Novel ceramic bone replacement material Osbone® in a comparative in vitro study with osteoblasts.

OBJECTIVE Hydroxyapatite (HA) is a very common ceramic material for bone replacement due to its similarity in composition to the mineral phase of natural bone. A recently developed bone graft material is Osbone(®), a synthetic HA ceramic available as porous granules with different sizes and block forms. The goal of this study was to characterise Osbone(®) in vitro in comparison to the already established calcium phosphate-based bone grafts Cerasorb M(®) and Bio-Oss(®). MATERIALS AND METHODS Adhesion and proliferation of SaOS-2 osteoblasts were evaluated quantitatively by determining DNA content and lactate dehydrogenase (LDH) activity and qualitatively by scanning electron microscopy (SEM). In addition, MTT cell vitality staining was performed to confirm the attachment of viable cells to the different materials. Osteogenic differentiation of the cells was evaluated by means of alkaline phosphatase (ALP) activity quantification as well as by gene expression analysis of osteogenic markers using reverse transcriptase PCR. RESULTS MTT staining after 1 day of adhesion showed viable cells on all examined materials. DNA content and LDH activity revealed proliferation of osteoblasts on Osbone(®) and Cerasorb M(®), but not on Bio-Oss(®) during cultivation over 28 days. SEM showed a well-spread morphology of cells attached to both Osbone(®) and Cerasorb M(®). We detected an increase of specific ALP activity during cultivation of osteoblasts on Osbone(®) and Cerasorb M(®) as well as expression of the bone-related genes ALP, osteonectin, osteopontin and bone sialoprotein II on both materials. CONCLUSIONS Osbone(®) granules support proliferation and osteogenic differentiation in vitro and are therefore promising candidates for in vivo applications.