Contrary to previous assumptions, it seems the cells that line blood vessels are derived from more than one source. In addition to their known developmental path, they can arise from progenitors of embryonic blood cells.
Blood-cell lineages and the endothelial cells that line the interior of blood vessels have an intertwined biology and interrelated embryonic origins. Our current knowledge indicates that endothelial cells differentiate directly from one of the three main cell layers of the early embryo (the mesoderm), and that a subset of endothelial cells subsequently gives rise to haematopoietic stem cells (HSCs)1,2, from which adult blood cells derive. In a paper in Nature, Plein et al.3 reveal a second origin for endothelial cells, and refine our understanding of the relationship between the endothelial and blood lineages.
