A stimulatory effect of Ca3ZrSi2O9 bioceramics on cementogenic/osteogenic differentiation of periodontal ligament cells

Abstract

The regeneration of periodontal tissues to cure periodontitis remains a medical challenge. Therefore, it is of great importance to develop a novel biomaterial that could induce cementogenesis and osteogenesis in periodontal tissue engineering. Calcium silicate (Ca–Si) based ceramics have been found to be potential bioactive materials due to their osteostimulatory effect. Recently, it is reported that zirconium modified calcium-silicate-based (Ca₃ZrSi₂O₉) ceramics stimulate cell proliferation and osteogenic differentiation of osteoblasts. However, it is unknown whether Ca₃ZrSi₂O₉ ceramics possess specific cementogenic stimulation for human periodontal ligament cells (hPDLCs) in periodontal tissue regeneration in vitro. The purpose of this study was to investigate whether Ca₃ZrSi₂O₉ ceramic disks and their ionic extracts could stimulate cell growth and cementogenic/osteogenic differentiation of hPDLCs; the possible molecular mechanism involved in this process was also explored by investigating the Wnt/β-catenin signalling pathway of hPDLCs. Our results showed that Ca₃ZrSi₂O₉ ceramic disks supported cell adhesion, proliferation and significantly up-regulated relative alkaline phosphatase (ALP) activity, cementogenic/osteogenic gene expression (CEMP1, CAP, ALP and OPN) and Wnt/β-catenin signalling pathway-related genes (AXIN2 and CTNNB) for hPDLCs, compared to that of β-tricalcium phosphate (β-TCP) bioceramic disks and blank controls. The ionic extracts from Ca₃ZrSi₂O₉ powders also significantly enhanced relative ALP activity, cementogenic/osteogenic and Wnt/β-catenin-related gene expression of hPDLCs. The present results demonstrate that Ca₃ZrSi₂O₉ ceramics are capable of stimulating cementogenic/osteogenic differentiation of hPDLCs possibly via activation of the Wnt/β-catenin signalling pathway, suggesting that Ca₃ZrSi₂O₉ ceramics have the potential to be used for periodontal tissue regeneration.