RESUMO
Using atomic absorption spectrum analysis, we found iron levels in exudates from chronic wounds to be significantly increased (3.71 +/- 1.56 micromol per g protein) compared to wound fluids from acute wounds derived from blister fluids (1.15 +/- 0.62 micromol per g protein, p < 0.02), drainage fluids of acute wounds (0.87 +/- 0.34 micromol per g protein, p < 0.002), and pooled human plasma of 50 volunteers (0.42 micromol per g protein). Increased free iron and an increase in reactive oxygen species released from neutrophils represent pathogenic key steps that --via the Fenton reaction - are thought to be responsible for the persistent inflammation, increased connective tissue degradation, and lipid peroxidation contributing to the prooxidant hostile microenvironment of chronic venous leg ulcers. We herein designed a selective pick-up dressing for iron ions by covalently binding deferoxamine to cellulose. No leakage occurred following gamma sterilization of the dressing and, more importantly, the deferoxamine-coupled cellulose dressing retained its iron complexing properties sufficient to reduce iron levels found in chronic venous ulcers to levels comparable to those found in acute wounds. In order to study the functionality of the dressing, human dermal fibroblasts were exposed to a Fenton reaction mimicking combination of 220 microM Fe(III) citrate and 1 mM ascorbate resulting in a 4-fold induction of matrix-degrading metalloproteinase 1 as determined by a matrix-degrading metalloproteinase 1 specific enzyme-linked immunosorbent assay. This induction was completely suppressed by dissolved deferoxamine at a concentration of 220 microM or by an equimolar amount of deferoxamine immobilized to cellulose. In addition, the Fe(III) citrate and ascorbate driven Fenton reaction resulted in an 8-fold increase in malondialdehyde, the major product of lipid peroxidation, as determined by high pressure liquid chromatography. This increase in malondialdehyde levels could be significantly reduced in the presence of the selective pick-up dressing coupled with deferoxamine suggesting that the deferoxamine dressing, in fact, prevents the development of a damaging prooxidant microenvironment and also protects from unfavorable consequences like matrix-degrading metalloproteinase 1 and lipid peroxide induction.