Development of a porcine model for chronic wound eschars and evaluation of a Bromelain based enzymatic debriding agent

Background: Advances in the development of novel therapies for chronic wounds has been limited by the lack of validated animal models. In this study, we describe the development of a novel porcine eschar model and compare the debridement efficacy of various concentrations of a novel Bromelain-based enzymatic debridement agent with collagenase.

Methods: Full-thickness excisional wounds were created on the three domestic pigs and injected intradermally with various concentrations and volumes of Doxorubicin. Wounds were monitored for a period of 46 days for the development of eschar and wound closure. After determining the optimal concentration (0.75mg/ml) and dose (0.5ml/cm2) of Doxorubicin resulting in non-healing eschars, these conditions were used to create additional wounds on another set of animals. The resulting eschars were treated with various concentrations (0.1%, 0.5%, 1%, 2%, 5%) of a novel Bromelain based enzymatic debridement agent* or Collagenase. The primary endpoint in this stage was greater than 95% removal of the central eschar at the end of the study period.

Results: Consistent eschars composed of 2 distinct areas (a central area of exudate and slough and a peripheral area of full-thickness necrosis) were seen after injection of 0.75mg/ml Doxorubicin (0.5ml/cm2). Complete removal of the central eschar was achieved in all wounds after 5 and 8 treatments with 5% and 2% of the Bromelain-based agent* respectively. Complete removal of the central eschar with Collagenase was achieved in 0% and 82% of the wounds after 10 and 16 treatments respectively.

Conclusions: We describe a porcine model for creating eschars similar to chronic wounds in humans. A novel Bromelain-based enzymatic debridement agent* was more effective than a commercially available Collagenase in removing eschars in this model.