We describe a rapid staining method to perform multispectral imaging on frozen tissues.
方法文章
We describe a rapid staining method to perform multispectral imaging on frozen tissues.
Multispectral fluorescence imaging on formalin-fixed paraffin-embedded (FFPE) tissues enables the detection of multiple markers in a single tissue sample that can provide information about antigen coexpression and spatial distribution of the markers. However, a lack of suitable antibodies for formalin-fixed tissues may restrict the nature of markers that can be detected. In addition, the staining method is time-consuming. Here we describe a rapid method to perform multispectral fluorescence imaging on frozen tissues. The method includes the fluorophore combinations used, detailed steps for the staining of mouse and human frozen tissues, and the scanning, acquisition, and analysis procedures. For staining analysis, a commercially available semiautomated multispectral fluorescence imaging system is used. Through this method, up to six different markers were stained and detected in a single frozen tissue section. The machine learning analysis software can phenotype cells that can be used for quantitative analysis. The method described here for frozen tissues is useful for the detection of markers that cannot be detected in FFPE tissues or for which antibodies are not available for FFPE tissues.
Recent advances in microscopic imaging techniques have significantly improved our knowledge and understanding of biological processes and disease states. In situ detection of proteins in tissues via chromogenic immunohistochemistry (IHC) is routinely performed in pathology. However, detection of multiple markers using chromogenic IHC staining is challenging1 and newer methods to use multiplex immunofluorescence (mIF) staining approaches, wherein multiple biological markers are labeled on a single tissue sample, are being developed. The detection of multiple biological markers is useful, because information related to tissue architecture, spatial distribution of cells, and antigen co-expression are all captured in a single tissue sample2. The use of multispectral fluorescence imaging technology has made detection of multiple biological markers possible. In this technology, using specific optics the fluorescence spectra of each individual fluorophore can be separated or "unmixed", enabling the detection of multiple markers without any spectral crosstalk3. Multispectral fluorescence imaging is becoming a critical approach in cell biology, preclinical drug development, clinical pathology, and tumor immune-profiling4,5,6. Importantly, the spacial distribution of immune cells (specifically CD8 T cells) can serve as a prognostic factor for patients with existing tumors7.
Various approaches to multiplex fluorescence staining have been developed and can be performed either simultaneously or sequentially. In the simultaneous staining method, all the antibodies are added together as a cocktail in a single step to label the tissue. UltraPlex technology uses a cocktail of hapten-conjugated primary antibodies followed by a cocktail of fluorophore-conjugated anti-hapten secondary antibodies. InSituPlex technology8 uses a cocktail of unique DNA-conjugated primary antibodies that are simultaneously added to the tissue followed by an amplification step and finally fluorophore-conjugated probes that are complementary to each unique DNA sequence on the primary antibody. Both of these technologies enable the detection of four markers plus 4’,6-diamino-2-phenylindole (DAPI) for nuclear staining. Two other approaches for simultaneous multiplex staining are based on secondary ion mass spectrometry9. The Hyperion Imaging System uses imaging mass cytometry10 to detect up to 37 markers. This technology uses a cocktail of metal-conjugated antibodies to stain the tissues, and specific areas of the tissues are ablated by a laser and transferred to a mass cytometer where the metal ions are detected. Another similar technology is the IONPath, which uses multiplexed ion beam imaging technology11. This technology uses a modified mass spectrometry instrument and an oxygen ion source instead of laser to ablate the metal-conjugated antibodies. While all these simultaneous multiplex staining approaches enable the detection of multiple markers, the costs involved for conjugating DNA, haptens, or metals to antibodies, the loss of tissue due to ablation, and the extensive image processing for unmixing cannot be underestimated. Moreover, kits and staining protocols are currently available only for FFPE tissues and developing custom panels entails additional time and expenditure.
The sequential multiplex staining method, in contrast, includes labeling the tissue with an antibody to one marker, stripping to remove the antibody, followed by sequential repeats of this process to label multiple markers12. The tyramide signal amplification (TSA) is the most frequently used sequential multiplexing method. Two other multiplexing technologies use a combination of simultaneous and sequential staining methods. The CODEX platform13 employs a cocktail of antibodies conjugated to unique DNA oligonucleotide sequences that are eventually labeled with a fluorophore using an indexed polymerization step followed by imaging, stripping, and repeating the process to detect up to 50 markers. The MultiOmyx multiplex staining approach14 is an iteration of staining with a cocktail of three to four fluorophore-conjugated antibodies, imaging, quenching the fluorophores, and repeating this cycle to detect up to 60 markers on a single section. Similar to the simultaneous multiplex staining method, while a broad range of markers can be detected, the time involved in staining, image acquisition, processing, and analysis is extensive. The stripping/quenching step involves heating and/or bleaching the tissue sample and thus, the sequential multiplex staining approach is commonly performed on FFPE tissues that maintain tissue integrity upon heating or bleaching.
Formalin fixation and subsequent paraffin embedding is readily performed in a clinical setting, tissue blocks are easy to store, and several multiplex staining protocols are available. However, the processing, embedding, and deparaffinization of FFPE tissues, as well as antigen retrieval15, a process by which antibodies can better access epitopes, is time-consuming. Furthermore, the processing involved in FFPE tissues contributes to autofluorescence16 and masks target epitopes, resulting in the variability and lack of antibody clone available to detect antigens in FFPE tissues17,18,19. An example is the human leukocyte antigen (HLA) class I alleles20. In contrast, snap freezing of tissues does not involve extensive processing steps prior to or after fixing, circumventing the need for antigen retrieval21,22, and making it beneficial for detecting a wider range of targets. Therefore, using frozen tissues for multispectral fluorescence imaging can be valuable to detect targets for preclinical and clinical studies.
Given the above mentioned limitations when using FFPE tissues, we asked whether multispectral fluorescence imaging can be performed on frozen tissues. To address this question, we tested a simultaneous multiplex staining method using a panel of fluorophore-conjugated antibodies to detect multiple antigens and analyzed the staining using a semiautomated multispectral imaging system. We were able to simultaneously stain up to six markers in a single tissue section within 90 min.
访问受限。请登录或开始试用以查看此内容。
Mouse spleen and HLF16 mouse tumor tissues23 were obtained from our laboratory. Human tonsil tissue was purchased from a commercial vendor. Details are provided in the Table of Materials.
1. Tissue Embedding
2. Cryosectioning
3. Selection of Antibodies and Fluorophores
NOTE: Before tissue staining, antibody clones that will robustly and specifically stain their antigens of interest within sequential sections from acetone fixed tissue must be validated. Some antibodies may require a different fixative, and their compatibility with other antibodies in the panel will also have to be empirically determined. The goal is also to identify fluorophores with minimal overlap that can be detected with the epifluorescence filters for DAPI, FITC, Cy3, Texas Red, and Cy5.
4. Staining
NOTE: The tissue rehydration and slide washes were performed in a Coplin jar. The blocking and antibody incubation steps were performed in a humidified slide box.
5. Preparing a Spectral Library
6. Multispectral Imaging
NOTE: Once the spectral library is created and verified, perform the following steps for the multiplex-stained slide.
7. Analyzing Multispectral Images via Cell Segmentation and Phenotyping
NOTE: After verifying the spectrally unmixed image, cell segmentation can be performed using the machine learning software, which will provide step-by-step instructions. Tissue segmentation was not performed here. If the panel includes one or more tissue specific marker and especially if the tissue is messy, tissue segmentation should be performed.
8. Exporting Images and Analysis Tables
访问受限。请登录或开始试用以查看此内容。
Detection of single-stained markers on frozen spleen sections
As the semiautomated imaging system uses a liquid crystal tunable filter (LCTF) system that allows for a wider range of wavelength detection25, and because no signal amplification steps were performed here, we first optimized the detection of our primary-conjugated antibodies for each marker on the microscope. An example is shown in Figure 1, where each single-stained marker is pseudo-c...
访问受限。请登录或开始试用以查看此内容。
Frozen tissues have extensively been used for mIF imaging to traditionally detect three to four markers31 on a tissue using the direct and indirect method32. In the direct method, antibodies are conjugated to fluorescing dyes or quantum dots33 to label the tissue, whereas in the indirect method, an unconjugated primary antibody is used to label the tissue followed by a fluorophore-conjugated secondary antibody that specifically recognizes the primary...
访问受限。请登录或开始试用以查看此内容。
The authors have no conflicts of interest to disclose.
Imaging and analysis guidance was provided by the Research Resources Center – Research Histology and Tissue Imaging Core at the University of Illinois at Chicago established with the support from the office of the Vice Chancellor for Research. The work was supported by NIH/NCI RO1CA191317 to CLP, by NIH/NIAMS (SBDRC grant 1P30AR075049-01) to Dr. A. Paller, and by support of the Robert H. Lurie Comprehensive Cancer Center to the Immunotherapy Assessment Core at Northwestern University.
访问受限。请登录或开始试用以查看此内容。
| 姓名 | 公司 | 目录编号 | 评论 |
|---|---|---|---|
| 丙酮(组织学级) | Fisher Scientific | A16F-1GAL | 固定组织 |
| Alexa Fluor 488 抗小鼠 CD3 | BioLegend | 100212 | 克隆 - 17A2;一抗偶联抗体 |
| Alexa Fluor 488,eBioscience 抗人 CD20 | ThermoFisher Scientific | 53-0202-82 | 克隆 - L26;一抗偶联抗体 |
| Alexa Fluor 555 小鼠抗 Ki-67 | BD生物科学 558617 | 一 | |
| Alexa Fluor 594 抗人 CD3 | BioLegend | 300446 | 克隆 - UCHT1;一 |
| Alexa Fluor 594 抗小鼠 CD8a | BioLegend | 100758 | 克隆 - 53-6.7;一 |
| Alexa Fluor 647 抗人 CD8a | BioLegend | 372906 | 克隆 - C8/144B;一抗偶联抗体 |
| Alexa Fluor 647 抗小鼠 CD206 (MMR) | BioLegend | 141711 | 克隆 - C068C2;一抗偶联抗体 |
| Alexa Fluor 647 抗小鼠 CD4 抗体 | BioLegend | 100426 | 克隆 - GK1.5;一抗偶联抗体 |
| C57BL/6 小鼠 | Charles River Laboratories | 27 | 用于多光谱训练的小鼠冷冻组织 |
| Coplin Jar | Sigma Aldrich | S6016-6EA | 再水化和洗涤玻片 |
| DAPI解决方案 | BD Biosciences 564907 | 核酸染色 | |
| 钻石白色 玻璃带电玻片 | DOT Scientific | DW7590W | 粘附组织切片 |
| Dulbecco磷酸盐缓冲盐水 1x(不含钙和镁) | Fisher Scientific | MT21031CV | 洗涤和稀释剂 |
| 金密封盖玻片 | ThermoFisher Scientific | 3306 | 保护染色组织 |
| 人正常扁桃体 OCT 冷冻组织块 | AMSBio | AMS6023 | 用于多光谱染色的人冷冻组织 |
| 人血清 1x | Gemini Bio-Products | 100-512 | 人体组织的封闭剂和稀释剂 |
| in告知 | Akoya Biosciences | 版本 2.4.1 | 机器学习软件 |
| PerCP/Cyanine5.5 抗人 CD4 | BioLegend | 300529 | 克隆 - RPA-T4;一抗偶联抗体 |
| PerCP-Cy 5.5 大鼠抗 CD11b | BD Biosciences | 550993 | 克隆 - M1/70;一抗偶联抗体 |
| Phenochart | Akoya Biosciences | 版本 1.0.8 | 全玻片扫描软件 |
| ProLong Diamond 抗淬灭封片剂 | ThermoFisher Scientific | P36965 | 封固剂 |
| 研究 低温恒温器 | Leica Biosystems | CM3050 S | 切片组织 |
| Superblock 1x | ThermoFisher Scientific | 37515 | 封闭小鼠组织 |
| Tissue-Tek OCT 解决方案 | Sakura Finetek | 4583 | 包埋组织 |
| Vectra 3.0 自动定量病理成像系统,6 张载玻片 | Akoya Biosciences CLS142568 | 半自动多光谱成像系统 | |
| Vectra Software | Akoya Biosciences | Version 3.0.5 | 作显微镜的软件 |
访问受限。请登录或开始试用以查看此内容。
申请许可以重复使用本 JoVE 文章的文本或图表
申请许可