The Role of Oxidative Stress in the Response of Endothelial Cells to Metals - Biologically Responsive Biomaterials for Tissue Engineering - page 82

amplify the corrosion process. All of these factors point to the contribution of the
cathodic half-reaction of corrosion to adverse tissue reactions, leading eventually
to aseptic loosening of implants.

4.7 Summary

Aseptic loosening of metal implants is mainly attributed to the formation of metal
degradation products. These include particulate debris and corrosion products, such
as metal ions (anodic half-reaction) and ROS (cathodic half-reaction). While numer-
ous clinical studies describe various adverse effects of metal degradation products,
detailed knowledge of metal-induced cellular reactions, which might be important
for possible therapeutic intervention, is not comprehensive. Since endothelial cells
are involved in both inflammation and angiogenesis, two processes which are criti-
cal for wound healing and integration of metal implants, the effects of different
metal alloys and their degradation products on these cells, were investigated.
Endothelial cells on Ti6Al4V alloy showed signs of oxidative stress, which was
similar to the response of endothelial cells to cathodic partial reaction of corrosion
induced directly on Ti6Al4V surfaces. These reactions of endothelial cells to metal
degradation products might play their role in the complex processes taking place in
the body following metal device implantation. In the worst case this could lead to
aseptic loosening of the implant and thus the requirement for revision surgery.
Knowledge of molecular mechanisms of metal-induced responses will hopefully
provide the possibility to interfere with undesirable processes at the implant/tissue
interface, thus extending the lifetime of the implant and the overall success of metal
implant applications.

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