Investigation Of Renal Localization And Survival Of BMSCs In CKI Mice Through SPION Labeling And AAP Recognition

The injury and loss of podocytes are critical in chronic glomerulop athy and progression.In recent years,some progress has been made in the treatment of renal diseases with stem cells.In order to understand the fate of exogenously transplanted stem cells,it is prerequisite to investigate the in vivo distribution and viability of them.Current live cell imaging techniques have their respective drawbacks and can’t answer these questions simultaneously.Previously we have screened the aptamers specifically binding mouse BMSCs and constructed an activatable aptamer fluorescence probe（AAP）.In the current study,we proposed to couple AAP with SPION and construct a dual-modal MSC tracking technique（SPION-AAP）,combining the respective advantages of sensitivity of fluorescen ce imaging and high resolution of MRI.Simultaneously,the recognition of AAP to MSCs would reflect the viability of the cells in vivo.In order to verify the feasibility of the dual-modal MSC imaging technique,adriamycin nephropathy model,a kind of foca l segmental glomerulosclerosis model,was constructed to simulate nephrotic syndrome（CKI）.Then,the renal localization and the viability of transplanted BMSC s in adriamycin nephropathy model was studied by MRI and AAP imaging in parallel.The study consists of the following three works:1、Adriamycin nephropathy model of Balb/c mice was established by multiple intravenous injection of adriamycin.The model was evaluated by the proteinuria level and the histopathology of the kidney.2、The efficiency of Fe₃O₄@CA-PLL and Fe₃O₄ in labeling BMSCs would be compared by Prussian blue staining,single cell iron content,and cell viability analysis.The recognition and specificity of a selected aptamer（Apt）to mouse BMSCs was verified by flow cytometry analysis and laser confocal microscopy.3、The migration,localization and activity of BMSCs to the renal injury sites were studied by coupling the MRI based on Fe₃O₄@CA-PLL with the fluorescence imaging technique based on AAP.Meanwhile,the localization and viability of BMSCs in the target kidney defect were verified by static histological analysis.