Background and Objectives: UV Fluorescence Excitation Imaging (u-FEI) has been shown to be a simple but robust, non-invasive and non-contact method to visualize cells with a high proliferative rate. We had demonstrated the ability of u-FEI to visualize the re-epithelialization of skin wounds in an organ culture system. In this work, we investigated the potential of u-FEI for visualization of wound closure of partial and full-thickness skin wounds.
Study Design: Partial and full-thickness skin wounds were created in the tail of rats. Wounds were imaged weekly using u-FEI system operating at 295/340nm excitation/emission wavelengths, which correspond to the excitation/emission bands of the endogenous fluorophore tryptophan. Histology and immunohistology were used to determine the association between fluorescence intensity and proliferation of keratinocyte cells.
Results: Similar to human skin, the skin of a rat tail heals by re-epithelialization. Keratinocytes migrated and proliferated from the edge and skin appendages of partial-skin wounds to close the wound by creating neo-epidermis. The fluorescence intensity of the whole wound area increased uniformly during week one and decreased to non-wounded control levels around week three. For full-thickness wounds, keratinocytes migrated only from the wound edges as skin appendages were missing. The fluorescence intensity was higher by the wound edge and marched towards the center during healing. H&E and immunohistology show that changes in fluorescence intensity corresponded to newly formed epidermis.
Conclusions: u-FEI of tryptophan allowed visualization of wound closure of partial and full-thickness skin wounds in an in vivo model of wound healing by epithelialization.
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