Single-cell sequencing maps scar-free skin regeneration in adult zebrafish, highlighting divergence from mammals

A study published in *PLOS Genetics* by İsmail Küçükaylak, Kai Halwas, Francisco Javier Martínez Morcillo, and colleagues at institutions including those listed in the author list has applied single-cell RNA sequencing and — for the first time in this context — HCR (hybridisation chain reaction)-based spatial transcriptomics to characterise the cellular and molecular dynamics of wound healing in adult zebrafish (*Danio rerio*).

Adult zebrafish retain the capacity for perfect skin regeneration after injury, leaving no scar. The study characterises the transient collagen-rich granulation tissue that forms intermediately and then fully regresses during zebrafish healing — a process that in adult mammals instead persists as fibrosis and scarring. By mapping gene expression across cell types and spatial positions at multiple timepoints, the researchers identify cellular programmes and signalling interactions that differ between the scar-free zebrafish response and the fibrotic mammalian response.

The comparative framework — pairing zebrafish data with mouse wound-healing datasets — provides a resource for identifying molecular targets potentially relevant to understanding why regenerative capacity is diminished in mammals. The work is published in *PLOS Genetics* and represents primary research. The findings contribute to the basic science of tissue regeneration, extracellular matrix remodelling, and the evolutionary biology of wound response.