Rhenium-188 labeled recombinant human plasminogen kringle5 (rhk5) and preliminary biodistribution: Evaluation in mice bearing A549 tumours | Rhenium-188 markiertes, rekombinantes humanes Plasminogen Kringle 5 (rhk5) und vorläufige Bioverteilung - Beurteilung bei Mäusen mit A549-Tumoren

Aim: Angiogenesis plays a critical role in tumour formation and metastasis. Suitable radiolabeled angiogenesis inhibitor can be used for noninvasive imaging of angiogenesis and radionuclide therapy. Here we prepare rhenium-188 labeled recombinant human plasminogen kringle5 (Re-188-rhk5) in a convenient manner than evaluate its properties in A549 lung adenocarcinoma. Methods: Re-188-rhk5 was obtained by conjugating His group at the C end of rhk5 with fac-[Re-188(H2O)(3)(CO)(3)](+). Chelating efficiency of fac-[Re-188(H2O)(3)(CO)(3)](+) and radiolabeling efficiency of Re-188-rhk5 were measured by radio thin-layer chromatography (RTLC). In vitro stability of Re-188-rhk5 was determined in human serum at 37 degrees C and analyzed by RTLC. Competition test was also performed to verify the specificity of binding. A biodistribution study was carried out in nude mice bearing A549 lung adenocarcinoma. Results: Re-188-rhk5 was obtained with a radiolabel efficiency of 66.1%, the radiochemical purity (RCP) can reach 95.2% after purification. Re-188-rhk5 showed high stability in human serum, the RCP was more than 80% even 12 h after incubation. Competition test showed a high binding specificity. Furthermore, this radio-complex was excreted mainly through kidneys and showed specific tumour uptake in mice bearing A549 tumours. Conclusion: Re-188-rhk5 was prepared by a simple method. Preliminary biodistribution results showed its potential as an agent for possible tumour imaging, therapy and encouraged further investigation.