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A new injectable dicalcium phosphate dehydrate (DCPD)-based cement material "PD" VitalOs Cement 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.

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Calcium phosphate compounds, in particular HA and β-TCP, are the principal synthetic materials used for bone substitutes. To assess the feasibility for further grafting of drug delivery systems, a pure HA was elaborated with specific internal material porosities and then tested on its biological effectiveness. The cell viability tests with L132 cells confirmed the excellent cytocompatibility of HA and the graphite powder. MC3T3-E1 osteoblasts were grown on HA conditioned with culture medium and FCS for 2h. All HA samples produced a higher proliferation and vitality rates than the TCPS controls; the micro-porous HA inducing the highest cell growth near 150%. The macro/meso-porous HA is easily colonized by MC3T3-E1 osteoblasts As to the cell morphology, no significant differences are observed between control cells and those grown on the HA samples. Cytochemical staining of osteoblasts revealed a well developed cytoskeleton with strong stress fibres oriented in the cells in their longitudinal direction. Labelling of the focal adhesion contacts with anti-vinculin showed a less developed adhesion process in the cells on the different HA substrates, which may explain the above mentioned increase of proliferation.

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Die durch Osteoklasten bewirkte Degradation von Keramiken wurde untersucht, um Wechselwirkungen zwischen Osteoklasten und Keramiken zu bestimmen, um somit die Qualität der Keramiken als günstiger Knochenersatz zu erstellen. Untersucht wird die Resorptionsaktivität der Osteoklasten auf Keramiken mit verschiedenen Lösungseigenschaften. Humane Osteoklasten wurden von einem Riesenzellentumor isoliert und auf Biokeramiken kultiviert: Hydroxylapatit (HA), ß-Tricalcium Phosphat (ß-TCP) und Kalzium Karbonat (Kalzit). Aktinmarkierung lässt das Zytoskelett erscheinen, und Keramikoberflächen wurden im Rasterelektronen-Mikroskop (REM) beobachtet. Auf allen Materialien erschien Aktin in seiner für Osteoklasten typischen Ringlokalisierung. REM-Aufnahmen zeigen einen deutlichen Unterschied in Form und Tiefe der Resorptionslagunen auf verschiedenen Keramiken. Auf reinem HA sind Degradationsflächen deutlich, jedoch nur oberflächlich sichtbar. Viele tiefe und gut begrenzte Resorptionslagunen erscheinen auf reinem ß-TCP. Resorptionszonen auf reinem Kalzit sind ausgedehnt und wenig tief; Mikrorauheit wurde ebenfalls entdeckt.