The Experimental Study Of SDF-1 & MCP-1 On MSCs Homing After Myocardial Infarction

Part I: Expression and significance of SDF-1 and MCP-1 after myocardial infarctionObjective:To investigate the dynamic changes of the expression of SDF-1 and MCP-1 in and around myocardial infarct site.Methods:Protein and mRNA of MCP-1 and SDF-1 expression were measured by immunohistochemistry and in situ hybridization in mid-infarct zone, peri-infarct zone and non-MI normal zone in infarcted hearts or sham operated hearts at 1, 2, 4, 7, 14, 28 and 56 days post operation.Results:MCP-1 expression increased at the first day, peaked at 2nd day and decreased thereafter post MI in the center of myocardial infarct site, peaked at 7th and decresed thereafter post MI in peri-myocardial infarct site. SDF-1 expression increased and peaked at the first day and decreased thereafter post MI in the center of myocardial infarct site and peri-myocardial infarct site. However, both MCP-1 and SDF-1 remained unchanged away from myocardial site and in sham operated hearts.Conclusions:Myocardial MCP-1 and SDF-1 expression were increased in mid- and peri-infarct site only in the early phase post MI. It may affect the repair of infarct myocardium. Part II: The effects of SDF-1 & MCP-1 on mesenchymal stem cells homing to myocardial infarct siteObjective:In the first part, we found that the expression of SDF-1 and MCP-1 increase in the early phase post MI, and the expression is not the same in different site of the myocardium.In this part, we are to investigate the effects of SDF-1 and MCP-1 on MSCs homing to myocardial infarct site.Methods:MSCs from donor rat were cultured and labeled with BrdU. MCP-1, SDF-1, MCP-1+SDF-1 or saline was injected into mid- and peri-infarct myocardium 4 days after MI. Then, a total of 5×106 cells in 2.5 mL of PBS or equal volume PBS alone were injected through the tail vein. The number of the labeled MSCs in the infarcted hearts was counted 3 days post injection. Cardiac function, expression of vascular endothelial growth factor (VEGF) and blood vessel density were assessed 28 days post injection. MI and non-MI saline injection groups were established as control.Results:The MSCs enrichment in the host hearts were more abundant in the MI groups than that in the non-MI group; MCP-1, SDF-1, MCP-1+SDF-1 injected group than control groups. Cardiac function improvement and blood vessel density in MCP-1, SDF-1, MCP-1+SDF-1 injected groups were more than control groups. MSCs enrichment and blood vessel density in MCP-1+SDF-1 injected group were more than MCP-1, SDF-1 injected group; but cardiac function had no difference among the three groups.Conclusion:SDF-1 and MCP-1 may enhance MSCs homing to injured heart and improved cardiac function by promoting neovascularization. The homing enhancement effect of SDF-1 plus MCP-1 is better than SDF-1 or MCP-1 respectively. Part III: The dose-effect relation of SDF-1 & MCP-1 on MSCs homing to myocardial infarct siteObjective:To investigate the dose-effect relation of SDF-1 and MCP-1 on MSCs homing to myocardial infarct site.Methods:MSCs from donor rat were cultured and labeled with BrdU. Fifty-six days after MI, different dose of MCP-1, SDF-1 or MCP-1+SDF-1 was injected into mid- and peri-infarcted zone evenly. Then, a total of 5×106 BrdU labeled MSCs in 2.5 mL of PBS were injected through the tail vein. The number of the labeled MSCs in the infarcted hearts was counted 3 days post injection. Cardiac function, expression of VEGF and blood vessel density were assessed 28 days post injection. Saline injection group was established as control.Results:The MSCs enrichment in the host hearts were more abundant in the MCP-1, SDF-1 injected groups than that in saline injected group, and the MSCs enrichment increased dose-dependently with the increase of the dose of MCP-1, SDF-1. Expression of VEGF and blood vessel density accorded with the MSCs enrichment. The MSCs enrichment and blood vessel density in MCP-1+SDF-1 injected group were more than those in MCP-1, SDF-1 injected groups. Cardiac function was improved more than 28 days before, but no difference was found among all the groups.Conclusions:There is no significantly autologous MSCs homing 56d after MI. SDF-1 and MCP-1 may enhance MSCs homing to injured heart dose-dependently. Homed MSCs may secrete VEGF and promote neovascularization. But homed MSCs fail to improve cardiac function, it may due to late therapy. The homing enhancement effect of SDF-1 plus MCP-1 is better than SDF-1 or MCP-1 respectively. Part IV: The effects of SDF-1 & MCP-1 on autologous bone marrow stem cells mobilized by G-CSF homing to myocardial infarct siteObjective:To investigate the effects of SDF-1 and MCP-1 on autologous bone marrow stem cells mobilized by G-CSF homing to myocardial infarct site.Methods:Fifty-six days after MI, 20μg·kg-1·d-1 recombinant human G-CSF was injected hypodermically in the rats for 5 days. Then 50μl MCP-1, SDF-1 or saline was injected into peri-infarct myocardium evenly. BrdU was injected peritoneally 50mg/Kg per day for 15days. 13 days later, the rats were sacrificed and the hearts were harvested for BrdU,CD45,CD90,VEGF,VIII detection. Cardiac function was assessed by Ultrasonic Cardiography before MCP-1, SDF-1 injection and rats sacrificed.Results:BrdU+, CD45+, CD90+ cell enrichment in the host hearts, expression of VEGF and blood vessel density were more in MCP-1, SDF-1 injected groups than saline injected group. CD45+ cell enrichment was more than that of CD90+ cell in MCP-1, SDF-1 injected groups. Cardiac function had no difference among all the three groups.Conclusions:SDF-1 and MCP-1 may enhance autologous bone marrow stem cells mobilized by G-CSF homing to injured heart. Homed bone marrow stem cells may secrete VEGF and promote neovascularization. But homed bone marrow stem cells fail to improve cardiac function, it may due to late therapy.