Consumer-focused section

  1. Date (published): **May 2, 2022
  2. Version (of this document): **v2.0
  3. Authors: **Diane Saunders, Heath Patterson, Liz McDonough, HuBMAP MxFBE assay team
  4. What is being measured? a. Tags*: Proteins; single-cell resolution; imaging b. Descriptive (optional): This spatial single-cell assay measures proteins. It is an Imaging-based spatial proteomics method. It provides quantitative and spatial analysis of over 40 protein markers across a whole tissue section at single-cell resolution.
  5. What analytical activities will the assay be used for within HuBMAP? a. Tags*: Map-Creation-for-Organs; Data Integration b. Descriptive (optional): […]
  6. What type of human samples are needed or used? a. Tags*: Fresh fozen, FFPE b. Link to sample metadata standards c. Descriptive (optional): […]
  7. Commercial Product: https://www.akoyabio.com/phenocycler/assays/** *Include tags that can be normalized across assays, allowing for assay filtering. When possible, use structured terminology (ontologies).

Assay Description

Primary Reference PMCIDs PMC8647621

Technology Overview

  • CODEX is a strategy for generating highly multiplexed images using traditional fluorescent imaging. In brief, antibodies to antigens of interest are labeled with unique oligonucleotide barcodes. The barcoded antibodies are then applied to a tissue sample where they bind to target antigens. Using a microfluidics robot integrated with a fluorescent microscope, complementary oligonucleotide probes tagged with fluorophores are introduced to the tissue sample in groups of three antigen-specific probes at a time, allowing hybridization to the barcodes on the target antibodies. Tissue images are captured in each fluorescent channel, the fluorophore-tagged probes are gently removed, and then the process is repeated until all antigens have been visualized. DAPI is imaged during each cycle, enabling generation of a composite image with up to 50 protein targets co-registered on a single tissue section.

Key Definitions

  • **Important terms used to describe CODEX data acquisition are defined and illustrated in the figures below.

CODEX-Fig1.png

  • **(A) The selected imaging region is automatically divided into tiles (individual fields of view).
  • **(B) Images are acquired with adjacent tiles overlapping (e.g., 30%), as indicated by shaded regions, to enhance image alignment. Images are captured as the stage moves across the region row by row or via a serpentine path.
  • **(C) Stitching is the process of aligning and merging tiles into a single composite image.
  • **(D) Multiple z planes (depths) are acquired at each (x,y) tile position.
  • (E) Segmentation algorithms, utilized during image processing, are used to visualize predicted cell boundaries based on nuclear and/or other cell morphology markers.
Term Definition
Alignment or registration Process of transforming different images into one coordinate system (registration of all channels in each cycle is performed)
Autofluorescence Endogenous fluorescence signal from tissue
Background subtraction Subtraction of autofluorescence intensity from total intensity
Channels Refers to the fluorescence excitation wavelengths used (e.g., 488, 540, 750); may also be by corresponding fluorophore names (e.g., DAPI, GFP, dsRED, Cy5)
CODEX CO-Detection by inDEXing
Cycle The process of adding three oligonucleotide-conjugated fluorophores to a tissue section in order to image the complementary-conjugated antibodies, then gently removing the fluorophores so a new set of antibodies can be visualized
Deconvolution Process of reversing the optical distortion that takes place in an optical microscope to “sharpen” images and improve definition
Fluorescence Light produced by a fluorophore that is bound to an oligonucleotide tag
Noise Intensity not produced by light but electronic fluctuations or electronic background
Pitch Distance between z-slices (images in z-stack)
Pixel The smallest adjustable point of a rasterized image (resolution refers to the number of pixels in an image)
Region User-defined imaging area
Signal Intensity (detector counts) produced by fluorescence, both endogenous and introduced
Stitching Process of combining multiple, overlapping fields of view (tiles) to generate a single, composite image of the tissue region
Tile Rectangular field of view acquired at imaging magnification
X plane Plane that determines width
Y plane Plane that determines height
Z plane Plane that determines depth
Z-stack A series of images produced at different stage heights or positions along the z-axis

Antibodies

Provider-focused section

Directories and Files

Directory structure

  • Structure the information as a table, exemplified below.
  • When possible, an agreed-upon single assay-specific directory structure should be used rather than allowing for variable directory names with regular expressions (more conducive to downstream Data Consumer use).
  • The directory structure should not include files. File definitions should happen in the “Files included” section where files can be more appropriately documented.
Directory Name Level Required? Description
raw/src 1 yes This is the raw, unmodified files coming from the instrument (e.g., Akoya system). [Populated by the data provider.]
lab/drv   yes Processed files produced by the lab that generated the data. [Populated by data providers.]
lab/processed 2 yes Image data that has been stitched and aligned and optionally has undergone background subtraction and deconvolution.
lab/segmented 3 no Computationally predicted boundaries of cellular (nucleus, cytoplasm) and/or anatomical structures.
hive   yes Processed files produced by HIVE using the common pipeline. [Populated by the HIVE.]
hive/processed 2 yes Image data that has been stitched and aligned and has undergone background subtraction and deconvolution.
hive/segmented 3 yes Computationally predicted boundaries of cellular (nucleus, cytoplasm) and/or anatomical structures.

Files Included

  • Structure the information as a table, exemplified below.
  • Files included (outside of the “lab” directory) should be agreed upon by the Assay Team and HIVE.
  • *When possible, “file types” should include a link to an external definition, as exemplified below.
  • When relevant, include a link to the program or pipeline used to generate each file. The program or pipeline used should be detailed in the “pipeline or data processing” metadata section below.
  • If the program/pipeline will perform any QA/QC filtering of the data when generating the file, note this in the file description with additional details provided in the “Data processing pipeline” section below.
  • Avoid regular expressions in file names unless absolutely necessary (e.g., to denote a batch of files as in a set of fastq files).
  • Files containing the metadata should also be included when relevant, for example, the TSV with assay-level metadata, the antibodies TSV, a file with the pipeline parameters, etc.
File File type Directory Input file or precursor data Generator program or pipeline with URL Description
*.czi or *.scn CZI or SCN raw n\/a [Akoya link?] Image data that is acquired directly from the microscope\; sometimes referred to as tiled or unstitched data.
*.tiff TIFF raw n\/a [Akoya link?] Image data that is acquired directly from the microscope; sometimes referred to as tiled or unstitched data.
.OME.tiff OME-TIF lab \/ processed n\/a   Images are a multi-page TIFF file comprised of all processed layers and metadata.
HandE.tif or vHE.tif TIFF raw n\/a [Pathology Microscope] H&E image or digital H&E image (if done).
antibodies .tsv TSV lab n\/a manual Tab delimited file listing the set of all antibodies used.
lab-processing .tsv TSV lab n\/a manual Comprehensive table containing the details of the lab-processing pipeline including all relevant parameters (if done).
dataset.json JSON lab experiment .json (if generated) manual HuBMAP internal metadata standards that describe microscopy acquisition details for imaging spatial proteomics methods.

Metadata

Sample-level

  • Any assay-specific considerations for the sample-level metadata should be detailed here. This is a required documentation element. To avoid any confusion, you should explicitly state if there are no assay-specific considerations. Example fields that may warrant assay-level definitions are included below.
Sample field name Sample type
[block; section; suspension]
Definition
Processing time    
Source storage time    

Assay-level

  • This is the assay-specific metadata that’s included in the assay metadata TSV files.
  • Please include full descriptions.
  • Structure the information as a table, exemplified below.
  • *THE FOLLOWING TABLE IS AN EXAMPLE — EDIT AS APPROPRIATE.
Field Required? Data type Description
       
       

Assay-level categorical field values

  • Categorical field options should be listed in the following table. *As the list will change over time, please coordinate the categorical lists with the HIVE.
Field [from above] Values [semicolon separated]
   
   

Antibody

HIVE data processing pipeline

  • This section is to be completed by the HIVE.
  • All pipeline processing steps should be detailed in the table below, including all parameter values used, as exemplified below.
  • A figure should be included, as relevant, to better elucidate the pipeline levels, with each level being fully described in the table.
  • Yes/No — The pipeline will produce the processed files from raw without human intervention. If “No”, then the required steps (human interventions) need to be detailed here.
  • This processing should detail any expected pre-processing of input file(s)?
  • The description should include what the processing step achieves.
  • Any manual interventions should be documented with links to publications, as relevant.
Level Program Version Input File Description
1 CIM software 1.2 Level 0 (.czi) - What pre-processing of input file is expected?
- What does this processing step achieve?
- Are there any manual interventions before output is finalized? If yes, provide link to publication that has an explanation.

Lab data processing pipeline

  • The same details as provided in the above section (“HIVE data processing pipeline”) should be detailed for each lab that uploads data that is processed independently from the HIVE.
  • Do not include the lab-processing details here; but rather include this lab-specific processing table of information with your data upload.
  • In the Files section, describe any files that include the details of the lab-processing pipeline.