Study on the debridement efficacy of formulated enzymatic wound debriding agents by in vitro assessment using artificial wound eschar and by an in vivo pig model.

Shi, Lei; Ermis, Ryan; Lam, Kan; Cowart, Jerry; Attar, Paul; Aust, Duncan

An in vitro efficacy study using newly developed artificial wound eschar (AWE) substrate was conducted for assessing enzyme dose response. The AWE substrate is prepared by the enzymatic conversion of fibrinogen to fibrin in the presence of collagen, fibrin, and elastin to form an insoluble planar matrix. AWE substrate was placed on Franz Diffusion Cells for continuously monitoring the debridement progress. A parallel in vivo study was performed using pig thermal-burn wounds. Papain at concentrations of 200, 400, 800, and 1,600 U/mg was used as the model debriding enzyme for both studies. The data from the first 5 hours of the in vitro testing showed that debriding activity increased as the enzyme concentration increased. The histological results of the in vivo biopsy samples showed that enzyme doses above 800 and 1,600 U/mg successfully achieved debridement on day 8, while lower treatment groups still contained eschar tissue. Using the histological measurement results (wound depth score) a dose response that correlated to the in vitro assessment was found. Granulation tissue maturity and reepithelialization displayed correlation with the enzyme dose. Results indicate that AWE substrate can be used to predict debridement efficacy in vitro when correlation to the in vivo assessment is achieved.