The Role of Oxidative Stress in the Response of Endothelial Cells to Metals

The involvement of endothelial cells in inflammation and blood vessel formation (angiogenesis) makes them important for the integration of metal implants. Metal degradation products can, however, influence these processes, possibly leading to ineffective wound healing, prolonged inflammation and eventually aseptic loosening of the implant. Different metal degradation processes have been shown to lead to ROS formation. Oxidative stress, therefore, can mediate the reactions of the human body to the implant. While the response of endothelial cells to oxidative stress has been well studied, the effects of ROS produced as the result of metal degradation have not been addressed as yet. Therefore, in this study the reactions of endothelial cells to the products of cathodic half-reaction of corrosion induced directly on Ti₆Al₄V alloy by electrochemical polarisation were investigated. Furthermore, models were developed to simulate inflammation- and corrosion-induced oxidative stress applied to endothelial cells grown on Ti₆Al₄V alloy and on cell culture polystyrene (PS) as a control. Endothelial cells grown on Ti₆Al₄V alloy were shown to be in a state of oxidative stress, which was further increased upon H₂O₂ treatment or electrochemical polarisation. The role of oxidative stress in aseptic loosening as well as the possibility to interfere with this process for a better therapeutical outcome are discussed in this chapter.