Austenitic stainless steels ASTM F138/139/745 are widely used for load bearing partial and total joint replacements. These biomaterials contain Cr and Ni, which would cause different systemic-toxic reactions during the time that the device is implanted in the body.
Samples of ASTM 745 have been subjected to localized corrosion by cyclic polarization tests, using a cell culture medium (CCM) as an electrolyte. In the present work, DMEM high glucose containing inorganic salts, vitamins, aminoacids, and supplemented with 10% inactivated fetal calf serum, was used as CCM. The aim was to release Cr and Ni ions to evaluate their possible cytotoxic effects.
Cytotoxicity was evaluates by Neutral red and MTT assays, using UMR-106 cell line. The mean values from the 24 determinations were compared to negative and positive controls. The negative control is the culture medium not exposed to any toxic agent, while the positive control consists of the culture medium with a toxic agent that causes a decrease in cell viability. The data were statistically analyzed by Student’s t-test, considering a critical p-value < 0.05.
The electrochemical results showed a fast increment in current density at potentials close to 0.800 V/Ref, which could be ascribed to the onset of localized corrosion. After that, the stainless steel showed high repassivation capacity, since the reverse scan ended at 0.600 V/Ref, with a short hysteresis loop. The CCM used as an electrolyte in the electrochemical test was subsequently used in the bioassays.
Neutral Red assay, which evaluates lost in cell viability when a determined element or compound affects the integrity of the plasmatic membrane, did not show significant differences between the CCM and the negative control. The MTT assay assesses the mitochondrial metabolic activity. Although the behaviour was different with respect to the negative control, the cell viability was higher than 100%, with critical p-value < 0.01.
The comparison with the positive control indicated that the cell viability was considerably greater in both assays, the critical p-value being lower than 0.001.
According to these results, under the specified tests conditions of the present work, the CCM tested did not cause cytotoxic effects on the cell line used. The reason for this behavior could be related to the fact that the Cr and Ni released during the localized corrosion did not reach concentration levels detrimental to cell viability.
|Category||Short file description||File description||File Size|