RESUMO
STUDY DESIGN: Osteoblastic cells derived from vertebral lamina and iliac crest were isolated and cultured under the same conditions (osteogenic medium, pH, temperature, and CO2 levels). OBJECTIVE: To compare proliferation and expression of osteoblastic phenotype of cells derived from vertebral lamina and iliac grafting. SUMMARY OF BACKGROUND DATA: Many factors play a role in the success of bone graft in spinal fusion including osteoblastic cell population. Two common sources of graft are vertebral lamina and iliac crest, however, differences in proliferation and osteoblastic phenotype expression between cells from these sites have not been investigated. METHODS: Cells obtained from cancellous bone of both vertebral lamina and iliac crest were cultured and proliferation was evaluated by direct cell counting and viability detected by Trypan blue. Alkaline phosphatase (ALP) activity was evaluated by thymolphthalein release from thymolphthalein monophosphate and matrix mineralization by staining with alizarin red S. Gene expression of ALP, osteocalcin, runt-related transcription factor 2, Msh homeobox 2, bone morphogenetic protein 7, intercellular adhesion molecule 1 precursor, osteoprotegerin, and receptor activator of NF-kB ligand was analyzed by real-time PCR. All comparisons were donor-matched. RESULTS: Proliferation was greater at days 7 and 10 in cells from vertebral lamina compared with ones from iliac crest without difference in cell viability. ALP activity was higher in cells from vertebral lamina compared with cells from iliac crest at days 7 and 10. At 21 days, mineralized matrix was higher in cells derived from vertebral lamina than from iliac crest. At day 7, gene expression of ALP, osteocalcin, runt-related transcription factor 2, Msh homeobox 2, bone morphogenetic protein 7, intercellular adhesion molecule 1 precursor, receptor activator of NF-kB ligand, and osteoprotegerin was higher in cells derived from vertebral lamina compared with iliac crest. CONCLUSION: Cell proliferation and osteoblastic phenotype development in cells derived from cancellous bone were more exuberant in cultures of vertebral lamina than of iliac crest.
Assuntos
Diferenciação Celular/fisiologia , Proliferação de Células , Ílio/citologia , Osteoblastos/citologia , Coluna Vertebral/citologia , Biomarcadores/análise , Biomarcadores/metabolismo , Matriz Óssea/química , Matriz Óssea/metabolismo , Regeneração Óssea/fisiologia , Transplante Ósseo/métodos , Calcificação Fisiológica/fisiologia , Técnicas de Cultura de Células , Células Cultivadas , Regulação da Expressão Gênica/fisiologia , Humanos , Ílio/fisiologia , Osteoblastos/fisiologia , Osteogênese/fisiologia , Fenótipo , Fusão Vertebral/métodos , Coluna Vertebral/fisiologiaRESUMO
The surgical technique of anterior vertebral arthrodesis has been modified by the introduction of cages in spinal surgery. The classical technique recommends removal of the vertebral endplate and exposure of bleeding cancellous bone. However, after the observation of cage subsidence during postoperative follow-up, the vertebral endplate is no longer removed, due to its greater mechanical resistance which can prevent cage subsidence. The mechanical characteristics of the vertebral endplate are well known, in contrast to its osteogenic potential, which was investigated in the present experimental study. The study was conducted on mongrel dogs of both sexes, which were submitted to anterior corpectomy at the cervical spine level. A cortico-cancellous bone graft removed from the tibia was used for the reconstruction of the vertebral segment, which was used with osteosynthesis plates. At the site of contact between the surface of the vertebral body and the bone graft, the vertebral endplate was completely removed and cancellous bone was exposed in the inferior vertebra, whereas in the superior vertebra of the arthrodesed vertebral segment only curettage was performed, and the vertebral endplate was preserved, as recommended for cage implantation. Twenty adult dogs of both sexes were divided into four experimental groups according to time of sacrifice (15, 30, 90, and 180 days). The consolidation of the bone graft with the vertebral body was evaluated by histology using hematoxilin-eosin and Gomori trichrome staining. In the interface between the bone graft and the vertebral body surface in which the vertebral endplate was not removed, graft consolidation was not observed in any of the group I animals (sacrificed after 15 days), and was observed in 1/5 animals of group II (30 days), in 2/5 animals of group III (90 days), and in 4/5 animals of group IV (180 days). In the interface between the graft and the vertebral body in which the vertebral endplate was removed, bone-graft consolidation was observed in all animals of all experimental groups (15, 30, 90, and 180 days). Bone-graft consolidation with the surface of the vertebral body was influenced by the removal or maintenance of the vertebral endplate. Due to the importance of this structure in current surgical procedures, this phenomenon deserves to be studied in more detail in order to understand the basic events involved in this process.