Functional mouse hair follicles can be added to parts of the body that scientists have grown successfully in the laboratory, but outside the body.
Using cells obtained from embryonic mice, for the first time researchers were able to produce hair follicle organoids – small, simple versions of an organ – that grew hair.
They were also able to influence hair pigmentation. Furthermore, the follicles functioned across multiple hair-growth cycles when transplanted into mice without hair.
The team believes that this research could aid in the treatment of hair loss and provide alternatives to existing models. Animal welfareScreening for drugs
During the embryo’s development, hair follicles are formed. The mesenchyme connective tissue layer and the epidermis outer skin layer interact to initiate the morphogenesis process, in which cells begin to join together to form an organ.
These epidermal-mesenchymal interactions that result in follicles are not very well understood. Although scientists have been able to create skin organoids from both mice and humans in a laboratory, it has not been possible to isolate follicles.
Organoid science is becoming more sophisticated over the years so a group of scientists, led by Tatsuto Kageyama, a biomedical engineer at Yokohama National University (Japan), decided to try it.
Two types of embryonic mouse cells were used to start the experiment: mesenchymal (epithelial skin) and epithelial (skin).
These cells were cultured in some cases with a substance called MatrigelA mouse-derived membrane preparation that assists cells in forming structures. Some cells were cultured with Matrigel.
It was remarkable. These two types of cells merged, and then spontaneously separated from the aggregate to form an organized structure.
These structures were not shaped by the Matrigel (or later), and didn’t develop into functional foollicles.
After six hours of seeding cells with Matrigel, however, structures formed from a core of epithelial cell and a shell mesenchymal cells.
Researchers claim that this arrangement increases the contact area between both cell types and facilitates the development of the blob to a follicle.
They were right. After 23 days, the core-shell blobs grew 2 millimeters in hair, with almost 100 percent success.
Researchers were able to observe how hair is formed and developed during this process.
A drug that stimulates melanocyte production, which is the cell responsible for pigmentation, was also tested.
This drug was added into the culture to make the hairs more pigmented.
Finally, they transplanted their cultured follicles into nude mice – lab mice specifically bred with a suppressed immune system – to observe if the organoids could integrate into a living body.
After transplantation, the organoids matured into full-follicles and produced hair for many growth cycles lasting at least 10 month.
Although this is a mouse-based study, it cannot be used to extrapolate to humans. Human research is the next step.
The team will not be using embryos for the study. Instead, they will use cells from adults to reverse engineer the cells. Stem cellsThey are hoping to cultivate the mesenchymal, epithelial, and other cells necessary for their success.
While this could be interesting in its own right, the final goal is quite ambitious. Their research could lead to treatment for conditions like pattern baldness or alopecia, which can affect any gender.
An in vitro model for hair follicle development and morphogenesis may be an alternative to animal testing.
The research of the team has been published in Science Advances.
