Hyaluronic acid in incision wound fluid: a clinical study with the Cellstick device in children.

When inserted into a human incision wound, the Cellstick device harvests inflammatory cells and collects wound fluid, reflecting time-related changes in cell populations and in wound fluid composition. Hyaluronic acid has been postulated to be an important factor in scar reduction in wound healing and in scarless fetal wound healing. The aim of this work was to determine the concentration and variation of hyaluronic acid and proportions of wound cells in closed surgical wounds in children at two time points. The Cellstick device was inserted subcutaneously into the wound at the end of an elective inguinal hernia operation on 37 healthy boys, and the devices were removed 3+/-1 or 24+/-3 hours after surgery. Haluronic acid concentration was measured from the wound fluid and a differential count of the wound cells was performed. There was a significant decrease in hyaluronic acid concentration from 3+/-1 to 24+/-3 hours after surgery (p<0.001, Kruskal-Wallis anova). The variance of hyaluronic acid concentration in wound fluid differed between the wounds at the two time points (p<0.01, Levene test for homogeneity of variance). A positive correlation between hyaluronic acid concentration and patient age (r=0.91, p<0.05, Spearman) at 3+/-1 hours post surgery and between HA and wound lymphocytes (r=0.38, p<0.05, Spearman) was also found. We conclude that the hyaluronic acid concentration in wound fluid peaks early in children and decreases significantly by 3 to 24 hours after surgery, and the concentrations in the wound fluid of healthy boys are more variable 3 hours than at 24 hours after surgery.

Wound cell variation in closed surgical wounds as measured with two independent methods.

BACKGROUND AND AIMS: It is not known, to what extent the observed cellular changes in healing surgical wounds are species-, individual- or site-specific or whether they depend on the research method used. The aim of this study was to compare two independent methods for harvesting wound cells from porcine wounds after two time intervals, and to assess individual changes of wound cell composition. MATERIAL AND METHODS: In a standardised wound model in six pigs, with eight dorsal skin incision wounds in each, the Cellstick device and the Wound Edge Contact (WEC) method were used to collect inflammatory cells from the same wounds at hour 6 or 24 post-surgery. The wound cells were stained by the May-Grünwald-Giemsa (MGG) -method and counted differentially. RESULTS: A significant difference was found between the 6 and 24 hour Cellstick specimen in the proportions of wound neutrophils (p = 0.007), lymphocytes (p = 0.02) and monocytes (p < 0.001). The differential counts of wound cells within each individual animal did not significantly differ from each other. Instead, a significant difference was found in the wound neutrophils (p = 0.001), lymphocytes (p = 0.04) and monocytes (p < 0.001) between the wounds of individual animals. The WEC method revealed the same significant differences in the wound cell proportions. CONCLUSIONS: The Cellstick and the WEC method gave analogous results with equal variances from the incision wounds for up to at least 24 hours after injury.

Duration of surgery and patient age affect wound healing in children.

The migration of inflammatory cells into a wound and their subsequent changes during wound healing are essential for the complex processes of tissue repair to occur. The aim of this work was to investigate the number of wound leukocytes during early wound healing at different time periods in children. Wound cells of 184 children aged 0-15 years, operated on for a benign disease in the lower abdominal region, were harvested with the Cellstick(R) device. The device was removed from the wound at 3, 6, or 24 hours after surgery and differential cell counts were performed. The cellular patterns were significantly influenced by the age of the patient and by the duration of the surgery. The proportions of neutrophils, lymphocytes, and monocytes changed significantly from 3-24 hours. Our results suggest that there is a distinct time-related change in the pattern of inflammatory cells in the early phase of wound healing in children. This pattern is affected by the age of the child and by the duration of the surgery.

Correlation between interleukin-6 and matrix metalloproteinase-9 in early wound healing in children.

Interleukin-6 and matrix metalloproteinase-9 concentrations in the wound fluid and their associations to cellular changes were determined in early wound healing. Wound healing of 75 children who underwent elective operations was studied with the Cellstick(R) device, which was inserted into the wound at the end of the operation and removed 3 or 24 hours post-wounding. Differential counts of the wound cells and interleukin-6 and matrix metalloproteinase-9 concentrations in the wound fluid were analyzed. Interleukin-6 and the matrix metalloproteinase-9 concentrations increased in parallel (r = 0.81). The proportion of wound neutrophils increased (p < 0.0001) and lymphocytes decreased (p < 0. 0001) between the observation times. The number of wound neutrophils had a strong correlation with both interleukin-6 (adjusted R2 = 0.41, p < 0.0001) and matrix metalloproteinase-9 concentrations (adjusted R2 = 0.37, p < 0.0001). The extracellular matrix degradation process of the early wound healing seems to be closely linked to the inflammatory response. Both of these measured markers are associated significantly with the neutrophil proportion in the wound.

Prediction of wound tensile strength: an experimental study.

Wound cell specimens were obtained using a Cellstic device after 24, 48 and 72 h healing time in guinea-pig skin wounds. Cell counts from these were compared with the tensile strength values of the same wounds 7, 14 or 21 days after operation. No single cell type was predictive of wound tensile strength, although absolute numbers of different cells and selected ratios of cell types on the second or third day after operation were more predictive. Absolute and proportional changes from day 1 to day 2 had the greatest predictive power with a mean error of 9.46 per cent (F = 13.6, P less than 0.0001). The same regression model was predictive in animals with lower wound tensile strengths given perioperative hydrocortisone (3 mg/100 g).