Human bone cell cultures in biocompatibility testing. Part I: osteoblastic differentiation of serially passaged human bone marrow cells cultured in α-MEM and in DMEM

Well-characterised human osteoblastic bone marrow cell cultures are a useful in vitro tool to analyse bone tissue/biomaterials interactions. In this work, human bone marrow was cultured in experimental conditions described to favour osteoblastic differentiation and, serially passaged cells were cultured in two widely used culture media, minimum essential medium Eagle, alpha modification ( α-MEM) and Dulbecco's modified Eagle's medium (DMEM). Cultures were grown for 35 d and compared concerning morphologic appearance on scanning electron microscopy (SEM), cell viability/proliferation, total protein content, activity of alkaline phosphatase (ALP) and ability to form calcium phosphate deposits. Results showed that cell proliferation was similar in cultures grown in the two media but ALP activity and ability to form mineralised deposits were lower in DMEM cultures. In both experimental situations, osteoblastic parameters were strongly reduced on cell passage, particularly from the first to the second subculture. In the experimental conditions used (presence of ascorbic acid, sodium β-glycerophosphate and dexamethasone in the primary and secondary cultures), osteoblastic differentiation was observed in the first and second subcultures grown in α-MEM and in the first subculture grown in DMEM. These results underline the importance of the definition of the experimental conditions in studies involving bone cell cultures.