preparation and biodistribution study of 99mtc-ec-annexin-spio as a tracer of radiation induced apoptosis in mice model

introduction: apoptosis is a major consequence of ionizing radiation in proliferative tissues and quantification of the apoptotic cells could be helpful for noninvasive assessment and estimation of the radiation absorbed dose. annexin v conjugated with super paramagnetic iron oxide nanoparticles (anx-spio) is a biological probe for detection of apoptotic cells using magnetic resonance imaging. this study aimed at assessing the biodistribution alterations of the labeled anx-spio within the mice body shortly after exposure to different doses of ionizing radiation. methods: 99mtc-ec-anx-spio was prepared and its in vitro stability was tested. the binding affinity of radiocomplex to apoptotic cells was validated in vitro. mice irradiated whole body with 2, 4 and 6 gy (60co gamma rays) and six hours later, radiocomplex was administrated intravenously and the biodistribution study was conducted 0.5, 1 and 2 hours later. results: the radiochemical purity of radiocomplex was 94% ± 3.4% and it showed a good stability in pbs and serum. the radiocomplex maintained its efficacy for in vitro binding to apoptotic cells.radiocomplex accumulated in the bone marrow of all irradiated mice (p