Wound blotting: a convenient biochemical assessment tool for protein components in exudate of chronic wounds

Because wound exudate includes secreted proteins that affect wound healing, its biochemical analysis is useful for objective assessment of chronic wounds. Wound blotting allows for collection of fresh exudate by attaching a nitrocellulose membrane onto the wound surface. To determine its applicability for several analysis methods and its executability in clinical wound assessment, this study comprised an animal experiment and clinical case reports. In the animal experiment, full-thickness wounds were created on the dorsal skin of mice, and exudate samples were collected daily by a conventional method and by wound blotting. Extremely small but adequate volumes of exudate were collected by wound blotting for subsequent analysis in the animal experiments. Immunostaining showed the concentration and distribution of tumor necrosis factor (TNF) α. The activity of alkaline phosphatase was visualized by reaction with chemiluminescent substrate. The TNF distribution analysis indicated three different patterns: wound edge distribution, wound bed distribution, and a mostly negative pattern in both the animal and clinical studies, suggesting association between the TNF distribution pattern and wound healing. Our results indicate that wound blotting is a convenient method for biochemical analysis of exudate and a candidate tool with which to predict the healing/deterioration of chronic ulcers.