药物非临床发育神经毒性研究的神经病理学评价策略

神经病理学评价是药物非临床发育神经毒性评价的重要组成部分和金标准,本文从发育神经毒性神经病理学评价的实验动物设计、优选的动物年龄、神经系统解剖和组织处理、以及病理结果的解释方面概述了标准化的发育神经毒性神经病理学评价原则和方法。介绍了药物非临床发育神经毒性研究神经病理学评价相关国际指导原则要求,为减少我国和其它国家及地区间实验程序的差异,为我国从事药物非临床发育神经毒性研究的病理学家提供一定参考。     

临床前药物安全评价毒性病理学靶器官毒性的检查及评价

临床前药物安全评价毒性病理学靶器官毒性的检查和评价要结合大体病理学、组织病理学及临床病理学检查结果进行全面考虑、逐步分析,并使用国际统一推荐的诊断术语及诊断标准,避免主观、不确切的诊断。简要介绍了临床前药物安全评价毒性病理学靶器官毒性检查的基本原则,大体病理学检查,组织病理学检查,毒性病理学诊断方法、程序及注意事项,诊断术语及诊断标准的国际统一,临床病理学参数分析,解剖病理学与临床病理学数据结合一致性分析等内容,以期为我国临床前药物安全评价毒性病理学靶器官毒性检查及评价提供一定参考。     

药物神经毒性的评价模型及应用

药物神经毒性是指由药物引起的对神经系统功能和/或结构的损害。神经毒性是药物不良反应之一,也是药物临床前安全性评价的重要方面。一般来说,研究和评价神经毒性的模型主要指体外模型和体内模型。体外模型包括二维单细胞培养（神经细胞系、原代神经细胞和神经干细胞）,三维多细胞培养（再聚集脑细胞）,以及器官型培养（类器官、器官芯片）等。体内模型包括传统的哺乳动物模型和非哺乳动物模型。非哺乳动物模型由于其结构简单、操作方便也逐渐被广泛地用于神经毒性评价,主要包括线虫、斑马鱼、果蝇等。仅靠单一体内模型或体外模型无法完整全面地评价药物神经毒性,因此对于不同的药物,需要选择合适的方法及模型组合进行综合评价,才能得出准确可靠的结论。     

SD大鼠神经干细胞评价药物神经毒性模型研究

目的：应用SD大鼠神经干细胞评价药物的神经毒性,为新药早期筛选和临床前安全性评价提供体外替代方法。方法：体外培养SD大鼠神经干细胞,传代后得到稳定的第二代神经球。以已知具有神经毒性的长春新碱、顺铂、瑞芬太尼、丙泊酚注射液、丙戊酸钠、苯妥英钠、丙烯酰胺、乙醇、氧化铁纳米粒子作为神经毒性阳性物质,以培养基作为神经毒性空白对照品;以没有神经毒性且具有促进神经细胞生长的神经生长因子作为检测模型的敏感性;以验证SD大鼠神经干细胞模型对神经毒性药物的检出能力。结果：长春新碱、顺铂、丙泊酚注射液、苯妥英钠、丙烯酰胺、氧化铁纳米粒子可引起全部或部分神经球解离破碎,神经干细胞坏死。顺铂、丙戊酸钠和苯妥英钠可见显著性的抑制神经球聚集。长春新碱、顺铂、瑞芬太尼、氧化铁纳米粒子、丙泊酚注射液、丙戊酸钠、苯妥英钠、丙烯酰胺、乙醇均表现剂量相关性的神经干细胞增殖毒性作用。神经生长因子可见促进神经球聚集及神经干细胞增殖。结论：本文以SD大鼠神经干细胞模型,以神经干细胞体外生长发育指标,验证了已知神经毒性抗肿瘤药物、麻醉剂、抗癫痫药物等的神经毒性特征。评价结果与这些药物已知的神经毒性作用特点一致,该评价方法可作为药物神经毒性临床前安全性评价研究的体外替代试验。     

非临床药物安全性评价中毒性病理学评价基本要素

毒性病理学是结合病理学和毒理学原理的科学,关注化合物潜在的毒性作用。毒理学研究中的组织病理学评价经毒性病理学家的长期实践已形成标准技术规程,在药物风险评估过程中起重要作用。本文针对非临床药物安全性评价中毒性病理学评价中病理学家的资质和职责、镜检前病理学家应获取的资料和信息、毒性病理学评价的一般流程、影响毒性病理学评价准确性和一致性因素等国际公认的基本要素进行了简要的阐述,同时说明按照标准技术规程进行非临床药物毒理学试验组织病理学评价可以减少诊断偏差,获得高质量的病理学报告,为病理学家、毒理学家以及监管机构的审查人员提供重要的数据和信息。     

药物神经毒性非临床安全性评价方法和技术概述

药物神经毒性非临床安全性评价是早期筛选神经毒性药物及降低药物研发风险的重要手段,而且能为后续的临床试验提供毒性证据支持。原国家食品药品监督管理总局(China Food and Drug Administration,CFDA)、经济合作与发展组织(Organization for Economic Co-operation and Development,OECD)的药物非临床安全性评价指导原则中涉及神经毒性及发育神经毒性研究的一般方法为啮齿类动物及非人灵长类动物实验的组织病理学检查和神经行为学检查。至今,动物实验技术已经从传统的显微镜微观检查形态发展到活体成像技术。随着国内外倡导动物福利和3R原则,即减少(reduction)、替代(replacement)和优化(refinement),以及体外替代模型的不断出现,将各种体外评价方法和技术,如神经细胞成像技术、神经电生理技术、组学技术等,经过验证后用于监管科学领域已成为国内外药物非临床安全性评价工作者努力的方向。但是,无论是体内试验还是体外替代方法都无法全面评价神经毒物的潜在风险,因此只有将适合的方法有效地结合才能在非临床准确、高效地评价药物的神经毒性。     

临床前药物安全性评价中的毒性病理学

毒性病理学是从形态学的角度阐明药物毒性造成的组织损伤,包括药物损伤类型、作用部位、病变程度和预后等基本问题,为临床前药物安全性评价研究提供客观准确的数据支持。因此,毒性病理学在药物安全性评价中具有重要作用,其数据或结论常常决定了许多药物研发项目的终止或继续。从毒性病理学的特点、规范性管理、病理学新技术的发展（包括原位杂交、激光扫描细胞技术、激光捕获显微切割等）,以及毒性病理学发展面临的问题等方面进行了简要论述。     

药物非临床毒性试验周围神经系统组织病理学评估研究进展

药物非临床毒性试验周围神经系统（peripheral nervous system,PNS）组织病理学评估分为4种情况：未知或预期无神经毒性的一般毒性试验、可能有躯体神经毒性的一般毒性试验、可能有自主神经病的一般毒性试验以及预期有神经毒性作用的专门神经毒性试验。美国毒性病理学会（Society of Toxicologic Pathology,STP）推荐最佳实践建议的目的是确保在药物非临床一般毒性试验和专门神经毒性试验的4种情况下,对PNS组织进行一致性、高效率取材、处理和评估。综述了PNS解剖的基本结构、PNS毒性试验情况分类及取材建议、PNS毒性试验不同情况下最佳实践建议、PNS神经病理学评估分析策略以及评估结果的记录,以期为我国药物非临床毒性试验中周围神经系统组织病理学评估提供一定参考。     

药物安全性研究中免疫系统的病理学评价

免疫系统是一个复杂的、涉及多个器官的系统,自身易受年龄、性别、环境等多个因素的影响,其正常的生理变异较大,因此在临床前安全性研究中评估药物所致的免疫毒性是一个巨大的挑战。目前,免疫系统的组织形态学评价是确定免疫毒性公认的基石。就免疫系统病理学评价相关的指导原则,以及胸腺、脾脏、淋巴结等重要免疫器官的病理学评价进行简要论述,以帮助毒性病理学家准确和一致性评价免疫系统中预期的或意外的药物所致的毒性改变。     

神经系统接触类器械的生物学评价要点和神经细胞培养技术简介

目前,有关与人体神经系统直接或者间接接触的植入类医疗器械越来越多。这些植入类医疗器械可能会引起神经系统结构和/或功能的不利反应,导致广泛的副作用,这些副作用则被称为医疗器械产品的神经毒性。由于神经系统有限的修复能力,因此增加了临床前评价神经毒性的重要性。目前,还没有特定的标准或指南来规范医疗器械产品的神经毒性评价要求。本文结合国内外最新的相关标准和参考文献,给出植入类医疗器械神经毒性评价的要点,为相关产品的临床前安全性评价、质量控制及注册前技术审评提供技术参考。     

纳米材料的神经毒性作用机制及评价方法

近年来,纳米材料在多种生物医学领域被广泛应用,其生物安全性也受到越来越多的关注。多种纳米材料可穿透血脑屏障进入中枢神经系统,产生神经毒性。本文讨论了纳米材料进入中枢神经系统的方式及因素;纳米材料的特异性以及非特异性的中枢神经毒性效应、外周神经毒性及其作用机制;并论述了国内外用于体内神经毒性、体外神经细胞培养模型的神经毒性以及替代的评价方法,为纳米材料的安全性评价及神经毒性探究提供参考。     

药物代谢酶遗传多态性对药物神经毒性的影响

神经毒性是药物常见的毒性反应之一。神经系统对药物引起的损害尤其敏感,药物引起神经系统结构和功能的微小改变即可表现出严重的精神或行为异常,因此药物引起的神经毒性越来越得到人们的关注。药物引起的神经毒性存在个体差异,其中遗传因素对这种差异的产生发挥重要作用。药物代谢酶影响药物体内的生物转化过程,因此代谢酶的遗传多态性在一定程度上决定了不同个体对药物神经毒性的易感性。本篇综述将着重探讨药物代谢酶中的细胞色素P450酶、谷胱甘肽转移酶和N-乙酰转移酶遗传多态性对药物神经毒性易感性的影响。     

Toxicologic evidence of developmental neurotoxicity of environmental chemicals

Developmental neurotoxicity constitutes effects occurring in the offspring primarily as a result of exposure of the mother during pregnancy and lactation. To exert their effect, these chemicals or their metabolites must pass the placenta and/or the blood-brain barrier. In experimental animals, exposure to neurotoxic chemicals during critical periods of brain development has induced permanent functional disturbances in the CNS. Although available data suggest that proper animal models exist, only few chemicals have been tested. Neurotoxicity testing is not required by national authorities for classification of chemicals. Epidemiological evidence is very limited, but severe irreversible effects have been observed in humans following in utero exposures to a few known developmental neurotoxicants. The large number of chemicals with a potential for developmental neurotoxicity in humans stresses the importance of generating basic kinetic data on these chemicals based on relevant experimental models. First of all, data are needed on their ability to pass the placenta and the developing blood-brain barrier, to accumulate, and to be metabolized in the placenta and/or the fetus. These kinetic data will be essential in establishing a scientifically based hazard evaluation and risk assessment.     

Challenges for blood-brain barrier (BBB) screening

Whilst blood-brain barrier permeability is an important determinant in achieving efficacious central nervous system drug concentrations, it should not be viewed or measured in isolation. Recent studies have highlighted the need for an integrated approach where optimal central nervous system penetration is achieved through the correct balance of permeability, a low potential for active efflux, and the appropriate physicochemical properties that allow for drug partitioning and distribution into brain tissue. Integrating data from permeability studies performed incorporating an assessment of active efflux by P-glycoprotein in combination with drug-free fraction measurements in blood and brain has furthered the understanding of the impact of the blood-brain barrier on central nervous system uptake and the underlying physicochemical properties that contribute to central nervous system drug disposition. This approach moves away from screening and ranking compounds in assays designed to measure or predict central nervous system penetration in the somewhat arbitrary units of brain-blood (or plasma) ratios.     

P-Glycoprotein, a gatekeeper in the blood-brain barrier

The blood-brain barrier is a major impediment to the entry of many therapeutic drugs into the brain. P-Glycoprotein is an ATP-dependent drug transport protein that is predominantly found in the apical membranes of a number of epithelial cell types in the body, including the blood luminal membrane of the brain capillary endothelial cells that make up the blood-brain barrier. Since P-glycoprotein can actively transport a huge variety of hydrophobic amphipathic drugs out of the cell, it was hypothesized that it might be responsible for the very poor penetration of many relatively large (>400 Da) hydrophobic drugs in the brain, by performing active back-transport of these drugs to the blood. Extensive experiments with in vitro models and with knockout mice lacking blood-brain barrier P-glycoprotein or other animal models treated with blockers of P-glycoprotein have fully confirmed this hypothesis. Absence of functional P-glycoprotein in the blood-brain barrier leads to highly increased brain penetration of a number of important drugs. Depending on the pharmacological target of these drugs in the central nervous system (CNS), this can result in dramatically increased neurotoxicity, or fundamentally altered pharmacological effects of the drug. Given the variety of drugs affected by P-glycoprotein transport, it may be of tremendous therapeutic value to apply these insights to the development of drugs that should have either very poor or very good brain penetration, whichever is preferred for pharmacotherapeutic purposes. The clinical application of P-glycoprotein blockers should also be considered in order to improve the blood-brain barrier permeability of certain drugs that currently display insufficient brain penetration for effective therapy.     

药物神经毒性评价体外模型的研究进展

神经毒性是药物安全性评价的重要方面。体外模型相比较体内动物实验在药物高通量筛选、分子机制研究、检测分析技术应用上具有显著优势。至今,研究和评价药物神经毒性的体外模型主要包括原代神经细胞培养、神经细胞系培养、诱导神经干细胞分化模型,三维细胞培养模型等。这些体外模型的复杂程度、对药物的敏感性及检测方法不尽相同。概述各种神经毒性体外模型的应用领域及研究进展,提出了神经毒性体外评价模型研究应用中存在的问题及今后的发展方向。     

Strategies for increasing drug delivery to the brain: focus on brain lymphoma

The blood-brain barrier (BBB) is a gate that controls the influx and efflux of a wide variety of substances and consequently restricts the delivery of drugs into the central nervous system (CNS). Brain tumours may disrupt the function of this barrier locally and nonhomogeneously. Therefore, the delivery of drugs to brain tumours has long been a controversial subject. The current concept is that inadequate drug delivery is a major factor that explains the unsatisfactory response of chemosensitive brain tumours. Various strategies have been devised to circumvent the BBB in order to increase drug delivery to the CNS. The various approaches can be categorised as those that attempt to increase delivery of intravascularly administered drugs, and those that attempt to increase delivery by local drug administration. Strategies that increase delivery of intravascularly injected drugs can manipulate either the drugs or the capillary permeability of the various barriers (BBB or blood-tumour barrier), or may attempt to increase plasma concentration or the fraction of the drug reaching the tumour (high-dose chemotherapy, intra-arterial injection). Neurotoxicity is a major concern with increased penetration of drugs into the CNS or when local delivery is practised. Systemic toxicity remains the limiting factor for most methods that use intravascular delivery. This review evaluates the strategies used to increase drug delivery in view of current knowledge of drug pharmacokinetics and its relevance to clinical studies of chemosensitive brain tumours. The main focus is on primary CNS lymphoma, as it is a chemosensitive brain tumour and its management routinely utilises specialised strategies to enhance drug delivery to the affected CNS compartments.     

Pain and the blood-brain barrier: obstacles to drug delivery

Delivery of drugs across the blood-brain barrier has been shown to be altered during pathological states involving pain. Pain is a complex phenomenon involving immune and centrally mediated responses, as well as activation of the hypothalamic-pituitary-adrenal axis. Mediators released in response to pain have been shown to affect the structure and function of the blood-brain barrier in vitro and in vivo. These alterations in blood-brain barrier permeability and cytoarchitecture have implications in terms of drug delivery to the central nervous system, since pain and inflammation have the capacity to alter drug uptake and efflux across the blood-brain barrier. An understanding of how blood-brain barrier and central nervous system drug delivery mechanisms are altered during pathological conditions involving pain and/or inflammation is important in designing effective therapeutic regimens to treat disease.