Fluorescence Guided Surgery using Near Infrared Nerve-specific Probes for Cranial Nerve Preservation

项目摘要 医源性神经损伤是外科手术中最令人恐惧的并发症之一，也是发病的主要原因 所有外科专科的医生虽然对维持其生命功能至关重要，但保留颅神经可重新 是颅底手术的一大挑战此外，随着微创手术的使用越来越多， 然而，在手术方法上，颅神经识别和可视化的困难被放大。颅神经通常 与颅底肿瘤密切相关，手术可以治愈，但必须平衡 伤害风险。与其他关键组织（例如，血管），神经修复产生可忽略的，不可靠的功能， 的改进。导致永久性运动或感觉残疾和慢性神经病变，限制患者 生活质量、就业能力和参与日常活动。唯一已知的避免神经损伤的方法是 以防止其发生。然而，没有临床批准的技术能够充分增强术中神经 可视化，其中结合神经解剖学知识，白色光可视化和神经生理学， 目前使用的是标准监测。这项工作将直接解决这一未满足的临床需求。荧光引导 外科手术（FGS）已经成功地融入临床医学，只有少数FDA批准的荧光团 (i.e.,荧光素、氨基乙酰丙酸/原卟啉IX [ALA/PpIX]、亚甲蓝和吲哚菁绿色[ICG]）。 虽然用于在颅骨外成像的FGS系统几乎完全在近红外（NIR，650-900 nm），用于神经外科的成像系统通常配备有在可见光中成像的能力。然而，在这方面， 所有临床FGS系统都有一个“800 nm”通道，设计用于ICG成像，包括神经外科显微镜 和宽视野外窥镜为了促进神经外科的临床翻译和实用性，本文的总体目标是 以产生具有与ICG匹配的光谱特性的神经特异性小分子荧光团。这本小说 探针将使颅神经可视化，其在光谱上不同于可见荧光素和ALA/PpIX 这通常用于肿瘤增强，同时使未来的临床翻译使用现有的神经， 外科FGS基础设施。NIR神经特异性探针的开发提出了一个综合挑战， 分子必须足够小以穿过紧密的血神经和/或血脑屏障（BNB和/或BBB， 分别），但具有足够的共轭度以达到NIR波长。这是一个特殊的挑战 在神经外科应用中，其中识别和可视化外周血管的界面处的结构， 和中枢神经系统（分别为PNS和CNS）是成功手术结果所必需的。在预- 在初步的工作中，我们的小组设计并开发了具有精致PNS特异性的NIR恶嗪探针 最近发现一个新的恶嗪探针库提供BBB交叉和CNS特异性， 还不存在适合于临床转化的试剂。在此，我们将开发近红外神经特异性荧光， 用于在有和没有肿瘤复染的情况下识别和可视化颅神经的一个或多个孔（即，荧光，荧光 rescein或ALA/PpIX）在脑膜瘤和神经鞘瘤动物模型中的作用。

PROJECT SUMMARY Iatrogenic nerve injury presents one of the most feared surgical complications and a major source of morbidity across all surgical specialties. While crucial to maintain their vital functions, preservation of cranial nerves re- mains a major challenge in skull base surgeries. Additionally, with the increased use of minimally invasive sur- gical approaches, difficulty with cranial nerve identification and visualization is amplified. Cranial nerves are often intimately associated with tumors of the skull base, where surgery can be curative, but must be balanced against injury risk. Unlike other critical tissues (e.g., blood vessels), nerve repair produces negligible, unreliable func- tional improvement. Permanent motor or sensory disabilities and chronic neuropathies result, limiting patient quality of life, employability and participation in daily activities. The only known method to avoid nerve injury is to prevent its occurrence. However, no clinically approved technology sufficiently enhances intraoperative nerve visualization, where a combination of neuroanatomical knowledge, white light visualization and neurophysiolog- ical monitoring are currently used. This work will directly address this unmet clinical need. Fluorescence Guided Surgery (FGS) has successfully integrated into clinical medicine with only a few FDA-approved fluorophores (i.e., fluorescein, Aminolevulinic/Protoporphyin IX [ALA/PpIX], methylene blue and indocyanine green [ICG]). While FGS systems for imaging outside the skull operate almost exclusively in the near infrared (NIR, 650-900 nm), imaging system for neurosurgery are commonly equipped with the ability to image in the visible. However, all clinical FGS systems have an “800 nm” channel designed to image ICG, including neurosurgical microscopes and wide-field exoscopes. To facilitate clinical translation and utility for neurosurgery, the overall goal herein is to generate a nerve-specific small molecule fluorophore with spectral properties matched to ICG. This novel probe would enable cranial nerve visualization that is spectrally distinct from the visible fluorescein and ALA/PpIX that are commonly used for tumor enhancement, while enabling future clinical translation using existing neuro- surgical FGS infrastructure. Development of a NIR nerve-specific probe has presented a synthetic challenge as molecules must be small enough to cross the tight blood nerve and/or blood brain barrier(s) (BNB and/or BBB, respectively), but with a sufficient degree of conjugation to reach NIR wavelengths. This is a particular challenge in neurosurgical applications where identification and visualization of structures at the interface of the peripheral and central nervous system (PNS and CNS, respectively) are required for successful surgical outcomes. In pre- liminary work, our group has designed and developed NIR oxazine-based probes with exquisite PNS specificity and recently discovered that a new library of oxazine probes provide BBB-cross and CNS specificity, however an agent suitable for clinical translation does not yet exist. Herein, we will develop NIR nerve-specific fluoro- phore(s) for identification and visualization of the cranial nerves with and without tumor counterstain (i.e., fluo- rescein or ALA/PpIX) in animal models of meningioma and schwannoma.