Abstract:Objective To investigate application of mutation protein of C2A domain of synaptotagmin I(Syt I-C2A-G4C) labeled with technetium in myocardial apoptosis imaging. Methods (1) The C2A domain of Syt I was labeled with 99Tcm using reduction photoetry of Tin chloride. Radiochemical purity was determined with thin layer chromatography. The binding activity with phosphatidylserine of radiolabeled protein was assessed using cell binding experiment.(2) Myocardial ischemia-reperfusion models were produced in 5 pigs. SPECT images were acquired at 2h after post injection of 99mTc-Cyt-C2A-G4C via the tail, and the ratio of target/background was also cal- culated using region of interest(ROI) method. Apoptosis in the ischemic myocardium was assessed using terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay. Results (1) The radiochemical purity of 99Tcm-Syt I-C2A-G4C was(96.42±0.76)%.(2) The radioactivity in the camptothecin-treated group was (5.23±0.38) folds higher than that of non-treated viable control group.(3)At 2 h post-injection of the radiotracer, the focal uptake of radioactivity was observed at the ischemic myocardium areas, and T/B ratio was 3.40± 0.43 . Myocardial apoptosis was confirmed by TUNEL assay in the ischemic myocardium with high radioactivity. Conclusion 99Tcm-Syt I-C2A-G4C should be a potential radiotracer for imaging of myocardial apoptosis.
[1] Wang Y,Ahmad N,Wang B,et al. Chronic precondition: a novel approach for cardiac protection[J]. Am J Physiol Heart Circ Physiol,2007,292(5): H2300-H2305. [2] Taki J,Higuchi T,Kawashima A,et al. Detection of cardiomyocyte death in a rat model of ischemia and reperfusion using 99Tc m-labeled Annexin V[J]. J Nucl Med,2004,45 (9):1536-1541. [3] Zhao M,Zhu X,Ji S,et al. 99mTc-labeled C2A domain of synaptotagmin I as a targeted-specific molecular probe for noninvasive imaging of acute myocardial infrarction[J]. J Nucl Med, 2006,47(8):1367-1374. [4] Zhao M,Beauregard DA,Loizou L,et al. Non-invasive detection of apoptosis using magnetic resonance imaging and a targeted contrast agent[J]. Nat Med,2001,7(11): 1241-1244. [5]方纬,王峰,季顺东,等. 99Tcm-FM2心肌细胞凋亡显像的实验研究[J].中华核医学杂志,2006,26(3):137-140. [6] Zhu L,Liu BL, Guo YZ. 99Tcm direct labeling of Annexin V for potential apoptosis imaging in vivo(Abstract)[J]. J Labeled Comp Radiopham, 2003, 46:S324. [7]周俊东,方纬,季顺东,等.用99Tcm标记突触结合蛋白I-C2A片段评价缺血预处理对心肌缺血再灌注损伤的保护作用[J].中华核医学杂志,2009,29(2):113-116. [8] Silva M,Benito A,Sanz C,et al. Erythropoietin can induce the expression of mbel-x(L)through stat-5 in eryth-ropoietin-dependent progenitor cell lines[J]. J Boil Chem, 1999,274(32): 22165-22169. [9] Zhou D,Chu W,Rothfuss J,et al. Synthesis,radiolabeling,and in vivo evaluation of an 18F-labeled isatin analog for imaging caspase-3 activation in apoptosis[J]. Bioorg Med Chem Lett,2006,16(19): 5041-5046. [10] Madar I,Ravert H,Nelkin B,et al. Characterization of membrane potential-dependent uptake of the novel PET tracer 18F-fluorobenzyl triphenylphosphonium cation[J]. Eur J Nucl Med Mol Imaging,2007,34(12): 2057-2065. [11] Aloya R,Shirvan A,Grimberg H,et al. Molecular imaging of cell death in vivo by a novel small molecule probe[J]. Apoptosis,2006,11(12): 2089-2101.