Different epidermal and dermal cell populations not only contribute to tissue homeostasis but also to wound repair and underlie tumour heterogeneity and progression.
Skin cellular behaviour and fate are regulated by interactions at the level of single cells, termed microniches, as well as on higher scales.
Individual niche components and transcription factors can be identified that significantly affect stem cell maintenance and behaviour.
Cell population-specific mechanisms regulate cellular plasticity and behaviour during wound repair and tumour development.
Epidermal stem cell plasticity is achieved by a loss of lineage specificity during wound healing, and may become permanent in skin cancer.
Skin architecture and function depend on diverse populations of epidermal cells and dermal fibroblasts. Reciprocal communication between the epidermis and dermis plays a key role in skin development, homeostasis and repair. While several stem cell populations have been identified in the epidermis with distinct locations and functions, it is now recognised that there is additional heterogeneity within the mesenchymal cells of the dermis. Here, we discuss recent insights into how these distinct cell populations are maintained and coordinated during development, homeostasis, and wound healing. We highlight the importance of the local environment, or niche, in cellular plasticity. We also discuss new mechanisms that have been identified as influencing wound repair and cancer progression.