A Simple In Vivo System for Studying Epithelialization, Hair Follicle Formation, and Invasion Using Primary Epidermal Cells from Wild-Type and Transgenic Ornithine Decarboxylase-Overexpressing Mouse Skin

The study introduced a tracheal xenotransplantation assay to investigate epithelialization, hair follicle formation, and tumorigenesis using primary epidermal cells from both wild-type and transgenic mice. It demonstrated that keratinocytes overexpressing ornithine decarboxylase (ODC) combined with v-Ha-ras infection became invasive and malignant, whereas those expressing only one of these factors did not. The assay was also effective for hair follicle reconstitution, with fresh keratinocytes and fibroblasts forming hair follicles more successfully than cultured cells. This system provided a controlled environment to explore keratinocyte physiology, gene expression, and hair follicle development, particularly when cell numbers were limited.