Approaches to Study Wound-Induced Hair Neogenesis (WIHN)

Embryonic wound repair proceeds with complete regeneration of the tissue without any scar formation, whereas tissue repair in adults usually results in scars and the tissue does not completely regain its preinjured state. Wound-induced hair neogenesis (WIHN) in adult rodents results in de novo hair follicle formation in the center of large wounds, mimicking regeneration processes seen in fetal tissue. The investigation of WIHN therefore provides a unique quantitative framework for scrutinizing the mechanistic underpinnings of regenerative repair, which can have clinical implications in the context of scarless healing. In this chapter, we present a detailed protocol for inducing wounds that lead to hair neogenesis in laboratory mice and facilitating the identification and characterization of distinct stages in neogenic hair follicle development. Additionally, we present a whole-mount alkaline phosphatase assay to distinguish de novo hair follicles. These protocols can facilitate studies toward obtaining a comprehensive understanding of WIHN and shedding light on the intricate molecular and cellular processes involved in mammalian regenerative repair.