Characterization of Ectomesenchyme as an Origin of Epidermal Stem Cells

The study "Characterization of ectomesenchyme as an origin of epidermal stem cells" demonstrates that ectomesenchyme, a type of cell derived from the ectoderm in mouse embryos, is a major source of epidermal stem cells in the skin. The researchers traced the ectomesenchymal lineages using P0-Cre;tdTomato mice and PDGFRa-Cre;tdTomato mice, and found a significant emergence of ectomesenchymal keratinocytes in the cranio-facial region of fetal skin. Single cell RNA/ATAC-seq and FACS analyses of neonate skin revealed that these ectomesenchymal keratinocytes occupied about 80% of the integrin a6-positive and Thy1-positive keratinocyte population, known as an epidermal stem cell-enriched fraction, in the cranio-facio-dorsal skin of adult mice. The study also confirmed the robust emergence of ectomesenchymal keratinocytes through the induction of keratinocytes from human iPS cell-derived ectomesenchyme in vitro.