Debridement Efficiency of Wound Gels by an in vitro Artificial Wound Eschar Model

Background: In chronic wounds, eschar and slough formation delays the wound healing process by providing a reservoir for microorganisms, devitalized tissue and inflammatory chemokines, which form a hostile local milieu to impede fibroblast and keratinocyte proliferation and migration. To encourage the wound healing process, advanced wound dressings should have the ability to breakdown eschar and slough to enhance the antimicrobial and antibiofilm ability and also help tissue repair and regeneration; however, there is no standard method to evaluate the ability of wound dressings to breakdown eschar and slough.

Purpose: In this study, a newly designed fluorescent artificial wound eschar (fAWE) model applied to examine efficacy of wound dressing gels on eschar debridement with/without enzymes was developed.

Methods: fAWE composed of 60% FITC-collagen, 10% Rhodamine-elastin, 10% Coumarin-fibrin, and 20% fibrin was made freshly by clotting fibrinogen with thrombin.  fAWE was placed into cell culture inserts and wound dressing gel was placed on top. The cell culture insert was put into a 6 well plate with 5 ml Tri-buffer. Another 5ml Tri-buffer with or without papain-urea were added into cell culture inserts. The 6-well-plate system was moved into a shaking incubator at 37C and sampled at set time points from 0 hour to 28 hours. The decomposition of each protein in fAWE substrate was measured by each fluorescent dye in the well.

Results and Conclusion: Compared to a control group with no gel, a concentrated surfactant gel preserved with antimicrobials (CSG) increased exudation of small molecules from cell culture inserts to culture plates. The results implied that the surfactant-based gel helps breakdown, degrade and decompose wound eschar and slough. The results of this initial study imply that a fAWE model can be used to measure the breakdown-degradation-decomposition of collagen, elastin and fibrin, which are the main components of wound eschar and slough.