Development of an in vitro fibrin clot model to evaluate fibrinolytic agents for wound care application.

OBJECTIVE: To describe an in vitro fibrin clot model that could reliably assess the fibrinolytic activity of enzymatic debriding agents for wound care application. METHOD: A model of a fibrin clot was reconstructed in vitro by mixture of human fibrinogen and (alpha)-thrombin supplemented with factor XIII. These clots were then treated with enzymatic ointments. Fibrinolytic activity was investigated by measuring D-dimer levels, using an automated immunoturbidimetric Liatest D-dimer assay. RESULTS: Collagenase and papain-urea ointments demonstrated fibrinolytic activity which was macroscopically visible. Their effect was identical on the in vitro reconstructed fibrin clot and ex vivo collected wound fibrin clot; collagenase and papain-urea both induced a complete degradation and dissolution of both fibrin clots after 24 hours of treatment. This was associated with an increase in D-dimer concentration. CONCLUSION: This reconstructed fibrin clot in vitro model has the potential to predict the efficacy of fibrinolytic agents and therefore appears to be a suitable model for in vitro assays. DECLARATION OF INTEREST: This study was supported by a grant from URGO Laboratory.

Stimulation of the proliferation of human dermal fibroblasts in vitro by a lipidocolloid dressing.

OBJECTIVE: The effect of Urgotul on normal human dermal fibroblast proliferation was studied in vitro and compared with that of two other dressings: Mepitel and Tulle Gras. METHOD: Proliferation was measured by the extent of thymidine incorporation into the replicating DNA of proliferative fibroblasts in contact with the complete dressing.Additional cell viability and metabolism were evaluated using MTT assay. Morphology and ultrastructure analysis were based on immunolabelling and confocal laser microscopy. RESULTS: Only Urgotul significantly stimulated thymidine incorporation, generally with a maximal proliferative effect at a contact time of 48 hours. This was confirmed by the observation of a greater number of dividing cells (mitotic cells) than in the control cultures. No cytotoxicity was observed following treatment with this dressing. Cells exhibited normal structural and ultrastructural features. CONCLUSION: Fibroblasts play a key role in dermal wound repair. The ability of Urgotul to promote fibroblast proliferation could explain its efficiency in the healing process of acute and chronic wounds. DECLARATION OF INTEREST: This study was supported by Urgo Laboratories.