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

OBJECTIVE To explore the method of preparation of 99mTc labeled AntiVEGF McAb 5-FU loaded polylactic acid nanoparticles(99mTc-5-FU-Ab-NPs), and investigate the biological distribution of the nanoparticles in human gas- tric carcinoma xenografts. METHODS Anti-VEGF monoclonal antibodyes(MCAB)in 5-FU-Ab-NPs were labeled with 99mTc using a modified Schwarz method.After isolation of the 99mTc-5-FU-Ab-NPs using a Sephadex G-250 column,the labeling percentage and radiochemical purity were determined using paper chromatog- raphy.The immunocompetence of the 99mTc-5-FU-Ab-NPs as tumor markers was determined using ELISA and immunohistochemistry.99mTc-5-FU-Ab-NPs (experimental group),99mTc-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 per gram(%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. RESULTS The percentage of 99mTc-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 99mTc-5-FU-Ab-NPs,and with time it was clearer at the 6th hour fol owing 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 increased 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. CONCLUSION The 99mTc-5-FU-Ab-NPs prepared in this study are adequate to meet the demands of the RII,and the immune targeting ability of the anti-VEGF MCAB is reliable.Six hours after injection,the 99mTc-5-FU-Ab-NPs showed a relatively high specific concentration shadow in the human gastric carcinoma xenografts.

OBJECTIVE To explore the method of preparation of 99m↑Tc labeled AntiVEGF McAb 5-FU loaded polylactic acid nanoparticles （99m↑TC-5-FU-Ab-NPs）, and investigate the biological distribution of the nanoparticles in human gastric carcinoma xenografts. METHODS Anti-VEGF monoclonal antibodyes （MCAB）in 5-FU-Ab-NPs were labeled with 99m↑Tc using a modified Schwarz method. After isolation of the 99m↑TC-5-FU-Ab-NPs using a Sephadex G-250 column, the labeling percentage and radiochemical purity were determined using paper chromatography. The immunocempetence of the 99m↑TC-5-FU-Ab-NPs as tumor markers was determined using ELISA and immunohistochemistry. 99m↑TC-5-FU-Ab-NPs （experimental group）, 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 per gram （%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. RESULTS The percentage of 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 %lD/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 %lD/g and the tumor to blood activity ratio （TB） of the experimental group at 6 h following the injection increased 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. CONCLUSION The 99m↑TC-5-FU-Ab-NPs prepared in this study are adequate to meet the demands of the RII, and the immune targeting ability of the anti-VEGF MCAB is reliable. Six hours after injection, the 99m↑TC-5-FU-Ab-NPs showed a relatively high specific concentration shadow in the human gastric carcinoma xenografts.