Blockade of α6-Integrin Reveals Diversity in Homing Patterns Among Human, Baboon, and Murine Cells

Our understanding of the mechanisms by which intravenously transplanted hematopoietic stem/progenitor cells (HSPCs) home to and engraft the bone marrow (BM) remains incomplete, but participation of adhesion molecules has been documented. We here demonstrate that blockade of the α6-integrin enhanced BM homing of human and nonhuman primate BM-derived HSPCs by >60% in the xenogeneic transplant model and led to significantly improved engraftment. The effect was limited to BM-derived HSPCs, as granulocyte-colony-stimulating factor mobilized peripheral blood or cord blood HSPCs express little or no α6 integrin. By contrast, despite high α6 integrin expression, no effect of α6 blockade on murine BM-HSPCs homing/engraftment was observed.