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

Abstract

In this study we have developed Ca 3ZrSi 2O 9 (Baghdadite) ceramics by incorporating Zirconium in Ca–Si system and determined their biological properties. Ca 3ZrSi 2O 9 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 Ca 3ZrSi 2O 9 ceramics was investigated. Scanning electron microscopy and immunofluorescence studies demonstrated that this material supports HOB cell attachment with organized cytoskeleton structure. Compared to CaSiO 3, Ca 3ZrSi 2O 9 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). Ca 3ZrSi 2O 9 ceramics supported the fusion of monocytes to form functional osteoclasts with their characteristic features of f-actin ring structures and the expression of α vβ 3 integrin consistent with functional activity. Osteoclasts cultured on Ca 3ZrSi 2O 9 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, Ca 3ZrSi 2O 9 supported the attachment of endothelial cells, which expressed the endothelial cell markers; ZO-1 and VE-Cadherin. Results presented here indicate that Ca 3ZrSi 2O 9 ceramics have the potential for applications in bone tissue regeneration.