Hubert Mayer

Influence of Basal Media Formulations and Calcium on Growth and Directed Differentiation of Human Osteogenic Cells In Vitro

For the generation of human bone tissue in vitro, we were searching for suitable methods to control the ongoing differentiation process of osteogenic cells with a possibility to switch between the expansion of immature pro- genitor cells and the differentiation into cells of the mature osteogenic phenotype producing mineralised extracellular matrix. This study is focussing on the influence of different basal media formulations which were tested using primary human cells derived from either sites of heterotopic ossification or trabecular bone. The different basal media formulations DMEM, �. MEM, RPMI 1640 and our in-house formulation ZKT-I revealed a substantial impact on cellular growth and differentiation. Cells in DMEM were growing relatively slow and differentiated rapidly into mature osteoblasts with strong matrix mineralisation, whereas cells in �. MEM were growing more rapidly with slightly slower differentiation and mineralisation kinetics. A strong mineralisation was always accompanied by apoptotic processes as indicated by higher levels of LDH in the supernatant. In contrast, cells in ZKT-I medium showed a sufficient growth with markedly retarded differentiation kinetics which made it most suitable for cell expansion. To induce cell-induced matrix mineralisation using ZKT-I, a moderate increase of the calcium concentration was shown to be a sufficient trigger. With this simple supplementation, ZKT-I proved to be highly suitable for both phases of bone tissue generation in vitro.

Cultivation of Primary Osteogenic Cells in Serum-Reduced or Serum-Free Culture Media: Attachment, Proliferation and Differentiation

The isolation, proliferation, and differentiation of primary osteogenic cells for the generation of highly viable bone implants in vitro is a field of intensive investigation. One major problem within this topic is the expansion and differentiation of osteogenic cells under defined medium conditions. We compared different strategies of media supplementation for an optimum expansion of cells preserving their osteogenic potential.