There are hopes that regenerative medicine will eventually replace organ transplants, and research is underway to create mini organs, known as organoids, from stem cells. The interaction between epithelial cells, derived from the epidermis and other tissues on the body's surface, and mesenchymal cells, responsible for binding cells together, are crucial for creating complex three‐dimensional tissues in‐vitro. However, this mechanism has yet to be fully clarified, and studies using typical model hair follicles have not yet produced mature follicles.
Tatsuto Kageyama and his colleagues of the Kanagawa Institute of Industrial Science and Technology have developed a method to produce follicular organoids that produce long mature hairs in‐vitro with high levels of efficiency. The team first focused on the spatial arrangement patterns of aggregates formed by mouse epithelial and mesenchymal cells in the early stages of culture. They found that in structures that excluded heterogeneity, hair follicles hardly regenerated at all. However, they regenerated with almost 100% efficiency in structures with strong heterogeneity.
In this study, the team confirmed that when hair follicle organoids, which it termed "hair follicloids," were transplanted into immunocompromised mice, the hair follicles grew back on the skin and repeatedly regrew hair for at least one year. Experiments on changes in hair color allowed the team to visualize the movement of melanosomes used to color hair shafts and to evaluate the effects of drugs that darken hair color.
These results shed some light on the mechanism by which hair follicles are regenerated in‐vitro. Hair follicloids are expected to see various uses, including as an in‐vitro model for understanding biological phenomena and as a screening tool for medications for gray hair and alopecia.
