Neurotoxicity of Magnetic Nanoparticles

描述（由申请人提供）：工程氧化铁超顺磁性纳米颗粒（MNPs）提供了有针对性的前沿诊断和治疗平台，因为它们能够被外部磁场引导，被功能化并穿透细胞和组织屏障。在磁力作用下研究MNP延长分化PC12细胞神经突生长的能力时，我们观察到MNP诱导的去分化、神经突丢失和细胞死亡随着氧化铁浓度的增加而增加，而用于MNP涂层的二巯基琥珀酸（DMSA）则没有。越来越多的证据表明，纳米颗粒的反应面积、渗透性和抗生物降解能力的增强，提高了它们相对于分子或体积对应物的细胞毒性潜力，这表明氧化应激（OS）是纳米毒性的一个关键范例。一个3层的过程，OS表现为活性氧（ROS）的激活和抗氧化防御（第1层），促炎反应（第2层）和DNA损伤导致细胞凋亡（第3层）。在体内应用后，纳米颗粒迅速受到巨噬细胞的挑战，这既缓冲了纳米颗粒潜在的纳米毒性，又减少了其治疗和诊断用途所需的循环时间。在一系列的中试体内研究中，我们使用大鼠坐骨神经作为联合模型来评估直接神经毒性和周围神经特有的有效的神经元内巨噬细胞浸润。在血管内微注射高度稳定、水溶性和抗团聚的阴离子dsa包被MNPs (AMNPs) 48小时内，我们观察到巨噬细胞的大量涌入，血红素加氧酶-1、白细胞介素-12、基质金属蛋白酶(MMP)-9和caspase 3的激活，所有这些都符合氧化应激模式。相比之下，在相应的假手术、对照DMSA和葡聚糖包被氧化铁MNPs显微注射中，只观察到轻微的神经毒性改变。利用工程和生物体外和体内结合的方法，本项目旨在确定氧化铁MNPs诱导中枢和周围神经毒性的机制和靶细胞。重点研究表面化学（DMSA、葡聚糖和金）在激活氧化应激信号和体内外生物分布中的作用。将结合SQUID磁强计、光、电子和共聚焦神经病理学、ros介导的促炎症和促凋亡细胞信号分析以及体内感觉和运动行为评估。本提案的总体目标是开发和测试在神经系统治疗和诊断平台中使用MNP的安全工程策略。公共卫生相关性

DESCRIPTION (provided by applicant): Engineered iron oxide superparamagnetic nanoparticles (MNPs) offer targeted cutting- edge diagnostic and therapeutic platforms due to their ability to be guided by an external magnetic field, be functionalized and penetrate cell and tissue barriers. In studying the capacity of MNPs to extend neurite outgrowth in differentiated PC12 cells under magnetic force, we observed MNP-induced de-differentiation, loss of neurites, and cell death with increasing concentration of iron oxide, but not dimercaptosuccinic acid (DMSA) used for MNP coating. Mounting evidence suggests that enhanced reactive area, permeability and resistance to biodegradation of nanoparticles promote their cytotoxic potential relative to molecular or bulk counterparts, implicating oxidative stress (OS) as a key paradigm of nanotoxicity. A 3-tier process, OS manifests in activation of reactive oxygen species (ROS) and antioxidant defense (tier I), pro-inflammatory response (tier II) and DNA damage leading to apoptosis (tier III). Upon their in vivo application, nanoparticles are quickly challenged by macrophages, which both buffer potential nanotoxicity of nanoparticles and reduce circulation time necessary for their therapeutic and diagnostic use. In a series of pilot in vivo studies, we used rat sciatic nerve as a combination model for assessment of direct neurotoxicity and effective intraneuronal macrophage infiltration that is unique to peripheral nerve. Within 48 hours of intrafascicular microinjection of anionic DMSA-coated MNPs (AMNPs) that are highly stable, water soluble and resistant to agglomeration, we observed a robust influx of macrophages, activation of heme oxygenase-1, interleukin-12, matrix metalloproteinase (MMP)-9 and caspase 3, all consistent with the oxidative stress paradigm. In contrast, only mild neurotoxic changes were seen in the corresponding sham procedures, control DMSA and dextran-coated iron oxide MNPs microinjections. Utilizing a combination of engineering and biological in vitro and in vivo approaches, this program aims to determine the mechanisms and target cells of central and peripheral neurotoxicity induced by iron oxide MNPs. Emphasis will be made on studying the role of surface chemistry (DMSA, dextran and gold) on activating oxidative stress signaling and biodistribution in vitro and in vivo. A combination of SQUID magnetometry, light, electron and confocal neuropathology, ROS-mediated pro- inflammatory and pro-apoptotic cell signaling analyses and in vivo sensory and motor behavioral assessments will be used. The overall goal of this proposal is to develop and test the engineering strategies that are safe for MNP use in therapeutic and diagnostic platforms in the nervous system. PUBLIC HEALTH RELEVANCE Magnetic nanoparticles (MNPs) offer cutting-edge drug delivery, molecular imaging and tissue engineering tools for all areas of medicine, including neurosciences. However, their enhanced reactive area, permeability and resistance to biodegradation promote their toxic potential. This proposal aims to determine the mechanisms of MNP neurotoxicity, immune activation of defense macrophage system, and develop advanced MNP formulation that are safe and robust for diagnostic, therapeutic and research use in the nervous system.