Figure 2.

Endothelial protein C receptor is a marker of fetal liver hematopoietic stem cells. (A) To measure the in vitro expansion activity of EPCR⁺ and EPCR⁻ populations obtained from the FL CD34⁺CD38⁻CD90⁺ population, 500 cells from each population were sorted and expanded in serum-free expansion medium (SFEM) supplemented with STF (stem cell factor, FMS-like tyrosine kinase 3 ligand and thrombopoietin). The first panel shows the flow cytometric analysis of the HSPC markers CD34 and CD90 in the progeny of EPCR⁺ and EPCR⁻ populations. EPCR⁺ cells are highlighted in black. The second panel shows the expansion rate of total cells and CD34⁺ cells derived from EPCR⁺ and EPCR⁻ cells over 3 weeks in culture. The experiment was performed in three independent samples in duplicate. Error bars represent the mean ± standard deviation. (B) To evaluate the in vivo repopulating activity of EPCR⁺ and EPCR⁻ populations, FACS-sorted cells from both populations were transplanted into sublethally (300 cGy) irradiated NSG mice (1000 cells/mouse) and the levels of human cell engraftment in BM were analyzed after 20 weeks. The experiments were performed for two samples. EPCR: endothelial protein C receptor; HSPC: hematopoietic stem and progenitor cells; BM: bone marrow. ***P≤0.001; ****P≤0.0001.