miR-17 promotes expansion and adhesion of human cord blood CD34(+) cells in vitro.
BACKGROUND
We have recently found that miR-17 is necessary in the cell-extrinsic control of cord blood (CB) CD34(+) cell function. Here, we demonstrated that the proper level of miR-17 is also necessary in the cell-intrinsic control of the hematopoietic properties of CB CD34(+) cells.


METHODS
The miR-17 overexpression and knockdown models were created using primary CB CD34(+) cells transfected by the indicated vectors. Long-term culture, colony forming, adhesion and trans-well migration assays were carried out to investigate the function of miR-17 on CB CD34(+) cells in vitro. NOD prkdc (scid) Il2rg (null) mice were used in a SCID repopulating cell assay to investigate the function of miR-17 on CB CD34(+) cells in vivo. A two-tailed Student's t-test was used for statistical comparisons.


RESULTS
In vitro assays revealed that ectopic expression of miR-17 promoted long-term expansion, especially in the colony-forming of CB CD34(+) cells and CD34(+)CD38(-) cells. Conversely, downregulation of miR-17 inhibited the expansion of CB CD34(+) cells. However, the overexpression of miR-17 in vivo reduced the hematopoietic reconstitution potential of CB CD34(+) cells compared to that of control cells. The increased expression of major adhesion molecules in miR-17 overexpressed CB CD34(+) cells suggests that the adhesion between miR-17 overexpressed CB CD34(+) cells and their niche in vivo is regulated abnormally, which may further lead to the reduced hematopoietic reconstitution capability of 17/OE cells in engrafted mice.


CONCLUSIONS
We conclude that the proper expression of miR-17 is required, at least partly, for normal hematopoietic stem cell-niche interaction and for the regulation of adult hematopoiesis.
Department of Medical & Research Technology, School of Medicine, University of Maryland, Baltimore, MD, 21201, USA. yangyx@bjmu.edu.cn.
Yuxia
Y
Yang
Institute of Systems Biomedicine, Department of Pathology, School of Basic Medical Sciences, Peking University, Beijing, China. saifengwang@bjmu.edu.cn.
Saifeng
S
Wang
Beijing Vitalstar Biotechnology Co., Ltd., Beijing, China. miaozhenchuan@vital-bj.com.
Zhenchuan
Z
Miao
Department of Histology and Embryology, School of Basic Medical Sciences, Capital Medical University, Beijing, China. mawei315@yahoo.com.
Wei
W
Ma
Tianjin Central Hospital for Obstetrics and Gynecology, Tianjin, China. zhangyanjumd@163.com.
Yanju
Y
Zhang
Center of Medical and Health Analysis, Peking University, Beijing, China. dud.su@163.com.
Li
L
Su
Department of Medical & Research Technology, School of Medicine, University of Maryland, Baltimore, MD, 21201, USA. 799932198@qq.com.
Mengyu
M
Hu
Department of Medical & Research Technology, School of Medicine, University of Maryland, Baltimore, MD, 21201, USA. zoujunhua2008@163.com.
Junhua
J
Zou
Institute of Systems Biomedicine, Department of Pathology, School of Basic Medical Sciences, Peking University, Beijing, China. yinyuxin@bjmu.edu.cn.
Yuxin
Y
Yin
Department of Medical & Research Technology, School of Medicine, University of Maryland, Baltimore, MD, 21201, USA. JLuo@som.umaryland.edu.|Department of Medical & Research Technology, Department of Pathology, School of Medicine, University of Maryland, College Park, USA. JLuo@som.umaryland.edu.
Jianyuan
J
Luo
D000818:Animals; D018952:Antigens, CD34 / Q000235:genetics / Q000378:metabolism*; D002448:Cell Adhesion; D002465:Cell Movement; D005312:Fetal Blood / Q000166:cytology; D006410:Hematopoiesis; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D016513:Mice, SCID; D035683:MicroRNAs / Q000235:genetics*
D018952:Antigens, CD34; C524941:MIRN17 microRNA, human; D035683:MicroRNAs