Root cause | Can stem cell transplantation really treat hair loss? Don’t rush to try it yet

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More and more people are suffering from hair loss, and the number is getting younger. There are more and more advertisements on the market for hair loss treatments, and stem cell transplantation is one of the new hair loss treatments that is being sought after. Many people believe that stem cell transplantation is an effective way to resolve their baldness crisis, save their hairline, and say goodbye to "bald people".

So, can stem cell transplantation really treat hair loss?

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As we age, we find that more and more of our relatives and friends are suffering from hair loss. Some have thinning hair, some have become bald overnight, and some are so smart that all their hair has disappeared. As a result, advertisements for solutions to hair loss are everywhere, but the actual results are not particularly ideal.

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In fact, the problem of hair loss can be said to be an international problem. Many issues have not been thoroughly studied, and many scientists with or without hair are racking their brains for this.

The number of people with hair loss is getting younger

According to the data from the National Health Commission, there are two main characteristics of people with hair loss in my country. First, the number of people with hair loss is huge. There are 250 million people with hair loss in my country, of which more than 160 million are men, mainly suffering from baldness, and nearly 90 million are women, mainly suffering from alopecia areata.

Second, people with hair loss are getting younger, with those born after 1990 being the most prone to hair loss. The majority of people with hair loss in China are between 18 and 50 years old, with those aged 26 to 30 accounting for more than 40%.

As we age, almost everyone may experience hair loss. Humans generally have 100,000 to 150,000 hairs, and losing a hundred or so hairs a day is normal. The lost hair will be quickly replaced by new hair, so there is no need to worry.

However, if hair falls out too much or new hair fails to grow, it can develop into a annoying hair loss problem.

Hair follicles are the key to solving hair loss problems

Let’s first understand the organ responsible for hair growth - the hair follicle.

Hair follicles are distributed all over our skin. Except for a few areas such as the palms, soles of the feet and lips, hair follicles are present in most other areas, and the head is one of the areas with the densest hair follicles.

The hair follicle is a bit like a long pocket. The upper part of the hair follicle is the hair, including the hair shaft part exposed on the body surface and the hair root part buried in the skin, and the lower part is the hair bulb, which is a bit like a light bulb. The lowest part is connected to the circulatory system through the dermal papilla, providing nutritional support for various cells in the hair follicle, promoting cell division and differentiation, and thus producing hair.

The hair follicles also have accessory structures such as the arrector pili muscle and sebaceous glands. The arrector pili muscle is a long muscle responsible for "goose bumps", and the sebaceous glands secrete sebum to protect the hair.

The hair follicle is a bag-like epithelium formed by a series of epidermal cells. Its base is the dermal papilla, which is recessed in the dermis and is closely connected to the circulatory system (blood vessels, lymphatic vessels, etc.) to provide nutrition to the hair. Copyrighted library images, unauthorized reproduction

Hair growth is cyclical, including growth phase, regression phase and resting phase. Under normal circumstances, 85%-90% of hair is in growth phase, which lasts for 2-5 years; only about 1% of hair is in regression phase, which lasts for about 2 weeks; then enters resting phase of 1-3 months, when 10%-15% of hair begins to fall out.

Under normal circumstances, hair follicle stem cells in the resting phase begin to differentiate into new hair follicle cells and gradually reconnect with the microcirculatory system. The hair follicles regain vitality and new hair grows, and the cycle repeats. However, due to various reasons, hair follicle stem cells cannot differentiate normally, causing the hair follicles to continue to shrink, and various hair loss problems follow.

Hair follicle stem cells become an important target for hair loss treatment

There are many reasons for hair loss, such as staying up late, excessive stress, endocrine disorders, age, genetics, diseases, etc. These external and internal factors will eventually affect the hair follicles, especially the normal function of hair follicle stem cells. Therefore, hair follicle stem cells have also become the focus of scientists' research on hair growth mechanisms and treatment of hair loss.

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For example, scientists from Harvard University in the United States announced in the internationally renowned academic journal Nature that they have successfully found the main cause of hair loss caused by excessive stress through a mouse model. It turns out that when the body is under excessive stress, it will secrete a stress hormone, corticosterone, which will reduce the activity of hair follicle stem cells. As a result, hair cannot be restored in time after falling out, leading to hair loss. This research is equivalent to finding a potential target for treating hair loss. If the body can inhibit the production of similar stress hormones, it may be possible to treat this type of stress-related hair loss problem.

The research team of the Icahn School of Medicine in the United States published a paper in the journal Science, proving that a type of smooth muscle called the dermal sheath plays an important role in maintaining the microenvironment of hair follicle stem cells. When the hair enters the regression phase, the contraction of the dermal sheath can pull the dermal papilla at the bottom of the hair follicle closer to the stem cell area at the top of the hair follicle, promoting hair loss while reactivating the hair follicle stem cells and entering a new growth cycle.

Once the dermal sheath is disordered, it may accelerate the shrinkage of hair follicles, which is also one of the causes of hair loss. At present, the dermal sheath has become one of the important targets for the treatment of hair loss. Scientists hope to develop drugs to prevent abnormal contraction of the dermal sheath, slow down the shrinkage of hair follicles, and delay the shedding of old hair shafts until new hair sprouts.

Scientists are keen on studying hair follicle stem cells. In addition to studying the mechanisms related to hair growth, it also brings hope for the development of drugs and methods to treat hair loss. For example, someone recently analyzed 15 clinical studies on the use of stem cell transplantation to treat androgenic alopecia conducted worldwide from 2015 to 2021. These clinical studies involved more than 600 people, and the stem cells used included hair follicle stem cells, adipose stem cells, and mesenchymal stem cells. Most stem cell transplants have a certain effect, and some clinical studies may increase hair density by about 30%, with basically no side effects.

Among them, Shadi Zari from the Department of Dermatology at the School of Medicine, University of Jeddah, Saudi Arabia, reported the results of a retrospective clinical study involving 140 patients with androgenic alopecia. Within 1 to 6 months of autologous stem cell transplantation, about 2/3 of the patients showed significant improvement in hair loss, and major indicators such as hair density, hair thickness, and number of hair follicles in the transplanted area increased significantly.

However, these studies are not controlled clinical trials, and the therapeutic effects are only short-term, so longer follow-up studies are needed.

A clinical trial of stem cell transplantation in Saudi Arabia showed some efficacy in treating androgenic alopecia (Shadi Zari, 2021)

in conclusion

Stem cell transplantation is considered to be one of the more promising treatments for hair loss. However, overall, stem cell transplantation is still in the clinical research stage and is not particularly mature. The relevant government departments have not approved large-scale applications, so friends with hair loss should be particularly cautious when choosing stem cell transplantation for treatment.

For young friends who do not have hair loss problems yet, the most important thing is to maintain a regular schedule, not stay up late, and not have too much stress, so as to prevent hair loss problems from bothering our lives too early.

Author: Tang Bo, PhD Research Librarian in Molecular Biology

Reviewer: Cheng Fang, Chief Physician, Department of Dermatology, Xingtai People's Hospital, Hebei Province

References:

1. Choi S, Zhang B, Ma S, et al. Corticosterone inhibits GAS6 to govern hair follicle stem-cell quiescence. Nature. 2021;592(7854):428-432. doi: 10.1038/s41586-021-03417-2.

2. Nicholas Heitman, Rachel Sennett, Ka-Wai Mok, et al. Dermal sheath contraction powers stem cell niche relocation during hair cycle regression. Science, 2019, eaax9131. DOI: 10.1126/science.aax9131.

3. Krefft-Trzciniecka, K.; Piętowska, Z.; Nowicka, D.; Szepietowski, JC Human Stem Cell Use in Androgenetic Alopecia: A Systematic Review. Cells 2023, 12, 951. https://doi.org/10.3390/cells12060951.

4. Zari S. Short-Term Efficacy of Autologous Cellular Micrografts in Male and Female Androgenetic Alopecia: A Retrospective Cohort Study. Clin Cosmet Investig Dermatol. 2021 Nov 19;14:1725-1736. doi: 10.2147/CCID.S334807. PMID: 34824538; PMCID: PMC8610382.

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