DETERMINATION OF ENDOGENOUS CYTOKINES IN CHRONIC WOUNDS

Objective This study objectively characterized the microenvironment of indolent, chronic wounds by developing a method by which minute quant ities of cytokines could be extracted from chronic wounds and separate ly identified. Summary Background Data Recombinant DNA technology and the ability to clone compounds such as cytokines allow new management schemes for the treatment of acute and chronic wounds. Before treatmen t with an exogenous cytokine is started, it would be helpful to know t he endogenous level of that cytokine in the wound. Although various me thods of extracting cytokines from acute wounds have been reported, no techniques have existed to reliably measure endogenous levels of cyto kines in chronic wounds. Methods Porous, inert hydrophilic dextranomer beads were tested for their ability to absorb or adsorb protein and c ytokines in vitro with either albumin or albumin laced with various kn own amounts of cytokines, and then from chronic human pressure ulcers. The Bradford protein assay was used to determine protein levels. Enzy me-linked immunosorbent assay (ELISA) techniques were used to determin e levels of platelet-derived growth factor (PDGF)-AB, basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), and transforming growth factor-Beta (TGF-beta) extracted by the beads. Results Between 88% and 98% of known amounts of albumin could be recovered. Similarly , more than 90% of the laced cytokines could be recovered. In 20 grade III/IV pressure ulcers, although protein concentrations were remarkab ly similar, endogenous levels of cytokine growth factors varied tremen dously. Platelet-derived growth factor-AB ranged from 49 to 867 pg/mL; bFGF from 47 to 697 pg/mL; and EGF from nondetectable io 247.5 pg/mL. TGF-B was not detected in 17 of the 20 pressure ulcers. Conclusions T his new technique appears useful for measuring endogenous levels of cy tokines. Levels of cytokines found in these chronic wounds are much lo wer than those reported from acute wounds. The marked variation found among the 20 wounds may help to explain the differences reported in re cent wound healing trials with exogenous cytokines.