Résumé
Objective To investigate the efficiency and mechanism of differentiation of reprogrammed adipose-derived stem cells (ADSCs) to neurons in vitro.Methods ADSCs from rats were cultured in vitro and then purified and identified.ADSCs at the third passage were divided into three groups:ADSCs without lentivirus-mediated gene transfection (blank group),ADSCs transfected with lentivirus carrying no neurogenin2 (Ngn2) (empty virus group) and ADSCs with lentivirus-mediated transfection of Ngn2 (Ngn2 group).All groups were induced in the medium containing cell growth factor for 15 days.The positive expression of neuron-specific nuclear protein (NeuN) in three groups was detected using immunofluorescence method so as to observe the efficiency of neuron differentiation.Expression variances of Mash1,Hes1 and Dll1 in each group were detected by Western blot analysis and the mechanism of differentiation was also discussed.Results After 15 days of induction,positive expression rate of NeuN in Ngn2 group,empty virus group,blank group was 90.12％,45.34％ and 40.26％ respectively,with significant differences among groups (P ＜ 0.01).Western blot analysis showed that Ngn2 group had a significantly higher expression of Dll1 (P ＜0.01) and obvious lower expressions of Hes1 and Mash1 (P ＜0.01),as compared with empty virus group and blank group.However,there were no significant differences of expression levels of Dll1,Mash1 and Hes1 between empty virus group and blank group (P ＞ 0.05).Conclusions After induction,the ratio of neuron differentiation of reprogrammed ADSCs is increased by almost 99％,as compared with simple ADSCs.The increased dfferentiation of reprogrammedADSCs to neurons may be associated with the inhibition of notch signaling through up-regulating Dll1 and down-regulating Mash1 and Hesl.
Résumé
BACKGROUND: One of mechanisms involved in treating cerebral ischemia with bone marrow mesenchymal stem cells (BMMSCs) implantation is paracrine action. However, few studies have reported this mechanism.OBJECTIVE: To observe the inhibitory effect of BMMSCs paracrine action on apoptosis and its mechanism after cerebral ischemia. METHODS: BMMSCs were isolated from rats with adherent culture. Rat cerebral ischemia model was established by the middle cerebral artery occlusion. A total of 24 rats were divided into 4 groups, with 6 animals in each group. Cell implantation medication group: rats were received U0126 medication after BMMSCs implantation; Non-implantation medication group: rats were received U0126 medication after PBS injection; Cell implantation control group: received solvent medication after BMMSCs implantation; Non-implantation control group: received solvent medication after PBS injection. At 7 days after operation, the expressions of vascular endothelial cell growth factor (VEGF) and p-ERK1/2 protein were measured by Western blot analysis, and the apoptosis cells in the area of ischemic penumbra and cortex were examined by TUNEL. RESULTS AND CONCLUSION: The VEGF protein content in the brain tissue was significantly greater in the cell implantation groups than that of the non-implantation group, with increased p-ERK1/2 and decreased apoptosis cells. The expression of p-ERK1/2 was down-regulated in rats which were administrated U0126 while the number of the apoptosis cells was increased, but the VEGF protein expression had no statistical difference. It suggested that BMMSCs can paracrine VEGF in the striatum of brain and play an inhibitory effect on apoptosis in the ischemia area via activating ERK1/2.