Bridging the gap between in vitro and in vivo evaluation of biomaterial-associated infections

Biomaterial-associated infections 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 postoperative 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 biomaterial-associated infections has been intensively studied before in vivo, until recently no in vitro methodology existed for this purpose. Just very recently various groups have proposed coculture experiments to evaluate the simultaneous response of bacteria and mammalian cells on a surface. As an initial step towards bridging the gap between in vitro and in vivo evaluations of biomaterials, we here describe bi- and tri-culture experiments that allow better evaluation of multifunctional coatings in vitro and therewith bridge the gap between in vitro and in vivo studies.