Topical tretinoin and epithelial wound healing

The effects of topical tretinoin on epithelial wound healing were studied using a porcine model. Eight animals were treated with 0.05% tretinoin cream daily for ten days prior to partial-thickness skin wounding. Daily tretinoin treatment was continued after wounding on two of eight animals. Treatment with topical tretinoin before wounding accelerated epithelial wound healing in partial-thickness wounds. Continued tretinoin treatment on the wounds themselves retarded reepithelialization. Biopsy specimens of wounds with continued tretinoin treatment revealed persistent inflammation and fibroplasia in the dermis. The healing epithelium itself displayed areas of spongiosis and intracytoplasmic pale eosinophilic periodic acid-Schiff-positive, diastase-resistant globules. These globules did not stain with alcian blue. These epidermal alterations may be a direct effect of tretinoin or may be secondary to the underlying inflammation. While the dermal inflammation associated with continued tretinoin treatment appears to retard reepithelialization, epithelial cell alterations may also play a role.