Summary

小鼠脑海马组织机械和酶解离联合

Published: October 21, 2021
doi:

Summary

该神经细胞解离方案适用于起始材料量低的样品,并产生用于下游分析的高活性单细胞悬浮液,并具有可选的固定和染色步骤。

Abstract

这种神经解离方案(商业成人脑解离试剂盒随附的方案的改编)优化了组织处理,为详细的下游分析(如流式细胞术或单细胞测序)做准备。神经解离可以通过机械解离(例如使用过滤器,斩波技术或移液器研磨),酶消化或其组合进行。神经元细胞的微妙性质可能使获得高活性,真正的单细胞悬浮液的努力复杂化,而单细胞分析所需的细胞碎片最少。数据表明,这种自动机械解离和酶消化的组合始终如一地产生高度可行(>90%)的单细胞悬浮液,克服了上述困难。虽然其中一些步骤需要手动灵巧,但这些步骤减少了样品处理和潜在的细胞损失。本手稿详细介绍了该过程的每个步骤,以装备其他实验室成功解离少量神经组织,为下游分析做准备。

Introduction

海马体最早是由博洛尼亚解剖学家Giulio Cesare Aranzio在1500年代描述的1。在命名这种新发现的结构时,Aranzio的灵感可能来自它与 海马1属海马的不可思议的相似之处。海马体参与压力反应,但因其在学习和记忆中的作用而广为人知。更具体地说,海马体负责声明性和空间记忆1的编码和检索。

海马体或海马体本身分为CA1(cornu ammonis),CA2和CA3子字段1。与神经系统的其他部分相比,海马体具有几个独特的定义特征,包括其可塑性和持续神经发生的潜力2。神经发生是神经干细胞增殖和分化的过程,随后它们被整合到预先存在的神经元网络中。神经发生仅限于齿状回的粒下区域和外心室(和嗅球)的室下区域3。虽然神经发生在胚胎发生中是丰富的,但它是一个终生的过程34。因此,本讨论将集中在海马体中的成人神经发生上。

脑室下和粒下区域是含有室管膜细胞和血管细胞的神经源性生态位,以及神经干细胞的未成熟和成熟谱系5。小胶质细胞有助于这些生态位作为免疫细胞来调节神经发生6.神经祖细胞是神经干细胞7的非干细胞后代。脑室下区存在三种类型的神经祖细胞:桡骨神经胶质细胞样B型细胞,C型转运扩增祖细胞和A型神经母细胞38。在脑室下区缓慢分裂的B型神经祖细胞可以分化成快速分裂的C型细胞8。随后,C型细胞分化为A型细胞8。这些神经母细胞通过喙状迁移流迁移到嗅球,然后分化成中间神经元或少突胶质细胞9。这些嗅球中间神经元是嗅觉短期记忆和联想学习的关键,而少突胶质细胞髓质化胼胝体9的轴突。大多数成人神经发生发生在齿状回的粒下区域,其中发现桡骨1型和非桡骨2型神经祖细胞3。大多数神经祖细胞注定要成为齿状颗粒神经元和星形胶质细胞10。星形胶质细胞通过间隙连接,形成网络以调节可塑性,突触活性和神经元兴奋性5。作为齿状回的主要兴奋性神经元,颗粒细胞提供从内嗅皮层到CA3区域11的输入。

神经干细胞群可以使用免疫磁性或免疫荧光分离策略1213进行分离。神经组织特别难以解离;这样做的努力通常会导致样品具有较差的细胞活力和/或无法产生用于下游分析的必要单细胞悬浮液。神经解离可以通过机械解离(例如使用过滤器,斩波技术或移液器研磨),酶消化或技术组合1415进行。在一项评估神经解离方法的研究中,比较了移液器研磨手动机械解离与移液器研磨和消化与各种酶的组合的可行性和质量15.质量根据制备的悬浮液15中细胞团块和DNA或亚细胞碎片的量进行分级。单独进行手动机械解离的胶质肿瘤的悬浮液的细胞活力显着低于用分散酶或DNase,胶原酶和透明质酸酶15的组合治疗。Volovitz等人承认不同方法之间可行性和质量的差异,并强调解离不足可能会降低下游分析的准确性15

在另一项研究中,作者比较了60多种不同的方法和培养的神经元细胞解离组合14。这些方法包括通过移液器研磨进行手动机械解离的八种不同变体,以三种不同间隔与五种单独酶的孵育比较,以及机械解离与酶消化或两种酶的组合的各种组合14。没有一种机械方法产生单细胞悬浮液14。四种单酶处理,十种组合酶处理,四种机械解离与酶消化组合产生单细胞悬浮液14。用TrypLE进行酶消化,然后用胰蛋白酶-EDTA最有效地解离样品14。顺便说一句,用TrypLE和/或胰蛋白酶-EDTA处理的样品倾向于形成凝胶状团块14。虽然这项研究是在培养的细胞上进行的,但它说明了移液器研磨或单独酶消化的缺点。

缺乏手动与自动机械解离的并排比较。然而,一组运行流式细胞术以比较整个小鼠大脑的手动和半自动机械解离与商业木瓜蛋白酶或胰蛋白酶解离试剂盒16。用解离器处理更一致地产生活细胞16。解离后,作者还分离出Prominin-1细胞,神经元前体细胞和小胶质细胞16。对于三个分离细胞群中的两个,当用解离器处理样品时,分离细胞的纯度略高于手动16。Reiß等人指出,移液技术中的人与人之间的差异阻碍了组织解离中活细胞群产量的可重复性16。作者得出结论,自动化机械解离使样品处理标准化16

本手稿中概述的解离方法是全自动机械解离和酶消化的组合,使用伴随商业成人大脑解离试剂盒17的解决方案。与标准方案不同,这种优化的方案减少了样品操作,产生了高度可行的单细胞悬浮液,并且用于处理最少量的起始组织。

Protocol

实验是根据UAMS机构动物护理和使用委员会批准的道德标准进行的。购买6个月大的雌性C57Bl6 / J野生型小鼠,并在恒定的12小时光/暗循环下分组饲养(每个笼子4只小鼠)。 1. 试剂的制备 准备可固定的活/死污渍储备溶液。用20μL二甲基亚砜(DMSO)重建荧光染料。 将小瓶包裹在铝箔中,将其标记为“重组”,并将其在-20°C下储存长达六个月。 用肝素制备0.9…

Representative Results

在核心设施中使用流式细胞仪处理样品,并使用用于流动分析的软件包评估结果数据。以前,对补偿对照进行分析 – 活/死污渍和阴性对照。如果使用多种荧光染料,应为每种抗体制备荧光减一(FMO)对照和单染色对照。基于分析的对照计算实验样品光谱重叠的补偿。对于细胞群鉴定,使用分层门控策略。主栅极排除了前向散射(细胞大小)与侧散射(粒度)图19,<sup cla…

Discussion

这种神经解离方案中的几个步骤需要熟练的技术和灵活性 – 灌注,上清液抽吸和髓鞘去除。在整个灌注过程中,内脏器官必须保持完整(除了移除隔膜和夹住心脏);这包括用蝴蝶针避开心脏的上腔室。虽然所需的含肝素的盐水量各不相同,但从心脏流出的透明液体表明该过程已完成。大脑必须完全正确灌注,此时它将呈现灰白色(图1)。通过灌注,红细胞去除步骤变得无?…

Declarações

The authors have nothing to disclose.

Acknowledgements

我们感谢Aimee Rogers提供实践培训和持续的产品支持。我们感谢 Amanda Burke 博士正在进行的故障排除和澄清讨论。我们感谢Meredith Joheim和UAMS科学传播小组对本手稿的语法编辑和格式化。这项研究得到了NIH R25GM083247和NIH 1R01CA258673(A.R.A)的支持。

Materials

1.5 mL Microcentrifuge Tubes Fisher Scientific 02-682-003 Basix, assorted color
15 mL Falcon Tubes Becton Dickinson Labware Europe 352009 Polystyrene
25 mL Serological Pipets Fisher Scientific 14-955-235
5 mL Round Bottom Polystyrene Test Tube Falcon 352052
500 mL Vacuum Filter/ Storage Bottle System Corning 431097
70 μm cell strainer Fisher Scientific 08-771-2
Adult Brain Dissociation Kit Miltenyi Biotec  130-107-677 Contains Enzyme P, Buffer Z, Buffer Y, Enzyme A, Buffer A, Debris Removal Solution
Aluminum Foil Fisher Scientific 01-213-105
Anti-ACSA-2-PE-Vio770, mouse, clone REA969 Miltenyi Biotec 130-116-246
Anti-Myelin Basic Protein Sigma-Aldrich M3821-100UG
Anti-PSA-NCAM-PE, human, mouse and rat, Clone 2-2B Miltenyi Biotec 130-117-394
BD LSRFortessa BD
BSA Sigma-Aldrich A7906-50G
CD11b-VioBlue, mouse, Clone REA592 Miltenyi Biotec 130-113-810
CD31 Antibody Miltenyi Biotec 130-111-541
Ceramic Hot Plate Stirrer Fisher Scientific 11-100-100SH
Dimethyl Sulfoxide Fisher Scientific BP231-100
Ethanol Pharmco by Greenfield Global 111000200
Falcon 50 mL Conical Centrifuge Tubes Fisher Scientific 14-432-22
Fine Scissors – Sharp Fine Science Tools 14060-09 Perfusion
FlowJo BD (v10.7.0)
gentleMACS C Tubes Miltenyi Biotec 130-093-237
gentleMACS Octo Dissociator with Heaters Miltenyi Biotec 130-096-427
Gibco DPBS (1X) ThermoFisher Scientific 14190144
Glass Beaker Fisher Scientific 02-555-25A
Heparin sodium Fresenius Kabi 504011
LIVE/DEAD Fixable Aqua Dead Cell Stain Kit ThermoFisher L34965
Magnetic Stir Bar Fisher Scientific 14-513-51
Noyes Spring Scissors Fine Science Tools 15012-12 Dissection
Paraformaldehyde Sigma-Aldrich 441244-3KG Prilled, 95%
Pipette tips GP LTS 20 µL 960A/10 Rainin 30389270
Pipette Tips GP LTS 250 µL 960A/10 Rainin 30389277
Pipette tips RT LTS 1000 µL FL 768A/8 Rainin 30389213
Rainin Pipet-Lite XLS (2, 20, 200, 1000 μL) Rainin 30386597
RBXMO FITC XADS Fisher Scientific A16167
Round Ice Bucket with Lid Fisher Scientific 07-210-129
Round-Bottom Tubes with Cell Strainer Cap Falcon 100-0087
S1 Pipet Fillers ThermoFisher Scientific 9541
Spatula & Probe Fine Science Tools 10090-13 Dissection & Perfusion
Surflo Winged Infusion Set 23 G x 3/4" Termuno SV-23BLK Butterfly needle
Test Tube Rack Fisher Scientific 14-809-37
Thermo Scientific Legend XTR Centrifuge ThermoFisher discontinued Or other standard table top centrifuge
Variable-Flow Peristaltic Pump Fisher Scientific 13-876-2 Low-flow model
VetFlo Starter Kit for Mice Kent Scientific VetFlo-MSEKIT Anesthesia mask, tubing, induction chamber, charcoal canisters
VetFlo Vaporizer Single Channel Anesthesia System Kent Scientific VetFlo-1210S 0.2–4 LPM
Vi-CELL XR Cell Viability Analyzer Beckman Coulter Life Sciences 731196 Cell Counting
Vi-CELL XR 4 Bags of Sample Vials Beckman Coulter Life Sciences 383721 Cell Counting

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Trujillo, M., McElroy, T., Brown, T., Simmons, P., Ntagwabira, F., Allen, A. R. Combined Mechanical and Enzymatic Dissociation of Mouse Brain Hippocampal Tissue. J. Vis. Exp. (176), e63007, doi:10.3791/63007 (2021).

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