Nerve-Specific Near-Infrared Fluorescent Contrast Agents for Image-Guided Surgery

描述(申请人提供)：在手术过程中保留神经的能力一直是一个令人烦恼的问题，因为周围的组织经常遮盖它们。事实上，对于大多数外科手术来说，神经损伤是主要的发病率。例如，在根治性前列腺切除术中，保留下腹下神经丛和海绵体神经是至关重要的。男性的能力和排尿控制依赖于这些神经的正常功能。目前，保留神经的前列腺癌根治术是基于外科医生对一般前列腺神经解剖的了解，而不是基于男性个体的神经可视化。理想的神经特异性造影剂应满足以下标准：1)具有在0.5至3之间的pH 7.4的对数密度以最大限度地穿透血神经屏障(BNB)；2)具有最大分子量d 500 Da以最大限度地透过BNB；3)结合神经特异性靶标并在神经中保留数小时；及4)是近红外(NIR)荧光团，其激发和发射波长在近红外“窗口”中介于700 nm至900 nm之间。近红外荧光团是图像引导手术特别令人兴奋的试剂，因为光子穿透最大，组织自发荧光最小，而且由导师的实验室开发的FLARE(荧光辅助切除和探查)成像系统已经上市，并正在三个不同的临床试验中使用。尽管耀斑系统有一个为神经可视化预留的波长通道，但目前还不存在神经特异的近红外荧光团。在申请人进行的初步研究中，已经合成了两种神经特异性药物，并发现它们能突出小鼠、大鼠和猪的多种神经结构。虽然这是一个积极的开端，但这些试剂在图像引导手术的吸收波长、发射波长、量子产率和溶解性性质方面还远未达到理想水平。该K01奖项的目标将是1)系统地修改现有的试剂以实现近红外激发和发射，2)开发一种可行的体内配方来量化该试剂的生物分布和清除性，以及3)在图像引导手术中进行动物验证研究。这款K01应用程序旨在为具有光学成像技术背景的候选人提供培训工具，这些背景来自达特茅斯大学与Brian Pogue博士合作的博士学位，但在光学造影剂开发或光学技术的临床翻译方面经验有限。通过K01奖项申请，应聘者要求接受对比剂化学和活体光学成像方面的强化培训。导师的实验室在近红外荧光造影剂的开发和光学技术的临床翻译方面拥有专业知识。联合导师的实验室在荧光团化学方面拥有20多年的经验。在这种学术环境下，K01的申请描述了一个职业发展计划和机构承诺，允许候选人在五年的时间内过渡到独立，同时她对具有深远临床意义的研究领域做出了贡献。

DESCRIPTION (provided by applicant): The ability to spare nerves during surgical procedures has remained a vexing problem because surrounding tissue often obscures them. Indeed, for a majority of surgical procedures, nerve damage is the major morbidity. For example, sparing of the inferior hypogastric plexus and cavernous nerve is of paramount importance during radical prostatectomy. Male potency and urinary continence is dependent on proper functioning of these nerves. At the present time, nerve-sparing radical prostatectomies are based on the surgeon's knowledge of general prostate nerve anatomy, rather than nerve visualization in individual men. The ideal nerve-specific contrast agent should fulfill the following criteria: 1) have a LogD at pH 7.4 between 0.5 to 3 to maximize blood-nerve-barrier (BNB) penetration, 2) have a MW d 500 Da to maximize BNB penetration, 3) bind to a nerve-specific target and be retained in nerve for several hours, and 4) be a near-infrared (NIR) fluorophore having excitation and emission wavelengths in the NIR "window" between 700 nm and 900 nm. NIR fluorophores are particularly exciting agents for image-guided surgery since photon penetration is maximal, tissue autofluorescence is minimal, and the FLARE (Fluorescence-Assisted Resection and Exploration) imaging system, developed by the mentor's laboratory, is already available and is being used in three separate clinical trials. Although the FLARE system has a wavelength channel reserved for nerve visualization, no nerve-specific NIR fluorophore presently exists. In preliminary studies conducted by the applicant, two nerve-specific agents have been synthesized and found to highlight a multitude of nervous structures in mice, rats and pigs. Although a positive start, these agents are far from ideal in absorption wavelength, emission wavelength, quantum yield, and solubility properties for image-guided surgery. The goals of this K01 award will be 1) to systematically modify the existing agents to achieve NIR excitation and emission, 2) to develop a viable in vivo formulation to quantify the agent's biodistribution and clearance and 3) to perform animal validation studies in image-guided surgery. This K01 application is designed as a training vehicle for a candidate with a strong background in optical imaging technology from her Ph.D. work with Dr. Brian Pogue at Dartmouth, but limited experience in the development of optical contrast agents or clinical translation of optical technology. Through the K01 award application, the candidate requests intensive training in contrast agent chemistry and in vivo optical imaging. The Mentor's laboratory has expertise in the development of NIR fluorescent contrast agents and the clinical translation of optical technology. The Co-Mentor's laboratory has over 20 years of experience in fluorophore chemistry. Within this academic environment, the K01 application describes a career development plan and institutional commitment that will permit the transition of the candidate to independence over a period of five years, while she simultaneously contributes to an area of investigation with profound clinical significance.