Hair Follicle Reconstruction and Stem Cells

De novo hair follicle (HF) formation in embryonic skin and hair growth in postnatal skin are the result of epithelial-mesenchymal interactions between specialized mesenchymal dermal papilla (DP) and epithelial stem cells that give rise to hairs. Adult HF is a valuable source of different lineages of stem cells (SCs) with morphogenetic potential. Epithelial stem cells are residing in the special compartment of HF (the bulge) and can be mobilized to regenerate the new follicle with each hair cycle and to reepithelialize epidermis during wound repair. This review summarizes the current knowledge on key characteristics of HF SC populations in terms of regenerative potential. General biological principles that govern the mesenchymal-epithelial interactions within the HF and the signaling pathways that control HF development are discussed. The main focus is on recent approaches to reconstruct folliculogenesis in vitro and perspectives of the tissue engineering in alopecia therapy