Vital Reactions and Wound Age Estimation

Wounds heal through a highly regulated, self-limited inflammatory response, however, precise inflammatory mediators have not been fully delineated. In this study, we report that in a mouse model of excisional skin wound healing the chemokine CX3CL1 and its receptor CX3CR1 were both highly induced at wound sites; CX3CL1 colocalized with macrophages and endothelial cells, whereas CX3CR1 colocalized mainly with macrophages and fibroblasts. Loss of CX3CR1 function delayed wound closure in both CX3CR1 knockout (KO) mice and in wild-type mice infused with anti-CX3CR1-neutralizing Ab. Conversely, transfer of bone marrow from donor wild-type mice, but not from donor CX3CR1 KO mice, restored wound healing to normal in CX3CR1 KO-recipient mice. Direct effects of CX3CR1 disruption at the wound site included marked reduction of macrophages and macrophage products, such as TGF-beta1 and vascular endothelial growth factor. Consistent with this, we observed reduced alpha-smooth muscle actin (a marker for myofibroblasts) and collagen deposition in skin from wounded CX3CR1 KO mice, as well as reduced neovascularization. Together, the data support a molecular model of skin wound repair in which CX3CR1 mediates direct recruitment of bone marrow-derived monocytes/macrophages which release profibrotic and angiogenic mediators.

Skin-wound healing is an orchestrated biological phenomena consisting of three sequential phases, inflammation, proliferation, and maturation. Many biological substances are involved in the process of wound repair, and this short and simplified overview of wound healing can be adopted to determine wound vitality or wound age in forensic medicine. With the development of genetically engineered animals, essential molecules for skin-wound healing have been identified. Especially, cytokines, and growth factors are useful candidates and markers for the determination of wound vitality or age. Moreover, bone marrow-derived progenitor cells would give significant information to wound age determination. In this review article, some interesting observations are presented, possibly contributing to the future practice of forensic pathologists. Copyright © 2010. Published by Elsevier Ireland Ltd.

To clarify biological roles of tumor necrosis factor receptor p55 (TNF-Rp55) -mediated signals in wound healing, skin excisions were prepared in BALB/c (WT) and TNF-Rp55-deficient (KO) mice. In WT mice, the wound area was reduced to 50% of the original area 6 days after injury, with angiogenesis and collagen accumulation. Histopathologically, reepithelialization rate was approximately 80% 6 days. Myeloperoxidase activity and macrophage recruitment were the most evident 1 and 6 days after injury, respectively. Gene expression of adhesion molecules, interleukin 1alpha (IL-1alpha), IL-1beta, monocyte chemoattractant protein 1, macrophage inflammatory protein 1alpha (MIP-1alpha), MIP-2, transforming growth factor beta1 (TGF-beta1) connective tissue growth factor (CTGF), vascular endothelial growth factor (VEGF), Flt-1, and Flk-1 was enhanced at the wound site. In KO mice, an enhancement in angiogenesis, collagen content, and reepithelialization was accelerated with the increased gene expression of TGF-beta1, CTGF, VEGF, Flt-1, and Flk-1 at the wound sites, resulting in accelerated wound healing compared with WT mice. In contrast, leukocyte infiltration, mRNA expression of adhesion molecules, and cytokines were significantly reduced in KO mice. These observations suggest that TNF-Rp55-mediated signals have some role in promoting leukocyte infiltration at the wound site and negatively affect wound healing, probably by reducing angiogenesis and collagen accumulation.