| Since the discovery of cadmium at the beginning of the20th, cadmium appearedwith high frequency in people’s daily life. The discharge of electroplating, mining,smelting, dye and chemical waste water pollute our water source and soil, as a result,crops and fishes containing excessive cadmium. cadmium’s biological half-life inhuman body is10-25years with a low clearance rate, eventually causing hugeaccumulation of cadmium in human body. The kidney, as the important target organsof cadmium poisoning, can accumulate one third of total absorption of cadmium. Thestructure and function injury of the kidney cannot be ignored. Therefore, the mainlytreatment measurement of patients with cadmium poisoning was support therapy atpresent; however, it only can make a remission, instead of repairing the kidney injury.It is urgent to find a scientific and effective method to cure kidney injury caused bycadmium in clinic. Bone mesenchymal stem cells (BMSCs) are multilineagedifferentiating, low immunogenic, easy to aquire, easy to isolation and culture, able ofhoming to injured organs and repair them, which possess the development potentialand application prospect in repairing the tissue injury. There have been studiesshowing that BMSCs can repair the kidney injury caused by ischemia-reperfusioninjury, and the liver injury caused by burn wound and so on, but it has not beenreported that whether BMSCs can cure kidney injury caused by cadmium. For theabove reasons, in this study, BMSCs were transplanted into the rats with cadmiumexposure to observe the repair effect of BMSCs on the kidney injury, and make apreliminary discussion on its repair mechanism, which will provide theoretical andexperimental evidence for clinical treatment on kidney injury caused by Cadmium.ObjectiveTo explore the repair effect of BMSCs on kidney injury of rats caused bycadmium, and charify the mechanism of the repair effect. MethodsAdherent culture method was applied to separate and purify BMSCs usingsuckling rats bone marrow. The cell cycle and surface markers of BMSCs，includingCD44, CD45and CD90, were detected by flow cytometry.30Wistar rats wererandomly divided into blank control group, model group (0.2mL saline was injectedinto rats by retro-orbital veins), and cell therapy group (0.2mL BMSCs was injectedinto rats by retro-orbital veins,1×107),10animals were each group. CdCl2wasinjected with the dose of0.4mgï¹'kg-1, five times a week, and the injections will lastfor5weeks to make the model of rats with kidney injury caused by cadmium; thesame volume of normal saline as that of rats in model group was injected into rats inblank control group. BMSCs labeled by CM-Dil were transplanted throughretro-orbital veins of rats in cell therapy group at the end of poisoning; the samevolume of normal saline was injected into rats in blank control group and modelgroup. Then the general status and body weight of rats were observed daily aftertransplantation. The kidney tissue and blood of rats were obtained2weeks aftertransplantation. The renal functional indexes including creatinine (CR), blood ureanitrogen (BUN), and β2-microglobulin (β2-MG) were detected by biochemicalmethod; the level of cadmium in kidney tissues of rats were detected by atomicabsorption spectrometry; viscera coefficient was calculated; the pathological changeswere observed by HE staining; the apoptotic percentage of kidney cells wasperformed by TUNEL method; the expressions of Bax, Bcl-2, Caspase-3, Beclin1and LC3B proteins were detected by immunohistochemical method; the relativeexpression level of Bax and Bcl-2was detected by Western blot. Laser ScanningConfocal Microscope was applied to observe the engraftment of BMSCs in kidneytissue of rats in cell therapy group2weeks after transplantation.ResultsBMSCs grew in good conditions. The results of flow cytometery showed that thecultured BMSCs were positive for CD44and CD90, barely expressed with CD45, andmost cells existed at the inactive stationary phase. Obvious depression was seen2weeks after transplantation in rats of model group, with obvious active status wasobserved in rats of cell therapy group, and the body weight of rats in cell therapygroup were significantly higher than that in model group (P＜0.05). The results of blood biochemical detection showed that，the kidney function of rats in cell therapygroup was significantly better than that in model group (P＜0.05). Viscera coefficientresult showed that compared with the blank control group, the kidney visceracoefficient of rats in model group was significantly lower (P＜0.05)， and the kidneyviscera coefficient of rats in cell therapy group was significantly higher than that inmodel group（P＜0.05）. The results of atomic absorption spectrometry showedthat trace amounts of cadmium was seen in the kidney tissues of rats in blank controlgroup, and a large amount of metal cadmium accumulated in the kidney tissues of ratsin model group and cell therapy group, and there was no significant differencebetween model group and cell therapy group. The pathological histology observationshowed that obvious morphological damage was observed in the renal tubules andglomeruli of rats in model group, and significant amelioration was observed in kidneyof rats in cell therapy group. TUNEL test results showed that the apoptosis percentageof kidney cells in the therapy group was significantly lower than that in model group(P<0.05). Immunohistochemistry results showed that the expressions of Bax,Caspase-3, Beclin1and LC3B proteins in kidney tissues of rats in model group weresignificantly higher than those in blank control group (P<0.05), and the expressionlevels of Bax, Caspase-3, Beclin1and LC3B proteins in kidney tissues of rats in celltherapy group were significantly lower than those in model group (P<0.05). Theexpressions of Bcl-2protein in kidney tissues of rats in model group weresignificantly lower than those in blank control group and cell therapy group weresignificantly higher than that in model group (P<0.05). Western blot results showedthat compared with blank control group, the relative expression levels of Bax inkidney tissues of rats in model group were significantly higher (P<0.05), and therelative expression level of Bcl-2were significantly lower (P<0.05), and theBcl-2/Bax ratio was significant lower (P<0.05). When compared with model group,the relative expression level of Bax in kidney tissues of rats were significantly lower(P<0.05), and the relative expression levels of Bcl-2were significantly higher(P<0.05), and the Bcl-2/Bax ratio was significant higher (P<0.05). Under the LaserScanning Confocal Microscope, BMSCs labeled by CM-Dil with red fluorescencecould be seen in kidney tissues of rats in cell therapy group. Conclusion:BMSCs could home in the injured kidney tissues after being transplantedthrough the vein, and exhibit obvious repair effect on kidney injury caused bycadmium, and the probable mechanisms may be associated with the inhibition ofkidney cell apoptosis and autophagy. |
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