Biomaterial-Driven Modulation of Macrophage Polarization in an Experimental Environment of Implant-Associated...

Implant-associated infections (IAIs) caused by Staphylococcus aureus are a major cause of orthopedic implant failure, driven by biofilm formation and chronic inflammation. Macrophages regulate bacterial clearance and tissue repair through polarization into pro-inflammatory (M1) and anti-inflammatory (M2) phenotypes. This systematic review evaluated preclinical in vivo studies according to PICO criteria (Population: IAI animal models; Intervention: functionalized biomaterials; Comparator: non-functionalized controls; Outcome: bacterial burden reduction associated with macrophage reprogramming). A PRISMA-guided search of PubMed, Scopus, Web of Science, and Embase (January 2015-December 2025) identified 23 eligible studies, assessed using SYRCLE's risk-of-bias tool. Due to heterogeneity, a narrative synthesis was performed without meta-analysis. Effect measures included bacterial CFU reduction, macrophage polarization markers, cytokine expression, and histological outcomes. In 87.5% of studies, macrophage modulation was associated with reduced bacterial load, biofilm disruption, and improved peri-implant tissue repair and bone integration. These findings support immunomodulatory biomaterials as promising strategies to manage IAIs through combined antibacterial and immune-regulatory mechanisms. However, further validation in larger animal models is required, particularly for nanomaterials. The protocol of this systematic review was registered on the Open Science Framework.