Science 361, eaat9804 (2018)
The adult mouse has 10 billion cells. It’d be an immense, if impossible, task to trace the lineage of each cell back to the mouse embryo through individual snap shots in time. But CRISPR is helping researchers take on the challenge.
The CRISPR-Cas9 system can be used to add or delete small sequences of DNA in developing organisms; the animal repairs these, but a “scar” is left behind that is then inherited in future cell divisions. Such barcodes have been used for lineage tracing in zebrafish, from work at the University of Washington in Seattle. Researchers at Harvard Medical School have now applied a CRISPR-barcoding approach to the mouse, following heart, limb, and placental cells in a 12-day old embryo back to their origins.