Bacterial Products Primarily Mediate Fibroblast Inhibition in Biomaterial Infection

Abstract

Purpose.The stimulation of fibroblast growth is essential for the normal healing and tissue integration of biomaterials. The local elevation of proinflammatory mediators in infected perigraft fluid (PGF) may inhibit this growth. We sought to determine whether infected PGF inhibited fibroblast growth, and, if so, whether this was primarily dependent on the biomaterial, bacteria, or host.Methods. In vivoDacron or expandable polytetrafluoroethylene (ePTFE) grafts, sterile or colonized with slime-producing (RP-62A, viable or formalin-killed) or nonslime-producing (RP-62NA)Staphylococcus epidermidis(1 × 107CFU/cm2), were implanted in Swiss Webster mice, and the PGF was harvested at 7 and 28 days. Antibodies to tumor necrosis factor α, interleukin 1α, interferon γ (7 μg/day), and indomethacin (50 μg/day) were administered by microinfusion pumps for 7 days and the PGF was harvested. Inhibition of the proinflammatory mediators was confirmed by enzyme-linked immunosorbant assay. The nontreated, heat-treated, or trypsin-digestedin vivoPGF was incubated with anin vitro[3H]thymidine murine fibroblast (ATCC CCL-12) proliferation assay.Results.Fibroblast inhibition was significant at 7 and 28 days with infected PGF incubation compared with sterile and was not dependent on bacterial slime production or viability. Dacron sterile PGF did not significantly inhibit fibroblasts compared with control, whereas sterile ePTFE stimulated (P< 0.05) fibroblasts. Treatment of the PGF with proinflammatory cytokines, heat, and trypsin failed to reverse fibroblast inhibition in the infected state.Conclusion.Biomaterial infection is associated with fibroblast inhibition that is dependent primarily on bacterial products and not the host or biomaterial. Conservative intervention strategies for graft infection need to address the problem of poor healing as well as bacterial clearance.