Neural stem cells restore hair growth through activation of the hair follicle niche

Several types of hair loss result from the inability of hair follicles to initiate the anagen phase of the hair regeneration cycle. Modulating signaling pathways in the hair follicle niche can stimulate entry into the anagen phase. Despite much effort, stem cell-based or pharmacological therapies to activate the hair follicle niche have not been successful. Here, we set out to test the effect of neural stem cell (NSC) extract on the hair follicle niche for hair regrowth. NSC extracts were applied to the immortalized cell lines HaCaT keratinocytes and dermal papilla cells (DPCs) and the shaven dorsal skin of mice. Treatment with NSC extract dramatically improved the growth of HaCaT keratinocytes and DPCs. In addition, NSC extract enhanced the hair growth of the shaven dorsal skin of mice. In order to determine the molecular signaling pathways regulated by NSCs, we evaluated the expression levels of multiple growth and signaling factors, such as insulin-like growth factor-1 (IGF-1), hepatocyte growth factor...