Cytotoxic effect of bone cements in HL-60 cells: distinction between apoptosis and necrosis

Ten PMMA-based bone cements used in prosthetic surgery have been studied wi th respect to the induction of programmed tell death (i.e., apoptosis) in H L-60 cells, which are remarkably sensitive to various apoptotic stimuli. An nexin V binding and propidium iodide (PI) exclusion were the methods for de tection of early apoptotic changes, while PI entry was considered as a mark er of necrosis. Hoechst 33342 staining was used to detect DNA fragmentation and Alamar blue (TM) was applied to measure oxide-reduction activity of ce lls. The production of reactive oxygen species (ROS) related to cell damage was verified using dichlorofluorescein-diacetate (DCFH-DA) oxidation to DC F. Under our experimental conditions, the cements tested, for the most part , were not toxic to leukemic cells at 4 and 24 h. After 24 h, three cements were able to induce cell death, with two eliciting both apoptosis and necr osis, and one cement acting mainly via apoptosis. Both processes of cell de ath are likely to be mediated by the production of oxygen-free radicals. Th ese findings provide potential leads for investigation into the molecular m echanisms of cell death, which are responsible for tissue damage by cements and intolerance of cemented prostheses. (C) 2000 John Wiley & Sons, Inc.