| Critical size bone defects arising from trauma, tumor resection, infection and skeletal abnormalities require assistance to provide skeletal continuity, mechanical support and eventual regeneration. Traditionally, materials strategies to address bone defects include the use of autogeneous grafts and flaps, allograft bone, non-degradable bone cement, metals and ceramics. All of these options have their associated problems such as the finite amount of tissue that can be harvested for autografts, the difficulty to shape grafts into the desired form, and the risk of immune rejection or disease transfer with allografts.The regeneration of fractured bone is based on the hypothesis that healthy progenitor cells, either recruited or delivered to an injured site, can eventually replace the lost or damaged bone tissue. Based on this suggestion, tissue engineering approaches attempt to create tissue replacements by culturing cells onto nature or synthetic three-dimensional matrixes. It is difficult to repair tissues by using cultured cells alone. In fact, a biomaterial with appropriate composition and three-dimensional structure to promote cellular adhesion, differentiation and the mechanic strength to provide as a scaffold for tissue regeneration is needed. So, it is very important for materials to be used in bone engineering.Three-dimensional porous polymeric matrixes are seen as one approach to enhance bone regeneration by creating and maintaining channels that facilitate progenitor cell migration, proliferation, and differentiation. However, their application is limited because of some shortcomings such as poor mechanical properties, toxicity of degradation product to cells and stress shielding to the surrounding bone or fatigue failure of the implants. For other materials to be considered, among which are natural bone derived biomaterials. DBM for example, has been shown to accelerate wound healing, and be used as a biocompatible and absorbable material in both animal and human bone defects. However, these materials can not meet the requirements of bone tissue engineering because of their poor mechanical properties and allergic reactions. Therefore, the research of improving ideal materials in bone engineering should be continuously carried out.Acellular matrixes, such as dermis and blood vessels had been shown to have good mechanical properties, biocompatibility, biodegradability. Also, their gross architecture and shape facilitate cells adhesion and proliferation. At the same time, allergic reactions and disease transmission may be avoided after treatment.Therefore, it is reasonable to predict that ACBM can be used as a prospective candidate to form a structural framework for bone engineering. In this study, ACBM material was prepared and evaluated for mechanical properties, general biocompatibility, effect of osteoinductive and osteoconductive. Subsequently, it was combined with rhBMP-2 by fibrin gelatin to constitute the slowly releasing carrier of tissue engineering bone. The scaffold was seeded with mesenchymal stem cells harvested from bone marrow of NZW rabbits to evaluate their performance as potential bone substitutes in vitro and in vivo.The main results and conclusions are as follows: 1. United with physical, chemical and biochemical methods, we successfully realized deantigenic treatment of xenogeneic bone in the formulations of ACBM. In vivo and in vitro evaluation of cellular and humoral immunity in recipients proved that ACBM has lower or no antigen with a good reliability. 2. Not only the components and structure of bone are being preserved in ACBM, but also the mechanical properties are similar to that of fresh bone. Compared with natural derived bone matrixs existing now, ACBM reserves the original structure and biomechanics. So, it is a suitable material for the repair of bone defects, especially for segmental bone defects in tubular bone.3. Scanning with SEM, it proved that the three-dimensional porous ACBM maintain channels that facilitate progenitor cell migration, proliferati...
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