Transplantation And The Biological Features Of Human Fetal Blood Hematopoietic Stem/progenitor Cells

[Abstract] Objective To study the biological features of human fetal blood hematopoietic stem/progenitor cells(HSPC),and their capacity of hematopoietic reconstitution in non-obese diabetic/severe combined immunodeficiency disease(NOD/SCID) mice. Methods Two-color flow cytometry was used to assess cell surface antigens coexpression of CD34 with CD38,HLA-DR and CD90 antigens in the HSPC in 21 human fetal blood samples(gestational age 18-29 wk) ,and compare their expression with 21 human cord blood samples. Moreover, Colony forming unit-granulocyte macrophage(CFU-GM) assays were measured in 10 cases of the fetal blood. Furthermore,human fetal blood mononuclear cells (MNCs) were transplanted into 6 cases of sublethally irradiated NOD/SCID mice. Results The percentage of CD34+ cells in fetal blood (2.2588±0.7209 vs 1.5729±0.4783, P=0.0004) was significantly higher than that of cord blood. The percentages of CD34+CD38- cells(1.2986±0.4706 vs 0.871±0.4095,P=0.0016)and CD34+CD90+ cells(0.93±0.4692 vs 0.56±0.3658,P=0.0324)in fetal blood were also higher than those of cord blood. The frequency of fetal blood CD34+ cells reached a peak in the gestational age of 20 wk.There were 194.3±73.6 CFU-GM in every 105 fetal blood MNCs.The quantity of CFU-GM reached a peak in the gestational age of 24 weeks or so. Four cases(4/6) human fetal blood MNCs could smoothly engraft sublethally irradiated NOD/SCID mice and reconstitute their hematopoiesis. Five weeks after the transplantation, human hematopoietic cells could be detected in marrow cells from NOD/SCID mice. Conclusions Human fetal blood has a higher frequency of hematopoietic stem/progenitor cells than cord blood. Human fetal blood MNCs can engraft NOD/SCID mice, repopulate their hemopoietic systems, and sustain long-term multi-lineage hemopoiesis in vivo. Human fetal blood possibly provide a new source of hematopoietic stem cell.