Histological and Immunohistochemical Biomarkers for Wound Age Estimation in Human Skin: A Systematic Review.

Accurate estimation of wound age is a critical challenge in forensic pathology, particularly for determining wound vitality and the interval between injury and death. Conventional histology often lacks sensitivity in the early post-traumatic stages, prompting investigation into molecular and immunohistochemical biomarkers. This review synthesizes evidence on histological and immunohistochemical markers used for wound age estimation in human skin, with attention to their applicability across different post-traumatic intervals. Very early wounds, from minutes up to one hour, are best characterized by markers related to haemostasis, mast cell activation, and early cytokine release, including fibronectin, CD62p (P-selectin), factor VIII-related antigen, tumor necrosis factor-alpha (TNF-α), and tryptase. Early wound stages, spanning hours, show transient mast cell accumulation and cytokine expression preceding inflammatory cell infiltration. Intermediate wounds, from one to ten days, are associated with immune cell phenotyping and chemokine expression, such as CD14, CD68, interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1), and macrophage inflammatory protein-1 alpha (MIP-1α). Late wounds, seven days or more, are marked by indicators of hypoxia response, angiogenesis, cellular stress, and extracellular matrix remodeling, including oxygen-regulated protein 150 (ORP150), ubiquitin, vascular endothelial growth factor (VEGF), matrix metalloproteinases, collagens, and aquaporins. No single marker provides sufficient accuracy across all healing phases, highlighting the need for multimodal approaches that combine morphological assessment with panels of temporally complementary biomarkers. Standardization of methods and additional high-quality human studies are essential to improve the reliability and forensic applicability of wound age estimation.