Effects of MA 956 superalloy and alpha-alumina particles on some markers of human osteoblastic cells in primary culture

One of the problems associated with the modem biomaterials used in prosthes es is osteolysis, which, although its exact origin is unknown, has been ass ociated with wear particles. Osteoblasts seem to participate directly in th is phenomenon. This paper investigates in vitro cellular response to the we ar particles from the metal substrate and ceramic covering (alpha -alumina) of a new titanium yttrium aluminum alloy, MA 956, that has been proposed a s a biomaterial because of its exceptional mechanical and electrochemical p roperties. The effect of different sizes (10 and 80 mum) of MA 956 and alph a -alumina particles on osteoblast function was studied in primary human bo ne cell cultures. Cells were harvested from trabecular bone fragments obtai ned during knee arthroplasty. Osteoblastic cell response to the particles w as measured by assaying C-terminal type I procollagen (PICP), alkaline phos phatase, and osteocalcin secretion, with and without 1.25(OH)(2)D-3 stimula tion, in the cell-conditioned medium. Both sizes of MA 956 and alpha -alumi na particles decreased PICP secretion in nonstimulated osteoblastic cells, but this secretion was not affected in the cultures stimulated with 1.25(OH )(2)D-3. Only the 10 mum alpha -alumina particles inhibited alkaline phosph atase activity in 1.25(OH)(2)D-3-stimulated and nonstimulated cultures. The rise in osteocalcin levels after 1.25(OH)(2)D-3 stimulation was lower in t he presence of the 10 mum MA 956 particles than in the presence of alpha -a lumina particles. Although both materials seem to ha ve directly affected i n vitro osteoblastic cell function, the increase in osteocalcin levels afte r 1.25(OH)(2)D-3 stimulation was lower after exposure to MA 956 particles t han the increase observed after exposure to alpha -alumina particles. There fore, it does not seem that osteocalcin stimulated bone resorption, suggest ing that MA 956 would be less likely to provoke osteolysis. (C) 2000 John W iley & Sons, Inc.