Cytotoxicity of silver dressings on diabetic fibroblasts

Abstract

A large number of silver-based dressings are commonly used in the management of chronic wounds that are at risk of infection, including diabetic foot ulcers. However, there are still controversies regarding the toxicity of silver dressings on wound healing. The purpose of this study was to objectively test the cytotoxicity of silver dressings on human diabetic fibroblasts. Human diabetic fibroblasts were obtained from the foot skin of four diabetic foot ulcer patients and cultured. The effect of five silver-containing dressing products (Aquacel Ag, Acticoat*Absorbent, Medifoam Ag, Biatain Ag and PolyMem Ag) and their comparable silver-free dressing products on morphology, proliferation and collagen synthesis of the cultured human diabetic fibroblasts were compared in vitro. In addition, extracts of each dressing were tested in order to examine the effect of other chemical components found in the dressings on cytotoxicity. The diabetic fibroblasts cultured with each silver-free dressing adopted the typical dendritic and fusiform shape. On the other hand, the diabetic fibroblasts did not adopt this typical morphology when treated with the different silver dressings. All silver dressings tested in the study reduced the viability of the diabetic fibroblasts and collagen synthesis by 54-70 and 48-68%, respectively, when compared to silver-free dressings. Silver dressings significantly changed the cell morphology and decreased cell proliferation and collagen synthesis of diabetic fibroblasts. Therefore, silver dressings should be used with caution when treating diabetic wounds.

Figure 1

Diabetic fibroblast morphology after 3 days of incubation with the different dressing disks. (Above) Cells without a dressing disk (control). (Lefts, from above to below) Cells treated with Aquacel, Algisite*M, Medifoam, Biatain and PolyMem. (Rights, from above to below) Cells treated with Aquacel Ag, Acticoat*Absorbent, Medifoam Ag, Biatain Ag and PolyMem Ag. The diabetic fibroblasts cultured in wells containing the silver dressings did not adopt the typical dendritic or fusiform apposition morphology. However, the cells treated with PolyMem Ag partially retained the typical fibroblast fusiform apposition morphology (magnification ×200).

Figure 2

Cell numbers in the control wells and wells containing the dressings. The numbers of silver‐containing dressing treated cells were significantly lower when compared to those of the control and silver‐free dressing group (*P < 0·05).

Figure 3

Collagen concentrations in the media of wells containing the dressing and control wells. Collagen synthesis was significantly reduced in the wells containing the silver dressing when compared to the control and silver‐free dressing wells (*P < 0·05).

Figure 4

Calcium and silver concentrations in the extracts of the dressings tested in this study.