RESUMEN
In this study, we investigated the behavior of fetal rat osteoblasts cultured up to 23 days on a bioactive apatite-wollastonite glass-ceramic (AW) and on the same material on which a carbonated apatite layer was formed by a biomimetic process (AWa). The specific activity of alkaline phosphatase activity was about 30% increased on AWa compared to AW disks at the last day of culture. Scanning electron microscopic (SEM) observations of the material surfaces after scrapping off the cell layers revealed that mineralized bone nodules remained attached to both surfaces but in larger numbers on AWa. The AWa/bone interfaces were also analyzed after fracturing the disks and by transmission electron microscopy (TEM). All these results indicated the importance of the surface composition in supporting differentiation of osteogenic cells and the subsequent apposition of bone matrix. Furthermore, prefabrication of a biological apatite layer by a biomimetic method could improve our knowledge of biomineralization processes and could find application as bone-repairing material.
Asunto(s)
Materiales Biomiméticos , Huesos , Fosfatasa Alcalina/metabolismo , Animales , Apatitas/farmacología , Ingeniería Biomédica , Materiales Biomiméticos/metabolismo , Materiales Biomiméticos/farmacología , Calcificación Fisiológica , Diferenciación Celular/efectos de los fármacos , Células Cultivadas , Cerámica/farmacología , Microscopía Electrónica de Rastreo , Osteoblastos/citología , Osteoblastos/metabolismo , Osteoblastos/ultraestructura , Ratas/embriología , Ácido Silícico/farmacologíaRESUMEN
In Xenopus laevis somitogenesis, somitic blocks undergo coordinated movements resulting in their detachment from the rest of the mesodermal ridge, followed by a 90 degrees rotation of the entire metamere. Here we investigated the function of type I cadherins in somitogenesis. Type I cadherins are Ca(2+)-dependent cell-cell adhesion molecules concentrated in the adherens junctions and highly expressed in the somitic tissue. We analyzed their role in somitogenesis by overexpressing either the intracellular (deltaE) and the extracellular (C-trunc) dominant-negative forms of cadherin. The resulting phenotype was a downward bend of the anterior-posterior axis in tadpole stage embryos. 12/101 antigen and X-Myo-D expression were altered. Microscopy revealed disorganization of the myotomes. Conversely, segmentation was conserved at the microscopic and molecular levels.