title: Evaluation of adenosine preconditioning with 99mTc-His10-annexin V in a porcine model of myocardium ischemia and reperfusion injury: preliminary study.
abstract: OBJECTIVE
  The goal of this study was to evaluate the feasibility of (99m)Tc-His(10)-annexin V for the detection of acute myocardial cell death and to assess the effect of adenosine preconditioning in a porcine model of myocardium ischemia and reperfusion injury (RI).
  
  
  METHODS
  (99m)Tc-His(10)-annexin V was prepared by one-step direct labeling, and RCP and radiostability were tested. The binding of (99m)Tc-His(10)-annexin V to apoptosis was validated in vitro using camptothecin-induced Jurkat cells. In vivo biodistribution was determined in mice by the dissection method. Ischemia of 20-30 min was induced by balloon occlusion of the epicardial coronary artery of the porcine model (n=14). Adenosine was infused intravenously in six pigs before coronary occlusion. (99m)Tc-His(10)-annexin V (n=12) was injected intravenously at 1 h after reperfusion. SPECT/CT was acquired at 3 h postinjection. Myocardial perfusion imaging (MPI) with (99m)Tc-MIBI was also performed 1 day after His(10)-annexin V imaging. Cardiac tissues were analyzed postmortem using hematoxylin-and-eosin and TUNEL staining. Caspase-3 activity was measured to confirm the presence of apoptosis.
  
  
  RESULTS
  (99m)Tc-His(10)-annexin V had a RCP >98% and high stability 2 h after radiolabeling; it could bind to apoptotic cells with high affinity. Biodistribution of (99m)Tc-His(10)-annexin V showed a predominant uptake in the kidney and relatively low uptake in the myocardium, liver and gastrointestinal tract; rapid clearance from blood and kidney was observed. In the untreated group, intense uptake of His(10)-annexin V was visualized in the defect which was shown in MPI, whereas in the adenosine group a mild uptake of (99m)Tc-His(10)-annexin was found in the risk area which showed no defects in the (99m)Tc-MIBI image. TUNEL staining and activated caspase-3 confirmed the ongoing apoptosis in RI. Adenosine preconditioning significantly diminished the level of apoptosis. Uptake of His(10)-annexin V in RI correlated with TUNEL-positive nuclei.
  
  
  CONCLUSIONS
  This study addresses the feasibility of imaging of myocardial cell death in acute ischemia and RI in pigs with (99m)Tc-His(10)-annexin V; it holds prospect for the detection of myocardial cell death in clinical practice. Adenosine preconditioning could attenuate the myocardial apoptosis; its cardioprotective effect might partially be fulfilled by suppressing the ongoing apoptosis in ischemia and reperfusion. Further study is warranted.
authors.affiliation: Department of Cardiology, Nanjing First Hospital Affiliated to Nanjing Medical University, 68 Changle Road, Nanjing 210006, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Ye
authors.forename: Wei
authors.initials: W
authors.lastname: Fang
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.forename: Zi-Chun
authors.initials: ZC
authors.lastname: Hua
authors.forename: Zizheng
authors.initials: Z
authors.lastname: Wang
authors.forename: Xiang
authors.initials: X
authors.lastname: Yang
mesh_terms: D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D017304:Annexin A5 / Q000097:blood / Q000737:chemistry / Q000493:pharmacokinetics; D053148:Caspase 3 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D004195:Disease Models, Animal; D004789:Enzyme Activation / Q000187:drug effects; D005240:Feasibility Studies; D005260:Female; D006639:Histidine / Q000737:chemistry*; D006801:Humans; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods*; D019169:Jurkat Cells; D008297:Male; D051379:Mice; D015428:Myocardial Reperfusion Injury / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology*; D015609:Organotechnetium Compounds; D011817:Rabbits; D011854:Radiochemistry; D013552:Swine; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D017304:Annexin A5; D015609:Organotechnetium Compounds; D006639:Histidine; D053148:Caspase 3; D000241:Adenosine