Treatment of circulating CD34(+) cells with SDF-1alpha or anti-CXCR4 antibody enhances migration and NOD/SCID repopulating potential.
OBJECTIVE
Stromal cell-derived factor-1alpha (SDF-1alpha) has been implicated in homing and engraftment of primitive hematopoietic progenitor cells (HPC) in studies demonstrating reduced NOD/SCID repopulating potential of HPC exposed to supra-physiologic concentrations of SDF-1alpha or anti-CXCR4. Outcome of CXCR4 signaling in some cells has been shown to be dependent on the concentration of SDF-1alpha. We aimed to determine whether similar concentration-dependent responses to CXCR4 signaling are present in CD34(+)cells.


METHODS
Human peripheral blood (PB), mobilized PB (MPB), or bone marrow (BM) CD34(+) cells were incubated for 30 minutes with different concentrations of SDF-1alpha or anti-CXCR4, washed, then assessed for in vitro hematopoietic potential, migration, and NOD/SCID repopulating potential.


RESULTS
Exposure of MPB or PB CD34(+) cells to 100 ng/mL SDF-1alpha increased tyrosine phosphorylation without subsequent proliferation or apoptosis. Spontaneous and SDF-1alpha-directed migration also increased in pretreated cells, despite previous exposure to SDF-1alpha. Cells exposed to 1 microg anti-CXCR4/10(6) cells displayed similar increases in activation and migration as cells exposed to SDF-1alpha, demonstrating the ability of anti-CXCR4 to activate the CXCR4 receptor. Interestingly, chimerism in NOD/SCID mice transplanted with MPB CD34(+) cells pretreated with SDF-1alpha or anti-CXCR4 was increased, while exposure of these cells to 10- to 100-fold higher concentrations of these proteins inhibited in vitro migration and NOD/SCID repopulating potential. Migration and NOD/SCID repopulating potential of BM CD34(+) cells remained unchanged after treatment with either protein.


CONCLUSIONS
These results illustrate the ability of SDF-1alpha and anti-CXCR4 to augment repopulating potential of CD34(+) cells, and suggest that HPC function can be favorably modulated through specific CXCR4 signaling.
Plett
P Artur
PA
Division of Hematology/Oncology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA. pplett@iupui.edu
Frankovitz
Stacy M
SM
Wolber
Frances M
FM
Abonour
Rafat
R
Orschell-Traycoff
Christie M
CM
D000328:Adult; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology*; D018952:Antigens, CD34 / Q000032:analysis; D001773:Blood Cells / Q000166:cytology / Q000187:drug effects; D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects; D015815:Cell Adhesion Molecules / Q000096:biosynthesis; D002465:Cell Movement / Q000187:drug effects; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000494:pharmacology*; D006085:Graft Survival / Q000187:drug effects; D006412:Hematopoietic Stem Cells / Q000187:drug effects*; D006801:Humans; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011828:Radiation Chimera; D019718:Receptors, CXCR4 / Q000037:antagonists & inhibitors* / Q000502:physiology; D015398:Signal Transduction; D013047:Specific Pathogen-Free Organisms; D033581:Stem Cell Transplantation; D014183:Transplantation, Heterologous
D000911:Antibodies, Monoclonal; D018952:Antigens, CD34; C515255:CXCL12 protein, human; D015815:Cell Adhesion Molecules; D054377:Chemokine CXCL12; D019743:Chemokines, CXC; C515256:Cxcl12 protein, mouse; D019718:Receptors, CXCR4; D011505:Protein-Tyrosine Kinases