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This study describes the direct association of in vivo burn scar contraction with the level of α-smooth muscle actin (α-SMA) in scar tissue, in a porcine burn model. The expression of α-SMA was investigated in 100 biopsies from 44 6-week old burn scars and in 85 biopsies from 16 2-week old burn wounds. Statistical analysis showed that the levels of α-SMA in 6-week old scars were significantly negatively correlated to scar size (r =−0.68) and the higher levels of α-SMA were observed in smaller scars. Moreover, α-SMA was also found to be significantly positively correlated to re-epithelialisation time (r =0.57) and scar thickness (r =0.58) and higher levels of α-SMA were detected in thicker scars with delayed wound closure. Further statistical analysis revealed that scar contraction can be explained best by the level of α-SMA expression and partially by scar thickness. Other variables, such as different dressings and individual pig, may also partly contribute to scar contraction. At week 2 after-burn, the level of α-SMA expression in 16 burn wounds was significantly related to the depth of burns and wound healing outcome. To our knowledge, this is the first study to provide in vivo evidence of the association of α-SMA expression with scar contraction, scar thickness, re-epithelialisation time and the depth of burn in a large animal burn model with scars similar to human hypertrophic scar. [Copyright &y& Elsevier]

Abstract: This is a study to compare wound healing among three types of dressings on a porcine model with deep-dermal-partial-thickness burns. The burns in this study were from eight animal trials conducted in the past for other purposes and only burns with a uniform pale appearance that had served as controls in original experiments were selected. In total, there were 57 burns in 33 pigs, using one of following three dressings: Acticoat (Silver) (3 trials), Jelonet (Gauze) (3 trials), and Solosite Gel/Jelonet (Gel/Gauze) (2 trials). The wound healing assessments included wound re-epithelialisation during a 6-week period, clinical and histological scar assessments at week 6 after burn. Of all wound healing/scar assessments, only re-epithelialisation showed statistical difference between dressings. Earlier re-epithelialisation was observed in Gel/Gauze dressings compared to Silver and/or Gauze dressings. However, this study revealed huge variation in wound healing outcome between 3 trials within both Silver and/or Gauze dressings, supported by significant differences on re-epithelialisation, clinical and histological scar measurements. In addition, it was found that larger animals healed better than smaller ones, based on weights from 21 pigs. Of all dressings, Silver delivers the best protection for wound colonization/infection. Wound colonization/infection was found to confine wound healing and lead to thinner RND in scars. From this study, we cannot find enough evidence to suggest the beneficial effect of one dressing(s) over others on burn wound healing outcome on a porcine model with small deep-dermal-partial-thickness burns with a relative small sample size. [Copyright &y& Elsevier]

Abstract: This study describes the evaluation of a clinical scar scale for our porcine burn scars, which includes scar cosmetic outcome, colour, height and hair, supplemented with reference porcine scar photographs representing each scar outcome and scar colour scores. A total of 72 porcine burn scars at week 6 after burn were rated in vivo and/or on photographs. Good agreements were achieved for both intra-rater reliability (correlation is 0.86–0.98) and inter-rater reliability (ICC=80–85%). The results showed statistically significant correlations for each pair in this clinical scar scale (p <0.01), with the best correlation found between scar cosmetic outcome and scar colour. A multivariate principle components analysis revealed that this clinical scar assessment was highly correlated with scar histology, wound size, and re-epithelialisation data (p <0.001). More severe scars are clinically characterised by darker purple colouration, more elevation, no presence of hair, histologically by thicker scar tissue, thinner remaining normal dermis, are more likely to have worse contraction, and slower re-epithelialisation. This study demonstrates that our clinical scar scale is a reliable, independent and valuable tool for assessing porcine burn outcome and truthfully reflects scar appearance and function. To our knowledge, this is the first study demonstrating a high correlation between clinical scar assessment and scar histology, wound contraction and re-epithelialisation data on porcine burn scars. We believe that the successful use of porcine scar scales is invaluable for assessing potential human burn treatments. [Copyright &y& Elsevier]