Magnetic Nanomaterial Labeled Bone Marrow Mesenchymal Stem Cells For Rat Liver Repair Following Hepatectomy

Objective: Hepatectomy is the main way of treating different kinds of benign or malignant diseases of liver and biliary tract. However, hepatectomy can leadto many complications, such as, bile duct injuries, infections of incision, bile leakages, abdominal hemorrhages, and liver failures that is the main complicationand the main reason of deaths in perioperative stage. Bone marrow mesenchymalstem cells (BMSCs) have multi-differentiation potentials, differentiating into hepatocytes in certain microenvironments, secreting multiply types of cytokines, promoting the repair of hepatic injuries, which has been used for treating varieties ofliver diseases. Nevertheless, BMSCs are seldom to research in hepatectomy. Theexperiment observes how BMSCs affect hepatectomy, by watching the surviving,distributing, and moving of labeled BMSCs with MRI.Methods: BMSCs were isolated and cultured primarily by whole bone marrow culture method, and surface antigens were measured by flow cytometry. Cellviability, growth curve, and SPIO labeling rate of SPIO (0-100mg/L) labeledBMSCs were evaluated using Trypan blue staining, absorbance, and Prussian blue staining, respectively. We establish the model of the rats that received70%hepatectomies. Rats were randomly assigned to a hepatectomy control group without transplantation (Group A), a thru-liver transplantation group (Group B), and a thru-spleen transplantation group (Group C), a non-surgery control group (GroupD). Liver repair was evaluated with MRI imaging of labeled BMSCs, and with serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST).Results: Flow cytometry measurement of passage3BMSC surface antigensdocumented that97.36%of cells were positive for CD29,99.61%for CD90, and 2.2%for CD45. There was no significant difference in cell viability on days1,3,5,7for all concentrations (0μg/mL,25μg/mL,50μg/mL,75μg/mL, or100μg/mL) of SPIO (P>0.05). However, there is a trend showing a correlationof increased concentration of SPIO used for labeling and decreased cell viability.The doubling time of BMSCs isolated from male SD rats was (36.78±2.48) hr.Doubling times for25μg/mL,50μg/mL,75μg/mL, and100μg/mL SPIO labeled BMSCs were33.16±1.64hr,34.78±1.67hr,37.44±3.50hr, and36.87±3.56hr respectively. There were no significant differences in the doubling times among the5groups (P>0.05). The results of Prussian Blue Staining: thelowest SPIO concentration (12.5μg/mL) had a significantly lower labeling rate than the other four groups (25μg/mL,50μg/mL,75μg/mL and100μg/mL)(P<0.05), whereas the higher concentrations did not have significant differences inlabeling rates (P>0.05). Serum levels of ALT and AST peaked for rats in each group on day1post-hepatectomy. ALT and AST serum levels decreased substantially during days1-3post-hepatectomy, and returned to normal levels on day7. Serum levels of ALT and AST in Groups B and C were significantly lowerthan the reference group on days1,3, and7following hepatectomy (P <0.05),while no significant differences were evident among Groups B, C, and A on days1,3, or7post-hepatectomy (P>0.05). GRET2*WI sequence MRI demonstrated an exceptionally low signal density in the remaining liver of Groups B andC rats compared to Group A on day3following hepatectomy. On day7, this difference was decreased but the altered signal region was enlarged for the remaining liver of Groups B and C rats compared to Group A. Altered signal density in Groups B and C continued to decrease as the time following hepatectomy increased. Statistical analysis of different regions’ liver SI values on days3,7, and14did not differ (P>0.05). However, the liver SI values for Groups B and Cwere significantly higher than Group A’s (P <0.05), although Groups B and Cdid not differ (P>0.05).Conclusion: The method of whole bone marrow culture was still a simple and effective way of isolating BMSCs from rats. We investigated the best labeling concentration of SPIO for BMSCs was25μg/mL and the impact of SPIO labeling on cell viability and proliferation of BMSCs. SPIO labeled BMSCs could repair the liver of hepatectomized rats as soon as possible thru-liver and thru-spleen, and the effect by thru-liver and thru-spleen did not differ. SPIO labeling per mits tracing of BMSCs with MRI imaging and differentiation from host cells. This visually documents the potential of BMSCs to repair damaged liver, as well as establish the feasibility and efficiency of stem cell transplantation.