 3-Quinasas/metabolismo , Unión Proteica/efectos de los fármacos , Proteínas Proto-Oncogénicas c-akt/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Transducción de Señal/efectos de los fármacos , Células Madre/efectos de los fármacos , Células Madre/enzimologíaRESUMEN
Previous studies have underlined the importance of endothelial dysfunction and microvascular occlusion in the pathogenesis of pulmonary artery hypertension (PAH). Since the endothelial progenitor cells (EPCs) are involved in maintaining endothelial homeostasis, we observed the change of peripheral EPCs in canines before and after PAH onset. PAH was induced by intra-pulmonary artery injection of dehydromonocrotaline (DHMC) in nine beagles. Before and 48 h and 6 weeks after DHMC injection, 40 ml peripheral blood was obtained from the femoral vein. Circulating EPCs were identified as CD133 + KDR + cells and numerated by fluorescence-activated cell sorter; the EPCs functional capacity was determined by in vitro tubule-forming assay. The senescence of EPCs was determined by beta-galactosidase staining. At each time point, 2 ml blood from femoral artery was obtained for arterial oxygen pressure (PaO(2)). Forty-eight hours after DHMC injection, treated beagles suffered from hypoxemia; however, both the number and the tubule-forming capacity of EPCs were transiently raised. Six weeks later, PAH was confirmed by obviously high mean pulmonary arterial pressure (20.2 +/- 1.64 vs. 11.3 +/- 2.0 mmHg, p < 0.05) and low PaO(2) (69.30 +/- 9.15 vs. 95.94 +/- 1.43 mmHg, p < 0.01) in beagles after DHMC treatment, and their EPCs exhibited a predominant decrease in either the number (206.1 +/- 26.8 vs. 632.8 +/- 42.8 cells/ml blood, p < 0.01) or the tubule-forming capacity (21.1 +/- 2.8 vs. 11.2 +/- 2.8 tubules/x200 field, p < 0.01). Additionally, senescence-associated beta-galactosidase-positive EPCs were significantly increased. Our data suggested that, after the acute stage of DHMC injury to pulmonary vessels, the EPCs from PAH beagles suffered from exhaustion and senescence.
Asunto(s)
Células Endoteliales/fisiología , Endotelio Vascular/citología , Hipertensión Pulmonar/inducido químicamente , Células Madre/citología , Células Madre/fisiología , Animales , Técnicas de Cultivo de Célula , Separación Celular , Células Cultivadas , Senescencia Celular , Modelos Animales de Enfermedad , Perros , Células Endoteliales/metabolismo , Citometría de Flujo , Masculino , Monocrotalina/análogos & derivados , Monocrotalina/farmacología , Neovascularización Fisiológica , Células Madre/metabolismoRESUMEN
Thymosin beta4, a G-actin-sequestering peptide, has been shown to play an important role in cell migration. However, little is known about the effect of thymosin beta4 on circulating endothelial progenitor cell (EPC) directional migration, which is essential for EPC-mediated reendothelialization and neovascularization. In our study, using a transwell migration assay, we showed that thymosin beta4 induced EPC migration in a concentration-dependent manner. Western blot analysis revealed that treatment of EPCs with thymosin beta4 resulted in a time and concentration-dependent phosphorylation of Akt, endothelial nitric oxide synthase (eNOS), and extracellular signal-regulated kinase (ERK)1/2. Functional analysis showed that thymosin beta4-induced EPC migration was blocked by phosphatidylinositol 3-kinase inhibitors (LY294002 or wortmannin) or eNOS inhibitor (Nomega-nitro-L-arginine methyl ester) but was not significantly attenuated by mitogen-activated protein kinase (MAPK)/ERK inhibitor (PD98059). These findings suggest that thymosin beta4 stimulates EPC directional migration via phosphatidylinositol 3-kinase/Akt/eNOS, rather than via MAPK/ERK signal transduction pathway.
Asunto(s)
Movimiento Celular/efectos de los fármacos , Endotelio Vascular , Óxido Nítrico Sintasa de Tipo III/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Transducción de Señal/efectos de los fármacos , Células Madre/efectos de los fármacos , Timosina/farmacología , Western Blotting , Técnicas de Cultivo de Célula , Ensayos de Migración Celular , Células Cultivadas , Relación Dosis-Respuesta a Droga , Endotelio Vascular/citología , Inhibidores Enzimáticos/farmacología , Quinasas MAP Reguladas por Señal Extracelular/antagonistas & inhibidores , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Humanos , Óxido Nítrico Sintasa de Tipo III/antagonistas & inhibidores , Inhibidores de las Quinasa Fosfoinosítidos-3 , Fosforilación , Proteínas Proto-Oncogénicas c-akt/antagonistas & inhibidores , Células Madre/citología , Células Madre/enzimologíaRESUMEN
AIM: To investigate the mechanisms of vasodilatation of plant-derived estrogen biochanin A. METHODS: Isolated aortic ring preparations from Sprague-Dawley rats were suspended in individual organ baths. The tension was measured isometrically. RESULTS: Biochanin A at the range of 10(-9)-10(-4) mol/L provoked concentration-dependent and endothelium-independent relaxation of the rings constricted by phenylephrine (10(-5) mol/L). Biochanin A caused concentration-dependent relaxation of denuded rings precontracted with KCl (6 x 10(-2) mol/L). Glibenclamide (3 x 10(-6) mol/L), a selective inhibitor of ATP-sensitive potassium channels, and tetraethylammonium (5 x 10(-3) mol/L), a Ca2+ -activated K+ channel inhibitor, significantly attenuated the relaxation induced by biochanin A. The vasoconstriction induced by phenylephrine was decreased by biochanin A in Ca2+ -free medium. CONCLUSION: The endothelium-independent relaxation of thoracic aorta induced by biochanin A might be mediated by ATP-sensitive K+ channels, Ca2+ -activated K+ channels and intracellular Ca2+ release from sarcoplasmic reticulum.