ABSTRACT
Bone defects and fracture nonunion are common problems, affecting as many as 1000 patients in the world every year, and are difcult to heal using current therapies. Previously, these cases have been treated by surgery, using techniques such as autologous bone grafting or articial bone grafting. However, autologous bone grafts have a number of problems including donor-site problems, the limitations of harvested bone, or the weak strength of graft-bone, while articial bone grafts also have associated problems caused by the use of biomaterials, including immunogenicity, biodegradation, or strength limitations. Bone regeneration is an attractive research eld of tissue engineering because of its high clinical requirement. It is widely recognized that various osteogenic growth factors regulate the proliferation and differentiation of osteogenic cells and enhance bone formation. However, the use of osteogenic growth factor alone requires large amounts of protein because of its short half-life. Furthermore, the response to osteogenic growth factor varies between human species and primates need larger amounts of osteogenic growth factor than rodents. Aging has also been reported to lead to a reduction in response. To overcome these problems and to reduce the amounts of osteogenic growth factor required, developments in new types of materials by use of drug delivery systems (DDS) and combined treatments with other reagents that can enhance bone regeneration are challenging. Thus, if one can accelerate bone regeneration using osteogenic growth factors in a suitable manner, this regeneration technology will provide a new clinical procedure bone repair and be substituted for autogenous and allogenous bone grafts or biomaterial implants. This chapter reviews the basic principle of controlled release systems and the recent developments of new materials for their potential applications in regenerative medicine therapy for bone regeneration. This chapter emphasizes that controlled release technology in combination with principle of tissue engineering represents a viable strategy for the development of certain engineered tissue replacements and tissue regeneration systems to enhance bone regeneration.
