Category Archives: Dermal Papilla Cells

Dermal Papilla Cells, Hormones, Serotonin

Hormonal Influences on Dermal Papilla Cells

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We have always been told that the hormone dihydrotestosterone (DHT) is by far the dominant cause of male pattern hair loss (aka androgenetic alopecia). However, numerous other hormones have positive and negative effects on scalp hair growth. I only realized this fully after a new study found yet another hormone to have an impact on hair growth. See the bottom of this post for a full list.

Serotonin and Hair Loss

A July 2025 publication by the renowned Dr. Junji Fukuda’s team in Japan found that serotonin (5-hydroxytryptamine, 5-HT) activates hair growth related genes in dermal papilla (DP) cells. Serotonin is both a neurotransmitter and a hormone. It is often confused with dopamine, since both are neurotransmitters, hormones and feel good molecules. Note that an older 2014 study also found that 5-HT plays a role in regulating hair pigmentation and stress-induced depigmentation.

In this study, the authors mention that circulating serotonin is mainly produced via intestine-microbiome interactions. They also briefly discuss how the microbiome produces various factors and metabolites that influence hair growth and hair regression. This has become an interesting new area of hair loss research, including via related research into the use of live biotherapeutic products to treat hair and skin disorders.

Serotonin Hormone and Hair Growth
Serotonin, hair growth and dermal papilla-intestine interactions. Source: Scientific Reports, July 2025.

Circulating Hormones and their Influence on Dermal Papilla Cells

One paragraph in the above study in regards to various hormones and their effect on hair growth caught my eye. Especially since I have covered a few of them on this blog (see highlighted links below) without realizing that the number has built up.

“Multiple circulating hormones influence DP cells. For example, dihydrotestosterone shortens the anagen phase of DP cells, while increased estrogen levels (e.g., during pregnancy) spur additional hair growth. Likewise, oxytocin and cortisol exert opposing effects on DP cells and hair growth, the former activating growth factor secretion (stimulatory) and the latter decreasing Gas6 expression (inhibitory). The circadian hormone melatonin promotes hair regeneration via activating Wnt signaling in DP cells. Research on novel hair growth-promoting hormones has accelerated worldwide in pharmaceutical and cosmetic industries, largely targeting these hormones.”

Other hormones that can affect hair growth include: the earlier mentioned serotonin; thyroid; growth hormone; testosterone; insulin and insulin-like growth factor (IGF); and prolactin.

Hormonal Influences on Dermal Papilla Cells

Below is a summary of all the hormones I have discussed in this post and their impact on hair growth (usually via impacting dermal papilla cells):

  • Dihydrotestosterone = Negative (-).
  • Estrogen = Positive (+).
  • Oxytocin = Positive (+).
  • Cortisol = Negative (-).
  • Melatonin = Positive (+).
  • Thyroid = Positive (+).
  • Testosterone = Negative (-).
  • IGF-1 = Positive (+).
  • Prolactin = Negative (-).
  • Serotonin = Positive (+).
Dermal Papilla Cells, Junji Fukuda, Yokohama National University

A Visit to Fukuda Lab at Yokohama National

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I have covered the work of esteemed and prolific Japanese hair loss researcher Dr. Junji Fukuda for almost ten years. I also wrote the below two detailed posts about his findings. The second of these is very lengthy because I have kept updating it for a few years.

Make sure to also check out the Yokohama National University based Fukuda Lab’s hair research page.

Update: June 15, 2025

Yet Another Visit to Fukuda Lab

Yet again, Tokyo TV visited world renowned hair loss researcher Dr. Junji Fukuda at Yokahama National University. A Japanese reader posted a link to the full video in the comments, but it did not load for me. However, I managed to find two of the segments on YouTube. You can turn on English captions in the videos. The Japanese viewer comments underneath the first video are funny.

Update: April 18, 2024

New Junji Fukuda interview given to Tokyo Television. Someone please translate it into English if you know Japanese. Not yet on YouTube.

Junji Fukuda TV Interview
Junji Fukuda TV Interview.

February 21, 2024

A Visit to Fukuda Lab at Yokohama National

Reader “Theo” just sent me a link to a very interesting diary of a hair transplant surgeon from Japan who just visited the Fukuda Lab.

Note that while Dr. Fukuda is based at Yokohama National University, the research seems to be taking place at Kanagawa Life Innovation Center (per the above link). One of the images also mentions the Kanagawa Center for Clinical Research & Strategy (KCCR). Yokohama is the second largest city in Japan and is the capital of Kanagawa Prefecture. Check out this PDF of the regenerative medicine sector at Kanagawa Prefecture.

From this visit and summary, I learn some very interesting things. There are three distinct methods in which Dr. Fukuda is pursuing hair regeneration. I mentioned them in my past lengthy post too, but now we have more clarity.

1) Dermal Papilla Cell Transplantation

“Dermal papilla cell transplantation is about to begin in Japan.“

Transplantation of dermal papilla cells (via stratified culture). I assume that the “stratified cuture” in the translation means 3D culturing. Dr. Fukuda mentions that Shiseido already conducted a clinical trial using 2D culturing. In this method, cells are are lined up on a flat surface when culturing, but it only resulted in a 5% increase in hair volume. The 3D method will likely be superior and the clinical trials are about to finally begin! It is hoped to be “put into practical use within five years”.

2) Transplantation of Hair Follicle Primordium

“I think this will take some time.”

The creation of hair follicle primordia means generating hair from scratch. i.e., hair multiplication. I previously discussed the Yokohama team’s process of achieving this via increasing and mixing epithelial cells and mesenchymal cells. These then form “hair follicle primordia“ that are transplanted to the same donor’s scalp in order to regenerate hair in thinning regions of the scalp.

Per the latest feedback from Dr. Fukuda, while this process has already been proven by them in mice, human hair is a different animal. Once the primordium tissue is transplanted to human heads, the direction and length grow haphazardly. He thinks that this will take some time.

3) Transplantation of Regenerated Hair Follicles in Vitro (Organoids)

“It will likely take more than 10 years before it can be used in humans.”

The final method is in vitro regenerated hair follicle transplantation (also called organoid). In this process, hair follicles are regenerated outside the body, lengthened by almost 100%, and then transplanted into the scalp. Per Dr. Fukuda, it will likely take more than 10 years before it can be used in humans.

Other Notes

In March 2023, Dr. Fukuda and his Yokohama team published an important hair regeneration related study. They made an improvement in the expansion of hair follicle stem cells (HFSCs) and dermal papilla cells via the use of a newly designed microwell array device.

The Fukuda Lab has even undertaken research on electric stimulation of human dermal papilla cells for hair regeneration.

So in one day we get two very unique insights and forecasts from Japan! Thanks again to “Theo” for all the stellar non-English language updates from Japan and South Korea.

Fukuda Lab Hair Research
Fukuda Lab’s hair research summary poster. Source:
Naohiro Uchida, Director of Almo Plastic Clinic Hair Transplantation.