Search

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]

Background: Silver dressings have been widely and successfully used to prevent cutaneous wounds, including burns, chronic ulcers, dermatitis and other cutaneous conditions, from infection. However, in a few cases, skin discolouration or argyria-like appearances have been reported. This study investigated the level of silver in scar tissue post-burn injury following application of Acticoat™, a silver dressing. Methods: A porcine deep dermal partial thickness burn model was used. Burn wounds were treated with this silver dressing until completion of re-epithelialization, and silver levels were measured in a total of 160 scars and normal tissues. Results: The mean level of silver in scar tissue covered with silver dressings was 136 μg/g, while the silver level in normal skin was less than 0.747 μg/g. A number of wounds had a slate-grey appearance, and dissection of the scars revealed brown-black pigment mostly in the middle and deep dermis within the scar. The level of silver and the severity of the slate-grey discolouration were correlated with the length of time of the silver dressing application. Conclusions: These results show that silver deposition in cutaneous scar tissue is a common phenomenon, and higher levels of silver deposits and severe skin discolouration are correlated with an increase in the duration of this silver dressing application. [ABSTRACT FROM AUTHOR]

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]

Abstract: This retrospective review examines healing in different sites on a porcine burn model; 24 pairs of burns on 18 pigs from other animal trials were selected for analysis. Each pair of burns was located on the either the cranial or the caudal part of the thoracic ribs region, on the same side of the animal. The burns were 40–50cm2 in size and of uniform deep-dermal partial thickness. Caudal burns healed significantly better than cranial burns, demonstrated by earlier closure of wounds, less scar formation and better cosmesis. To our knowledge, this is the first detailed study reporting that burn healing is affected by location on a porcine burn model. We recommend that similar symmetrical burns should be used for future comparative assessments of burn healing. [Copyright &y& Elsevier]