Transferrin-labeled magnetolipsomes: preparation and magnetic resonance imaging in vitro / 中国组织工程研究

ABSTRACT

BACKGROUND:Transferrin (Tf) is one suitable ligand to be conjugated to drug delivery systems to achieve site-specific targeting and desired therapeutic effect, due to its specific binding to transferrin receptors (TfR), and high expression on the surface of tumor cells. Contrast agents are also modified with Tf to achieve specific tumor imaging. OBJECTIVE:To prepare Tf-labeled magnetoliposomes (MLs), and characterize their utility as TfR targeted MR specific contrast agent in vitro. METHODS:MLs and Tf-MLs were prepared by lipid film hydration method and covalent coupling method, respectively. Tf-MLs were characterized by their mean size, zeta potential, polyindex, r2 relaxivity, Tf-binding efficacy and cytotoxicity.In vitro MRI contrasting properties of the suspended nanoparticles incubated with HepG2 cells were determined. RESULTS AND CONCLUSION:The mean diameter, polydisperisity index, zeta potential and r2 relexivity of Tf-ML were 95.1 nm, 0.21,-1.25 mv and 94.62 mmol-1/s, respectively. The coupling efficiency was calculated and the values obtained were 59.4 μg Tf/μmol phospholipid corresponding to about 27 molecules of Tf-MLs. After a 2-hour incubation with rhodamine-labeled Tf-MLs, rhodamine fluorescence was detected intensively in the plasma membrane and the cytoplasm of the TfR-overexpressing HepG2 cells. In contrast, Tf-ML showed little binding in MCF-7 cells that had low TfR level. HepG2 cels incubated with Tf-ML showed much higher intracellualar iron density than incubated with non-targeted MLs.In vitro MR T2WI of cells demonstrated the centrifuge tube containing HepG2 cells incubated with Tf-MLs produced a lower visible signal intensity than that treated with non-targeted MLs. Tf-MLs showed their potentials such as high r2 relaxivity, specific binding ability characteristics. These results suggest the availability of Tf-MLs to serve as a targeted contrast agent.