Specificity of Hematopoietic Stem and Progenitor Cell Homing to Bone Marrow: A Perspective

Little is known about the hematopoietic stem and progenitor cell membrane recognition and adhesion molecules which mediate their specific patterns of movement into and out of the marrow compartment during steady state hematopoiesis and during pathological conditions. Implicit in the cellular targeting of these cells to marrow stroma, or "homing", is a high degree of molecular specificity. Identification of homing determinants and knowledge of their function in conferring specificity to these events may provide new insight into the localization of hematopoietic stem cells within the bone marrow, directly impacting clinical stem cell transplantation. In addition, a homing protein gene/promoter complex, or a stromal counter-receptor gene, may provide a valuable target for driving expression of gene constructs in early hematopoietic cells.