Bone marrow mesenchymal cells: biological properties and clinical applications.

In postnatal mammals, the primary site of hematopoiesis is the bone marrow (BM) extravascular compartment. As cells mature, they are released into the vascular compartment through the endothelium and the adventitial layer of mature blood elements. In the BM extravascular space, a dense network of cells constitutes the bone marrow microenvironment (BMM). The BMM provides structural and functional support for the self-renewal and differentiation of hematopoietic progenitor cells as cytokines and cell-to-cell interactions within proliferation niches of the BMM regulate these processes. In this paper, recent advances in understanding the nature of BMM cells are described with a specific focus on mesenchymal progenitors describing their main biological properties and potential clinical applications