Abstract
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Objectives The goal of this study is to synthesize and evaluate F-18-labeled C2A domain of synaptotagmin (18F-C2A-GST) and F-18 labeled rh-His10-annexin V as two promising PET tracers for the detection of apoptosis.
Methods 18F-C2A-GST and 18F-rh-His10-annexinV were preparedby labeling C2A-GSTand rh-His10-annexinVwith N-succinimidyl 4-18F-fluorobenzoate (18F-SFB), respectively, the binding ratio with apoptotic cell were validated in vitro using camptothecin-induced Jurkat cells. In vivo biodistribution of the two 18F-labeled tracers was determined in mice by dissection method and micro PET dynamics imaging.
Results 18F-C2A-GST and 18F-rh-His10-annexinV were labeled by conjugating the corresponding proteins with 18F-SFB. The radiochemical purity of both tracers was higher than 95%, and remained stable 3 h later. 18F-C2A-GST and 18F-rh-His10-annexinV bind to apoptotic cells, and significantly elevated radiotracer-uptakes were detected in camptothecin-induced Jurkat cells compared to that in untreated groups. Biodistribution in the mice showed these two 18F labeled tracer showed rapid blood clearence and relatively low uptake in the liver, spleen, and heart.
Conclusions 18F-C2A-GST and 18F-rh-His10-annexinV can be easily prepared with conjugation of 18F-SFB. Due to their rapid blood clearance and low uptake in abdomen organ, they might have more advantages in the detection of apoptosis, in comparison with the corresponding technetium labeled compounds, especially for the early evaluation of tumor therapy efficacy.
- © 2009 by Society of Nuclear Medicine