ABSTRACT
<p><b>BACKGROUND</b>Previous studies have shown that resveratrol increases endothelial progenitor cell (EPC) numbers and functional activity. Increased EPC numbers and activity are associated with the inhibition of EPC senescence. In this study, we investigated the effect of resveratrol on the senescence of EPCs, leading to potentiation of cellular function.</p><p><b>METHODS</b>EPCs were isolated from human peripheral blood and identified immunocytochemically. EPCs were incubated with resveratrol (1, 10, and 50 µmol/L) or control for specified times. After in vitro cultivation, acidic β-galactosidase staining revealed the extent of senescence in the cells. To gain further insight into the underlying mechanism of the effect of resveratrol, we measured telomerase activity using a polymerase chain reaction (PCR)-enzyme-linked immunosorbent assay (ELISA) technique. Furthermore, we measured the expression of human telomerase reverse transcriptase (hTERT) and the phosphorylation of Akt by immunoblotting.</p><p><b>RESULTS</b>Resveratrol dose-dependently inhibited the onset of EPC senescence in culture. Resveratrol also significantly increased telomerase activity. Interestingly, quantitative real-time PCR analysis demonstrated that resveratrol dose-dependently increased the expression of the catalytic subunit, hTERT, an effect that was significantly inhibited by pharmacological phosphatidylinositol 3-kinase (PI3-K) blockers (wortmannin). The expression of hTERT is regulated by the PI3-K/Akt pathway; therefore, we examined the effect of resveratrol on Akt activity in EPCs. Immunoblotting analysis revealed that resveratrol led to dose-dependent phosphorylation and activation of Akt in EPCs.</p><p><b>CONCLUSION</b>Resveratrol delayed EPCs senescence in vitro, which may be dependent on telomerase activation.</p>
Subject(s)
Humans , Cells, Cultured , Cellular Senescence , Endothelial Cells , Cell Biology , Stem Cells , Cell Biology , Stilbenes , Toxicity , Telomerase , MetabolismABSTRACT
<p><b>BACKGROUND</b>Hepatitis B virus (HBV) replication has been reported to be involved in many extrahepatic viral disorders; however, the mechanism by which HBV is transinfected into extrahepatic tissues such as myocardium and causes HBV associated myocarditis remains largely unknown.</p><p><b>METHODS</b>In this study, endothelial progenitor cells (EPCs) were infected by HBV and then transfused into ischemic model of mice. HBV surface and core antigen as well as mutation of HBV particles were detected by immunohistochemistry, fluorescent activated cell sorter and transmission electron microscopy in vitro and in vivo.</p><p><b>RESULTS</b>Human cord blood EPCs, but not human umbilical vein endothelial cells (HUVECs) could be effectively infected by taking up HBV in vitro. HBV envelope surface and core antigen expressions were first detectable in EPCs at day 3 after virus challenge, sustained for up to 11 days, and decreased thereafter. Similarly, the virus particles were the most abundant in EPCs in the first week observed by a transmission electron microscope, and declined in 3 weeks after HBV infection. HBV DNA but not HBV cccDNA in EPCs were detectable even 3 weeks after virus challenge, as shown by PCR analysis. Furthermore, intravenous transplantation of HBV-treated EPCs into myocardial infarction Sprague & Dawley rats model resulted in incorporation of both EPCs and HBV into injured endothelial tissues of capillaries in the ischemic border zone.</p><p><b>CONCLUSIONS</b>These results strongly support that EPCs serve as virus carrier mediating HBV trans-infection into the injured myocardial tissues. The findings might suggest a novel mechanism for HBV-associated myocarditis.</p>