HSC-independent definitive hematopoiesis persists into adult life

Cell Rep. 2023 Mar 28;42(3):112239. doi: 10.1016/j.celrep.2023.112239. Epub 2023 Mar 11.

Abstract

It is widely believed that hematopoiesis after birth is established by hematopoietic stem cells (HSCs) in the bone marrow and that HSC-independent hematopoiesis is limited only to primitive erythro-myeloid cells and tissue-resident innate immune cells arising in the embryo. Here, surprisingly, we find that significant percentages of lymphocytes are not derived from HSCs, even in 1-year-old mice. Instead, multiple waves of hematopoiesis occur from embryonic day 7.5 (E7.5) to E11.5 endothelial cells, which simultaneously produce HSCs and lymphoid progenitors that constitute many layers of adaptive T and B lymphocytes in adult mice. Additionally, HSC lineage tracing reveals that the contribution of fetal liver HSCs to peritoneal B-1a cells is minimal and that the majority of B-1a cells are HSC independent. Our discovery of extensive HSC-independent lymphocytes in adult mice attests to the complex blood developmental dynamics spanning the embryo-to-adult transition and challenges the paradigm of HSCs exclusively underpinning the postnatal immune system.

Keywords: AGM region; B-1a cells; CP: Developmental biology; HSC precursors; HSC-independent hematopoiesis; adaptive immune lymphocytes; hemogenic endothelial cells; lineage tracing mouse models; mouse embryo; multi-potent progenitors.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bone Marrow
  • Cell Lineage
  • Endothelial Cells*
  • Hematopoiesis
  • Hematopoietic Stem Cells*
  • Mice