Immunohistochemical study of CD31 and α-SMA expression for age estimation of porcine skin wounds

Age estimation of wounds in veterinary forensic investigations is based on the presence and amount of granulation tissue. However, accurate age assessment is challenging and new time-dependent markers are warranted to support and improve the current procedure. The objective of this study was to evaluate the expression of CD31-positive blood vessels and alpha-smooth muscle action (alpha-SMA)-positive myofibroblasts in granulation tissue in order to evaluate their value as markers for porcine wound age estimation in a veterinary forensic context. Immunohistochemical expression of CD31 and alpha-SMA in 14 experimental porcine skin wounds of different ages (4, 6, 8, 10, 18, 27 and 35 days) and 11 forensic porcine wound specimens (of unknown age) were evaluated. CD31-positive blood vessels and alpha-SMA-positive myofibroblasts were present in the granulation tissue in the experimental wounds at all time points. A significant decrease in the mean blood vessel counts was found in wounds aged 18, 27 and 35 days compared with wounds aged 6 days (P < 0.001), when assessing both the superficial and deep part of the wound bed. alpha-SMA expression was lower at 27 and 35 days post wounding compared with 6-18 days post wounding. Combined assessment of three parameters (mean blood vessel counts in the superficial and deep wound beds and alpha-SMA expression) could approximately specify the age of the wounds as either 6-18 days or >= 27 days. In two of the forensic cases a combination of the three parameters yielded results that were similar to the experimental wounds, indicating a wound age of 6-18 days or >= 27 days, respectively. In the remaining forensic cases a combination of the three parameters did not show the same expression pattern as in the experimental wounds. The results indicate that in some forensic cases the application of CD31 and alpha-SMA markers appeared to support the current procedure for porcine wound age estimation, but this must be combined with pathological characteristics.(c) 2023 Elsevier Ltd. All rights reserved.

Automated summary

This study evaluated the expression of CD31-positive blood vessels and alpha-SMA-positive myofibroblasts in granulation tissue as markers for porcine wound age estimation in veterinary forensic investigations. The results showed that a combination of three parameters (mean blood vessel counts and alpha-SMA expression) could approximately determine the age of the wounds. However, in some forensic cases, the application of these markers did not match with the expression pattern observed in experimental wounds.