[Clinical application of tissue engineered bone repair of human craniomaxillofacial bone defects]

To explore the feasibility of tissue engineered bone formation in human being using human bone marrow stromal cells (hBMSCs) and the possibility of clinical repair of craniomaxillofacial bone defects with tissue engineered bone.

Total 11 patients of cranial defects and aperture piriformis bone depression were included in this study. The hBMSCs were isolated by Percoll gradient centrifugation from patient's bone marrow aspirated from iliac crest. The hBMSCs were cultured in vitro and induced to become osteogenic cells in the DMEM medium containing 10% self-serum, beta-glycerophosphate (10 nmol/L) dexamethasone (10(-8) mol/L), L-2-ascorbic acid (50 micro mol/L), and 1, 25 (OH)(2)VD(3)(10 nmol/L). Induced hBMSCs of passage 3 were harvested and seeded onto partly demineralized allogenic bone matrix (pDBM) to form a cell-scaffold construct and in vitro co-culture for 1 week. The defects were repaired with the cell-scaffold construct. In 3 cases of aperture piriformis bone depression, one side was repaired with hBMSC/pDBM, while the other side was repaired by pDBM alone. All cases were followed up for 1, 3, 6 months post-operation as short-term evaluation and 1 to 2.5 years post-operation as long-term evaluation by three-dimensional computerized tomography (3D-CT) and clinical examination. In 2 cases who received secondary surgery, extra engineered bone tissue and control pDBM were harvested at the implantation sites for histological examination and immunohistochemistry.

3D-CT demonstrated that engineered bone was formed in 3 to 6 months post-operation. Additionally, formed bone maintained stable up to 1 - 2 years without absorption. Histologically, engineered bones revealed their structures similar to that of normal bone in HE staining. Interestingly, endochondral ossification was also observed in engineered bone. Immunohistochemistry shows positive staining of osteonectin and osteocalcin in engineered and normal bones. In contrast, implanted pDBM was completely degraded in 3 - 6 months as revealed by 3D-CT. Histologically, degraded pDBM and fibrous tissue were observed in the sites where pDBM alone was implanted.

Tissue engineered bone can be formed in human being. Engineered bone can be used to repair clinical bone defect with satisfactory result. Furthermore, the result of this study proves that tissue engineered bone is possible for clinical application.