In vitro studies on the influence of precultural conditioning method on osteoblast reactions of a new type of injectable calcium cement material

A new injectable dicalcium phosphate dehydrate (DCPD)-based cement material "PD" VitalOs Cement (R) was studied to elucidate the process of equilibrium occurring in the early stage of implantation. The present study investigated the pH variations of the cement sample-immersing culture medium at determined intervals, time-dependent calcium/phosphate release, cell proliferation, and vitality in the cells-cement coculture milieu, after different preculture conditionings of the samples. Measurement of pH variation showed that without renewing the medium, pH value of sample lixiviate medium first dropped and, after 70 h, gradually balanced. When medium was renewed each day, pH value of lixiviate medium first descended and, after 24 h, gradually returned to pH 7.2. The cell viability revealed an excellent cytocompatibility of the cement. Both cell proliferation and vitality test showed that the preculture conditioning treatment is important at least for good performance of osteoblasts growing on the surface of calcium phosphate hydraulic cement (CPHC) samples in vitro. The results of calcium and phosphate assays clearly showed that this cement material can continuously dissolve to release calcium and phosphate in the liquid cell culture environment. The decrease of proliferation in some experimental groups with short conditioning is due to an excess of acid, which still can have some influence on cell growth after 24 h, since the biological milieu is not continuously renewed as in in vivo conditions. (c) 2005 Wiley Periodicals, Inc.