Macrophages are the main cells involved in inflammatory processes and in the primary response to debris derived from wear of implanted CoCr alloys. The biocompatibility of wear particles from a high carbon CoCr alloy produced under polarization in hyaluronic acid (HA) aqueous solution was evaluated in J774A.1 mouse macrophages cultures. Polarization was applied to mimic the electrical interactions observed in living tissues. Wear tests were performed in a pin-on-disk tribometer integrating an electrochemical cell in phosphate buffer solution (PBS) and in PBS supplemented with 3 g/L HA, an average concentration that is generally found in synovial fluid, used as lubricant solution. Wear particles produced in 3 g/L HA solution showed a higher biocompatibility in J774A.1 macrophages in comparison to those elicited by particles obtained in PBS. A considerable enhancement in macrophages biocompatibility in the presence of 3 g/L of HA was further observed by the application of polarization at potentials having current densities typical of injured tissues suggesting that polarization produces an effect on the surface of the metallic material that leads to the production of wear particles that seem to be macrophage-biocompatible and less cytotoxic. The results showed the convenience of considering the influence of the electric interactions in the chemical composition of debris detached from metallic surfaces under wear corrosion to get a better understanding of the biological effects caused by the wear products.

Background: Oxygen free radical and reactive oxygen species are involved in many diseases and ageing. Scavening enzymes represent one of the several natural defence mechanisms against free radical induced damage. Catalase (CAT) is an enzyme that is involved in antioxidant defence. Objective: In order to establish a comprehensive profile of the erythrocyte CAT activity during ageing, we investigated this activity in human erythrocytes from 2,827 apparently healthy Spanish subjects (1,388 males and 1,439 females). Methods: We divided the subjects into twelve age groups (newborns and 1–3, 4–9, 10–19, 20–29, 30–39, 40–49, 50–59, 60–69, 70–79, 80–89, and >90 years of age) to evaluate ageing changes. The CAT activity was measured in haemolysates by the method of Aebi (see text). Results: No significant variations with respect to sex were detected, except for the 70- to 93-year age groups. In these elderly subjects, the CAT activity in males remained constant with no significant variations between age groups, whereas the CAT activity showed a significant increase in females. This fact is considered to be one of the outcomes of the greater longevity in females. Significant age-related modifications in erythrocyte CAT activity appeared in the group of newborns (p < 0.001), in the group 1–3 years of age (p < 0.025), and in the elderly groups: 70–79 years (p < 0.025) and 80–89 years (p < 0.05) of age. Conclusion: Our results confirm that the CAT activity in the Spanish population shows an interindividual variability and suggest that this variability may be due, at least in part, to the age of the individuals.

The study of the biocompability of the metallic materials is a priority treating to avoid the osteolysis and aseptic loosening of prosthesis. Wear debris is considered one of the main factors responsible for aseptic loosening of orthopedic endoprostheses. We examined the response of mouse osteoblasts MC3T3-E1 to high carbon cobalt-chrome (HCCoCr) particles obtained a) from wear-corrosion assays on a pin-on-disk tribometer using as pair an alumina ball and a disc of a HCCoCr alloy, and b) HCCoCr bulk particles obtained by nitrogen gas atomization from an alloy used in clinic for prostheses application. Mitochondrial activity and lactate dehydrogenase activity assayed in 2D and 3D osteoblasts cell culture models were used to evaluate the cellular response to size, shape, and chemical composition of the metallic particles. 2D cell model was used to study the direct interaction of cells with particles and 3D cell cultures was used to more closely mimic in vivo conditions. The results showed that vimentin was overexpressed in the 2D osteoblasts cultures in presence of metal particles. This might be related to the appearance of pseudotumor in the peri-prosthetic vicinity described in some implanted patients.

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