Hair for naked mice
Naked mouse grew new hair on a silicone chip
Daria Spasskaya, N+1
Japanese researchers have mastered a highly productive method of growing germinal hair follicles in a 96-well die. Scientists implanted germinal structures grown in vitro into the skin of a "naked" mouse, after which it grew hair. The technology, which in the future will help in the treatment of baldness in humans, is described in the journal Biomaterials.
Hair follicles are formed in the skin during embryonic development due to the interaction of epithelial cells and mesoderm, which exchange biochemical signals. In adulthood, hair follicles are no longer formed anew, but they can be "transplanted" from a donor skin area – this approach is most often used in regenerative medicine to restore hair.
Since the formation of the follicle has learned to model "in vitro", researchers are also developing methods for transplanting structures from epithelial and mesenchymal cells into the skin, followed by the formation of hair follicles from germ structures. This approach, however, is quite time-consuming, and the effectiveness of hair germination is less than 40 percent.
Researchers from the National University of Yokohama (Japan) found out that the embryonic structures of follicles (HFG – hair follicle germs) are formed even in suspension, when embryonic cells of epithelial and mesenchymal origin are mixed. At the same time, the scientists managed to scale the process of growing HFG by planting a suspension of cells in the wells of a special 96-well chip coated with polydimethylsiloxane (dimethicone). This inert polymer is one of several types of silicone oil. The silicone coating provided oxygen access to the cells – this condition turned out to be important for the formation of cellular aggregates.
The scheme of the experiment (drawings from the article in Biomaterials)
Different types of cells for growing follicles were obtained from a piece of skin of a mouse embryo. After three days of incubation in suspension, the cells spontaneously sorted to form the embryonic structure of the follicle. After that, the wells were filled with collagen, the resulting "matrix" with embryos was cut into strips and implanted into the skin of a mouse devoid of hair (nude lines). After 18 days at the implantation site – on the side or on the head – the animal grew hair. Scientists have estimated that the germination efficiency was 68 percent. Using scanning electron microscopy, the authors confirmed the formation of normal hair follicles at the implantation sites.
Hair growth on the back and on the head of a naked mouse
after implantation of embryonic follicles
According to the authors, they managed to grow similar germ structures using human keratinocytes (differentiated epithelial cells) and hair papilla cells from connective tissue, and now scientists intend to master the production of HFG from progenitor stem cells.
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