Scientists have developed new genetic tools to track cell lineage in mammals, creating comprehensive maps of how a single fertilized egg develops into millions of cells.
Key facts
- •The new lineage maps track development from a single fertilized egg to hundreds of millions of cells.
- •PEtracer, developed by Jonathan Weissman’s team, uses prime editing to place marks at more than 100 sites in the genome.
- •Jay Shendure’s DNA Typewriter technology logs cell divisions on a string of DNA, functioning like a ticker tape.
- •The research allows scientists to study developmental processes that occur in opaque tissues where live imaging is impossible.
- •The collected data is intended to support the development of AI models for predicting embryogenesis.
Researchers led by HHMI investigators Jonathan Weissman and Jay Shendure have independently developed methods to reconstruct cellular family trees in mice. By engineering cells to record their own division history into their DNA, the teams created the most complete lineage maps for a mammal to date. These tools allow scientists to trace how cells commit to their fates during development, overcoming the challenge of studying embryos that grow hidden from view inside the mother.
Recording Cell History in DNA
Because mammalian embryos develop in utero, they cannot be observed in real time like transparent roundworms. To bypass this, researchers engineered cells to write their history into their genomes. Each time a cell divides, it adds a permanent, heritable mark to its DNA. By sequencing these cells later, researchers can read these records to determine both the cell's current type and its ancestral lineage.
New Tools for Lineage Mapping
Jonathan Weissman’s team at the Whitehead Institute developed a technique called PEtracer, unveiled in 2025, which uses prime editing to install marks at over 100 genomic sites. In separate research, Jay Shendure’s team at the University of Washington utilized a 2022 technology called DNA Typewriter. By injecting these components into mouse eggs, both teams successfully tracked lineage as the embryos developed into millions of cells.
Applications in Biology and Medicine
These lineage maps provide insights into how cells differentiate to form tissues and how embryos respond to genetic or environmental stressors. The technology is also expected to help researchers study tumor initiation, growth, and therapy resistance. Additionally, the data will be used to train AI models with the goal of creating a 'virtual embryo' to predict developmental outcomes.
Timeline
- 1983Researchers created a cell fate map for the roundworm by observing cell division under a microscope.
- 2022Jay Shendure and his team at the University of Washington developed the DNA Typewriter technology.
- 2025Jonathan Weissman and his team unveiled the PEtracer technique for installing genetic marks.
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This article was independently rewritten by ManyPress editorial AI from reporting originally published by Phys.org.
