Effect of polyhexanide and gentamycin on human osteoblasts and endothelial cells

Infection of total joint replacements is painful, disabling and difficult to treat because of the increasing bacterial resistance against antibiotics. In view of this, antiseptics show limited bacterial tolerance and have a broad-spectrum antimicrobial activity. However, the application of antiseptics to bone is insufficiently studied in literature. Therefore, we investigated the biocompatibility of the antiseptic polyhexanide with bone related cells and asked whether supplementation to bone cement is appropriate in the management of total arthroplasty infections.

We performed an in vitro study with immortalised human foetal osteoblast cells (hFOB 1.19) and human endothelial cells (EAhy 926). The cultured cells were exposed to media containing various concentrations of gentamicin (12.5-800 microg/ml) and polyhexanide (0.0006-0.01%) for six hours. We measured the phase-contrast microscopy images, the cell viability, cell number and the alkaline phosphatase activity as a parameter for osteogenic function.

The exposure of hFOB and endothelial cells to polyhexanide showed a severe reduction of viability and cell number. Gentamicin did not have negative effects on hFOB and endothelial cell number and viability. The alkaline phosphatase activity of hFOB showed a significant decrease after exposure to polyhexanide and gentamicin. The viability and the cell number of endothelial cells seem more negatively affected by polyhexanide than the parameters of the hFOB-cells.

The exposure of human osteoblasts and endothelial cells to polyhexanide at concentrations with questionable antibacterial activity resulted in severe cell damage whereas exposure to high dosed gentamicin did not. These results raise questions as to the feasibility of using antiseptics in bone cement for the treatment of total arthroplasty infections. Further in vivo studies are necessary to show the in vivo relevance of these in vitro findings.