Peer Review of Secreted Frizzled-Related Protein 4 Inhibits the Regeneration of Hair Follicles

In 2019, a study by Guo et al. investigated the inhibitory effect of Secreted Frizzled-related protein 4 (sFRP4) on hair growth. The study found that sFRP4 can inhibit, but not completely block, the hair regeneration cycle. However, the reviewers suggested improvements for the study. They recommended a more thorough analysis of the Wnt signaling pathway to confirm if the effect of sFRP4 on hair growth is mediated through this pathway. They also suggested a clearer description of the effect of sFRP4 on hair growth, including quantifications of hair cycle stages. Additionally, they pointed out inconsistencies in the results and discussion sections regarding the effect of sFRP4 on the structure of hair follicles. The reviewers also recommended evaluating the expression pattern of sFRP4 during the whole hair regeneration cycle, including anagen and telogen periods.