New research in animals has identified a microRNA that appears to modulate the growth of hair.
The study, which appears in the journal Science Advances, may lay the groundwork for future hair regrowth treatments that are more effective and less invasive than the current options.
Hair loss is commonly associated with getting older. However, it can also be due to hormonal changes, as well as environmental and genetic factors.
Key treatments for hair loss are minoxidil and finasteride. While the Food and Drug Administration (FDA) have approved both treatments, neither is particularly effective, and both require frequent reapplication.
As the authors of the present study note, “Both are designed not for hair loss treatment but serendipity.”
As a consequence, scientists are exploring alternative ways to stimulate hair regrowth. Research typically focuses on encouraging the hair follicles — the parts of the skin that grow hair — to move from a resting state to an active state.
Rather than transplanting hair follicles, which can be costly and relies on a ready supply of donors, more recent research has attempted to stimulate hair follicle cells in the laboratory. Scientists then apply these cells directly to the area of the scalp that is balding.
However, research has shown that for this to be effective in stimulating growth, the hair follicle cells require culturing in the right conditions. These conditions involve a 3D sphere.
The hair follicle cells need to communicate with other cells to shift the hair follicle from a passive to an active state. They do this best in a 3D environment, rather than a flat 2D environment.
In the present study, the researchers began by corroborating this previous research. They did this by treating mice with 2D cultured follicle cells, 3D cultured follicle cells in a keratin scaffold, and minoxidil.
As with previous research, they found that the 3D cultured follicle cells transplanted onto the areas of baldness were more effective than either the 2D cultured follicle cells or minoxidil. After 15 days, the mice that underwent treatment with the 3D cultured follicle cells recovered 90% of their hair.
Dr. Ke Cheng, a professor in the Department of Molecular Biomedical Sciences at the College of Veterinary Medicine, North Carolina State University, Raleigh, and leader of the research, notes, “The 3D cells in a keratin scaffold performed best, as the spheroid mimics the hair microenvironment, and the keratin scaffold acts as an anchor to keep them at the site where they are needed.”
“But we were also interested in how [dermal papillae] cells regulate the follicle growth process, so we looked at the exosomes, specifically, exosomal [microRNAs] from that microenvironment.”
Dermal papillae (DP) cells help regulate hair follicle activity. MicroRNAs are molecules that help regulate the way genes send communications. They are found in small sacs, known as exosomes.
The researchers looked at the exosomes of both the 2D and 3D cultured cell follicles. They noticed that in the 3D cultured cell follicles, the microRNA miR-218-5p was encouraging the gene communication that signals hair growth.
They confirmed this when they found that increasing the microRNA increased hair follicle activity, whereas inhibiting it stopped the hair follicle from functioning.
The team’s finding is potentially valuable, as while the implantation of 3D cultured cell follicles is effective in stimulating hair follicle activity, the process of transplantation is laborious and costly.
“Cell therapy with the 3D cells could be an effective treatment for baldness, but you have to grow, expand, preserve, and inject those cells into the area. [MicroRNAs], on the other hand, can be utilized in small molecule-based drugs. So potentially, you could create a cream or lotion that has a similar effect with many fewer problems. Future studies will focus on using just this [microRNA] to promote hair growth.”