Figure 1.

Diagram of mesenchymal stem cell hierarchy. At top of diagram are indicated the MAPCs that posses a higher proliferative and differentiative potential compared to classical MSCs. These may represent a more primitive subset of stem cells that could be the common precursor of MSCs, HSCs and EPCs. In the diagram are indicated the mesenchymal and non-mesenchymal cell types that originate from these different classes of stem cells. The dashed lines indicate putative differentiation pathways. MSCs: Mesenchymal stem cells; MAPCs: Multipotent adult progenitor cells; HSCs: Hematopoietic stem cells; EPCs: Endothelial progenitor cells.