Cell death and proliferation in Nd-YAG laser, electrocautery, and scalpel wounds on mice skin

The purpose of this study is to compare cell death and proliferation in laser, electrocautery and scalpel wounds on the mice epidermis. Wounds were examined by transmission electron microscopy, the detection of free 3′-OH DNA ends and immunohistochemistry of proliferating cell nuclear antigen (PCNA), inducible nitric oxide synthase (iNOS), keratinocyte growth factor (KGF) and keratinocyte growth factor receptor (KGFR). Reepithelization was first observed 5 days after scalpel and laser incisions and 7 days after electrocautery incision. Ultrastructurally, keratinocytes in both electrocautery and laser wounds showed similar post-apoptotic necrotic changes. Interestingly, dividing cells were often observed 3 days after laser incision. Apoptotic index in electrocautery wounds was higher than in laser wounds, although there was no significant difference in the PCNA expression level between them. The expression of iNOS, KGF and KGFR in laser wounds was more intense than in electrocautery wounds. In scalpel wounds, keratinocytes did not show significant changes in morphology or of markers of cell death and proliferation during the observation period. Therefore, the increase in the number of dividing cells and in the expression level of iNOS, KGF and KGFR may induce earlier and thicker reepithelization in laser wounds than in electrocautery and scalpel wounds.