Dermal Papilla-Derived Wnt Ligands Are Required for Adult Hair Follicle Growth

The study from April 30, 2016, demonstrated the crucial role of Wnt ligands, produced by dermal papilla cells (DPCs), in the growth and regeneration of adult hair follicles. The researchers genetically deleted Wntless, a protein responsible for exporting Wnt molecules, in DPCs and observed a significant delay in postnatal hair growth. Only about 30% of hair follicles in Wntless mutant mice reached the anagen III stage, and none reached full anagen, compared to the majority of normal hair follicles. The mutant mice also entered a premature destructive phase of the hair cycle, with over 90% of their hair follicles in the catagen stage by postnatal day 40. The study also found a reduced size of the DP compartment in mutant hair follicles and a complete absence of Versican, a DP signature gene. The proliferation and differentiation of matrix cells were greatly reduced in mutant hair follicles, although hair follicle stem cells were maintained. These findings underscored the importance of Wnt ligands in hair growth and regeneration.