BEHAVIOR OF FETAL-RAT CHONDROCYTES CULTURED ON A BIOACTIVE GLASS-CERAMIC

We examined the behavior of fetal rat chondrocytes cultured on a bioac tive glass-ceramic containing apatite and wollastonite (A.W.G.C.). Bio material surface topography and profiles were evaluated by bidimension al profilometry and revealed a rough surface for the glass-ceramic com pared to the plastic coverslips used as controls. Chondrocyte attachme nt was evaluated by measuring the number of attached cells after one d ay of culture and by morphological observations. Chondrocytes attached in great numbers to the material surface by means of focal contacts c ontaining vinculin and beta 1-integrin. Fluorescent labeling of actin and vimentin revealed a poor spreading of chondrocytes on the bioactiv e glass-ceramic compared to the plastic coverslips, where the cells ap peared to adhere intimately to the surface and exhibited polygonal arr ays of stress fibers. During the following days of culture, chondrocyt es proliferated, colonized the surface of the material, and, finally, on day 10, formed nodular structures composed of round cells separated by a dense extracellular matrix. Furthermore, these clusters of round cells were positive for type II collagen and chondroitin sulfate, bot h hard markers of the chondrocyte phenotype. In addition, protein synt hesis, alkaline phosphatase activity, and proteoglycan production were found to increase gradually during the culture period with a pattern similar to that observed on control cultures. These results demonstrat e that the bioactive glass-ceramic tested in this study appears to be a suitable substrate for in vitro chondrocyte attachment, differentiat ion, and matrix production. (C) 1997 John Wiley & Sons, Inc.