Preparation of tissue engineered bone and in vivo osteogenesis using alginate and xenograft bone composite technology / 中国组织工程研究

ABSTRACT

BACKGROUND: Alginic acid has a relatively mild gel condition and good biocompatibility, and it has been widely used in bio-tissue engineering.OBJECTIVE: To construct bone tissue engineering scaffolds using alginate gel composite bone xenograft approach, and to observe the cell biological properties and in vivo osteogenic potential in scaffolds.METHODS: The bone marrow was harvested from two 2-week-old New Zealand rabbits, 1 ×10~(-8)mol/L recombinant human bone morphogenetic protein-2 was used to induce bone marrow mesenchymal stem cells. The induced bone marrow mesenchymal stem cells at the second generation were incubated into 1% sodium alginate gel, after cultured for 4 days, the cell morphology in gel was observed by hematoxylin-eosin staining. Bone marrow mesenchymal stem cells at the second generation were divided into simple DMEM gel group and DMEM containing 1% sodium alginate gel group, followed by a culture of 7 days. Then bone morphogenic protein-2 immunohistochemical staining was performed. A total of 24 nude mice were randomly divided into two groups, both sides of the thigh muscle pockets were implanted with bone marrow-derived mesenchymal stem cells/alginate gel/bovine cancellous bone complex as an experimental group, with bone marrow-derived mesenchymal stem cells/bovine cancellous bone as a control group. At 2 and 4 weeks post-operation, the osteogenesis in the composite was observed by histological examination, the percentage area of new bone or cartilage was determined using image analysis system.RESULTS AND CONCLUSION: The bone marrow-derived mesenchymal stern cells in the sodium alginate gel exhibited a well-stacked morphology, they suspended in a gel, showing cell division and mitosis phase. In the simple DMEM gel group and DMEM gel containing 1% sodium alginate group, the immunohistochemical results showed that, cell division and proliferation were normal, with prominence at a variety of forms, large nucleus, and clear nucleolus. The bone morphogenetic protein-2 expression had no significant difference between the simple DMEM gel group and DMEM gel containing 1% sodium alginate group (P>0.05).Scanning electron microscopy revealed that, the alginate gel evenly composited in bovine cancellous bone micropores, cell grew at different planes. Animal experiments showed that there were significant differences regarding the percentage of new bone or cartilage area between the experimental group and control group at 2 and 4 weeks postoperation (P< 0.05). It is indicated that constructing bone tissue engineering scaffolds by using alginate gel/bovine cancellous bone, complies with the ultra-structural principle of tissue engineering scaffolds, can maximize the cell loads, achieve good bio-performance, without adverse affects on the proliferation, osteogenic phenotype and related biological properties of bone marrow-derived mesenchymal stem calls, the in vivo osteogenic efficiency was high.