PROSTAGLANDINS MEDIATE THE EFFECTS OF TITANIUM SURFACE-ROUGHNESS ON MG63 OSTEOBLAST-LIKE CELLS AND ALTER CELL RESPONSIVENESS TO 1-ALPHA,25-(OH)(2)D-3

Surface roughness affects proliferation, differentiation (alkaline pho sphatase and osteocalcin), local factor production [transforming growt h factor (TGF beta) and prostaglandin E-2 (PGE(2))], and response to 1 ,25-(OH)(2)D-3 (1,25) of MG63 osteoblast-like cells. In this study, we examined whether the effect of surface roughness on MG63 cells is med iated by prostaglandins produced by the cells. Unalloyed titanium (Ti) disks were pretreated with HF/HNO3 (PT) and then machined and acid-et ched (MA). Disks were also coarse grit-sandblasted (SB), coarse grit-s andblasted and acid-etched (CA), or plasma-sprayed with Ti particles ( PS). The surfaces, from smoothest to roughest, were PT, MA, CA, SE, an d PS. MG63 cells were cultured to confluence on the Ti disks in the pr esence or absence of 10(-7) M indomethacin (Indo), a specific inhibito r of cyclooxygenase activity, resulting in decreased prostaglandin pro duction. When the cells reached confluence, cell number, cell layer al kaline phosphatase specific activity (ALPase), and osteocalcin (OC) an d latent TGF beta (LTGF beta) production were determined. In addition, confluent cultures which had been grown in the absence of Indo were e xposed to 10(-7) M 1,25, 10(-7) M Indo, or a combination of the two fo r 24 h. On the OC, and LTGF beta were increased. When indomethacin was present throughout the culture period, the effect of surface roughnes s on cell number, OC, and LTGF beta was abolished. ALPase was reduced, but surface roughness-dependent effects were still observed. Addition of indomethacin to confluent cultures for 24 h had no effect on any o f the parameters examined, with one exception: Cells cultured on MA su rfaces exhibited a more differentiated phenotype. 1,25 increased all p arameters examined on SB, CA, and PS surfaces. When indomethacin was a dded with 1,25, the 1,25-dependent effects on cell number and OC and L TGF beta production were abolished; however, ALPase was unaffected Thi s indicates that bone cell response to systemic hormones may be modifi ed by implant surface roughness. This effect may be mediated, at least in part, by prostaglandins produced by the same cells. (C) 1998 John Wiley & Sons, Inc.