Closed-Chest Cell Injections into Mouse Myocardium Targeted by Ultrasound

描述（由申请人提供）：心内细胞植入和治疗基因注射已被提出作为缺血性心脏病的治疗方法。然而，最近的文献中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，并报告了不同的发现，从心脏功能的改善到缺乏改善和缺乏分化的干细胞。本提案旨在评估以下假设，即这些矛盾部分源于心肌壁而不是左心室腔注射的不同成功，以及高分辨率超声心动图的无创成像可以准确地靶向注射到正常和梗死小鼠心脏，为研究潜在的细胞植入和基因治疗提供临床相关系统。首先，注射超声心动图造影剂和荧光微球的混合物，将超声引导注射时观察到的针头位置与组织学检查证明的实际注射部位联系起来。在系统优化后，高分辨率超声心动图将用于引导经胸将标记细胞植入手术梗死小鼠的心脏，靶向梗死边界区并证明概念的有效性。该系统将用于研究标记的骨髓来源细胞通过心肌迁移到受损组织的能力，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。它还将用于比较梗死过程中心内细胞植入与梗死后几天植入的效果，这是一个更具有临床相关性的模型，没有回声引导很难实现；以及多次。这将导致进一步的研究靶向注射到梗死边界区骨髓源性细胞和表达生长因子的成肌细胞。相关性：所谓的成体干细胞的植入和编码生长因子的基因的注射是治疗心脏功能低下的潜在治疗方法，心脏功能低下通常困扰着心脏病发作的幸存者。许多实验可以在小鼠身上进行；然而，他们的心脏太小，很难以临床相关的方式进行注射。这项研究将使用高分辨率的超声波来引导这种注射进入老鼠的心脏，而不需要手术，这将使老鼠成为更好的实验模型。

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.