Pre-Aggregation of Scalp Progenitor Dermal and Epidermal Stem Cells Activates the WNT Pathway and Promotes Hair Follicle Formation In Vitro and In Vivo Systems

In the 2019 study by Su et al., researchers found that pre-aggregating scalp-derived dermal progenitor cells with foreskin-derived epidermal stem cells in a 2:1 ratio activated the WNT signaling pathway and led to the formation of early hair follicle structures both in vitro and in vivo. The addition of WNT3a protein to the culture medium enhanced this effect, while a WNT inhibitor blocked it. The in vivo experiments, which were repeated three times using cells from three different donors, showed that pre-aggregated cells grafted onto mice skin resulted in hair shaft formation, with the greatest number of hairs forming in the pre-aggregated group. The study concluded that this method supports the rapid formation of hair follicle organoids and could be used for studying hair regeneration, assessing hair stem cells, and screening for hair growth-promoting compounds.