Bones were considered to be the very important partof our body in terms of the pivotal role played by it in the whole body.
Boneis the storage house of calcium which can regulate the concentration of Ca2+ in the human body. Moreover, bone marrow contains hematopoietic stem cellswhich are responsible for the production of mature blood cells in bone marrow6. In addition, the bonesprovide high mechanical strength, to support body’s organization. Bones are highly mineralized connective tissuethat forms the skeleton of most vertebrates and have properties such ashardness, toughness, and self-healing 7, 8. The hard bone iscomposed of organic matter and inorganic matter, of which organic matteraccounts for about 30% of the total dry weight. This mainly composed by about90 to 95% Collagen, 1% glycosaminoglycan and about 5% of other proteins8, that provides certaintoughness for the hard bone.
Correspondingly, inorganic matter accounts for about70% of the dry weight, mainly calcium and phosphorus, that is responsible for thehardness of hard bone. Therefore, the bones have both toughness and hardness,so that it can form a skeleton to support body weight, to protect internalorgans and for other functions. Moreover, bones are also important site for hematopoiesisand for the storage and release of calcium, phosphorus, magnesium and sodiumions. Bone marrow mesenchymal stem cells (BMSCs), Can differentiate into hardbones, cartilage, tendons, muscles, skin and adipose tissue.
There are alsodifferent types of hematopoietic stem cells in the marrow cavity, resulting inred blood cells and white blood cells, that have the function of transportinggas (O2 and CO2) and immune ability 9. In the process of bonedifferentiation, a series of reactions are involved. In these reactions, particularlyin complicated reactions, the extracellular matrix plays number of roles, suchas providing cell support and attachment, as well as separating the tissues andcells from each other10. On the other hand, thechanges of physiological microenvironment can trigger the continual secretionof cells11. In the regulation of cells, these coordinatedmessages indicate that the cells acquire specific differentiation, such as theregulation of cell development, proliferation, migration and function. Therefore,in tissue engineering applications and tissue remodeling, the interaction ofcells with the extracellular matrix is ??an important issue12.