TITANIUM SURFACE-ROUGHNESS ALTERS RESPONSIVENESS OF MG63 OSTEOBLAST-LIKE CELLS TO 1-ALPHA,25-(OH)(2)D-3

Surface roughness has been shown to affect differentiation and local f actor production of MG63 osteoblast-like cells. This study examined wh ether surface roughness alters cellular response to circulating hormon es such as 1 alpha,25-(OH)(2)D-3. Unalloyed titanium (Ti) disks were p retreated with HF/HNO3 CPT) and then were machined and acid-etched (MA ). Ti disks also were sandblasted (SE), sandblasted and acid etched (C A), or plasma sprayed with Ti particles (PS). The surfaces, from smoot hest to roughest, were: PT, MA, CA, SE, and PS. MG63 cells were cultur ed to confluence on standard tissue culture polystyrene (plastic) or t he Ti surfaces and then treated for 24 h with either 10(-8) M or 10(-7 ) M 1 alpha,25-(OH)(2)D-3 or vehicle (control). Cellular response was measured by assaying cell number, cell layer alkaline phosphatase spec ific-activity, and the production of osteocalcin, latent (L) TGF beta, and PGE(2). Alkaline phosphatase activity was affected by surface rou ghness; as the surface became rougher, the cells showed a significant increase in alkaline phosphatase activity. Addition of 1 alpha,25-(OH) (2)D-3 to the cultures caused a dose-dependent stimulation of alkaline phosphatase activity that was synergistic with the effect caused by s urface roughness alone. 1 alpha,25-(OH)(2)D-3 also caused a synergisti c increase in osteocalcin production as well as local factor (LTGF bet a and PGF(2)) production on the rougher CA, SE, and PS surfaces, but i t had no effect on the production on smooth surfaces. The inhibitory e ffect of surface roughness on cell number was not affected by 1 alpha, 25-(OH)(2)D-3 except on the SE surface. 1 alpha,25-(OH)(2)D-3 decrease d cell number, increased alkaline phosphatase activity and osteocalcin production, and had no effect on LTGF beta or PGE(2) production by MG 63 cells grown on tissue culture polystyrene. These data suggest that bone cell response to systemic hormones is modified by surface roughne ss and that surface roughness increases the responsiveness of MG63 cel ls to 1 alpha,25-(OH)(2)D-3. They also suggest that the endocrine syst em is actively involved in normal bone healing around implants. (C) 19 98 John Wiley & Sons, Inc.