The responses of osteoblasts, osteoclasts and endothelial cells to zirconium modified calcium-silicate-based ceramic

In this study we have developed Ca3ZrSi2O9 (Baghdadite) ceramics by incorporating Zirconium in Ca–Si system and determined their biological properties. Ca3ZrSi2O9 ceramics possess apatite-formation ability in simulated body fluid, indicating their potential bioactivity. The response of human osteoblast like cells (HOB), osteoclast and endothelial cells when cultured on Ca3ZrSi2O9 ceramics was investigated. Scanning electron microscopy and immunofluorescence studies demonstrated that this material supports HOB cell attachment with organized cytoskeleton structure. Compared to CaSiO3, Ca3ZrSi2O9 ceramics induced increased HOB proliferation and differentiation as shown by increased methyltetrazidium salt (MTS), alkaline phosphatase activity, and mRNA expression levels of bone-related genes (Collagen type I, alkaline phosphatase, Bone Sialoprotein, receptor activator of NF-κB ligand and osteoprotegerin). Ca3ZrSi2O9 ceramics supported the fusion of monocytes to form functional osteoclasts with their characteristic features of f-actin ring structures and the expression of αvβ3 integrin consistent with functional activity. Osteoclasts cultured on Ca3ZrSi2O9 expressed increased levels of osteoclast-related genes; Cathepsin K, Carbonic Anhydrase II, Matrix metalloproteinase-9, receptor activator of NF-κB and Calcitonin Receptor, consistent with the formation of functional osteoclasts. In addition to HOB and osteoclasts, Ca3ZrSi2O9 supported the attachment of endothelial cells, which expressed the endothelial cell markers; ZO-1 and VE-Cadherin. Results presented here indicate that Ca3ZrSi2O9 ceramics have the potential for applications in bone tissue regeneration.