Methods in Hair Research: How to Objectively Distinguish Between Anagen and Catagen in Human Hair Follicle Organ Culture

The document discussed the development of a standardized system to distinguish between anagen VI and early catagen stages in human hair follicle organ culture, which was crucial for identifying potential hair growth promoters or inhibitors. Researchers established qualitative and quantitative criteria, including morphological assessments and immunohistochemical markers, to differentiate these stages. Anagen VI hair follicles exhibited a larger hair matrix, more onion-shaped dermal papilla, and higher melanin content, while early catagen follicles had a thinner hair matrix and more oval dermal papilla. Quantitative analysis showed more DAPI+ and Ki-67+ cells in anagen VI follicles, indicating higher proliferation, and more TUNEL+ cells in early catagen follicles, indicating higher apoptosis. The study also explored the effects of eflornithine, a hair growth inhibitor, confirming its ability to impair hair shaft elongation and promote catagen-like regression. This research provided a reliable framework for distinguishing hair cycle stages, enhancing the accuracy and reproducibility of hair follicle assays.