Temporal expression of wound healing-related genes in skin burn injury

Determination of the age of burns, as well as of wounds induced mechanically, is essential in forensic practice, particularly in cases of suspected child abuse. Here, we investigated temporal changes in the expression of 13 genes during wound healing after a burn. The expression of cytokines (IL-1β, IL-6, IL-10, TNF-α, and IFN-γ), chemokines (KC, MCP-1), proliferative factors (TGF-β, VEGF), proteases (MMP-2, 9, 13) and type I collagen in murine skin was examined by real-time PCR at 3, 6, 9, and 12 h and 1, 2, 3, 5, 7, and 14 days after a burn. Based on macroscopic and histological appearance, the healing process of a burn consists of 3 phases: inflammatory (from 3 h to 1 day after the burn), proliferative (from 1 to 7 days), and maturation (from 7 to 14 days). Expression of IL-1β, IL-6, TNF-α, IFN-γ and KC increased significantly in a biphasic pattern from 3 or 6 h to 12 h or 1 day and from 3 or 5 days to 7 days. Expression of MCP-1 increased significantly from 6 h to 5 days. Expression of both IL-10 and TGF-β increased significantly from 12 h to 7 days. Expression of VEGF, MMP-2, MMP-13 and type I collagen increased significantly from 3 days to 7 or 14 days. Expression of MMP-9 increased significantly from 6 h to 14 days. Our results suggest that evaluating the expression of a combination of these genes would enable the exact estimation of the age of a burn.