[Study on the mechanism of enhancing homing efficiency of human hematopoietic stem/progenitor cells into bone marrow after manipulation with tumor necrosis factor alpha in xenotransplanted BALB/c mouse model].
OBJECTIVE
To investigate the role of tumor necrosis factor (TNF) alpha on the homing efficiency of hematopoietic stem/progenitor cells (HS/PC) into bone marrow and its mechanism.


METHODS
CFSE-labeled umbilical cord blood (UCB) CD34+ cells were transplanted into irradiated (control group) or combined with TNF alpha prepared (experimental group) BALB/c recipient mice. The distribution in peripheral blood, liver, lung and homing characteristics in bone marrow and spleen of UCB CD34+ cells, in BALB/c recipient mice were determined 20 hours after xenotransplantation by flow cytometry (FACS) and their homing efficiency was calculated. ELISA was used to measure serum SDF-1 alpha level. CXCR4 expression levels of on UCB CD34+ cells were assessed by FACS pre-/post-manipulation with TNF alpha. SDF-1 alpha expression level in bone marrow and spleen was tested by immunohistochemistry.


RESULTS
UCB CD34+ cells mainly home into recipient mice bone marrow and spleen; The homing efficiency in experimental group bone marrow [(0.65 +/- 0.13)%] was significantly higher than that in control ones [(0.30 +/- 0.09)%, P < 0.01], whereas the homing efficiency in experimental group spleen was dramatically lower than that in control ones (P < 0.01); Treatment with TNF alpha did not affect recipient serum SDF-1 alpha level; After 18 hours co-cultured with TNF alpha, the CXCR4e expression level on UCB CD34+ cells was similar to that on fresh ones; TNF alpha treatment induced significantly higher SDF-1 alpha expression on osteoblastic and stromal cells in bone marrow, and reversed spleen SDF-1 alpha gradient that was originally favorable for CD34+ cells homing.


CONCLUSIONS
TNF alpha enhances the homing efficiency of HS/PC via up-regulating SDF-1 alpha gradient in bone marrow, and might be an useful enhancer for HS/PC homing in clinical practice.
Dai
Hong-sheng
HS
State Key Laboratory of Experimental Hematology, Institute of Hematology & Blood Diseases Hospital, CAMS & PUMC, Tianjin 300020, China.
Gao
Jing-tao
JT
Zhang
Tong-wen
TW
Yang
Zhou
Z
Che
Yong-zhe
YZ
Zheng
Yi-zhou
YZ
D000818:Animals; D018952:Antigens, CD34; D001853:Bone Marrow; D002465:Cell Movement; D002469:Cell Separation; D054377:Chemokine CXCL12 / Q000378:metabolism; D005260:Female; D005312:Fetal Blood / Q000166:cytology; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D019718:Receptors, CXCR4 / Q000378:metabolism; D019172:Transplantation Conditioning; D014183:Transplantation, Heterologous; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D018952:Antigens, CD34; D054377:Chemokine CXCL12; D019718:Receptors, CXCR4; D014409:Tumor Necrosis Factor-alpha