99mTc-HYNIC-annexin V SPECT imaging of acute stroke and its response to neuroprotective therapy with anti-Fas ligand antibody.
ABSTRACT The first aim of the study was to determine whether (99m)Tc-HYNIC-annexin V, a marker of cellular stress and apoptosis, can detect ischemic injury in patients with acute stroke. Secondly, we wished to test radiolabeled annexin's ability to monitor therapy in a rodent model of focal ischemic injury.
SPECT imaging of patients was performed between 1 and 2 h after intravenous injection of 30 mCi (1,110 MBq) of tracer. Eight MFL4 (anti-FasL) antibody-treated (400 microg i.p. days 0 and 3) and 21 control adult male Sprague-Dawley rats underwent small animal SPECT imaging with 5-10 mCi (185-370 MBq) of tracer, 1 and 6 days after a 2-h intraluminal thread occlusion of the left middle cerebral artery.
Two patients with acute stroke had regions of multifocal annexin uptake that correlated with sites of restricted diffusion on MRI. Anti-FasL antibody treatment significantly reduced annexin uptake by 92% with a 60% decrease in the number of caspase-8 staining (apoptotic) neurons on day 1. On day 6, treated animals had an 80% reduction in tracer uptake with a 75% decrease in infarct size as compared with controls. Annexin uptake in controls and treated animals (day 6) linearly correlated with infarct size (r (2)=0.603, p=0.0036) and the number of TUNEL-positive (apoptotic) nuclei (r (2)=0.728, p=0.00084).
Annexin imaging shows foci of increased uptake at sites of ischemic injury in patients with acute stroke. Annexin imaging can assess the effects of therapy for ischemic cerebral injury in rats, suggesting its potential as a non-invasive indicator of drug efficacy in future clinical trials.
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ABSTRACT: Objective(s):To investigate the effects of local mild hypothermia on the expression of Fas, FasL and MMP-3 after cerebral ischemia-reperfusion in rats.Materials and Methods:Male Wistar rats were divided into sham-operated group (Sham), normothermia group (NT), and hypothermia group (HT). MCAO/R model was established by Longa’s method, and reperfusion was allowed after 2 hr occlusion. Mild hypothermia (33±0.5°C) for 6 hr was initiated at the start of reperfusion. Immunohistochemistry was performed to determine expression Fas, FasL, and MMP-3.Results:Infarct volume was reduced in the hypothermia group (18.43±4.23%) compared with the normothermia group (24.76±5.76%) (P<0.05). In mild hypothermia group, numbers of Fas-positive and MMP-3 positive cells were significantly less than those of normothermia group (P<0.05). Neurological functional scores of mild hypothermia were significantly improved (P<0.05).Conclusion:Mild hypothermia decreases infarct volume after cerebral ischemia-reperfusion, reduces Fas and MMP-3 expression, but increases FasL in cerebral ischemia-reperfusion rats.Iranian Journal of Basic Medical Sciences 06/2014; 17(6):454-9. · 0.60 Impact Factor
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ABSTRACT: Cell death is one of the pathophysiological hallmarks after stroke. Markers to image cell death pathways in vivo are highly desirable. We previously showed that fluorescently labeled Annexin A5 (AnxA5), which binds specifically to phosphatidylserine (PS) on dead/dying cells, can be used in experimental stroke for monitoring cell death with optical imaging. Here we investigated whether dual-labeled AnxA5 (technetium and fluorescence label) can be used for single-photon emission computed tomography (SPECT) of cell death in the same model. C57Bl6/N mice were subjected to 60-minute middle cerebral artery occlusion (MCAO) and underwent SPECT imaging at 24, 48, and 72 hours afterwards. They were injected intravenously with either PS-binding AnxA5 or the nonfunctional AnxA5 (negative control), labeled with 99mTc and Alexa Fluor 568, respectively. After SPECT imaging, brain sections were cut for autoradiography and fluorescence microscopy. Ethanol-induced cell death in the femur muscle was used as positive control. We detected dual-labeled AnxA5 in the model of ethanol-induced cell death in the femur muscle, but not after MCAO at any time point, either with SPECT or with ex vivo autoradiography or fluorescence microscopy. Dual-labeled AnxA5 appears to be unsuited for visualizing death of brain cells in this MCAO model.Journal of Cerebral Blood Flow & Metabolism advance online publication, 2 July 2014; doi:10.1038/jcbfm.2014.115.Journal of Cerebral Blood Flow & Metabolism 07/2014; 34(9). DOI:10.1038/jcbfm.2014.115 · 5.34 Impact Factor
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ABSTRACT: Focal cerebral ischemia is among the main causes of death and disability worldwide. The ischemic core often progresses, invading the peri-ischemic brain; however, assessing the propensity of the peri-ischemic brain to undergo secondary damage, understanding the underlying mechanisms, and adjusting treatment accordingly remain clinically unmet challenges. A significant hallmark of the peri-ischemic brain is dysfunction of the blood-brain barrier (BBB), yet the role of disturbed vascular permeability in stroke progression is unclear. Here we describe a longitudinal in vivo fluorescence imaging approach for the evaluation of cortical perfusion, BBB dysfunction, free radical formation and cellular injury using the photothrombosis vascular occlusion model in male Sprague Dawley rats. Blood-brain barrier dysfunction propagated within the peri-ischemic brain in the first hours after photothrombosis and was associated with free radical formation and cellular injury. Inhibiting free radical signaling significantly reduced progressive cellular damage after photothrombosis, with no significant effect on blood flow and BBB permeability. Our approach allows a dynamic follow-up of cellular events and their response to therapeutics in the acutely injured cerebral cortex.Journal of Cerebral Blood Flow & Metabolism advance online publication, 27 August 2014; doi:10.1038/jcbfm.2014.147.Journal of Cerebral Blood Flow & Metabolism 08/2014; 34(11):1791-1801. DOI:10.1038/jcbfm.2014.147 · 5.34 Impact Factor