Preparation of a folate-mediated tumor targeting ultraparamagnetic polymeric micelles and its in vitro experimental study

Abstract

Objective To evaluate the tumor targeting characteristic of the Folate-SPIO-DOX-Micelles by in vitro studies,and to test the feasibility of monitor tumor targeting using it and clinical MRI.Methods The polymeric micelles,Folate-SPIO-DOXO-Micelles were prepared.The in vitro tumor cell targeting efficacy of these folate modified and DOX or SPIO-loaded micelles (Folate-SPIO-DOX-Micelles)was evaluated by observing the cellular uptake of micelles by human hepatic carcinoma cells(Bel 7402 cells) which overexpressed folate surface receptors. Cell suspensions were incubated with Folate-SPIO-DOXO-Micelles for 1 h.Prussian blue staining was performed to show intracellular irons.Flow cytometry was used to further quantify the cellular uptake of the nanoparticles into Bel 7402 cells.MRl was performed to show the signal intensity changes by using T2 WI sequences at a clinical 1.5 T MR system.Results Prussian blue staining showed much more intracellular iron in cells incubated with Folate-SPIO-DOX-Micelles than the cells incubated with the non-targeting SPIO-DOX-Micelles.As revealed by flow cytometry,the mean fluorescence intensity of cells in the folate group and the non-folate group were 117.88 and 46.33,respectively.The T2 signal intensity in MRI of cells treated with the folate targeting micelles decreased significantly (when the concentration of SPIO in cell culture medium was 5,10,20,40,and 80 μg/ml,respectively,T2 signal intensity decreased by -5.02%,-23.58%,-45.89%,-70.34%,and -92.41%,respectively).In contrast,T2 signal intensity did not show obvious decrease for cells treated with the folate-free micelles (when the concentration of SPIO in cell culture medium was at 5,10,20,40,and 80 μg/ml,respectively,T2 signal intensity decreased by -3.77%,-2.16%,-2.18%,-2.74% and -19.77%,respectively).Conclusion The polymeric micelles,Folate-SPIO-DOX-Micelles has good targeting ability to the hepatic carcinoma cells in vitro,and the cell targeting events of the micelles can be monitored by using a clinical MR scanner. Key words: Folic acid; Magnetic resonance imaging; Carcinoma,hepatocellular; Animals,laboratory