Preparation Of ～(188)Re-AS And Its Bioactivity And Distribution In Mice

There is cumulative evidence that angiogenesis,the prosess of blood vessel formation,is important for the development of solid tumors and their metastasis. Angiostatin (AS), detected by O'Reilly in 1994, is a 38kD internal fragment of plasminogen. AS has since been proved to be a highly potent angiogenesis inhibitor that specifically targets proliferating endothelial cells and triggers endothelial cell apoptosis through which inhibits tumor grow.The combination of radioisotopes and AS can not only been a novel radiotracer for in vivo tumor and metastasis foci imaging but also can treat entity tumor by " bi-target". The physical characteristics of Re is choiceness and it is a perspective radioisotope. In preliminary experiments we study the method of labeling AS with rhenium and the biodistribution of the compound so as to base the foundation for further research.AIMThis paper has attempted to provide a perspective of ~188Re-labeled AS, It' s radiolabeling characteristics, quality control of radioimmunoconjugates, in vitro stability, bioactivity and the biodistribution in mice. Furthermore, it will be useful to explore the value of ~188Re-AS on antiangiogenic effect.METHODS1. The extracted AS was validated and the direct radiolabeling approach was taken to label AS with Re.The best labeling condition was screened by cross design.2. The labeling efficiency of the production was measured by paper chromatography, It' was supported by Newhua filter paper in double developing solvents to detect the Rf value.3. The stability of ~188Re-AS was evaluated in bovine serum albumin(BSA),saline and cysteine(Cys).4. The bioactivity of ~188Re-AS was detected by inhibition experiment of vessel endothelial in ECV304 cell line.5. The biodistribution of Re labeled AS was studied after intravenous injection in the tail vein of small rats for different time points.6. Statistics method: the data was analyzed with SPSS11.0 statisticsoftware and cross design was used in the screening of optima conditions. RESULTS1. The Rf value of ~188ReO4- ,~188Re colloid ,~188Re-AS is 0.8-0.9, 0.0 0.0-0.1 in 9g/L saline and 0.8-0.9 , 0.0, 0.7-0.8 in ethanol: ammonia:water(2:1:5 v/v). The best experimental condition was described below: AS 100μg, 20g/LSnCl2 (dissolved in 1 mol/L hydrochloric acid)200 μ1, 0.1 mol/L sodium tartrate (dissolved in 0.05 mol/L hydrochloric acid), and then ~188ReO4- 37 MBq was added,pH was 4.0 and the compound was incubated at 90℃ for 1 h, the labeling efficiency can achieve 76.3%.2. The radioactivity remained associated with the ~188Re-AS respectively declined by 2.5%,5%, 8% after 1 h, 3 h, 24 h in 0.9% saline solution, declined by 4%, 7.5%, 15% in 10g/L BSA.The radioactivity can be decreased in different molar ration of Cys. It decreased by no more than 15% when the molar ration was 5 in 3 hours. This indicates that the production is compareing stable in vitro.3. Treated ECV304 cells with ~188Re-AS and AS in various dosage and took 0.2M 6-aminocaproic acid as control. They both had inhibition effects on ECV304 cell line but the effect of ~188Re-AS was stronger than AS. That indicates ~188Re-AS had better biological activity than AS.4. The study of distribution in mice indicated: There was higher uptake in liver and kidney than the other organs in different times. The radioactivity...