Sustained alterations in biodistribution of stem/progenitor cells in Tie2Cre+α4f/f mice are hematopoietic cell autonomous

• Published in: Blood 2007-01, Vol.109 (1), p.109-111
• Main Authors: Priestley, Gregory V., Ulyanova, Tatiana, Papayannopoulou, Thalia
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Hematologic and hematopoietic diseases; Hematopoiesis; Medical sciences
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2006-06-026427

We have generated Tie2Cre+α4f/f mice with documented α4-integrin ablation in hematopoietic and endothelial cells. A prominent feature in this model is a sustained, significant increase in circulating progenitors at levels higher than the levels seen with Tie2Cre+VCAM-1f/f mice. To test whether phenotypic differences are due to contributions by ligands other than VCAM-1 in bone marrow, or to α4-deficient endothelial cells or pericytes, we carried out transplantation experiments using these mice as donors or as recipients. Changes in progenitor biodistribution after transplantation were seen only with α4-deficient donor cells, suggesting that these cells were necessary and sufficient to reproduce the phenotype with no discernible contribution by α4-deficient nonhematopoietic cells. Because several similarities are seen after transplantation between our results and those with CXCR4−/− donor cells, the data suggest that VLA4/VCAM-1 and CXCR4/CXCL12 pathways contribute to a nonredundant, ongoing signaling required for bone marrow retention of progenitor cells during homeostasis.