Evaluation of early efficacy of tumor radiation therapy using NIRF imaging
TIAN Rong1, SUN Hong-fang2, KUANG An-ren1, PAN Dong-feng3
1. Department of Nuclear Medicine, West China Hospital of Sichuan University, Chengdu 610041, China;2. Radiochemical Department, Peking University, Beijing 100083, China;3. Radiology Department, University of Virginia, VA 22903, USA
Abstract：Objective: In order to investigate whether near-infrared fluorescence(NIRF) labeled annexin V could also demonstrate apoptotic cells in small animal model. Methods: Cy5.5-annexin V, a novel NIRF contrast agent was synthesized and characterized. Its binding ability to target apoptotic cells was demonstrated in vitro. MCa-29 tumor cells were inoculated in the hind legs of mice to set up the animal models. The mice were divided into radiation and non-radiation groups. Cy5.5-annexin V was injected into mouse intravenously 6 hours after radiation. The imaging was performed 24 hours after injection. Results: The binding affinity, Kd, to phosphatidylserine(PS) was 2.51nM for the Cy5.5-annexin V and 1.54nM for the unmodified annexin V respectively. The results of flow cytometry and confocal fluorescence microscopy showed Cy5.5-annexin V targeted non-viable mouse thymocytes in similar patterns to FITC-annexin V. Fluorescence images of mice with MCa-29 tumor cells demonstrated that the fluorescence intensity in the radiated tumors was higher than that in untreated tumors. Conclusion: Cy5.5-annexin V could be useful in the early evaluation of radiation effect of the tumor.
2008, Vol. 19 
