An investigation into the role of oxygen free radical scavengers in preventing polymethylmethacrylate-induced necrosis in an osteoblast cell culture

This study examined the effect of polymethylmethacrylate (PMMA) on osteocyt ic necrosis and the role of free radical scavengers in minimizing this dama ge. Bovine osteoblast cells with a characteristic phenotype were seeded at a density of 4x10(4) cells/cm(2) and cultured in a DMEM supplemented with 1 0% fetal calf serum. A transwell insert with 2 cc of PMMA was suspended abo ve the culture, and a time log response curve was established following elu sion of free radicals around the osteoblast media. Chemiluminescence was us ed to determine quantitative free radical release. Using a Student's two-ta iled t test there was a significant difference in the amount of hydroxyl ra dical released at 1-6 hours compared with controls (P=.028). Using histolog ic markers, there was a significant correlation between the use of PMMA and osteoblast cell necrosis. Transwell plates were coated with varying concentrations of mannitol, a kno wn hydroxyl radical scavenger. A log dose response curve was established. T here was a clear statistical association between a 10% mannitol solution an d a reduction in the free radical release from PMMA (P=.03). Similarly, usi ng Trypan blue histologic staining, there was a significant reduction in PM MA-induced cell necrosis when 10% mannitol was used as a scavenger (P=.01). A Rockwell superficial hardness test was used to determine whether mannito l had any effect on the surface hardness of the polymer. No statistical dif ference could be found between those treated with mannitol and controls at a depth of up to 1 mm. These results demonstrate hydroxyl radical is released from the polymerizat ion reaction of PMMA. These radicals cause cell death in an osteoblast cult ure medium. This has been addressed using a 10% mannitol solution, which re duced cell necrosis.