Ontwikkeling van een nieuwe anti-infectieuze enveloppe voor medische hulpmiddelen

Implantation of cardiac implantable electronic devices (CIEDs) has increased over the last decades due to the expansion of indication of the devices and progressive aging of the human population. While these devices improve the quality of life and longevity for cardiac patients, they also carry several risks of complications, with infections being among the most severe. CIED infections (CIEDIs) are primarily biofilm-related, caused by gram-positive staphylococci, particularly coagulase-negative staphylococci and Staphylococcus aureus. These infections have been associated with substantial costs, morbidity, and both short- and long-term mortality, underscoring the need for preventive measures. Given the clinical success of drug-eluting envelopes in reducing CIEDI incidences, this PhD aims to develop and validate a next-generation drug-elution envelope. This envelope consists of a pro-regenerative scaffold that releases a novel antimicrobial drug combination, including a biofilm-inhibiting compound and a conventional antibiotic. The first step in the development process involved selection of the most promising 2-aminoimidazole (2-AI) biofilm-inhibiting compound. Hereto, we explored the benefits of introducing a novel functional group, an amino group, to the most promising 2-AI classes for clinical use. The 2N-substituted 5-aryl-2-AI (5-Ar-2-AI) classes showed the greatest activity improvement after amination. Consequently, an elaborate structure-activity-toxicity relationship study revealed a clear correlation between n-alkyl and halogen substitutions on the one hand and the activity and toxicity levels of the compounds on the other hand. Balancing activity and toxicity led to identification of N1-(5-phenyl-1H-imidazol-2-yl)heptane-1,7-diamine dihydrochloride (RC46) as the optimal biofilm inhibitor for clinical applications. Additionally to biofilm inhibition, RC46 also showed strong bactericidal activity. This complementary feature was deemed beneficial for the current application, providing a rapid and effective way to prevent acute CIEDIs, alongside the more passive prevention of delayed CIEDIs offered by the biofilm-inhibiting activity. Given the critical role of this growth-inhibiting activity, further characterization of this activity was necessary, leading to the investigation of the potentially associated resistance mechanism and the potential for combination therapy with conventional antibiotics to enhance their efficacy and reduce resistance evolution. Resistance induction studies in Staphylococcus aureus revealed that resistance to RC46 developed more slowly than to several conventional antibiotics. Whole-genome sequencing of RC46-resistant populations suggested that resistance in S. aureus arises from mutations in the mprF gene, resulting in an increased positive membrane charge that repels the cationic RC46. Additionally, the obtained resistance mechanism led to cross-resistance to moxifloxacin and collateral sensitivity to minocycline. In line with trends from previous studies, combination of RC46 with these antibiotics resulted in increased and decreased resistance evolution respectively. Finally, in terms of efficacy enhancement, additive interactions were observed between minocycline and RC46 against gram-positive species, whereas synergy was observed against Escherichia coli. In the final step of the development, the promising combination of RC46 and minocycline was incorporated in a pro-regenerative CIED envelope, composed of an electrospun nanofiber scaffold. RC46 concentrations in the CIED envelope were optimized, after which RC46-incorporated samples provided in vitro proof of the bacterial efficacy against S. epidermidis and E. coli. CIED envelopes containing the combination of RC46 and minocycline were subsequently tested in an in vivo proof-of-concept study, which provided initial evidence of the novel envelope's efficacy in preventing E. coli infections. While this data highlights the potential of the newly developed CIED envelope, further optimization and validation are still required.