Cellular interactions between stromal macrophages and haematopoietic cells

The haematopoietic microenvironment is essential for the maintenance of steady-state haematopoiesis both in vivo and in vitro (1). This is thought to be via close-range cellular interactions between the stromal cells of the microenvironment and the haematopoietic stem cells and progenitors. To date, however, little is known concerning the precise mechanisms by which stromal cells regulate haematopoiesis, either under steady-state or induced conditions.