Immunomodulatory antibacterial surfaces to prevent implant-related infection

Abstract

As orthopedic surgeries become more frequent, so do implant-associated infections. Typically, the major risk of infection is due to bacterial colonization, this jeopardizes the integration of the implant ultimately leading to catastrophic failures. Additionally, the previous misapplication of antibiotics has led to resistant bacterial strains which are increasingly difficult to treat. The objective of this review is to highlight alternatives to conventional antibiotic therapies in the context of implant-related infections. After presenting the key cell types involved in the immune response, the tuneability of biomaterials in terms of their physical, chemical, and biological aspects will be addressed. It is discussed how novel methods stimulate the host immune system and thus utilize the body's innate defense systems to prevent infection. Moreover, strategies supporting the immune system to fight already established infections will be examined. The variety of reviewed antimicrobial and immunomodulatory strategies is diverse, ranging from nanotextured surfaces to systems releasing metal nanoparticles able to either kill bacteria directly or through the interaction with immune cells. As representatives of biological stimulators, special attention will be paid to antimicrobial peptides and growth factors, either released into the adjacent tissue or attached to the implant surface. Lastly, emphasis is devoted to bacteria-responsive systems providing on-demand delivery of pharmaceuticals. This review summarizes the latest state of immunomodulatory strategies combating implant-related infections mitigating the growing risk of antibacterial resistant bacteria. Concluding, future research perspectives for immunomodulatory biomaterials will be provided.