TISSUE-REACTIONS TO LEAD SAMPLES IN A LATE INFECTION RAT MODEL

Tissue reactions to rat lead samples, model ii ng for clinically used leads, were investigated in a late infection model, in which injection of bacteria was performed after a 3-week encapsulation process. At th e site of injection, detachment of the original fibrous capsule, wound fluid infiltration, fibrin formation and granulocyte and macrophage i nfiltrations, occurred. Spreading of infection did not occur via the g enerally assumed direct bacterial adhesion to materials, but through b lood vessels at the outside of capsules and through wound fluid passag e at the interface a nd in the lumen of the lead sam pie. At day 5, in fection had spread a II over, but, a pa rt from two sma II abscesses, seemed to be suppressed at day 10. However, probably due to iu mina I bacterial growth, at weeks 3 and 6 the reaction intensified showing la rger abscesses with accumulations of lymphocytes. The results of this study represent a good basis for further studies aimed at developing i nfection-resistent lead material. Research efforts are first directed on modification of material surfaces to provide controlled release of antimicrobial agents.