Cellular interactions in hemopoietic progenitor cell homing: a review.

Within the bone marrow microenvironment, dynamic cellular interactions are constantly occurring. These interactions involve hemopoietic stem cells, progenitor cells and maturing cells, physically interacting with other cells, some of which may function as accessory cells, and others which comprise the stromal elements; hemopoietic cells also interact with non-cellular elements, such as glycoproteins and fibrous proteins of the extracellular matrix (ECM). These interactions serve to regulate normal hemopoiesis by allowing the communication of regulatory information, migration and subsequent homing of stem cells within specific organs, and presentation of hemopoietic growth factors in a biologically relevant fashion. The goal of this review is to examine the specific cellular interactions that relate to the phenomenon of homing of intravenously transplanted stem cells to the bone marrow.