Injectable bone

Tissue engineering applies the principles of biology and engineering to the development of functional substitutes,for example 1) cells, 2) scaffolds, 3) some cytokines, for lost tissues. The meaning of this bone regeneration is that it decreases the needed tissues and burden of patients. In this time, we applied to mesenchymal stem cells (MSCs) from the own bone marrow as cell sources. MSCs are thought to be multipotent cells that can replicate. And we also used a beta-tricalcium phosphate (beta-TCP) as a scaffold and fibrin glue as materials to regenerate a injectable bone and we injected into the subcutaneous space on the dorsum of the rat. After 8 weeks of implantation, it could be confirmed newly formed bone and fibrin glue functioned as a injectable materials without loosing the cell activity and the proliferation of MSCs. Next we applied Platelet Rich Plasma (PRP) to improve the ability of osteogenesis. PRP contains some cytokines and are expected to promote the increase of osteogenesis. The merit is not immunity rejection from autologous blood collected in the immediate preoperative period. The admixtures of PRP or fibrin glue have fluidity and gel-like consistency as the thrombin mixing. They can be injected with a syringe in tissues. We named this "Injectable Bone". According to the histological observations, the MSCs with PRP were well formed mature bone and neovascularization compared with control (defect only) after 8 weeks implantation. These results demonstrated that the mixture of MSCs and PRP were useful as injectable bone substitute and its ability of bone regeneration is almost equal to autogenous particulate cancellous bone and marrow (PCBM).