PLoS ONE (Jun 2008)

A novel role for PECAM-1 (CD31) in regulating haematopoietic progenitor cell compartmentalization between the peripheral blood and bone marrow.

  • Ewan A Ross,
  • Sylvie Freeman,
  • Yan Zhao,
  • Tarvinder S Dhanjal,
  • Emma J Ross,
  • Sian Lax,
  • Zubair Ahmed,
  • Tie Zheng Hou,
  • Neena Kalia,
  • Stuart Egginton,
  • Gerard Nash,
  • Steve P Watson,
  • Jon Frampton,
  • Christopher D Buckley

Journal volume & issue
Vol. 3, no. 6
p. e2338


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Although the expression of PECAM-1 (CD31) on vascular and haematopoietic cells within the bone marrow microenvironment has been recognized for some time, its physiological role within this niche remains unexplored. In this study we show that PECAM-1 influences steady state hematopoietic stem cell (HSC) progenitor numbers in the peripheral blood but not the bone marrow compartment. PECAM-1(-/-) mice have higher levels of HSC progenitors in the blood compared to their littermate controls. We show that PECAM-1 is required on both progenitors and bone marrow vascular cells in order for efficient transition between the blood and bone marrow to occur. We have identified key roles for PECAM-1 in both the regulation of HSC migration to the chemokine CXCL12, as well as maintaining levels of the matrix degrading enzyme MMP-9 in the bone marrow vascular niche. Using intravital microscopy and adoptive transfer of either wild type (WT) or PECAM-1(-/-) bone marrow precursors, we demonstrate that the increase in HSC progenitors in the blood is due in part to a reduced ability to migrate from blood to the bone marrow vascular niche. These findings suggest a novel role for PECAM-1 as a regulator of resting homeostatic progenitor cell numbers in the blood.