2.1. Sample preparation
Because of histological, physiological, and immunological similarities of porcine skin and human skin (Schmook et al., 2001; Avon and Wood, 2005; Zak et al., 2011), skin samples of euthanized 8–12 months old American Yorkshire pigs were tested within 5 h from acquisition. The samples were embedded in a filtered paper soaked in 0.9% NaCl solution and the hair was removed with a surgical knife. Samples containing the stratum corneum and a significant portion of the epidermis were obtained by shearing off an outer skin layer of a few micrometers thickness with a surgical blade. This method is preferred over chemical isolation techniques because it allows for tissue separation with minimal damage and without undesirable chemical effects. Dermis samples were obtained from whole skin samples by shearing off most of the hypodermis with a surgical knife. After testing, the samples were frozen on dry ice.
