title: Hematopoietic progenitor cell mobilization by granulocyte colony-stimulating factor and erythropoietin in the absence of matrix metalloproteinase-9.
abstract: The use of mobilized hematopoietic progenitor cells (HPC) has largely replaced the use of bone marrow HPC for autologous and allogeneic transplantation; however, the mechanisms of HPC mobilization remain unclear. A better understanding of these mechanisms, may allow the development of improved (potentially more rapid and/or higher yield) HPC mobilization strategies, especially for patients who mobilize poorly using current mobilization protocols. Clinically, granulocyte colony-stimulating factor (G-CSF) is widely used to induce HPC mobilization, and evidence suggests that metalloproteinase enzymes released by activated granulocytes play an important role in the G-CSF-induced HPC mobilization. These enzymes may act to disrupt putative cell-cell and/or cell-extracellular matrix interactions within the hematopoietic microenvironment thereby releasing HPC into the blood. Matrix metalloproteinase-9 (MMP-9) appears to be important for G-CSF-induced mobilization. Using an MMP-9 knock-out (KO) mouse model, we investigated the role of MMP-9 in G-CSF and erythropoietin (EPO)-based HPC mobilization at clinically relevant cytokine doses. There were few hematologic or hematopoietic differences between the wild-type and MMP-9KO mice during steady-state hematopoiesis. When treated subcutaneously with EPO (500 U/kg per day) and G-CSF (15 microg/kg per day) for 5 days and assayed on day 6, similarly increased extramedullary hematopoiesis and numbers of HPC in the spleen and blood were observed for both the wild-type and MMP-9KO mice. These data demonstrate that MMP-9 is not required for EPO + G-CSF mobilization and that alternative mobilization mechanisms must be active at clinically relevant cytokine concentrations.
authors.affiliation: Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198-6395, USA. snrobins@mdanderson.org
authors.forename: S N
authors.initials: SN
authors.lastname: Robinson
authors.forename: S M
authors.initials: SM
authors.lastname: Seina
authors.forename: J C
authors.initials: JC
authors.lastname: Gohr
authors.forename: J G
authors.initials: JG
authors.lastname: Sharp
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D003114:Colony-Forming Units Assay; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology*; D006410:Hematopoiesis / Q000187:drug effects / Q000235:genetics; D019650:Hematopoietic Stem Cell Mobilization / Q000379:methods*; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects; D020780:Matrix Metalloproteinase 9 / Q000172:deficiency* / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D023421:Models, Animal; D011994:Recombinant Proteins; D013154:Spleen / Q000166:cytology
chemical_list: D011994:Recombinant Proteins; D016179:Granulocyte Colony-Stimulating Factor; D020780:Matrix Metalloproteinase 9