Chitosan membranes in a rat model of full-thickness cutaneous wounds: healing and IL-4 levels.

OBJECTIVE: The aim of this study was to examine the effect of chitosan membrane on wound healing. METHOD: The effect of chitosan membranes was evaluated in an experimental rat model. On day 0, circular full-thickness skin sections were excised from the scalps of rats. The wounds were then measured and the surrounding area tattooed. Rats were sacrificed either immediately after excision, or randomised into control and chitosan groups and followed up on day 3, 7, 14 or 21. Control group wounds were covered with Aquacel (wound dressing). Chitosan group wounds were covered with chitosan membranes and the wound dressing. Wounds and the distances between the tattooed marks were measured on follow-up, the wound sites were harvested and histologically examined, and serum interleukin (IL-4) levels were analysed. RESULTS: A total of 54 rats were examined and all time points included 6 control and 6 chitosan treated animals, except for day 0 which consisted of control animals only. On day 3, wounds in the chitosan group were significantly (p<0.05) smaller (60±6% versus 78±19% of the original wound area) than in the control group. Chitosan membranes were found to degrade at the wound sites between days 7 and 14. Leukocyte counts were lower in the chitosan group than in the control group on day seven (p<0.05). IL-4 levels were significantly higher on day 7 (p<0.001) and 14 (p<0.001) in the chitosan group. CONCLUSION: According to our results chitosan membrane may promote early wound healing, reduce inflammation and affect the IL-4 pathway, however, the membrane degrades at the wound site after day 7.

Amniotic membrane reduces wound size in early stages of the healing process.

OBJECTIVE: To investigate the effects of dispase de-epithelialised, glycerol cryopreserved amniotic membrane (AM) on full-thickness skin defects, using a rat model. METHOD: Skin defects of 15 mm diameter were surgically created and measured on the scalps of 53 male rats. Animals were divided into two groups and followed for 0, 3, 7, 14 or 21 days. AM group wounds were covered with de-epithelialised AM and sodium chloride-moistened Aquacel (ConvaTec Inc.); control group wounds were covered with sodium chloride-moistened Aquacel alone. After the follow-up, wounds were measured again, serum samples were taken and wound sites were harvested for histological analysis. Systemic interleukin-4 (IL-4) levels were analysed from serum. RESULTS: On day 3, a statistically significant difference (p < 0.01) was observed in mean wound size, with wound size in the AM group smaller than in the control group (60 ± 12% vs 81 ± 13% of the original size); other time points showed no significance difference in wound size between the two groups. We could not detect differences between the groups in histological parameters or serum IL -4 levels. CONCLUSION: According to this study, AM enhances early stage wound healing in terms of wound size but its effect decreases in later phases. The IL-4 results provide no clear evidence that IL-4 contributes to the effect of AM on wound healing. DECLARATION OF INTEREST: This study was financially supported by the Competitive Research Funding of the Tampere University Hospital (Grant 9H041, 9J047). The authors have no additional conflicts of interest to declare.