Are fibrocytes present in pediatric burn wounds?

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.