The quality of human skin xenografts on SCID mice: A noninvasive bioengineering approach

Background: Animal models are important tools for studies in skin physiology and pathophysiology. Due to substantial differences in skin characteristics such as thickness and number of adnexa, the results of animal studies cannot always be directly transferred to the human situation. Therefore, transplantation of human skin on to SCID (severe combined immunodeficiency) mice might offer a promising tool to perform studies in viable human skin without the direct need for human volunteers. Objectives: To characterize the physiological and anatomical changes of a human skin transplant on a SCID animal host. Methods: In this study human skin was transplanted on to 32 SCID mice and followed for 6 months. Barrier function was assessed by transepidermal water loss (TEWL; tewametry) and moisture content of the stratum corneum was studied by measurement of electrical capacitance (corneometry). Results: The results showed considerable deviations of TEWL values and skin hydration between the grafts and human skin in vivo. The human skin showed epidermal hyperkeratosis and moderate sclerosis of the corium 4 and 6 months after transplantation on to SCID mice. Conclusions: Our results indicate that human skin does not completely preserve its physiological and morphological properties after transplantation on to SCID mice. Therefore, results from experiments using this model system need to be discussed cautiously.