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.
Fourth Department of Internal Medicine, Sapporo Medical University School of Medicine, Sapporo, Japan. mkobune@sapmed.ac.jp
Masayoshi
M
Kobune
Yutaka
Y
Kawano
Sho
S
Takahashi
Kohichi
K
Takada
Kazuyuki
K
Murase
Satosi
S
Iyama
Tsutomu
T
Sato
Rishu
R
Takimoto
Yoshiro
Y
Niitsu
Junji
J
Kato
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