Revealing the Hidden World of Cells
New imaging techniques shed light on cellular behavior in tissues.
Naomi Martin, Paul Olsen, Jacob Quon, Jazmin Campos, Nasmil Valera Cuevas, Josh Nagra, Marshall VanNess, Zoe Maltzer, Emily C Gelfand, Alana Oyama, Amanda Gary, Yimin Wang, Angela Alaya, Augustin Ruiz, Cade Reynoldson, Cameron Bielstein, Christina Alice Pom, Cindy Huang, Cliff Slaughterbeck, Elizabeth Liang, Jason Alexander, Jeanelle Ariza, Jocelin Malone, Jose Melchor, Kaity Colbert, Krissy Brouner, Lyudmila Shulga, Melissa Reding, Patrick Latimer, Raymond Sanchez, Stuard Barta, Tom Egdorf, Zachary Madigan, Chelsea M Pagan, Jennie L Close, Brian Long, Michael Kunst, Ed S Lein, Hongkui Zeng, Delissa McMillen, Jack Waters
― 8 min read
Table of Contents
- The Thrill of Discovery
- The Need for Quality Control
- Characterizing Imperfections
- Sample Preparation Problems
- Assessing Tissue Quality
- Understanding Transcript Density
- The Impact of Detection Efficiency
- Variability Across Imaging Sessions
- Data Loss Frustrations
- Variability Across Platforms
- The Role of Quality Control Software
- Real-World Applications
- Conclusion: The Future of Spatial Molecular Imaging
- Original Source
- Reference Links
Spatial molecular imaging is a powerful method used to study the arrangement and behavior of cells in their natural environment, specifically within tissues. Think of it like finding hidden treasures in a large garden, where each plant represents a different type of cell. This technology allows scientists to see how these "plants" are growing, how they communicate with each other, and where they are located, all without uprooting them.
By using these modern imaging techniques, researchers have been able to create detailed maps of various tissue types, including the human heart and brain. Just like a tourist map highlights key landmarks, these maps highlight important features of cell types and their relationships.
The Thrill of Discovery
Scientists are always looking for new ways to learn about the complex world of cells. With advances in spatial imaging, they have been able to gather a wealth of information about how genes are expressed within tissues. This is like opening a treasure chest filled with different gems, each representing valuable information about how the body works.
Researchers have focused especially on the brain, which houses a myriad of cell types. By combining imaging methods, they have been able to produce atlases-like illustrated maps-showing where each cell type is located. This information is crucial for understanding not just normal functioning but also diseases like Alzheimer’s.
Quality Control
The Need forAs exciting as this technology is, it's not without its challenges. Imagine trying to read a map that is smudged and hard to decipher. In scientific research, imperfections can arise during the imaging process, leading to incorrect conclusions. These errors can occur at multiple stages, including sample preparation, the chemical processes used for imaging, and the imaging itself.
To address these issues, researchers need to evaluate the quality of their dataset, ensuring that the information they interpret is accurate. Just as travelers check their maps for accuracy before setting out on their journeys, scientists must confirm the reliability of their data.
Characterizing Imperfections
To highlight the importance of quality control, researchers have developed tools to identify and understand errors in imaging results. Think of it as a quality inspector checking a shipment of apples for any blemishes.
One such tool specifically looks at a popular imaging method called MERFISH, which stands for Multiplexed Error-Robust Fluorescence In Situ Hybridization. This method allows scientists to visualize individual RNA molecules within cells. By collecting data from numerous tissue samples, the researchers can find common mistakes that occur during the imaging process.
Sample Preparation Problems
One major source of errors comes from the sample preparation phase. Imagine trying to bake a cake but dropping half of the ingredients on the floor! In the case of tissue samples, damage or detachment from the underlying surface can occur, resulting in missing information.
When tissues are improperly handled, parts of them may not be captured by the imaging process. This is like trying to take a group photo but having some people hiding behind others. To deal with this, scientists developed a system that classifies pixels from their images into different categories, helping them identify which areas are usable and which are not.
Assessing Tissue Quality
Once tissues are prepared and imaged, scientists need to assess the quality of the images they receive. The quality of the images is crucial for ensuring that the data obtained is reliable. This is like checking the clarity of a photograph before sharing it with friends.
One approach involves analyzing how many areas of the tissue are actually visible versus how many are damaged or detached. With the help of computer programs, researchers can classify these areas into specific categories, enabling them to filter out incomplete or low-quality images.
Understanding Transcript Density
One important aspect of spatial imaging is transcript density, which refers to how much genetic material can be found in a given area. This is a bit like counting how many apples are in a basket. Ideally, researchers would expect the density to vary based on the types of cells present in the tissue.
However, unexpected fluctuations in transcript density can lead to confusion about what the data actually means. For example, if some sections of tissue have unusually low density, it could indicate a problem with tissue preparation or imaging. This level of variability makes the analysis more complicated, requiring scientists to look closely at their results, much like a detective piecing together clues at a crime scene.
Detection Efficiency
The Impact ofAnother key factor in spatial molecular imaging is detection efficiency. This refers to how well the imaging method is able to capture the presence of RNA molecules. If the detection is inconsistent across different areas, researchers may end up with incomplete or skewed data. It's like trying to catch fish in a pond but only being able to scoop in certain areas.
In an ideal world, every part of the tissue would have the same chance of being accurately imaged. Unfortunately, this is rarely the case. Some areas may yield much more accurate data while others fall short. This unevenness can lead to major discrepancies in results, making it challenging to draw meaningful conclusions.
Variability Across Imaging Sessions
Over time, it has been noted that variability can occur across different imaging sessions. This is similar to how weather can change from day to day. Sometimes, one session might yield clearer results than another, impacting the consistency of the data collected.
As scientists continue to work with these imaging technologies, they have noticed patterns in the variability, prompting them to establish guidelines for better practices. By refining their methods and standardizing protocols, researchers can work toward minimizing the discrepancies that arise.
Data Loss Frustrations
Much like a magician's assistant disappearing from the stage, data loss can be an annoying obstacle in spatial imaging. When data is lost, it can be challenging to determine exactly what went wrong. Researchers developed algorithms to identify areas where the data appears to be missing, allowing them to flag these discrepancies before moving on to the next steps of their analysis.
However, it's not merely about finding the missing pieces. The impact of that data loss on the overall results must also be examined. If a significant number of genes have been lost from the analysis, it's likely that the conclusions drawn could be quite different from the truth. This makes quality control even more vital in the imaging process.
Variability Across Platforms
The technology used in spatial molecular imaging varies across platforms, each with its strengths and weaknesses. It’s akin to a buffet where every dish has its own unique flavor-sometimes delightful, sometimes mysteriously undercooked. By comparing datasets from different imaging technologies, researchers can gain insights into how these platforms perform under similar conditions.
However, this comparison is not as straightforward as it might seem. Variability across individual experiments can make it difficult to discern which results are reliable. By standardizing methods and documenting findings, scientists can work towards understanding the efficiency of each platform and generating a clearer picture of the overall landscape of spatial imaging.
The Role of Quality Control Software
To assist in navigating this maze of data, specialized software has been developed to help researchers check for imperfections and assess quality. Much like a trusty GPS guides lost travelers, this software can identify anomalies in the data, helping scientists figure out which portions of their datasets are reliable and which may be suspect.
By focusing on the most common issues, the software enables quick checks, ensuring that researchers don’t waste time on flawed data. It gives them confidence that the results they interpret are as accurate as possible, allowing for informed conclusions about cellular behavior and gene expression.
Real-World Applications
The information gathered through spatial molecular imaging has numerous real-world applications. For instance, it can help neuroscientists better understand disorders like Alzheimer’s, giving them insight into the changes that occur in brain cells over time. In this way, spatial imaging can contribute to our understanding of many diseases and conditions.
Moreover, by improving quality control measures, researchers can ensure that they are building upon solid foundations of data. This allows for ongoing discoveries in biology, paving the way for advancements in medicine and treatment options.
Conclusion: The Future of Spatial Molecular Imaging
As spatial molecular imaging techniques continue to evolve, there is hope for even greater accuracy and reliability in the data collected. Scientists are dedicated to refining their methods, improving quality control, and developing new software tools to enhance the overall reliability of their results.
By forming a consensus around best practices and standardizing methodologies, researchers aim to streamline their processes and maximize the insights gained from their experiments. The ultimate goal is to deepen our understanding of the intricate cellular world and to unlock the secrets that lie within our tissues.
So, whether it’s through the lens of a microscope or the heart of an imaging system, the quest for knowledge in the realm of spatial molecular imaging continues-a never-ending journey filled with promise and excitement!
Title: MerQuaCo: a computational tool for quality control in image-based spatial transcriptomics
Abstract: Image-based spatial transcriptomics platforms are powerful tools often used to identify cell populations and describe gene expression in intact tissue. Spatial experiments return large, high-dimension datasets and several open-source software packages are available to facilitate analysis and visualization. Spatial results are typically imperfect. For example, local variations in transcript detection probability are common. Software tools to characterize imperfections and their impact on downstream analyses are lacking so the data quality is assessed manually, a laborious and often a subjective process. Here we describe imperfections in a dataset of 641 fresh-frozen adult mouse brain sections collected using the Vizgen MERSCOPE. Common imperfections included the local loss of tissue from the section, tissue outside the imaging volume due to detachment from the coverslip, transcripts missing due to dropped images, varying detection probability through space, and differences in transcript detection probability between experiments. We describe the incidence of each imperfection and the likely impact on the accuracy of cell type labels. We develop MerQuaCo, open-source code that detects and quantifies imperfections without user input, facilitating the selection of sections for further analysis with existing packages. Together, our results and MerQuaCo facilitate rigorous, objective assessment of the quality of spatial transcriptomics results.
Authors: Naomi Martin, Paul Olsen, Jacob Quon, Jazmin Campos, Nasmil Valera Cuevas, Josh Nagra, Marshall VanNess, Zoe Maltzer, Emily C Gelfand, Alana Oyama, Amanda Gary, Yimin Wang, Angela Alaya, Augustin Ruiz, Cade Reynoldson, Cameron Bielstein, Christina Alice Pom, Cindy Huang, Cliff Slaughterbeck, Elizabeth Liang, Jason Alexander, Jeanelle Ariza, Jocelin Malone, Jose Melchor, Kaity Colbert, Krissy Brouner, Lyudmila Shulga, Melissa Reding, Patrick Latimer, Raymond Sanchez, Stuard Barta, Tom Egdorf, Zachary Madigan, Chelsea M Pagan, Jennie L Close, Brian Long, Michael Kunst, Ed S Lein, Hongkui Zeng, Delissa McMillen, Jack Waters
Last Update: 2024-12-07 00:00:00
Language: English
Source URL: https://www.biorxiv.org/content/10.1101/2024.12.04.626766
Source PDF: https://www.biorxiv.org/content/10.1101/2024.12.04.626766.full.pdf
Licence: https://creativecommons.org/licenses/by/4.0/
Changes: This summary was created with assistance from AI and may have inaccuracies. For accurate information, please refer to the original source documents linked here.
Thank you to biorxiv for use of its open access interoperability.
Reference Links
- https://vizgen.com/products/
- https://vizgen.com/resources/fresh-and-fixed-frozen-tissue-sample-preparation
- https://www.ilastik.org/
- https://info.vizgen.com/mouse-liver-access
- https://info.vizgen.com/mouse-brain-data
- https://www.10xgenomics.com/datasets/xenium-in-situ-analysis-of-alzheimers-disease-mouse-model-brain-coronal-sections-from-one-hemisphere-over-a-time-course-1-standard
- https://www.10xgenomics.com/datasets/fresh-frozen-mouse-brain-replicates-1-standard
- https://nanostring.com/products/cosmx-spatial-molecular-imager/ffpe-dataset/human-frontal-cortex-ffpe-dataset/
- https://resolvebiosciences.com/open-dataset/?dataset=mouse-brain-2021
- https://github.com/AllenInstitute/merquaco
- https://merquaco.readthedocs.io/en/latest
- https://portal.brain-map.org/atlases-and-data/bkp/abc-atlas