Detection of in vivo protease activities using PARACEST MRI contrast agents

描述（由申请人提供）：蛋白酶是许多病理和生物过程的重要生物标志物，通常是化疗药物的靶标。磁共振成像（MRI）是识别可疑病变的杰出诊断工具，但由于对病理组织与正常组织缺乏特异性，因此存在许多假阳性结果。能够检测转移性肿瘤的蛋白酶生物标志物或抗肿瘤治疗反应的MRI造影剂的开发将大大提高MRI检测和评估癌症的特异性。我们已经开发了一种全新的蛋白酶反应MRI造影剂，通过顺磁化学交换饱和转移（PARACEST）检测。这种机制允许选择性地检测每一种PARACEST造影剂，因此在一次MRI扫描过程中可以同时检测到多种PARACEST造影剂，例如蛋白酶无反应的PARACEST造影剂可以作为“对照”来解释药物的药代动力学。此外，我们是第一个在体内动物模型中证明PARACEST造影剂检测的研究团队。我们将把我们的成果与PARACEST造影剂结合起来，在体内动物模型中检测多种酶反应性PARACEST造影剂。更具体地说，我们将设计并应用PARACEST造影剂，在体内MCF-7c3人乳腺癌小鼠模型中检测trail诱导的肿瘤细胞凋亡过程中的caspase-3。我们还将设计并应用PARACEST造影剂在MCF-7和MBA-MB-231乳腺癌小鼠体内模型中同时检测组织蛋白酶B和尿激酶纤溶酶原激活剂。我们的特定目标的成功实现将导致新的平台技术，可以立即用于许多临床前研究，并且可以作为进一步研究的基础，以获得这种新型诊断分子显像剂的临床批准，以检测癌症和其他病理组织中的蛋白酶生物标志物。叙述：一种全新的蛋白酶反应性MRI造影剂已经开发出来，可以通过顺磁化学交换饱和转移（PARACEST）检测。此外，PARACEST造影剂可以在体内动物模型中检测到。这项研究应用将这些成果与PARACEST造影剂结合起来，在体内动物模型中检测多种酶反应性PARACEST造影剂。

DESCRIPTION (provided by applicant): Proteases are important biomarkers for many pathologies and biological processes and are often targets of chemotherapeutics. Magnetic Resonance Imaging (MRI) is an outstanding diagnostic tool for identifying suspicious lesions, but suffers from many false-positive results due to a lack of specificity for pathological tissues versus normal tissues. The development of MRI contrast agents that can detect protease biomarkers of metastatic tumors or the response to anti-tumor therapies would greatly improve the specificity of MRI for detecting and evaluating cancer. We have developed a fundamentally new type of protease-responsive MRI contrast agent that is detected through PARAmagnetic Chemical Exchange Saturation Transfer (PARACEST). This mechanism allows each PARACEST contrast agent to be selectively detected, so that multiple PARACEST contrast agents may be simultaneously detected during a single MRI scan session, such as a protease-unresponsive PARACEST contrast agent that can serve as a `control' to account for the pharmacokinetics of the agents. Furthermore, we are the first research team to demonstrate the detection of PARACEST contrast agents within in vivo animal models. We will combine our accomplishments with PARACEST contrast agents to detect multiple enzyme-responsive PARACEST contrast agents within in vivo animal models. More specifically, we will design and apply PARACEST contrast agents to detect caspase-3 during TRAIL-induced tumor cell apoptosis in an in vivo mouse model of MCF-7c3 human mammary carcinoma. We will also design and apply PARACEST contrast agents to simultaneously detect cathepsin B and urokinase Plasminogen Activator in an in vivo mouse model of MCF-7 and MBA-MB-231 mammary carcinoma. The successful achievement of our specific aims will result in new platform technology that can be immediately used during many pre-clinical studies, and that can be used as a foundation for further studies to gain clinical approval for this new type of diagnostic molecular imaging agent to detect protease biomarkers in cancer and other pathological tissues. Narrative: A fundamentally new type of protease-responsive MRI contrast agent has been developed that is detected through PARAmagnetic Chemical Exchange Saturation Transfer (PARACEST). Furthermore, PARACEST contrast agents can be detected within in vivo animal models. This research application will combine these accomplishments with PARACEST contrast agents to detect multiple enzyme-responsive PARACEST contrast agents within in vivo animal models.