ROTATING-WALL VESSELS, PROMISING BIOREACTORS FOR OSTEOBLASTIC CELL-CULTURE - COMPARISON WITH OTHER 3D CONDITIONS

Osteoblastic cells cultured on microcarriers in bioreactors are a pote ntially useful tool to reproduce the in vivo three-dimensional (3D) bo ne network. The aim is to compare different types of 3D and two-dimens ional (2D) osteoblastic culture. ROS17/2.8 cells are cultured in a bio reactor (rotating-wall vessel) or in two kinds of control (3D petri di sh, 3D Percoll) and on two types of microcarrier (Cytodex 3 and Biosil on). Growth and morphology are determined by cell count and SEM, and d ifferentiation is determined by dosage of alkaline phosphatase (ALP) a ctivity and northern blots (ALP and osteocalcin (OC)). SEM shows that Biosilon microcarriers are the best substrate. Proliferation in the RW V and 3D petri dish is still in the exponential phase, whereas growth in the 2D culture reaches a plateau after eight days of culture. ALP a ctivity and the ALP and OC mRNA levels are similar at day 8 for both t he RWV and 3D petri dish. However, at day 10, cells are more different iated in the RWV. The study shows that osteoblasts are both proliferat e and differentiate in 3D structures. A BrDU immunocytochemical approa ch shows that only the cells in the periphery of the aggregates prolif erate. Therefore the bioreactor may be a suitable tissue culture model for investigation of growth and differentiation processes in tissue e ngineering.