Scientists grow hair in laboratory and open front against baldness

Scientists at Yokohama National University in Japan have successfully grown hairs from mouse embryo cells in the laboratory.

The new research, published on the 21st in the scientific journal Science Advances, unveiled the mechanism necessary to “reprogram” cells to produce hair. When implanted in the rodents, the wires continued to grow.

The study used three-dimensional models (similar to in vivo miniatures of organs and tissues at the microscopic scale) to create hair follicles – a kind of “pouches” located in the layer of skin that contain the hair-growing structures. It is estimated that each hair follicle produces 3 to 5 hairs before dying and giving way to another cell.

However, in people with disorders that cause hair loss (known as alopecia), the hair follicles are unable to produce hair, so the person ends up losing their hair and may develop baldness.

Although still in its infancy, the experiment paves the way for research into drugs and treatments that can reverse baldness and other hair disorders.

To test whether it was possible to obtain the wires in the laboratory, the scientists created the structures that would give rise to the experiment from two types of embryonic cells, related to the formation of tissues and organs of the embryos: the epithelial cells, more external, and the mesenchymal cells, which form bones, cartilage, and other bone marrow-related structures.

Generally speaking, in a developing embryo, these cells differentiate to form the corresponding structures. When there are flaws in this process, for example when the genes that produce these structures are “turned off”, a person can develop baldness. There are different causes for alopecia, but the best known are hereditary, due to the presence of genes that inhibit hair growth, or autoimmune.

In the three-dimensional model, the cells were reorganized and added to a matrix that contained other structures involved in the production of the threads. After about three days, the cells formed perfect hair follicles, which produced hair shafts (the visible part of the strands) with almost 100% efficiency.

After 23 days of culture, the follicles already had a length of about 3 mm.

The cultured follicles, when implanted in the mice, still produced several growth cycles. Growth cycles are important because they provide the different phases of hair formation. In general, androgenic alopecia (the most common type of baldness) occurs because the cycles are short and it is not possible to guarantee all phases, emphasize the scientists.

Finally, they added a substance that helped stimulate the production of melanin, which gives color to the hair. As a result, the pigmentation of the hairs improved significantly.

According to the authors, the experiment offered the first bases for a model of manufacturing hair follicles in vitro from mouse embryonic cells and in a scalable way, but “the cultivation must still be optimized for humans”.

“A next step would be to replace rodent cells with human fetal or newborn cells, but a series of ethical restrictions must be considered. Because of this, we are investigating the use of stem cells [também chamadas pluripotentes] or donor hair to create these organelles,” the authors wrote.

Biochemist and professor at the Department of Cell Biology, Embryology and Genetics at UFSC (Federal University of Santa Catarina) Andrea Gonçalves Trentin commented on the study at the request of the report. According to her, the research is very promising and interesting, as it was able to develop a platform to obtain the hair follicle (capillary) in a three-dimensional culture system, as an alternative to the use of animals.

“The vast potential [do experimento]including the study of developmental biology, pathologies associated with alopecia, drug testing and application in regenerative medicine, are some of the highlights”, he says.

An important step now is to look for sets of human cells that can serve as a basis for organelles and that are also scalable in the laboratory. “While it is still challenging to grow human hair follicles with current technology, recent discoveries have significantly advanced the biotechnological knowledge that can provide these potential cells, including chemical or molecular reprogramming of genes.”