Therapeutic Effect And Mechanisms Of Induced Pluripotent Stem Cells And Long-term Ischemic Preconditioning On Arterial Injury

Objective:Induced Pluripotent Stem cells (iPS) have great therapeutic potential for human diseases. In our previous study showed that integrin β1is the dominant integrin β unit that mediates the adhesion of iPS and endothelial cells. According to literature, microRNA217, through its target Sirtl, regulates cell mobility, endothelial differentiation and angiogenesis. In this study, we aimed to determine if induced Pluripotent Stem cells (iPS) inhibited neointimal injury and the roles of intergrin β1and microRNA217in a mouse model of femoral injury.Methods:Standard wire-induced femoral injury was performed in male C57BL/6J mice at age of8-10weeks. PBS, MEF (mouse embryonic fibroblast), iPS or iPS transfected with intergrin β1siRNAs, control RNAs or microRNA217were injected into the mice via tail vein1h and3days after modeling, respectively. The dose of cells per injection was6x104cells in200μ1PBS. The injected iPS labeled with red fluorescence dye PKH were identified on the luminal surface of injured femoral artery by confocal fluorescence microscopy at24h after injection. The injected iPS at at5days and3weeks was identified by FISH staining targeted TetO gene. The TetO gene was introduced into iPS when producing iPS and therefore not existing in host cells. The ratio of neointima/media thicknesses of the injured artery harvested at5days and3weeks after injury was evaluates using HE stained cross sections.Results:Intravenous administered iPS trafficking to luminal surface of the injured femoral artery within24h after injection. All injured femoral arteries were re-endothelialized at3weeks. IPS but not MEF inhibited neointimal proliferation of the injured arteries compared to PBS. Transfecting iPS with siRNAs of intergrin β1not only abolished the protective effect of iPS but also induced thrombosis in injured arteries, leading to animal death around5days after injury. When the dose of iPS transfected with intergrin β1siRNAs was reduced to one sixth (2injections of1×104cells in200p.1PBS), the cells had neither therapeutic effect nor prothrombotic effect. Transfection of iPS with microRNA217abolished selectively homing and therapeutic effect of iPS. The behavior and function of iPS transfected with control RNAs were similar to untreated iPS. TeTO-positive cells were identified in the injured arteries of animals receiving iPS or iPS transfected with control RNAs but not in injured arteries of other animals at5days and3weeks after modeling.Conclusion:We successfully prepared induced pluripotent stem cells and established a mouse model of intimal injury of femoral artery. Intravenous administered iPS selectively homed to luminal surface and inhibited neointimal proliferation of the injured artery in intergrain β1and microRNA217dependent manners. Objective:Using the experimental left middle cerebral artery obstruction (MACO) model of rat, we’ve studied the prolonged effect of brain short term ischemic preconditioning (IPC) on the brain ischemia-reperfusion injury and investigated the roles of HO-1and adenosine receptor Al.Methods:12weeks male Wistar rats were used, the left internal carotid artery of the experimental groups had been clipped for20minutes as IPC, while in control groups, the same artery had been clipped for2seconds as IPC. Two groups were both treated respectively with PBS, HO-1inducer Hemin, HO-1inhibitor Znpp and adenosine receptor Al antagonist DPCPX; after three weeks, MCAO model had been successfully built in all groups. We adopted the neurological deficit scores and the brain infarct area (TTC staining) to evaluate the roles of IPC and HO-1. Immunohistochemistry and Western blotting were performed for testing the expression of HO-1and adenosine receptors.Results:Longa Neurological Deficit Score showed IPC for20minutes could significantly improve the neurological function and reduce the brain infarct area of the MCAO rats. Hemin can promote the protective effect of IPC. The results of Immunohistochemistry and Western blotting showed that the expression of HO-1, adenosine receptors Al and A2a are higher in the marginal zone than in the infarct zone. Western blotting showed that Znpp could increase the expression of HO-1of feedback after IPC.Conclusion:We are the first to find that short term IPC has prolonged effect on brain ischemia-reperfusion injury and the effect can at least sustain for3weeks; HO-1plays an important role in the prolonged effect of IPC; There is a certain correlation between HO-1and the adenosine receptor Al in the effect on the brain ischemia-reperfusion.