Studies on the Distribution and Radioimmunoimaging of ~(99m)Tc-Labeled 5-Fluorouracil Loaded Immunological Nanoparticles in Tissues and Human Gastric Carcinoma Xenografts

摘要

OBJECTIVE To explore the method of preparation of ~(99m)Tc labeled Anti VEGF McAb 5-FU loaded polylactic acid nanoparticles (9~(99m)Tc-5-FU-Ab-NPs), and investigate the biological distribution of the nanoparticles in human gastric carcinoma xenografts.rnMETHODS AntiVEGF monoclonal antibodyes (MCAB) in 5-FU-Ab-NPs were labeled with 9~(99m)Tc using a modified Schwarz method. After isolation of the 9~(99m)Tc-5-FU-Ab-NPs using a Sephadex G-250 column, the labeling percentage and radiochemical purity were determined using paper chromatography. The immunocompetence of the 9~(99m)Tc-5-FU-Ab-NPs as tumor markers was determined using ELISA and immunohistochemistry. 9~(99m)Tc-5-FU-Ab-NPs (experimental group), 9~(99m)Tc-labelled murine multiclonal IgG loaded polylactic acid and nanoparticles (control group) were injected via the tail vein into SCID mice bearing human gastric carcinoma. A radio-immunity ECT image was developed at 2 and 6 h after the injection. Following the ECT imaging, the mice were sacrificed, their tissue and tumor radioactivity distribution determined, and percentage of the injected-dose pergram (%ID/g) and tumor/ nontumor (T/NT) ratio calculated. High performance liquid chromatography (HPLC) was used to determine the 5-FU concentration in the tumor tissue and blood in the mice of both groups.rnRESULTS The percentage of 9~(99m)Tc-5-FU-Ab-NPs labeling was 90%～95%. There was no obvious decrease in the antibody activity before and after labeling. The radio-immuno-imaging (RII) showed that the tumor image had developed 2 h after injection of the ~(99m)Tc-5-FU-Ab-NPs, and with time it was clearer at the 6th hour following the injection. The %ID/g of the tumor tissue at both 2 h and 6 h after the injection was significantly higher compared to the control group. The tumor %ID/g and the tumor to blood activity ratio (TB) of the experimental group at 6 h following the injection in creased compared to that at 2 h, and at the same time, 5-FU concentration in the tumor of the experimental group continuously increased over time, and showed a significant difference compared to the 5-FU concentration in the tumor of the control group.rnCONCLUSION The 9~(99m)Tc-5-FU-Ab-NPs prepared in this study are adequate to meet the demands of the RIl, and the immune targeting ability of the anti-VEGF MCAB is reliable. Six hours after injection, the 9~(99m)Tc-5-FU-Ab-NPs showed a relatively high specific concentration shadow in the human gastric carcinoma xenografts.