Development of three-dimensional tissue-engineered models of bacterial infected human skin wounds

While infected skin wounds are on the increase because of ageing populations, rising incidence of diabetes, and antibiotic resistance, we lack relevant in vivo or in vitro models to study many aspects of bacterial interaction with skin. The aim of this study was to develop three-dimensional models of normal human skin to study bacterial infection. The common dermatological pathogens Staphylococcus aureus and Pseudomonas aeruginosa were used to infect tissue-engineered skin, and the course of infection in the skin was examined over several days. Two forms of model were developed-one in which bacteria were introduced directly to 10 mm wounds in the epidermis, and another in which wounds were created by burning a 4 mm hole in the center of the tissue before inoculation. The bacteria flourished within the engineered skin, and colonized the upper epidermal layers before invasion into the dermis. Infection with P. aeruginosa caused a loss of epidermis and de-keratinization of the skin constructs, as well as partial loss of basement membrane. These novel complex human skin infection models could be used to investigate microbial invasion of normal skin epithelium, basement membrane, and connective tissue, and as a model to study approaches to reduce bacterial burden in skin wounds.