Therapeutic effect of placenta-derived mesenchymal stem cells on hypoxic-ischemic brain damage in rats

Background: Oxidative stress is involved in the development of hypoxic-ischemic brain damage (HIBD). In this study, we investigated the therapeutic effects of placenta-derived mesenchymal stem cells (PD-MSCs) and explored the NF-E2-related factor-2/heme oxygenase-1 (Nrf2/HO-1) signaling pathway in treating HIBD. Methods: P7 rats were subjected to hypoxic-ischemic brain injury and randomly divided into four groups (control, HIBD, HIBD+PD-MSCs, and HIBD+fibroblasts). Forty-eight hours after the induction of HIBD, 5x10(5) of PD-MSCs were injected into cerebral tissue in the HIBD+ PD-MSCs group, while the same dose of fibroblasts were injected in the HIBD+ fibroblasts group. Morris Water Maze, gross and pathological changes were tested at P28. The level of malondialdehyde (MDA) was detected in rats' hippocampus. RT-PCR and western blot analysis were used to evaluate the changes of Nrf2/HO-1. Results: The HIBD group showed significantly longer escape latency and a lower frequency of original platform crossing in the Morris Water Maze compared with the control group. Rats receiving PD-MSCs showed significant improvement of HIBD. The pathological changes were evident after HIBD, but ameliorated in the PD-MSCs group. Compared with the control group, HO-1 and Nrf2 were up-regulated at gene and protein levels in the HI brain, beginning at 6 hours and peaking at 48 hours (P<0.05). The expression of HO-1 and Nrf2 in the PD-MSCs treatment group was more pronounced than in the HIBD group (P<0.01). PD-MSCs also decreased MDA production in the brain tissue. Conclusion: These results demonstrate that PD-MSCs have neuroprotective effect during the treatment of HIBD and that the mechanism may be partly due to alleviating oxidative stress.