MR Molecular Imaging Of HCC Employing Regulated Ferritin Gene Carried By Cationic Carrier Vector

Purpose:Early diagnosis is essential to reduce liver cancer mortality,and molecular diagnosis in magnetic resonance imaging(MRI)is an emerging technology with high expectations.The chief aim of present work is to use ferritin gene as an endogenous contrast agent,modified by alpha-fetoprotein(AFP)promoter,carried by a highly safe vector,to produce signal contrast on T2-weighted MR imaging,and provide high specific target for subsequent therapy.Methods:PEI-(3-CD(PC)was synthesized as a novel vector.The optimum nitrogen/phosphorus ratio(N/P)of PC/plasmid DNA complex was determined by gel retardation,biophysical properties and transmission electron microscope morphological analysis.The transfection efficiency was observed by fluorescence microscope and analyzed by flow cytometry.Cellular iron accumulation caused by ferritin overexpression was verified by Prussian blue staining,and the resulting contrast imaging effect was examined by MRI.Results:The cyclodextrin(CD)modified cationic polymer PEI-β-CD has a cell viability of approximately 95%at a concentration of 100 μg/ml,much safer than high molecular weight PEI(molecular weight:25kD,PEIskD)and cationic liposomes Lipofectamine2000(Lipo).PC can condense plasmid DNA(pDNA)at a N/P ratio of 50 with suitable biophysical properties,which help it be taken up by cells easily.Particle size:143.25±2.49nm,polydispersity index:0.211 ±0.02,zeta potential:17.94±0.20mv,transmission electron microscope:compact spheroid nanosystem.PC/pDNA at a N/P of 50 can reach the similar transfection as the positive control PEI25skD and Lipo,and the transfection efficiencies are 13.1%,15.3%,and 15.3%respectively.The cationic polymer PC,carrying Fth regulated by AFP promoter,transfected hepatoma cells.And the overexpressing ferritin up-regulate transferrin receptpr to increase the intracellular iron load.The short-term iron imbalance initiated by the regulation of AFP promoter only occurred in hepatoma cells,resulting in the signal contrast on MRI.There was no significant difference in the signal intensity among PC,PEI25kD and Lipo group(P<0.01).Conclusion:These results illustrate that regulated ferritin gene carried by PC could be used as an endogenous contrast agent for MRI detection of hepatocellular carcinoma(HCC).This molecular imaging technique may promote safer early diagnosis of HCC,and provide higher specific target for the next drug treatment.