Closed-Chest Cell Injections into Mouse Myocardium Targeted by Ultrasound

描述(申请人提供)：心肌细胞内植入和注射治疗性基因已被提议作为治疗缺血性心脏病的方法。然而，最近的文献包含了许多相互矛盾的结果。不同的研究小组将相同的细胞群注入小鼠心脏，并报告了不同的结果，从心脏功能的改善到缺乏改善或缺乏分化的干细胞。这项建议旨在评估这样一种假设，即这些矛盾在一定程度上源于心肌壁而不是左心室腔内注射的不同成功程度，以及高分辨率超声心动图的非侵入性成像可以准确地定位对正常和梗死小鼠心脏的注射，提供了一个临床相关的系统，用于研究潜在的细胞植入和基因治疗。首先，将注射超声心动图造影剂和荧光微球的混合物，以将回声引导注射过程中观察到的针头位置与组织学检查所证明的实际注射位置相关联。在系统优化后，将使用高分辨率超声心动图引导经胸将标记细胞植入外科梗死小鼠的心脏，瞄准梗死边缘区域并展示概念验证。该系统将用于研究通过靶向注射标记细胞与不同大小和颜色的荧光微球混合的方式，标记的骨髓来源细胞通过心肌迁移到受损组织的能力。它还将用于比较梗死过程中心肌内细胞植入与梗死后几天内植入的效果，这是一种更具临床相关性的模型，如果没有回声引导，很难实现；以及多次植入。这将导致进一步的研究，定向注射到梗死区的骨髓来源的细胞和表达生长因子的成肌细胞。相关性：植入所谓的成体干细胞和注射编码生长因子的基因是治疗心脏功能不良的潜在方法，这种疾病通常困扰心脏病发作的幸存者。许多实验可以在老鼠身上进行；然而，它们的心脏太小，很难以临床相关的方式注射到它们体内。这项研究将使用高分辨率超声波引导这样的注射到小鼠的心脏，而不需要手术，并将使小鼠成为此类实验的更好的模型。

DESCRIPTION (provided by applicant): Intramyocardial cell implantation and injection of therapeutic genes have been proposed as therapies for ischemic heart disease. However, the recent literature contains numerous contradictory results. Different research groups inject identical cell populations into mouse hearts and report disparate findings, ranging from improvement of cardiac function to lack of improvement and absence of differentiated stem cells. This proposal is designed to evaluate the hypothesis that these contradictions stem, in part, from varying success of injection into the myocardial wall rather than the left ventricular cavity, and that non-invasive imaging with high resolution echocardiography can accurately target injections into normal and infarcted mouse hearts, providing a clinically relevant system with which to study potential cell implantation and gene therapies. First, a mixture of echocardiography contrast agent and fluorescent microspheres will be injected to correlate the observed needle position during echo-guided injections with the actual injection site as evidenced by histological examination. After the system has been optimized, high resolution echocardiography will be used to guide transthoracic implantations of labeled cells into the hearts of surgically infarcted mice, targeting the infarct border zone and demonstrating proof of concept. The system will be used to study the ability of labeled bone marrow derived cells to migrate through cardiac muscle to damaged tissue by targeted injections of labeled cells mixed with fluorescent microspheres of different sizes and colors. It will also be used to compare the effects of intramyocardial cell implantation during the infarction procedure to implantation several days after infarction, a more clinically relevant model that is very difficult to achieve without echo-guidance; as well as at multiple times. This will lead to further studies of targeted injection into the infarct border zone of both bone marrow-derived cells and myoblasts expressing growth factors. RELEVANCE: The implantation of so-called adult stem cells and the injection of genes encoding growth factors are potential treatments for poor cardiac function that typically plagues heart attack survivors. Many experiments can be carried out in mice; however, their hearts are so small that it is difficult to inject into them in a clinically relevant way. This research will use high-resolution ultrasound to guide such injections into the mouse heart, without surgery, and will make the mouse a much better model for such experiments.