 Finally, the elasticity modulus of the ECM, partially provided by MSCs in the bone marrow, has been shown to direct the differentiation and activity of stem cells nearby.The landscape of the HSC niche in the bone marrow is constantly changing, and the acellular factors, as much as the cellular factors, are beginning to reveal the complexity of hematopoietic regulation.Osteoblasts, bone-forming cells, interact with HSCs and provide proliferative signals.