Macrophage-mediated phagocytosis of bacteria adhering on biomaterial surfaces

Biomaterial-associated infections (BAI) constitute a major clinical problem that is difficult to treat and often necessitates implant replacement. Pathogens can be introduced on an implant surface during surgery or postoperatively and compete with host cells attempting to integrate the implant. The fate of a biomaterial implant has been depicted as a race between bacterial adhesion and biofilm growth on an implant surface versus tissue integration. Until today, in vitro studies on infection risks of biomaterials or functional coatings for orthopedic and dental implants were performed either for their ability to resist bacterial adhesion or for their ability to support mammalian cell adhesion and proliferation. Even though the concept of the race for the surface in BAI has been intensively studied before in vivo, until recently no in vitro methodology existed for this purpose. Currently, various groups have proposed co-culture experiments to evaluate the simultaneous response of bacteria and mammalian cells on a surface. In this thesis, we describe biculture, and tri-culture experiments that allow better evaluation of multi-functional coatings in vitro and therewith bridge the gap between in vitro and in vivo studies. Several biomaterial surfaces were investigated to prevent or eliminate bacterial infection while promoting tissue integration. In addition, from the experiments described in this thesis, an outlook on future treatment of biomaterial-associated biofilms is given in the general discussion.