Denning-Kendall Patricia, Singha Sakon, Bradley Ben, Hows Jill
University of Bristol Division of Transplantation Sciences, Bristol, United Kingdom.
Stem Cells. 2003;21(1):61-70. doi: 10.1634/stemcells.21-1-61.
Recent studies have demonstrated defective bone marrow homing of hematopoietic stem cells after cytokine expansion culture. Adhesion receptors (ARs) are essential to the homing process, and it is possible that cytokine culture modulates AR expression. We studied changes in expression of very late antigen-4 (VLA-4), VLA-5, L-selectin, leukocyte function-associated antigen-1 (LFA-1), CD44, and the stromal cell-derived factor-1 (SDF-1) receptor, CXCR4, during cytokine culture of cord blood (CB) CD34(+) cells. Expression of ARs was studied by flow cytometry on CB CD34(+) cells in whole blood, after purification and during culture for up to 10 days. Cells were cultured with stem cell factor (SCF), thrombopoietin (TPO), Flt3-ligand (Flt3), and G-CSF. Results showed that 80% or more of uncultured CD34(+) cells were positive for VLA-4, L-selectin, LFA-1, CD44, and CXCR4 while 50% were positive for VLA-5. Purification of CD34(+) cells did not affect AR expression, but cytokines increased expression three- to nine-fold throughout the 10-day culture period. In contrast, expression of CXCR4 decreased. Expression changes of ARs and CXCR4 on CD34(+)/CD38(-) cells mirrored those of the total CD34(+) population. The results indicate that cytokine culture significantly increases AR expression on CB CD34(+) cells, which may be related to the decrease in homing of cytokine-cultured hematopoietic stem cells.
近期研究表明，细胞因子扩增培养后造血干细胞的骨髓归巢存在缺陷。黏附受体（ARs）对归巢过程至关重要，细胞因子培养可能会调节AR的表达。我们研究了脐血（CB）CD34(+)细胞在细胞因子培养过程中，极迟抗原-4（VLA-4）、VVLA-5、L-选择素、白细胞功能相关抗原-1（LFA-1）、CD44以及基质细胞衍生因子-1（SDF-1）受体CXCR4的表达变化。通过流式细胞术研究全血、纯化后以及长达10天培养过程中CB CD34(+)细胞上ARs的表达。细胞用干细胞因子（SCF）、血小板生成素（TPO）、Flt3配体（Flt3）和粒细胞集落刺激因子（G-CSF）进行培养。结果显示，未培养的CD34(+)细胞中80%或更多对VLA-4、L-选择素、LFA-1、CD44和CXCR4呈阳性，而50%对VLA-5呈阳性。CD34(+)细胞的纯化不影响AR的表达，但在整个10天的培养期内，细胞因子使表达增加了三至九倍。相比之下，CXCR4的表达下降。CD34(+)/CD38(-)细胞上ARs和CXCR4的表达变化与总CD34(+)群体的变化一致。结果表明，细胞因子培养显著增加了CB CD34(+)细胞上AR的表达，这可能与细胞因子培养的造血干细胞归巢减少有关。
