Esterase-sensitive hyperpolarized 13C probes for simultaneous imag

项目概要： 代谢异常与癌症、糖尿病等多种代谢性疾病有关。 心血管疾病。代谢状态改变的重要标志包括燃料的变化 组织中酸度调节的偏好和丧失。迄今为止，能源的常规评估 活组织中的新陈代谢和酸度仍然是一个挑战。灵敏的成像方式可以 因此，非常需要提供这些重要生物标志物的准确表征。在这个 应用，我们的目标是建立一系列超极化（HP）13C富集分子，可以 被内源性酯酶激活，产生 pH 和代谢成像探针 组织。这些富含 HP 13C 的化合物的成功开发将允许组织酸度和 注射单次成像后可同时表征代谢信息 探针。这些应用的候选分子必须化学稳定，可以高度极化 通过动态核极化 (DNP)，具有长 13C T1，并且对酯酶高度敏感 水解。一旦水解，分子必须迅速分解，形成一对pH成像 探针、HP 13CO2 和 HP H13CO3-，以及富含 HP 13C 的代谢底物，例如 13C- 丙酮酸。在这里，我们提出了一系列具有13C-的乙基烷基混合酸酐碳酸酯化合物 碳酸盐和羧基碳均富集。这些碳中心有很长的T1制造过程 它们适用于 HP 13C 成像应用。此外，这些有机小分子预计 通过 DNP 有效偏振，显着提高 13C MR 成像灵敏度。最后但不是 至少，这些混合酸酐中的酯官能团预计非常容易受到 通过酯酶水解。一旦注入循环系统，我们预计这些 HP 13C 混合酸酐 碳酸酯将被酯酶快速水解，产生单酰基碳酸酯分子。这些 中间体预计会分解，产生 HP 13CO2 和富含 HP 13C 的代谢产物 分别用于组织中 pH 测量和代谢分析的底物。在本研究的目标 1 中， 我们将用 13C-乙酸酯、 13C-丙酮酸合成富含 13C 的乙基酰基混合酸酐碳酸酯， 或13C-丁酸酯作为酰基部分。 HP 13C 参数，例如 T1、信号增强和化学 还将评估这些化合物的稳定性。在目标2中，我们将调查HP的生产 13CO2/H13CO3- 和 HP 13C 在分离的酯酶溶液中通过酯酶水解代谢底物， 分离大鼠血浆、血液以及大鼠肝脏和心脏组织的匀浆。最后，我们将评估 这些 HP 13C 探针在小鼠和大鼠中的急性毒性以及体内成像功效（目标 3）。 这项研究的成功执行可能会产生一系列 HP 13C 成像探头，这些探头可以 对与代谢相关的组织中的组织 pH 值和能量代谢进行同步成像 疾病。

PROJECT SUMMARY: Abnormal metabolism is associated with a number of metabolic diseases such as cancer, diabetes, and cardiovascular diseases. Important markers for the altered metabolic states include changes in fuel preferences and loss of acidity regulations in tissues. To date, routine assessments of energy metabolism and acidity in viable tissues remain a challenge. Sensitive imaging modalities that can provide accurate characterization of these important biomarkers are therefore highly desirable. In this application, we aim to establish a series of hyperpolarized (HP) 13C-enriched molecules that can be activated by an endogenous enzyme esterase to produce both pH and metabolic imaging probes in tissues. Successful development of these HP 13C-enriched compounds will allow for tissue acidity and metabolic information to be simultaneously characterized following an injection of a single imaging probe. Molecular candidates for these applications must be chemically stable, can be highly polarized by dynamic nuclear polarization (DNP), have long 13C T1’s, and be highly sensitive to esterase hydrolysis. Once hydrolyzed, the molecules must quickly decompose to form a pair of pH imaging probes, HP 13CO2 and HP H13CO3-, as well as a HP 13C-enriched metabolic substrate such as 13C- pyruvate. Here, we propose a series of ethyl alkyl mixed anhydride carbonate compounds with 13C- enrichments at both the carbonate and carboxyl carbons. These carbon centers have long T1 making them suitable for HP 13C imaging applications. Moreover, these small organic molecules are expected to be efficiently polarized by DNP with significantly improved 13C MR imaging sensitivity. Last but not least, the ester functional group in these mixed anhydrides is expected to be highly susceptible to hydrolysis by esterase. Once injected into the circulation, we expect that these HP 13C-mixed anhydride carbonates will be rapidly hydrolyzed by esterase producing monoacyl carbonate molecules. These intermediates are expected to decompose, producing HP 13CO2 and a HP 13C-enriched metabolic substrate for pH measurement and metabolism analysis in tissues, respectively. In Aim 1 of this study, we will synthesize 13C-enriched ethyl acyl mixed anhydride carbonates with 13C-acetate, 13C-pyruvate, or 13C-butyrate as the acyl moiety. HP 13C parameters such as T1, signal enhancement and chemical stability of these compounds will also be evaluated. In Aim 2, we will investigate the production of HP 13CO2/H13CO3- and HP 13C metabolic substrate by esterase hydrolysis in solutions of isolated esterase, isolated rat plasma, blood, and homogenates of rat liver and heart tissues. Finally, we will evaluate the acute toxicity as well as the in vivo imaging efficacy of these HP 13C probes in mice and rats (Aim 3). Successful execution of this study could lead to a series of HP 13C imaging probes that allow for simultaneous imaging of tissue pH and energy metabolism in tissues associated with metabolic diseases.