Tissue engineering has been a promising alternative for bone regeneration. Previous studies have successfully repaired bone defect with osteoconductive biomaterials and mesenchymal derived cells. When bone defects, particularly large bone defects, are repaired using tissue engineering technology, angiogenesis is a prerequisite step to achieve the successes of bone regeneration. However, unlike organ transplants, where there is a pre-existing vascular supply, the tissue-engineered bone is usually devoid of pre-existing vasculature. This study aimed to construct vascularized tissue engineered bone in an ectopic osteogenesis rabbit model. The tissue engineered bone was constructed with osteogenic rabbit bone marrow mesenchymal stromal cells (BMSCs) and hydroxyapatite-collagen I scaffolds. The tissue engineered bone was implanted into the dorsal subcutaneous tissue of New Zealand rabbits. At 2, 4, 8, and 12 weeks post-implantation, the implants were then harvested and subjected to hematoxylin and eosin and immunohistochemistry staining; the osteogenic, vascularized, and osteoclastic gene expression levels were also examined by the qRT-PCR. It showed that de novo blood vessels and bone trabeculae gradually increased from the 2nd week to the 12th week, while the osteoclast activity remained low accordingly, and the ectopic bone formed in the 12th week. In conclusion, the vascularized tissue engineered bone could form 12 weeks after implantation, and could be harvested for therapy of bone defect.
[1]Fengxian Cent Hosp, Dept Orthoped, Shanghai 201400, Peoples R China.
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