Bone formation in calcium-phosphate-coated titanium mesh

The osteogenic activity of porous titanium fiber mesh and calcium phosphate (Ca-P)-coated titanium fiber mesh loaded with cultured syngeneic osteogenic cells was compared in a syngeneic rat ectopic assay model. In 30 syngeneic rats, (Ca-P)-coated and non-coated porous titanium implants were subcutaneously placed either without or loaded with cultured rat bone marrow (RBM) cells. Fluorochrome bone markers were injected at 2, 4, and 6 weeks. The rats were sacrificed, and the implants were retrieved at 2, 4, and 8 weeks post-operatively. Histological analysis demonstrated that none of the (Ca-P)-coated and non-coated meshes alone supported bone formation at any time period. In RBM-loaded implants, bone formation started at 2 weeks. At 4 weeks, bone formation increased. However, at 8 weeks bone formation was absent in the non-coated titanium implants, while it had remained in the (Ca-P)-coated titanium implants. Also, in (Ca-P)-coated implants more bone was formed than in non-coated samples. In general, osteogenesis was characterized by the occurrence of multiple spheres in the porosity of the mesh. The accumulation sequence of the fluorochrome markers showed that the newly formed bone was deposited in a centrifugal manner starting at the center of a pore. Our results show that the combination of Ti-mesh with RBM cells can indeed generate bone formation. Further, our results confirm that a thin Ca-P coating can have a beneficial effect on the bone-generating properties of a scaffold material.