This suggests that the cyclical growth of HFs depends on the activation of follicular stem cells.[21] We determined the localization of HFSC stemness via immunofluorescence double-labeling and found that the fluorescent signals of K15 and CD200, proteins associated with HFSC stemness, were significantly enhanced in the exosome group compared to those in the model group. This evidence concerns the gene CD200 and Hand-foot syndrome.