Expanding Horizons in Gene Mapping: The Seq-Scope-X Method
Imagine being able to peer into the intricate workings of a living tissue, revealing the precise locations of every gene in action. That's the groundbreaking achievement of the Seq-Scope method, developed at the University of Michigan in 2021. This technology revolutionized gene activity mapping within intact tissue at microscopic resolution, allowing researchers to measure all expressed mRNA molecules and pinpoint their exact locations within the tissue using an Illumina sequencer machine.
The Seq-Scope team, led by Dr. Jun Hee Lee, has now taken this technology to a whole new level. Their latest findings, published in Nature Communications, showcase the power of the Seq-Scope-eXpanded, or Seq-Scope-X, method, which pushes the boundaries of gene mapping even further.
Overcoming Resolution Limits
Dr. Lee explains, "We wondered what we might see if we had even better resolution. But we realized that that is actually physically impossible."
The key to overcoming this limitation lies in the process of preparing tissue slides for analysis. When molecules are diffused from the tissue to the array for sequencing, this diffusion is limited to around a micron. To break through this barrier, the team devised a clever strategy.
Expanding the Tissue
They made the tissues proportionally larger by embedding them in hydrogel and infusing them with water, allowing the tissues to grow. This expansion technique was the brainchild of graduate student Angelo Anacleto, who collaborated with Dr. Hee-Sun Han, a Professor of Chemistry at the University of Illinois Urbana-Champaign.
By increasing the tissue size, the team could analyze it using their Seq-Scope methodology, revealing a more detailed picture of the transcriptome within the tissue.
Unveiling Cellular Delineation
The Seq-Scope-X method proved its worth by providing an even greater resolution of the delineation between cells and the transcripts of different structures within cells, such as the nucleus and cytoplasm. This level of detail was previously unattainable with previous methods.
Computational Insights
The team's computational methods, developed by Dr. Hyun Min Kang, a Professor of Biostatistics at the U-M School of Public Health, played a crucial role. These methods enabled the identification of differences between mRNAs transcribed in the nucleus versus the cytoplasm in liver cells, showcasing the technology's ability to uncover complex cellular dynamics.
Pushing the Boundaries
Dr. Lee emphasizes the potential of this tool, stating, "We have kind of pushed the limit by another order of magnitude so we can get richer information. This technology is really moving fast, with resolution improving roughly four-fold each year for nearly a decade. We are glad that University of Michigan is at the major inflection point."
This breakthrough not only enhances our understanding of gene activity but also opens up new avenues for research, allowing scientists to explore previously inaccessible cellular intricacies.
