Mobilization studies in mice deficient in either C3 or C3a receptor (C3aR) reveal a novel role for complement in retention of hematopoietic stem/progenitor cells in bone marrow

• Published in: Blood 2004-03, Vol.103 (6), p.2071-2078
• Main Authors: Ratajczak, Janina, Reca, Ryan, Kucia, Magda, Majka, Marcin, Allendorf, Daniel J., Baran, Jarek T., Janowska-Wieczorek, Anna, Wetsel, Rick A., Ross, Gordon D., Ratajczak, Mariusz Z.
• Format: Article
• Language: English
• Subjects: Animals; Arginine - analogs & derivatives; Arginine - pharmacology; Benzhydryl Compounds - pharmacology; Biological and medical sciences; Bone Marrow Cells - cytology; Bone Marrow Transplantation; Cell differentiation, maturation, development, hematopoiesis; Cell Movement - drug effects; Cell Movement - immunology; Cell physiology; Complement Activation - drug effects; Complement C3 - genetics; Female; Fundamental and applied biological sciences. Psychology; Granulocyte Colony-Stimulating Factor - pharmacology; Hematopoietic Stem Cells - cytology; Membrane Proteins - antagonists & inhibitors; Membrane Proteins - genetics; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Mutant Strains; Molecular and cellular biology; Radiation Chimera; Receptors, Complement - antagonists & inhibitors; Receptors, Complement - genetics
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2003-06-2099

The mechanisms regulating the homing/mobilization of hematopoietic stem/progenitor cells (HSPCs) are not fully understood. In our previous studies we showed that the complement C3 activation peptide, C3a, sensitizes responses of HSPCs to stromal-derived factor 1 (SDF-1). In this study, mobilization was induced with granulocyte colony-stimulating factor (G-CSF) in both C3-deficient (C3–/–) and C3a receptor–deficient (C3aR–/–) mice as well as in wild-type (wt) mice in the presence or absence of a C3aR antagonist, SB 290157. The data indicated (1) significantly increased G-CSF–induced mobilization in C3–/– and C3aR–/– mice compared with wt mice, (2) significantly accelerated and enhanced G-CSF–induced mobilization in wt, but not in C3–/– or C3aR–/–, mice treated with SB 290157, and (3) deposition of C3b/iC3b fragments onto the viable bone marrow (BM) cells of G-CSF–treated animals. Furthermore, mobilization studies performed in chimeric mice revealed that wt mice reconstituted with C3aR–/– BM cells, but not C3aR–/– mice reconstituted with wt BM cells, are more sensitive to G-CSF–induced mobilization, suggesting that C3aR deficiency on graft-derived cells is responsible for this increased mobilization. Hence we suggest that C3 is activated in mobilized BM into C3a and C3b, and that the C3a-C3aR axis plays an important and novel role in retention of HSPCs (by counteracting mobilization) by increasing their responsiveness to SDF-1, the concentration of which is reduced in BM during mobilization. The C3a-C3aR axis may prevent an uncontrolled release of HSPCs into peripheral blood. These data further suggest that the C3aR antagonist SB 290157 could be developed as a drug to mobilize HSPCs for transplantation.