Tissue-Engineered Bone Formation In Vivo for Artificial Laminae of the Vertebral Arch Using β-Tricalcium Phosphate Bioceramics Seeded With Mesenchymal Stem Cells

Study Design. A rabbit laminectomy model was used to evaluate the efficacy of artificial laminae of vertebral arch using bone marrow-derived mesenchymal stem cells (MSCs) transplanted in porous beta-calcium phosphates (beta-TCP) bioceramics. Objective. The aim of this study was to establish artificial lamina of the vertebral arch for bone tissue engineering using beta-TCP bioceramics seeded with MSCs in a rabbit model of decompressive laminectomy. Summary of Background Data. Decompressive laminectomy may induce various degrees of scar tissue and adhesion formation in the epidural space, and thus is the most common cause of failed back surgery syndrome. However, there is no effective method of bone defect treatment to control and reduce the scar tissue formation. Methods. MSCs were harvested from New Zealand rabbits (2-week old) by femoral bone marrow extraction. These cells were seeded into porous beta-TCP bioceramics and cultivated for up to 3 weeks in the presence of osteogenic supplements. Segmental defects (20 x 8 mm) were created in 48 adult New Zealand rabbits that underwent laminectomy at the L5 to L6 levels. The animals were transplanted with cell media (control), beta-TCP bioceramics (group I), or MSC-loaded beta-TCP bioceramics (group II). Bone formation was evaluated after operation using scanning electron microscopy, computed tomography, magnetic resonance imaging, histomorphometry, and immunohistochemistry. Results. Scanning electron microscopy showed that MSCs filled the pores and surfaces of bioceramics in MSC-loaded beta-TCP. In addition, significant increases in bone formation were observed in group II compared with other groups. Computed tomography and magnetic resonance imaging at 16 weeks showed that the artificial lamina of the vertebral arch was successfully formed. Hematoxylin-eosin and Masson trichrome staining were used to show the artificial laminae of the vertebral arch and the degraded bioceramics. In addition, immunohistochemistry results showed that the expression of bone morphogenetic protein-2 increased significantly in group II compared with group I at 2,4, and 8 weeks after implantation (P < 0.05). Conclusion. beta-TCP bioceramics seeded with MSCs are a promising source of tissue-engineered bone for the artificial lamina of the vertebral arch.