Description
Advances in pluripotent stem cell and reprogramming technologies have given hope of generating hematopoietic stem cells (HSC) in culture. To succeed, greater understanding of the self-renewing HSC during human development is required. We discovered that glycophosphatidylinositol-anchored surface protein GPI-80 (Vanin 2) defines a distinct subpopulation of human fetal hematopoietic stem/progenitor cells (HSPC) with self-renewal ability. CD34+CD90+CD38-GPI-80+ HSPC were the sole population that maintained proliferative potential and undifferentiated state in bone marrow stroma co-culture, and engrafted in immunodeficient mice. GPI-80 expression also enabled tracking of HSC migration between human fetal hematopoietic niches. The most highly enriched surface protein in GPI-80+ HSPC as compared to their progeny was Integrin alpha-M (ITGAM), which in leukocytes cooperates with GPI-80 to support migration. Knockdown of either GPI-80 or ITGAM was sufficient to perturb undifferentiated HSPC in stroma co-culture. These findings indicate that human fetal HSC utilize common mechanisms with leukocytes for cell-cell interactions governing HSC self-renewal.