[Reactive oxygen species mediate the injury and deficient hematopoietic supportive capacity of umbilical cord derived mesenchymal stem cells induced by iron overload].

Objective: To explore the effects of iron overload on umbilical cord derived mesenchymal stem cells (UC-MSC) and elucidate the involvement of reactive oxygen species (ROS) in this process.

Methods: The iron overload model of MSC was established by in vitro addition of ferric ammonium citrate (FAC) into culture medium. Cell proliferation and apoptosis were determined by Annexin V/PI double staining and population doubling time (DT) respectively. Co-culture system was used to assess the hematopoietic support capacity of UC-MSC in different groups. Thereafter the ROS level was detected with fluorescent probe 2', 7'-dichlorofluorescin diacetate (DCFH-DA). And the ROS related signaling factors of p-p38MAPK, p38 MAPK, P53 were measured by Western blot.

Results: (1) The DT of UC-MSC in iron overload group was significantly longer than that of control ((24.43 ± 2.72) h vs (16.03 ± 2.31) h, P < 0.05). But the difference was insignificant after two passages (P > 0.05). (2) Apoptosis in iron overload group was higher than that of control (12.75% ± 0.32% vs 3.63% ± 0.80%, P < 0.05). (3) The colony forming capacity of mononuclear cell (MNC) co-cultured with UC-MSC of iron overload group for 1/2 weeks significantly decreased. (4) The ROS level of UC-MSC with iron overload was higher than that of control in time and concentration-dependent fashions and it peaked at 400 µmol/L of FAC for 12 h (1499 ± 86 vs 548 ± 97, P < 0.05). (5) The expressions of p-p38MAPK and P53 increased in response to FAC compared with control. But such an effect was partially inhibited after the use of antioxidants.

Conclusions: Iron overload may impair the proliferation, survival and hematopoiesis supportive function of UC-MSC by enhancing the generation of ROS. And ROS stimulates the signaling pathways of p-p38MAPK and P53.