Biological features and transplantation of human fetal blood hematopoietic stem/progenitor cells

Yinghui LAI; Yongrong LAI; Yuying LU; Wuning MO

ABSTRACT

BACKGROUND:

Currently the hematopoietic stem cells can be obtained from bone marrow, peripheral blood and cord blood, so it is expected to search a new source of stem cells in order to satisfy the clinical transplantation needs. From the 5th week of pregnancy, the blood sinusoid system develops completely in liver, and then hematopoietic stem cells can move with blood flow.

OBJECTIVE:

To observe the biological features of human fetal blood hematopoietic stem/progenitor cells (HS/PCs), and their transplantation into non-obese diabetic/severe combined immunodeficiency disease (NOD/ SCID) mice.

DESIGN:

Control trial.

SETTING:

Department of Hematology, First Affiliated Hospital of Guangxi Medical University. MATERIALS①Cell resource Twenty-one fetal blood samples were from dead fetus [gestational age of 18-29 weeks, mean (24.2±3.2) weeks] and twenty-one full-term cord blood samples were provided from the Department of Obstetrics, First Affiliated Hospital of Guangxi Medical University between October 2002 and February 2003, with the consent of their relatives.②Experimental animal Twelve NOD/SCID female mice of 6-7 weeks old were bred in sterility and super-clean operation board.

METHODS:

Flow cytometer was used to assess cell surface markers of HS/PCs including CD34, CD38, HLA-DR and CD90 in 21 human fetal blood samples, and their expressions were compared with 21 human cord blood samples. Moreover, human fetal blood mononuclear cells (MNCs) were transplanted into 6 NOD/SCID mice irradiated sublethally. After 5 weeks, human leukocytic content was also detected in bone marrow of mice with flow cytometer while human Cart-1 gene in recipients' bone marrow was sensed with polymerase chain reaction (PCR).MAIN OUTCOME

MEASURES:

① Expressions of HS/PCs surface markers in fetal blood and cord blood. ②Implantation of fetal blood cells into NOD/SCID mice.

RESULTS:

①The percentage of CD34+ cells in fetal blood was significantly higher than that of full-term cord blood [(2.258 8±0.720 9)%,(1.572 9±0.478 3)%, P=0.000 4]. The percentages of CD34+CD38- cells and CD34+CD90+ cells in fetal blood were also higher than those of fullterm cord blood [(1.298 6±0.470 6)%, (0.871 0±0.409 5)%, P=0.001 6;(0.930 0±0.469 2)%, (0.560 0±0.365 8)%, P=0.032 4].②Four cases (4/6)of human fetal blood MNCs smoothly transplanted the hematopoiesis of sublethally irradiated NOD/SCID mice. Five weeks after the transplantation, human leukocyte and Cart-1 gene could still be detected in marrow cells of NOD/SCID mice.

CONCLUSION:

Human fetal blood contains more HS/PCs than cord blood. Human fetal blood MNCs can engraft bone marrow of NOD/SCID mice and reconstitute general hemopoiesis of marrow and lymph systems.Human fetal blood is a new possible source of pluripotential hematopoietic stem cell.