通过流式细胞术分离原代小鼠视网膜神经节细胞（RGC）
1Department of Ophthalmology, Hamilton Eye Institute,University of Tennessee Health Science Center, 2Department of Microbiology, Immunology and Biochemistry,University of Tennessee Health Science Center, 3Department of Anatomy and Neurobiology,University of Tennessee Health Science Center, 4Department of Pharmaceutical Sciences,University of Tennessee Health Science Center
Summary
数百万人患有导致不可逆失明的视网膜退行性疾病。许多这些疾病的常见因素是视网膜神经节细胞（RGC）的丧失。该详细方案描述了通过流式细胞术的阳性和阴性选择分离原代鼠RGC。
Abstract
神经退行性疾病往往对受影响者有破坏性的影响。除了正常老化之外，视网膜神经节细胞（RGC）损失也涉及一系列疾病，包括糖尿病性视网膜病变和青光眼。尽管它们的重要性，RGC迄今为止非常难以研究，部分原因在于它们仅占视网膜中各种细胞的一小部分。此外，目前的分离方法使用细胞内标记来鉴定产生非活细胞的RGC。这些技术还涉及冗长的分离方案，因此缺乏获得和分离RGC的实用，标准化和可靠的方法。这项工作描述了一种有效，全面和可靠的方法，使用基于正选择标准和阴性选择标准的方案从小鼠视网膜分离原代RGC。所提出的方法允许未来RGCs的研究，目的是更好地了解专业由神经退行性疾病中功能性RGCs的丧失导致的视力下降。
Introduction
RGC是终末分化的神经元，因此，原代细胞是实验所必需的。用于分离和富集原代小鼠视网膜神经节细胞（RGC）的方案的开发是揭示RGC健康和体外变性的机制的基础。这对于寻求产生潜在疗法以促进RGC功能并尽量减少死亡率的研究尤为重要。 RGC的变性与视网膜退行性疾病如青光眼，糖尿病性视网膜病变和正常衰老有关。虽然RGC损失的具体细胞机制尚不清楚，但已经确定了一系列危险因素。缺乏视神经头1,2,3的氧合导致RGC死亡4 ，并且作为兴奋性和i激活之间的动态平衡的干扰个体RGCs内的抑制性受体5,6 。一系列挑战妨碍了使用这些细胞进行深入研究的进展。首先，鼠视网膜中RGCs的数量很少。 RGC占总视网膜细胞7,8,9的不到1％。第二，大多数RGC特异性标记物是细胞内蛋白质10,11,12 。基于这些标记的选择使细胞不可行，这排除了下游功能分析。最后，目前可用的协议冗长，缺乏标准化13,14 。早期RGC分离方案是基于免疫方法。 Barres 等人 15 适应经典免疫基于对抗胸腺细胞抗原（也称Thy1）（细胞表面标记）的免疫阳性，在阳性选择之前，将大部分视网膜细胞从单核细胞和内皮细胞排除第二步。几年后，Hong et al。组合磁珠分离技术与细胞分选策略分离更高纯度的RGC 16 。在许多科学应用中仍然使用磁珠。一起，磁珠和流式细胞术方案提高了分离细胞的纯度。然而，这些纯化系统尚未被标准化用于从解离的视网膜分离鼠RGCs。
流式细胞仪是一种强大的分析方法，可以测量细胞悬浮液的光学和荧光特性。以高水平的灵敏度定量和定性分析细胞，为细胞群体提供多维分析通货膨胀。细胞鉴别基于两个主要物理性质：细胞大小或表面积，粒度或内部复杂性17 。可以通过组合具有类似激发波长和不同排放物的荧光染料标记的抗体来进行多维分析。流式细胞术是快速，可重复和敏感的。多重激光器通过流式细胞术允许单个细胞的更多的多维分析。因此，它是研究细胞学标本的有吸引力的方法。荧光激活细胞分选（FACS）使用通过流式细胞术鉴定的多维表型差异将单个细胞分类为不同的亚群。
在过去十年中，多种表面和细胞内蛋白已被鉴定为用于选择细胞（包括神经元）的潜在生物标志物。试图从大鼠中分离RGC的初步研究使用Thy1作为神经节细胞l标记。不幸的是，Thy1， 也就是 CD90，在其他啮齿动物物种18,19,20中具有多个同种型，并且由多个视网膜细胞类型19,20表达，使其成为RGC的非特异性标记。在视网膜中的单核细胞群体中发现另一个表面标志物CD48，包括巨噬细胞和小神经胶质细胞。使用这两个表面标记，修饰的RGC特征-Thy1 +和CD48 neg细胞 – 被开发出15,16,21,22。不幸的是，这两个选择标准不足以选择高度富集的研资局人口。为了解决这一未满足的需求，基于多层次正，负选择标准，开发了流式细胞仪方案23已知的细胞表面标志物以富集和纯化原代鼠RGC。
Protocol
以下议定书中详细列出的所有程序均由田纳西大学健康科学中心（UTHSC）的机构动物护理和使用委员会（IACUC）审查委员会批准，并遵循视力与眼科研究协会（ARVO）声明使用协议动物实验动物实验指南（实验室动物资源研究所，人体护理和实验动物使用公共卫生服务政策）。 准备仪器，解决方案和媒体 注意：有关材料，试剂，工具和仪器报告?…
Representative Results
RGC的深入研究受到许多因素的阻碍，包括其频率低，缺乏强大和标准化的隔离方法。 图1显示了用于视网膜分离的方法。根据分析方法存在摘除程序的变化，例如摘除核素是体内实验的一部分27 。在安乐死小鼠中进行该方案的摘除。 如图1A- B所示，镊子被放置在眼睛下方并被拉起以引?…
Discussion
FACS是净化细胞群体的首选技术。其他分离方法包括免疫沉淀，磁珠和补体固定消耗。 FACS与这些其他方法的优点是基于同时鉴别具有不同程度的强度的细胞表面标志物。分子的荧光强度与蛋白质表达量成比例。到目前为止，RGC的分离仅基于Thy1（CD90）阳性和CD48阴性15,16,22,34，而不管使用的分离方法如何。最近已经显示，Thy1 + CD48 neg表型不足以分离表达RGC细胞内标志物…
Divulgations
The authors have nothing to disclose.
Acknowledgements
作者要感谢微生物学，免疫学和生物化学系高级插图师Tim Higgins先生提供技术视频协助; Matthew W. Wilson博士进行讨论，还有Jablonski和Morales-Tirado实验室的成员对他们的帮助意见。这项工作得到了阿尔康研究院青年研究员奖（VMM-T），田纳西大学研究基金会（VMM-T），国家眼科学院EY021200（MMJ），格温奖学金（VMM-T）等的支持。格温博士后研究金（ZKG），国防军医学研究和物资司令部（VMM-T）以及研究预防盲人无限制赠款。
Materials
| Anti-mouse CD15 PE | BioLegend | 125606 | Clone MC-480 |
| Anti-mouse CD48 PE-Cy7 | BioLegend | 103424 | Clone HM48-1 |
| Anti-mouse CD57 | Sigma Aldrich | C6680-100TST | Clone VC1.1 |
| Anti-mouse CD90.2 AF700 | BioLegend | 105320 | Clone 30-H12 |
| Brilliant Violet 421 Goat Anti-mouse IgG | BioLegend | 405317 | Clone Poly4053 |
| Purified Anti-mouse CD16/32 | BioLegend | 101302 | FcgRII/III block, Clone 93 |
| Zombie Aqua | BioLegend | 423102 | Live cell/ Dead cell discrimination |
| Fetal Bovine Serum | Hyclone | SH30071.03 | U.S. origin |
| AbC Total Antibody Compensation Bead Kit | Thermo Fisher Scientific | A10497 | Multi-species Ig |
| Neurobasal Medium | Thermo Fisher Scientific | 21103049 | Add serum to media prior to culture. |
| Phosphate-Buffered Saline (PBS) | Thermo Fisher Scientific | 10010049 | Saline solution |
| Dissection Microscope | Olympus | SZ-PT Model | Stereo Microscope |
| Sorvall Centrifuge | Thermo Scientific | ST 16R | All centrifugation performed at RT |
| Base Plate – Dissection Pan | Fisher Scientific | SB15233FIM | A wax plate can also be used |
| Forceps | Aesculap | 5002-7 | 4 ½ inches |
| Iris Scissors, Straight | Aesculap | 1360 | 5 ½ inches |
| Falcon 15 mL conical tubes | Fisher Scientific | 352097 | Polypropylene tubes |
| Falcon 50 mL conical tubes | Fisher Scientific | 352098 | Polypropylene tubes |
| BD FACS Tubes | Fisher Scientific | 352003 | Polypropylene tubes |
| 40 mm dishes | MidSci | TP93040 | Tissue culture treated |
| 70 μm nylon strainer | MidSci | 70ICS | sterile |
| 40 μm nylon strainer | MidSci | 40ICS | sterile |
| BD 10 mL syringe | Fisher Scientific | 301604 | Disposable Syringe without needle |
| Pestles | MidSci | PEST | sterile |
| Wheaton Vials | Fisher Scientific | 986734 | No Liner |
| BD 30 G needle | Fisher Scientific | 305128 | 1 inch |
| Hausser Scientific Bright-Line Glass Counting Chamber | Fisher Scientific | 0267151B | Hemocytometer |
| Gibco Trypan blue 0.4% Solution | Fisher Scientific | 15250061 | Viability Dye |
| Eppendorf tubes | Fisher Scientific | 05-402-25 | 1.5mL |
| EVOS Floid Cell Imaging | Thermo Fisher Scientific | 447113 | Fluorescence Imaging with a 20x objective |
| 100% Ethanol | Fisher Scientific | 04-355-452 | Used to make 70% Ethanol |
| Pipet-Lite LTS Pipette L-1000XLS+ | Rainin | 17014282 | LTS Pipette |
| Pipet-Lite LTS Pipette L-200XLS+ | Rainin | 17014391 | LTS Pipette |
| Pipet-Lite LTS Pipette L-20XLS+ | Rainin | 17014392 | LTS Pipette |
| Rack LTS 1000 mL – GPS-L1000S | Rainin | 17005088 | Blue Rack Sterile Tips |
| Rack LTS 250 mL – GPS-L250S | Rainin | 17005092 | Green Rack Sterile Tips |
| Rack LTS 20 mL – GPS-L10S | Rainin | 17005090 | Red Rack Sterile Tips |
| FACSAria II Cell Sorter | BD Biosciences | N/A | Custom order |
| LSR II Cytometer | BD Biosciences | N/A | Custom order |
| Abca8a | Thermo Fisher Scientific | Mm00462440_m1 | Müller cells |
| Aldh1al | Thermo Fisher Scientific | Mm00657317_m1 | Müller cells |
| Aqp4 | Thermo Fisher Scientific | Mm00802131_m1 | Astrocytes |
| Calb2 | Thermo Fisher Scientific | Mm00801461_m1 | Amacrine, Horizontal |
| Cd68 | Thermo Fisher Scientific | Mm03047340_m1 | Retinal Pigment Epithelial Cells |
| Gad2 | Thermo Fisher Scientific | Mm00484623_m1 | Amacrine |
| Hprt | Thermo Fisher Scientific | Mm01545399_m1 | House keeping gene |
| Lhx1 | Thermo Fisher Scientific | Mm01297482_m1 | Horizontal |
| Lim2 | Thermo Fisher Scientific | Mm00624623_m1 | Horizontal |
| Nrl | Thermo Fisher Scientific | Mm00476550_m1 | Photoreceptors |
| Ntrk1 | Thermo Fisher Scientific | Mm01219406_m1 | Horizontal |
| Pcp4 | Thermo Fisher Scientific | Mm00500973_m1 | Bipolar, Amacrine |
| Pou4f1 | Thermo Fisher Scientific | Mm02343791_m1 | Retinal Ganglion Cells |
| Prdx6 | Thermo Fisher Scientific | Mm00725435_s1 | Astrocytes |
| Prkca | Thermo Fisher Scientific | Mm00440858_m1 | Bipolar |
| Prox1 | Thermo Fisher Scientific | Mm00435969_m1 | Horizontal |
| Pvalb | Thermo Fisher Scientific | Mm00443100_m1 | Amacrine |
| Rbpms | Thermo Fisher Scientific | Mm02343791_m1 | Retinal Ganglion Cells |
| Rom1 | Thermo Fisher Scientific | Mm00436364_g1 | Photoreceptors |
| Rpe65 | Thermo Fisher Scientific | Mm00504133_m1 | Retinal Pigment Epithelial cells |
| Slc1a3 | Thermo Fisher Scientific | Mm00600697_m1 | Astrocytes |
| Slc6a9 | Thermo Fisher Scientific | Mm00433662_m1 | Amacrine |
| Sncg | Thermo Fisher Scientific | Mm00488345_m1 | Retinal Ganglion Cells |
| Tubb3 | Thermo Fisher Scientific | Mm00727586_s1 | Retinal Ganglion Cells |
| Vim | Thermo Fisher Scientific | Mm01333430_m1 | Müller cells |
| Taqman Universal Master Mix | Thermo Fisher Scientific | 4440047 | qPCR Reagent |
| miRNeasy Mini Kit | Qiagen | 217004 | RNA Isolation |
| SuperScript VILO cDNA Synthesis Kit | Thermo Fisher Scientific | 11754250 | cDNA synthesis |
| Taqman PreAmp Master Mix | Thermo Fisher Scientific | 4391128 | Pre-Amplification step |
| BD Cytofix/ Cytoperm | BD Biosciences | 554714 | Fixation/ Permeabilization Buffer |
| BD Perm/ Wash | BD Biosciences | 554723 | Permeabilization Solution |
| RBPMS | Santa Cruz Biotechnology | sc-86815 | intracellular antibody |
| SNCG | Gene Tex | GTX110483 | intracellular antibody |
| BRN3A | Santa Cruz Biotechnology | sc-8429 | intracellular antibody |
| TUJ1 | BioLegend | 801202 | intracellular antibody |
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Citer Cet Article
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