[Effect and mechanism of iron-catalyzed oxidative stress on mesenchymal stem cells]

To explore effect of iron overload on the proliferation and apoptosis of mesenchymal stem cell(MSCs) and the possible mechanism.

Iron overload model of MSCs was established by adding ferric ammonium citrae (FAC) into the culture medium at different concentrations (100, 200, 400 Μmol/L) and incubated for different lengths of time (12, 24, 48 h). The levels of labile iron pool (LIP) and reactive oxygen species (ROS) were measured to confirm oxidative stress state in the model. Changes in cell proliferation and apoptosis after iron overload were measured through population double time(DT)and annexin V-PI assay. Finally, the expressions of phosphorylated p38 mitogen activated protein kinase (P-p38MAPK), p38MAPK, protein kinase B (AKT), and p53 were determined through Western blot analysis to investigate which ROS-mediated signaling pathway was involved in this process.

The LIP level of MSCs was significantly increased by FAC treatment at 400 Μmol/L (mean fluorescence intensity 482.49±20.96 vs. 303.88±23.37, P<0.05). The level of intracellular ROS was positively correlated with the concentration of FAC and reached a peak level when cultured with 400 Μmol/L FAC (P<0.05).After treatment with 400 Μmol/L FAC at different time points (12 h, 24 h, and 48 h), the DT of MSCs was (1.47± 0.11) d, (1.80±0.13) d, and (2.04±0.14) d, respectively, which was signifcantly longer than that of the control, which was(1.20±0.05)d (P<0.05).The apoptosis rate was also significantly higher in iron overload group[(3.51±1.17)% vs.(0.66±0.62)%, P<0.05]with consequent increase in the expressions of P-p38MAPK, p38MAPK, and p53 proteins in iron overload group, while no significant difference was found in the expression of AKT.

Iron overload can inhibit the proliferation of MSCs and induce their apoptosis through the generation of ROS, which is probably due to the stimulation of p38MAPK- p53 signaling pathway.