Brinedew

Unpublished draft

Cell lineage recorders

Lineage recorders are molecular tools that the researchers use to track how cells divide, build tissues, and change over time. By introducing artificial DNA barcodes or editing sites into cells—often via CRISPR-Cas9 or prime editing—these tools accumulate stable mutations or sequential insertions that map out an organism’s cellular family tree.

Lineage recorders are extensively used in cancer evolution research, as well as in developmental biology and organoid engineering.

Taxonomy of lineage recorders:

Barcode-Based and Static Recorders

  • Exogenous synthetic barcodes: Plasmids or viral integrations carrying fixed random DNA sequences that mark clones upon division.
  • Recombinase-based switchers: Utilizes site-specific recombinases (like Cre or Dre) to stochastically flip or excise DNA segments, generating combinatorial expression states.

Dynamic Genome-Editing Recorders

  • Canonical CRISPR-Cas9 systems: Induces targeted double-strand breaks and insertions/deletions (scars) at specific genomic target arrays over time.
  • Homing guide RNA (hgRNA) arrays: Directs Cas9 to cut its own encoding locus, drastically accelerating mutation rates and diversity for finer tree resolution.
  • Base and prime editors: Introduces precise transition mutations or small insertions without double-strand DNA toxicity, reducing cell damage and saturation limits.

Natural and Epigenetic Recorders

  • Somatic mutation accumulation: Leverages naturally acquired mitochondrial DNA mutations, copy number variations (CNVs), or single-nucleotide variants.
  • Epigenetic memory markers: Tracks heritable DNA methylation patterns and chromatin accessibility landscapes across cell divisions.
  • CRISPR-Cas9 lesions: Induces targeted, random mutations at specific genomic sites during cell division to create unique heritable identity tags.
  • DNA Typewriters: Systems that sequentially write barcodes into cell’s genome over time to record complex cellular event histories.
  • iTracer: A dual-channel tool combining reporter barcodes and inducible CRISPR editing, frequently applied in human cerebral organoids to monitor clonality.
  • CHYRON & intMEMOIR: Advanced writing mechanisms that continuously insert new nucleotides or switch digital memory states to reconstruct lineage trees using single-cell sequencing or microscopy.