FLOW-CYTOMETRY FOR ASSESSING BIOCOMPATIBILITY

Flow cytometry (FCM) was examined as a possible procedure for measurin g in vitro the biocompatibility of implant materials for orthopedic an d dental surgery. The human osteoblast-Like cell Line MG63 was grown o n hydroxyapatite (HA) and P2O5 glass-reinforced HA composite discs and compared with the same cells grown on polystyrene culture dishes. Whi le morphological observation at the light and electron microscopic lev els showed no major deleierious effects, FCM indicated that cell size was somewhat reduced, particularly by growth on the HA composite. More over, this material also appeared to delay the progression of the cell s from the G0/G1 into the S phase of the cell cycle. In addition to th is low level of inhibition of cell growth relative to control cultures , FCM analysis also demonstrated that the glass-reinforced HA caused s ome down-regulation of the expression of osteocalcin and fibronectin, two antigens which play a vital part in the integrity and function of bone and soft connective tissue, respectively. These results thus show , first, that although HA and the HA composite used in these experimen ts were generally biocompatible, they nevertheless had certain subopti mal effects on the cells; and second, that FCM could be a highly usefu l procedure for effectively screening and evaluating important biologi cal responses to implant materials. (C) 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 41, 649-656, 1998.