The Distribution And Scintigrahpy Of Rhenium-188 Labeled NGR In Nude Mice Bearing Hepg2 Hepatoma

Objective: To label the peptide NGR containing Asn-Gly-Arg sequence by rhenium-188 and evaluate its radiochemical characteristics, biodistribution and imaging in nude mice bearing human HePG2 hepatoma. Methods: 1. The tumor angiogenesis targeting NGR containing peptide was labeled by 188-Rhnium directly by using 2-Mercapto-ethanol as reductant and sodium gluconate as middle ligand. 2. The nude mice bearing human HePG2 hepatoma were randomly divided into 7 groups (5 mice for each group), each mouse was intravenous injection of 7.4 MBq ¹⁸⁸Re-NGR,for the control group the mouse was blocked 100μg unlabeled NGR followed by ¹⁸⁸Re-NGR 1 hour later. The mice was sacrificed at 1,2,4,8,12h,24h after injection of ¹⁸⁸Re-NGR. The tumor/muscle (T/NT) value and biodistribution were calculated by % ID/g technique (percentage activity of injection dose per gram of tissue). The SPECT static imaging of another 3 mice were obtained at 1,2,4,8 12h and 24h after injection of ¹⁸⁸Re-NGR. Results: The labeling yield of ¹⁸⁸Re-NGR was more than 85%, with radiochemical purity (RCP) more than 90%. In vivo, ¹⁸⁸Re-NGR can specifically bind with tumor. The tumor uptake was 2.84±0.51%ID/g at 1h, the most uptake was 4.62±0.71%ID/g at 12h and remains 2.01±0.38%ID/g at 24h, while the tumor uptake of ¹⁸⁸Re-NGR in the blocking group was 1.03±0.21%ID/g. The ¹⁸⁸Re-NGR was secreted from kidney leading to the highest uptake 14.73±0.84 at 8h. The uptake in other tissues was continuously decreased result in a reasonable higher T/NT measured by ROI. The xenografted tumor became visible at 1h and was the most clearly at 12h.Conclusion: ¹⁸⁸Re-NGR can be efficiently prepared and favorably target tumor angiogenesis and should be a potential agent for tumor radiotherapy.