No abstract

If neutrophils predominate, the wound is probably less than a couple of days old. When macrophages are abundant the wound is probably a few days to weeks old. However, as expected from the review of the literature, the inflammatory cell infiltrate may be low or absent in burn wounds, which can render determination of the age of burn wounds difficult.

Proteomics is the analysis of the protein complement of the genome. The technique involves extracting proteins from the tissue being examined; separating the proteins using methods such as two-dimensional gel electrophoresis and then identifying the proteins by mass spectrometry. This paper describes the application of proteomics to incised wounds of the rat to determine if this technology could be applied to the important forensic issue of determining the age of wounds. Experimental incised skin wounds were inflicted on rats 5, 15, 30 and 60 minutes, 3, 6, 12 and 24 hours and 2, 5, 7 and 12 days before euthanasia. Each wound was excised and frozen at 80 degrees C; protein extracts were prepared and subjected to two-dimensional polyacrylamide gel electrophoresis over the range pH 3 to pH 10. Protein spots were identified using Matrix-assisted Laser Desorption/Ionisation Time-of-Flight (MALDI-TOF) mass spectrometry. A number of proteins were identified in skin wounds. After wounding the most prominent change was in the level of haemoglobin, which was elevated in wounds five minutes old and remained elevated for three hours, falling to near control levels after 12 hours. This pilot study has illustrated the feasibility for proteomics to be applied to determining wound age.

Early expression of p53 protein in thermal burns of guinea pig skin has been reported. This study sought to determine if expression occurred in thermal burns of human skin and if immunohistochemical demonstration of p53 protein could be utilised to distinguish ante-mortem from post-mortem injuries as well as indicating the age of a lesion in the living subject. Biopsy samples were obtained from live patients and post-mortem examinations. Immunohistochemistry was used to demonstrate the presence of p53 protein. Staining was assessed by field counting of epithelial cell nuclei. In live subjects there was a tendency for early (six hour to five day) expression, with peak levels occurring around one to two days. Late samples (13 to 23 days) demonstrated minimal or no expression. In contrast, burn wounds from post-mortem examination demonstrated greater staining for p53 protein in the late (28 to 77 day) samples than in the early ones. It appears that expression of p53 protein may assist in the ageing of ante-mortem, but not post-mortem, burn wounds. This implies that results obtained from live subjects may not be applicable to post-mortem material and that any putative method for determining the age of a wound should be tested in both situations.

Objective of the study is to investigate for the presence of fibrocytes, a leucocyte found at sites of injury with fibroblast-like properties, within pediatric burn wounds. Seventy 3 mm punch biopsies were taken from 53 burn wounds in 33 children between 7 months and 15 years of age at the time of planned operative debridement and grafting. After fixation and sectioning, immunohistochemistry (IHC) staining was performed for CD34, pro-collagen I, alpha smooth muscle actin, transforming growth factor beta1 and Leucocyte Specific Protein-1 (LSP-1). The presence of fibrocytes was confirmed by double immunofluorescence staining with antibodies to CD34 or LSP-1 with pro-collagen I. CD34 positive cells were present in all burn wound biopsies. Using IHC staining, in 18 patients cells positive for CD34 and pro-collagen I were identified; in 17 patients, cells positive for CD34 and alphaSMA and in 17 patients also cells positive for LSP-1 and pro-collagen I. Double immunofluorescence for CD34/pro-collagen I and LSP-1/pro-collagen I confirmed the presence of fibrocytes in specimens from 17 of 18 patients positive for these markers on IHC. Of the 17 patients whose burn wounds were complicated by hypertrophic scarring, fibrocytes were identified in 88% (n = 15) compared with 18% of those without hypertrophic scarring (P < .001). This study represents the first report of the presence of fibrocytes in acute pediatric burn wounds. These cells appear to be involved in the local response to burn wound injury and may correlate with the later development of hypertrophic burn wound scarring.