Wound healing monitoring using near infrared fluorescent fibrinogen

We demonstrate a method for imaging the wound healing process with near infrared fluorescent fibrinogen. Wound healing studies were performed on a rat punch biopsy model. Fibrinogen was conjugated with a near infrared fluorescent dye and injected into the tail vein. Fibrinogen is a useful protein for tracking wound healing because it is involved in fibrin clot formation and formation of new provisional matrix through transglutaminase's crosslinking activity. Strong fluorescence specific to the wound was observed and persisted for several days, indicating that the fibrinogen is converted to crosslinked fibrin. Administration of contrast agent simultaneously with wound creation led to primary labeling of the fibrin clot, indicating that the wound was in its early phase of healing. Administration on the following day showed labeling on the wound periphery, indicating location of formation of a new provisional matrix. This method may prove to be useful as a diagnostic for basic studies of the wound healing process, in drug development, or in clinical assessment of chronic wounds.