Interaction with human stromal cells enhances CXCR4 expression and engraftment of cord blood Lin(-)CD34(-) cells.
OBJECTIVE
Transplantation of hematopoietic stem cells (HSCs) is usually accomplished through intravenous injection, a complex process that requires recognition of bone marrow vasculature and migration to a supportive microenvironment. Hence, some populations of HSCs, including cord blood (CB) Lin(-)CD34(-) stem cells, do not engraft well in bone marrow (BM) of nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice. In this study, we examined the effect of human stromal interactions on the properties of CB Lin(-)CD34(-) cells.


METHODS
CD34 and CXCR4 expression on fresh CB Lin(-)CD34(-) cells and CB Lin(-)CD34(-) cells cocultured with human stromal cells were analyzed. Homing activity and engraftment of these cells were assessed using NOD/SCID mice. In an attempt to identify the stromal CXCR4-inducing factor, CB Lin(-)CD34(-) cells were cocultured with a noncontact culture system in the presence of several inhibitors.


RESULTS
Coculture with human stromal cells induced expression of CD34 and CXCR4 on CB Lin(-)CD34(-) cells. CXCR4 expression on CB Lin(-)CD34(-) cells was induced even in the noncontact culture condition, suggesting that this CXCR4-inducing factor is soluble. Moreover, CXCR4 induction was inhibited by the soluble Wnt inhibitor DKK1. Furthermore, these cells acquired homing activity and engrafted in the BM of NOD/SCID mice after intravenous injection.


CONCLUSIONS
These findings may be useful for understanding the role of stromal cells in homing and engraftment of HSCs.
Kobune
Masayoshi
M
Fourth Department of Internal Medicine, Sapporo Medical University School of Medicine, Sapporo, Japan. mkobune@sapmed.ac.jp
Kawano
Yutaka
Y
Takahashi
Sho
S
Takada
Kohichi
K
Murase
Kazuyuki
K
Iyama
Satosi
S
Sato
Tsutomu
T
Takimoto
Rishu
R
Niitsu
Yoshiro
Y
Kato
Junji
J
D000818:Animals; D018952:Antigens, CD34 / Q000032:analysis; D000943:Antigens, Differentiation / Q000032:analysis; D001853:Bone Marrow; D002450:Cell Communication; D002634:Chemotaxis, Leukocyte / Q000502:physiology; D018920:Coculture Techniques; D005312:Fetal Blood / Q000166:cytology*; D006085:Graft Survival; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000737:chemistry / Q000145:classification / Q000502:physiology*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000502:physiology; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D019718:Receptors, CXCR4 / Q000096:biosynthesis* / Q000235:genetics; D012995:Solubility; D017154:Stromal Cells / Q000502:physiology*; D014183:Transplantation, Heterologous; D015854:Up-Regulation / Q000502:physiology; D051153:Wnt Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics
D018952:Antigens, CD34; D000943:Antigens, Differentiation; C527276:CXCR4 protein, human; C501126:DKK1 protein, human; D036341:Intercellular Signaling Peptides and Proteins; D019718:Receptors, CXCR4; D051153:Wnt Proteins