EFFECTS OF INTERMITTENT OR CONTINUOUS GRAVITATIONAL STRESSES ON CELL-MATRIX ADHESION - QUANTITATIVE-ANALYSIS OF FOCAL CONTACTS IN OSTEOBLASTIC ROS-17 2.8 CELLS/

The relationship between cell morphology and cell metabolism and the r ole of mechanical load in bone remodeling is well known. Mechanical st imulation induces changes in the shape of osteoblasts, probably mediat ed by reorganization of focal contacts. We studied the influence of gr avity (Gz) variations occurring during parabolic flight on osteoblast focal adhesion of ROS 17/2.8 osteosarcoma cells subjected to 15 or 30 parabolic flights. Significant flight-induced shape changes consisted of decreased cell area associated with focal contact plaque reorganiza tion. Identical durations of continuous mechanical stress induced by c entrifugation (2 Gz) or clinorotation (Gz randomization) had no major effect on cell focal adhesion. ROS 17/2.8 G2/M synchronization by trea tment with nocodazole inhibited the flight-induced decrease in adhesio n parameters. We concluded that ROS 17/2.8 cells are sensitive to Gz s witches and that their adaptation is at least dependent on microtubule function. (C) 1997 Academic Press.