大鼠慢性心肌梗塞的组织学定量分析
Summary
The post-mortem assessment of myocardial infarction (MI) in rodents is based on quantification of the infarct on stained heart sections. We describe an accurate method to quantify the infarct size using systematic sampling of harvested rat hearts from base to apex and image analyses of trichrome-stained histological sections.
Abstract
Myocardial infarction is defined as cardiomyocyte death due to prolonged ischemia; an inflammatory response and scar formation (fibrosis) follow the ischemic injury. Following the initial acute phase, chronic remodeling of the left ventricle (LV) modifies the structure and function of the heart. Permanent coronary ligation in small animals has been widely used as a reference model for a chronic model of MI. Thinning of the infarcted wall progressively develops to transmural fibrosis. Histological assessment of infarct size is commonly performed; nevertheless, a standardization of the methods for quantification is missing. Indeed, important methodological aspects, such as the number of sections analyzed and the sampling and quantification methods, are usually not described and therefore preclude comparison across investigations. Too often, quantification is performed on a single section obtained at the level of the papillary muscles. Because novel strategies aimed at reducing infarct expansion and remodeling are under investigation, there is an important need for the standardization of accurate heart sampling protocols. We describe an accurate method to quantify the infarct size using a systematic sampling of harvested rat heart and image analyses of trichromatic stained histological sections obtained from base to apex. We also provide evidence that calculating the expansion index (EI) allowed for infarct size assessment, taking into account changes of the left ventricle throughout the remodeling.
Introduction
心肌梗死（MI）是全球死亡和残疾的主要原因。冠状动脉心脏疾病是主要原因; MI缺血连续冠脉事件，如阻塞造成的。当未在第一6小时内进行再灌注，局部缺血诱导的不可逆的心肌坏死。在患者中，心肌梗死的表征依赖于不同的诊断工具，包括临床体征，心电图，生物标志物，超声心动图，MRI影像的血浆水平的评估，以及组织学分析1。急性和慢性心肌梗塞是根据相对于冠状动脉闭塞时的心肌坏死的定时列为损伤的两个不同阶段。急性期，在第7天发生，与心肌细胞的损失，广泛炎症，和成纤维细胞的招募相关联。亚急性期，其特征在于所述心脏组织和瘢痕形成的愈合，发生1和4之间 – 6周。梗死，心室壁变薄，心室扩张的扩张表征慢性期。左心室重构粗放逐步导致严重的心脏衰竭2。
MI永久左前降支（LAD）结扎引起慢性代表心肌梗死的标准啮齿动物模型。冠状动脉结扎模仿冠状动脉闭塞。梗塞的大小取决于该结扎的部位上。是用经典的生物标志物血浆水平，如肌钙蛋白执行在啮齿动物模型心肌缺血损伤的表征我和T 3，超声心动图，MRI和组织学4,5。生物标记水平与心肌死亡的程度相关。超声心动图检查评估从区域室壁运动异常导致左心功能受损。此外，非侵入性的成像技术，如MRI或高分辨率超声心动图，允许在壁运动的减少的评估，以减少灌注和存活心肌，和壁变薄的瘢痕区域的体积。 LV尺寸允许梗死面积的准确的评价。最后，可行和死心肌的量化可以用收获内心的组织切片的特殊污渍的进行尸检，并允许梗死面积（IS）的验证。另一个重要的特征是梗塞膨胀指数（EI）6的评价。在EI与内的第3天透梗死并启动有关。在EI的特征在于在壁厚的逐步减少，增加了在LV空腔尺寸，并在左心室的形状随之变化。
为了评估的新的治疗方法的治疗效果 – 尤其是，根据细胞，基质再生策略，以及在啮齿动物中的MI的基因递送精确的评估是极其重要的。当在乳头肌水平而获得的单个横截面测得，在IS大小可能由于存在于梗塞的发展以下LAD结扎的大变异被偏置;心尖梗塞可能会再遮掩。重要的是，更准确的方法来确定的梗死面积已为7-9小鼠或大鼠10所示。然而，IS不足以准确量化左室重构或重塑的治疗引起的减少（或预防措施）。事实上，IS通常表示为评估对心脏的横截面总左心室体积的百分比。虽然这种方法是有效的急性心肌梗死，重塑过程中发生的左心室壁的变薄仍在评估11,12。梗塞大小和结构变化的完整形态量化应量化的几个参数，如心内膜和心外膜的长度和直径，以及梗塞和健康领域。我们描述一个方法论APPRoach准确评估MI和重构的一种慢性大鼠模型。
Protocol
Representative Results
Discussion
该议定书中的关键步骤
纤维组织可在使用心脏收获和图像的系统抽样一种慢性心肌梗死大鼠模型准确地评估分析从基地获得到顶点三色染色组织切片。两个步骤是成功的协议实现尤为重要。首先，对于心脏收获使用氯化钾使心肌以松弛状态被维持。本步骤是从不同的心梗塞尺寸的比较重要的。第二，在布安溶液中的部分的过夜固定是至关重要的，以获得明亮的?…
Disclosures
The authors have nothing to disclose.
Acknowledgements
The study was supported by the Swiss National Foundation [SNF 310030-149986 to MNG], the University of Fribourg, and Fribourg Hospital.
Materials
| Acrylic rat heart matrix 2mm | 72-5015 | Harvard Appartus | |
| INSPIRA ADVANCED VOLUME CONTROLLED VENTILATOR | HARVARD APPARATUS | 557058 | |
| CATHETER INSYTE 14G | BD | 381267 | |
| O.C.T | BDHA361603E | VWR | |
| TTC | T8877-10G | Sigma Aldrich | |
| Mayer hematoxylin | MHS32-1L | Sigma Aldrich | |
| Acid Fuchsin CI 42685 |
F8129-50G | Sigma Aldrich | |
| Ponceau Xylidin CI 16150 |
P2395-25G | Sigma Aldrich | |
| Orange G CI 16230 |
O3756-100G | Sigma Aldrich | |
| Light green CI 42095 |
L5382-25G | Sigma Aldrich | |
| KCl | P9333-500G | Sigma Aldrich | |
| Xylol | 10315083 | HoneyWell | |
| Ethanol absolute | 10303990 | HoneyWell | |
| 2-methylbutane | M32631-1L | Sigma Aldrich | |
| Stereogical microscope | SM2800 | Nikon | |
| Formaldehyde | 99340 | Reactolab | |
| Embedding cassette | K113.1 | Carl Roth | |
| Bersoft Image measurement Software | Bersoft.com | Licensed software |
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