Phase-Change Contrast Agents for Ultrasound Detection of Breast Cancer

描述（由申请人提供）：微泡造影剂与超声联合使用，目前已被FDA和其他全球机构批准为血管剂，用于增强超声心动图和肝脏成像。在研究领域，它们也被用作分子显像剂，用于检测血管生成、炎症和易损斑块，仅举几例。此外，它们也被转化为临床超声介导的溶栓剂（即超声溶栓）。然而，尽管它们很实用，但由于它们相对较大（1 - 5微米）且不能外渗到组织空间，它们也主要局限于脉管系统。最近，我们的实验室开发了一种新的相变造影剂（pcca），它由100纳米、超声可激活、脂质包被、全氟碳填充的液滴组成，设计用于血管外分布，然后转化为微泡，用于超声组织成像。这些pcca由非常低沸点的液体全氟碳化合物（十氟丁烷，bp = -1.1℃，八氟丙烷，bp = -36.7℃）组成，在生理温度（37℃）下稳定，可以激活成具有低超声能量输出的可想象的微气泡（FDA批准的机械指标）。此外，使用标准的临床超声仪可以实现向微泡的转换。关于它们向组织外渗的能力的研究正在进行中，这是以前拨款的重点。目前，我们正在测量PCCA外渗水平，作为增强渗透性和滞留效应（EPR）的指示。在这项新提案的重点中，我们希望现在研究细胞内递送这些pcca的方法，以便在体外和体内乳腺癌细胞的细胞环境中激活，以用于选择性乳腺肿瘤细胞成像。此外，我们希望开展体外研究，以确定细胞内产生的微泡空化是否能促进肿瘤细胞的破坏。作为靶向介质，我们将使用人表皮生长因子受体（hEGFR）作为更精确递送和细胞内摄取的生物标志物。因此，本提案的目标是制定针对egfr的pcca；1)高选择性细胞内成像；2)通过超声介导的细胞内空化产生的微泡，开始监测体外选择性乳腺肿瘤细胞破坏。这些目标的成功实现将使我们的实验室能够设计出第一种用于血管外应用的超声介导的诊断和治疗药物。

DESCRIPTION (provided by applicant): Microbubble contrast agents used in conjunction with ultrasound are currently approved by the FDA and other global agencies as vascular agents for enhancing echocardiographic and hepatic imaging. They are also used in the research arena as molecular imaging agents for detection of angiogenesis, inflammation, and vulnerable plaque to name but a few. In addition, they have been translated to the clinic as ultrasound-mediated thrombolytic agents as well (i.e. Sonothrombolysis). Yet despite their utility, they are also restricted primarily to the vasculature due to their relatively large size (1 - 5 microns) and inability to extravasate into the tissue space. Recently, our laboratory has developed new phase-change contrast agents (PCCAs) that are comprised of a 100 nm, ultrasound-activatable, lipid-coated, perfluorocarbon-filled droplet designed for extravascular distribution followed by conversion to microbbubbles for ultrasound tissue imaging. These PCCAs consist of very low boiling liquid perfluorocarbons (decafluorobutane, bp = -1.1¿C, octafluoropropane, bp = -36.7¿C), stable at physiologic temperatures (37¿C) and activatable into imagable microbubbles with low ultrasound energy outputs (FDA approved mechanical indices). Furthermore, conversion to microbubbles is acheivable using standard clinical ultrasound machines. Studies are ongoing with respect to their ability to extravasate into tissue and are the focus of a previou grant. Currently, we are measuring levels of PCCA extravasation as an indication of enhanced permeability and retention effect (EPR). In the focus of this new proposal, we wish to now study methodology for intracellular delivery of these PCCAs for activation inside the cellular milieu of breast cancer cells in vitro and in vivo for the purposes of selective breast tumor cell imaging. I addition, we wish to embark on in vitro studies to determine if intracellular cavitation of the resultant microbubbles can promote tumor cell destruction. As a medium for targeting, we will use the human epidermal growth factor receptor (hEGFR) as a biomarker for more precise delivery and intracellular uptake. Thus, the goal of this proposal is to formulate EGFR-targeted PCCAs for; 1) highly selective intracellular imaging and; 2) initiate monitoring for selective breast tumor cell destruction in vitro via ultrasound-mediated intracellular cavitation of the resultant microbubble. Successful accomplishment of these goals will poise our laboratory for designing the first ultrasound-mediated diagnostic and therapeutic agent for extravascular applications.