In-vitro Test Of Targeted Nano Magnetic Resonance Contrast Medium C225-USPIO Against EGFR

Objective To investigate the immunobinding activity,toxicity and the capability to magnetic resonance imaging of targeted nano contrast medium C225-USPIO in vitro. Methods Etuximab (C225) and ultrasmall superparamagnetic iron oxide (USPIO) were connected by carbodiimide to form targeted nano contrast medium C225-USPIO against EGFR. The conjugation efficiency, which indicates the percentage of the C225 conjugated to USPIO with respect to the total amount used for preparation of nanoparticles, was determined by BCA protein assay kit. The immunobinding activity of C225-USPIO to the nasopharyngeal carcinoma cell line SUNE1 was confirmed by flow cytometry. The MTT-based toxicity and proliferation assay was performed to analyse the potential toxicity of C225-USPIO. Flow cytometry analysis demonstrates apoptosis of SUNE1 cells and Beas-2B cells cultured by C225-USPIO over 24 hours and 48 hours. Prussian blue staining was used to detect C225-USPIO targeted binding to SUNE1 cells. Magnetic resonance imaging (MRI) signal strength variation was detected by 4.7T MRI, after C225-USPIO,IgG-USPIO,USPIO with Fe concentration 75μg/ml incubating SUNE1,Beas-2B cells for 2 hours.Result BCA protein assay kit displayed that the highest binding of C225 was 68.54% when USPIO connecting with C225 in the proportion of 1:2. As indicated by flow cytometry, C225-USPIO had well immunobinding activity with EGFR on the surface of SUNE1 cells (p=0.025). The MTT assay and the flow cytometry analysis showed that C225-USPIO did not affect proliferation and apoptosis of SUNE1 and Beas-2B cells (p>0.05). And as indicated by Prussian blue staining, C225-USPIO could specifically bind with EGFR on the surface of SUNE1 cell, while no iron depositions were observed in the control group. C225-USPIO decreased the signal intensity of MRI T2 significantly in the SUNE1 cells group, as indicated by 4.7T MRI.Conclusion C225-USPIO did not affect proliferation and apoptosis of SUNE1 and Beas-2B cells. C225-USPIO is demonstrated to be able to selectively accumulate in SUNE1 cells, resulting in a marked decrease of MRI T2-weighted signal intensity.