MINERALIZATION IN SERIALLY PASSAGED HUMAN ALVEOLAR BONE-CELLS

Well-characterized human bone cell cultures have been regarded as a us eful tool to study bone control mechanisms and also to analyse bone/bi omaterials interactions. In the present study, human alveolar bone cel ls were cultured in alpha-minimal essential medium (alpha-MEM) contain ing 10% foetal bovine serum (FBS), 50 mu g/ml ascorbic acid, 10 mM sod ium beta-glycerophosphate and either in the presence or in the absence of 10 nM dexamethasone (Dexa). Cultures were characterized concerning cell viability/proliferation, alkaline phosphatase (ALP), acid phosph atase (ACP) and tartraric acid resistant phosphatase (TRAP) activities , and formation of mineralized areas. Cell proliferation increased gra dually for approximately 20 days. In the presence of Dexa, cells forme d isolated or interconnected multilayered clusters that increased with culture time. Histochemical assays revealed strong positive reactions for ALP and calcium and phosphates deposits, mainly in relation to ce lls associated with the clusters. High levels of ALP activity (biochem ical determination) were observed. Cells cultured in the absence of De xa showed significantly lower ALP activity and no calcium and phosphat es deposits were present. Serially passaged cells kept the proliferati on rate constant but a decrease in ALP activity was observed either in the presence or in the absence of Dexa. The ability to form mineraliz ed areas (cultures fed with Dexa) also decreased on serial subculture.