The preliminary study of molecular imaging of colorectal cancer cells with superparamagnetic iron oxide-based MR targeting probe containing vascular endothelial growth factor in vitro

Objective: To develop a superparamagnetic iron oxide (SPIO)-based MR probe containing vascular endothelial growth factor(VEGF) to investigate their biological and chemical properties and targeting effect of colorectal cancer cells in vitro. Methods: The anti-VEGF-SPIO probe was fabricated with VEGF antibody and SPIO through chemical method. Its biological and chemical properties and reflexivity were tested with SDS-PAGE and MRL The SW620 cells incubated with anti-VEGF-SPIO probe for 30, 60 and 90 minutes respectively and compared with marrow mesenchymal stem cell at 37 degree C. The comparison among groups was conducted by using analysis of variance and LSD-t test. The MRI results were confirmed by the Prussian blue staining. The comparison among groups was performed by analysis of variance and factorial experiment. Results: SPIO-based MR probe containing VEGF was successfully contributed and isolated. The reflexivity of anti-VEGF-SPIO probe was 0.0426 x 106 mol/s. The immunofluorescence and prussia blue stain proved high expression of VEGF in SW620 cells. Anti-VEGF-SPIO probe and SW620 cellscombined at 37 degree C in vitro MRI proved the SW620 cells incubated with anti-VEGF-SPIO probe appeared hypointense on T2WI and T2* WI. MR signal were 392 ± 7, 91 ± 8, 264 ± 10 for 30, 60 and 90 minutes respectively, which were statistically different from that before incubation 679 ± 12 (F=4735.489, P< 0.01). The intensity decreased most significantly at 60 minutes in vitro. Its MR signal 82 ± 7 were statistically different compared with marrow mesenchymal stem cell 689 ± 43, t=39.167,P<0.05). While SW620 cells incubated without SPIO were not statistically different compared with marrow mesenchymal stem cell, which were 419 ± 59 and 400 ± 41 respectively(t=-0.718, P>0.05). Conclusion: Nanoscale iron particles containing the anti-vascular endothelial growth factor molecular probe can evaluate tumor angiogenesis at the receptor level, which provides a new way of the tumor angiogenesis diagnosis and anti-angiogenesis therapy. (authors)