Image-guided Ultrasound-triggered Tumor Therapy

描述（由申请人提供）：超声提供了一种独特的图像引导治疗方法。首先，使用回声对比成像检测肿瘤血管系统。接下来，应用聚焦的高强度超声脉冲序列来激活造影剂/药物载体材料，并在超声区域释放治疗剂。在本应用中，我们提出了新一代超声触发药物载体材料的设计和评估。药物载体微泡和脂质体结构将被用于释放抗肿瘤药物或血栓生成酶进入肿瘤血管。药物在肿瘤肿块中的选择性沉积将会实现。对肿瘤的靶向细胞毒作用和靶向血栓形成会抑制肿瘤的生长和凋亡。具体目标（R21期）：1；制备可靶向的微泡药物递送结构，并从脂质体、附着于微泡的脂质体和微泡载体中进行超声介导的模型染料标记物释放。评价脂质体/颗粒膜组成、结构、相变温度和超声强度、频率和脉冲特性对释放效果的影响，以达到最佳释放效果。2. 在细胞培养中评估微泡/脂质体/药物构建物对活化内皮的靶向性，评估药物释放、凝胶和内皮细胞培养沉积。3. 超声介导的微泡/脂质体/酶的体外“触发”活化研究评估释放和治疗酶转化底物的有效性。4. 评估超声能量在体内皮下肿瘤中摧毁微泡药物载体系统的能力，图像引导靶向超声应用焦点。具体目标（R33期）：1；研究静脉给药后微泡和微泡脂质体在小鼠模型中的急性毒性、生物分布、血管行为和靶向性，比较药物载体颗粒壳和含量的回声成像、荧光和放射性标记。2. 通过超声成像、放射性标记物和荧光标记物的生物分布、荧光体内光学成像和组织组织学以及长期生存动物研究，研究微泡、脂质体/复合物和囊化细胞毒性药物在超声区域的体内积累。3. 超声激活凝血酶药物载体结构；在活体显微镜下模型血管区域选择性释放凝血酶。监测血液和微泡流过目标组织。4. 在实体肿瘤的超声照射过程中，通过超声触发凝血酶从肿瘤血管区域的微泡结构中选择性地释放出来，并与细胞毒性药物负载颗粒结合，证明了肿瘤生长的抑制。治疗后监测肿瘤内血流。对药物载体配方及超声活化参数进行最终优化。

DESCRIPTION (provided by applicant): Ultrasound offers a unique approach to image-guided therapy. First, tumor vasculature is detected using echo contrast imaging. Next, focused, higher-intensity ultrasound pulse sequence is applied to activate contrast/drug carrier material and release the therapeutic agent in the insonated area. In this application we propose the design and evaluation of a new generation of ultrasound-triggered drug carrier materials. Drug carrier microbubbles and liposome constructs will be applied to release antitumor agents or thrombus-generating enzyme into tumor vasculature. Selective drug deposition in the tumor mass will be achieved. Targeted cytotoxic effect on the tumor and targeted thrombosis will result in restriction of tumor growth and apoptosis. Specific aims (R21 Phase): 1. Prepare targetable microbubble drug delivery constructs and perform ultrasound-mediated release of model dye markers from liposomes, liposomes attached to microbubbles, and microbubble carriers. Evaluate release efficacy as a function of liposome/particle membrane composition, structure, phase transition temperature and ultrasound intensity, frequency and pulse characteristics to achieve optimal release. 2. Evaluate targetability of microbubble/liposome/drug constructs to activated endothelium in cell culture, assess drug release, gel and endothelial cell culture deposition. 3. Study ultrasound-mediated "triggering" activation of microbubble/liposome/enzyme constructs in vitro; evaluate release and therapeutic enzyme availability to convert the substrate. 4. Assess the ability of ultrasound energy to destroy microbubble drug carrier systems in an in vivo subcutaneous tumor on demand with image-guided targeting of ultrasound application focus. Specific aims (R33 Phase): 1. Study acute toxicity, biodistribution, vascular behavior and targeting of microbubbles and microbubble-liposomes constructs in a mouse model after intravenous administration comparing echo imaging, fluorescence and radioactive labeling of shells and contents of drug carrier particles. 2. Investigate in vivo accumulation of microbubbles, liposomes/complexes, and encapsulated cytotoxic agents in the areas of insonation, by ultrasound imaging, biodistribution of radiolabeled and fluorescent markers, fluorescence in vivo optical imaging, and tissue histology, as well as longer-term survival animals studies. 3. Perform ultrasound activation of thrombin drug carrier constructs; release thrombin selectively in the areas of model vasculature during intravital microscopy. Monitor blood and microbubble flow through target tissue. 4. Demonstrate arrest of tumor growth by ultrasound-triggered release of thrombin from microbubble constructs selectively in the areas of tumor vasculature during insonation of a solid tumor, per se and in combination with cytotoxic drug-loaded particles. Monitor blood flow within the tumor after treatment. Perform final optimization of the drug carrier formulation and ultrasound activation parameters.