Neuroscience and Neuroengineering Center, Med-X Research Institute and School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China.
PLoS One. 2013 Sep 24;8(9):e75561. doi: 10.1371/journal.pone.0075561. eCollection 2013.
Transient middle cerebral artery occlusion (tMCAO) model is widely used to mimic human focal ischemic stroke in order to study ischemia/reperfusion brain injury in rodents. In tMCAO model, intraluminal suture technique is widely used to achieve ischemia and reperfusion. However, variation of infarct volume in this model often requires large sample size, which hinders the progress of preclinical research. Our previous study demonstrated that infarct volume was related to the success of reperfusion although the reason remained unclear. The aim of present study is to explore the relationship between focal thrombus formation and model reproducibility with respect to infarct volume. We hypothesize that suture-induced thrombosis causes infarct volume variability due to insufficient reperfusion after suture withdrawal. Seventy-two adult male CD-1 mice underwent 90 minutes of tMCAO with or without intraperitoneal administration of heparin. Dynamic synchrotron radiation microangiography (SRA) and laser speckle contrast imaging (LSCI) were performed before and after tMCAO to observe the cerebral vascular morphology and to measure the cerebral blood flow in vivo. Infarct volume and neurological score were examined to evaluate severity of ischemic brain injury. We found that the rate of successful reperfusion was much higher in heparin-treated mice compared to that in heparin-free mice according to the result of SRA and LSCI at 1 and 3 hours after suture withdrawal (p<0.05). Pathological features and SRA revealed that thrombus formed in the internal carotid artery, middle cerebral artery or anterior cerebral artery, which blocked reperfusion following tMCAO. LSCI showed that cortical collateral circulation could be disturbed by thrombi. Our results demonstrated that suture-induced thrombosis was a critical element, which affects the success of reperfusion. Appropriate heparin management provides a useful approach for improving reproducibility of reperfusion model in mice.
短暂性大脑中动脉闭塞（tMCAO）模型广泛用于模拟人类局灶性缺血性卒中，以便在啮齿动物中研究缺血/再灌注脑损伤。在 tMCAO 模型中，管内缝线技术广泛用于实现缺血和再灌注。然而，该模型中的梗死体积变化通常需要大样本量，这阻碍了临床前研究的进展。我们之前的研究表明，尽管原因尚不清楚，但梗死体积与再灌注的成功有关。本研究旨在探讨局部血栓形成与梗死体积重现性之间的关系。我们假设，由于缝线撤出后的再灌注不足，缝线引起的血栓形成导致梗死体积的变异性。72 只成年雄性 CD-1 小鼠接受 90 分钟的 tMCAO，并在有无腹腔内肝素给药的情况下进行。在 tMCAO 前后进行动态同步辐射微血管造影（SRA）和激光散斑对比成像（LSCI），以观察脑血管形态并测量体内脑血流。通过梗死体积和神经评分评估缺血性脑损伤的严重程度。我们发现，根据缝线撤出后 1 小时和 3 小时 SRA 和 LSCI 的结果，肝素治疗组小鼠的再灌注成功率明显高于肝素对照组（p<0.05）。病理特征和 SRA 显示，血栓形成于颈内动脉、大脑中动脉或大脑前动脉，这阻碍了 tMCAO 后的再灌注。LSCI 显示皮质侧支循环可能被血栓干扰。我们的结果表明，缝线诱导的血栓形成是影响再灌注成功的关键因素。适当的肝素管理为改善小鼠再灌注模型的重现性提供了一种有用的方法。
