Safety of umbilical cord blood-derived mesenchymal stem cells [MSCs] following 5-azaserine induction and inhibition of human cardiac myocyte apoptosis by MSCs

To further study the safety and effect of the umbilical cord blood [UCB]-derived mesenchymal stem cells [MSCs] on apoptosis of human cardiac myocyte [HCM]. The UCB was collected at the time of delivery with informed consent obtained from 10 donors. The UCB-derived MSCs was treated with 5-azaserine [5-AZA], and further introduced differentiation into cardiomyocytes. The telomerase activity, G-banding patterns of chromosomal karyotypes, tumor formation in nude mice, reverse transcription polymerase chain reaction [RT-PCR], and the inhibited apoptosis of UCB-derived MSCs were further investigated. This study was carried out in the laboratory of Beijing Shijitan Hospital, Beijing, China and Inheritance Research Section of Chinese Medical Institute, Beijing, China from July 2005 to December 2007. The MSCs-derived from UCB were differentiated into cardiomyocytes in vitro, possessed telomerase activity after 5-AZA induction, and no abnormal chromosomal karyotypes were observed. Expression of p53, cyclinA, cdk2, beta-actin, C-fos, h-TERT and c-myc were similar in MSCs before and after 5-AZA treatment. There was no tumor formation injected into nude mice. The UCB-derived MSCs significantly inhibited apoptosis of human cardiomyocytes. Umbilical cord blood-derived MSCs are safe and effective source of cell-transplantation treatment, and can inhibit the apoptosis of human cardiomyocytes in co-cultured

Rac1 regulates the release of Weibel-Palade Bodies in human aortic endothelial cells / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The release of Weibel-Palade Bodies (WPB) is a form of endothelial cell activation. But the signal transduction pathway leading to WPB release is not yet defined. We hypothesized that small G-protein rac1 and reactive oxygen species (ROS) mediate the ligand induced release of Weibel-Palade Bodies.</p><p><b>METHODS</b>We tested this hypothesis by using wild-type and mutant adenoviral rac1 expression vectors, and by manipulating the production and destruction of superoxide and hydrogen peroxide in human aortic endothelial cells (HAEC).</p><p><b>RESULTS</b>Thrombin (1.0 Unit, 30 min) induced the increase of WPB release by 3.7-fold in HAEC, and that H2O2 (0.1 mmol/L, 30 min) induced by 4.5-fold. These results correlated with thrombin-stimulated activation of rac-GTP binding activity by 3.5-fold, and increase of ROS production by 3.4-fold. The dominant negative adenoviral rac-N17 gene transfer dramatically inhibited the release of WPB by 64.2% (control) and 77.3% (thrombin-stimulation), and decreased ROS production by 65.5% (control) and 83.6% (thrombin-stimulation) compared with non-infected cells, respectively. Anti-oxidants, catalase and N-acetyl-cysteine significantly decreased the release of WPB by 34% and 79% in control cells, and further decreased by 63.6% and 46.7% in rac-N17 transferred cells compared with non-infected cells. We also confirmed that rac1 was located upstream of ROS in the WPB release pathway.</p><p><b>CONCLUSIONS</b>Small G-protein rac1 medicates ligand-induced release of Weibel-Palade Bodies in human aortic endothelial cells, and the signal pathway of WPB release is a rac1-dependent ROS regulating mechanism.</p>