The cross-talk between ROS and p38MAPKα in the Ex Vivo expanded human umbilical cord blood CD133(+) cells.

This study investigated the correlation between and compared the effects of reactive oxygen species (ROS) and p38 mitogen-activated protein kinase α (p38MAPKα) in the ex vivo expanded umbilical cord blood (hUCB) CD133(+) cells. hUCB CD133(+) cells were cultured in the hematopoietic stem cells (HSCs) culture medium with N-acetylcysteine (NAC, an anti-oxidant), p38MAPKα-specific inhibitor (SB203580) or their combination. The levels of ROS and expression of phosphorylated p38MAPKα (p-p38) in CD133(+) cells were flow cytometrically detected. The efficacy of ex vivo expansion was evaluated by the density of CD133(+) cell sub-group colony-forming cells (CFC) and cobblestone area-forming cells (CAFC) assay. Our results showed decreased ROS levels in NAC, SB203580, and their combination treatment groups were almost 37%, 48%, and 85%, respectively. Furthermore, SB203580 abrogated the activation of p38MAPKα more obviously than NAC. Moreover, the CD133(+) cells in SB203580 treatment group had a 21.93±1.36-fold increase, and 14.50±1.19-fold increase in NAC treatment group, but only 10.13±0.57-fold increase in control group. In addition, SB203580 treatment led a higher level increase in the number of CFU and CAFC than NAC did. These findings suggested that, in expanded CD133(+) cells, ROS activates p38MAPKα, which, in turn, induces ROS production, and p38MAPKα might be the most suitable regulator in ROS-p38MAPKα pathway for the promotion of HSCs ex vivo expansion.