Category Archives: Rodney Sinclair

The Arrector Pili Muscle (aka the Goosebump Muscle)

Several weeks ago, the arrector pili muscle got significant coverage in a few newspapers around the world. Famed Australian dermatologist Dr. Rodney Sinclair co-authored an important paper titled “The arrector pili muscle, the bridge between the follicular stem cell niche and the interfollicular epidermis” that was just published this month. Dr. Sinclair has been involved in this area of hair loss research for a few years and already published similar findings several times in the past decade. Nevertheless, Australian newspapers were especially interested in this latest study and its findings as evidenced by articles such as this one and this one.

The Arrector Pili Muscle

Arrector pili muscles are small muscles attached to individual human hair follicles on both the scalp as well as body (so we have millions of these muscles throughout our bodies). Contraction of these muscles causes hairs to stand up, a phenomenon that is known as goosebumps. Therefore, the arrector pili muscle is often referred to as the goosebump muscle.

The Arrector Pili Muscle Degeneration and Hair Loss

In recent years, a few studies have come out that suggest a possible connection between the arrector pili muscle degenerating (where it gets replaced by fat) and hair loss due to the subsequent disconnection between various hair follicle stem cell populations. It is possible that an intact arrector pili muscle plays a crucial role in the maintenance of follicular integrity and stability.

However, there are many uncertainties about this theory that I discuss in the next section. It seems that while in alopecia areata (AA) patients the arrector pili muscle remains intact, this is not true in androgenetic alopecia (AGA) patients (and unfortunately over 95 percent of balding men suffer from AGA). So this could be why it is much easier to grow back hair for people with AA compared to people with AGA. However, the rate at which the arrector pili muscle degenerates and gets replaced by fat varies substantially between patients and between individual hairs on the same scalp. Some miniaturized vellus hairs in balding regions might even never lose most of their arrector pili muscle connection.

Points of Contention

  • According to Dr. Sinclair’s own quote from a past paper, “It remains unclear whether arrector pili muscle regression is a cause or effect of permanent follicle miniaturization“. I think this is the crux of the issue surrounding this theory/hypothesis.
  • It seems like hair that is transplanted from the back of a person’s scalp to the front of that same person’s scalp regenerates the arrector pili muscle. A very important related study from 2012  comes to us from Japan. So it might be very possible to regenerate this muscle.
  • There are 100s of anecdotal reports on the internet of people regrowing long-lost hair. On the internet, you can find many reports of old men who recently started taking Dutasteride for enlarged prostate issues and have subsequently noticed hair regrowth on areas of their scalps that have been totally devoid of any visible hair for decades. Maybe they regenerated their arrector pili muscles; or maybe their arrector pili muscles always remained intact in spite of severe AGA; or maybe one can regenerate hair without the need for having any intact arrector pili muscles?
  • It is unclear when exactly we have a point of no return where the arrector pili muscle is largely or entirely replaced by fat and hair stops growing (either as a cause or effect — see first bullet point above). It seems like there is significant variation depending on person and hair follicle. In many cases, the arrector pili might not be entirely degenerated and replaced by adipose tissue even in areas of the scalp where one has been bald for several decades. In such cases, subsequent hair and muscle regeneration could perhaps even be possible via something like Dutasteride or Finasteride?

It would seems that just as with out bodies, muscle beats fat yet again. However, as is always the case in the world of hair, nothing is ever straightforward! Even fat has significant hair growth benefits in the correct circumstances.

Brief Items of Interest, October 2016

Hair loss news first:

Update: A day after I wrote this post, CNN covered JAK inhibitors in a new article (in a pleasant surprise, they also looked at the androgenetic alopecia — AGA — angle).  Usually, all these articles on JAK inhibitors only look at alopecia areata (AA).  Yet again, Dr. Christiano says she is optimistic that JAKs could work on AGA patients (but only in a topical form).  Dr. Brett King is not optimistic, but he is still testing it out (in a lotion form) on his AA patients (probably the ones who also have AGA).  In the above article, the one AA patient who they show with regrown hair after being on oral JAK inhibitors did not regrow hair that he lost to AGA, although it is impossible to tell whether he did not regrow 100 percent of his AGA hair loss or not.  In any event, we will only know for sure about this once they test topical JAK inhibitors out so people should not get so emotional about this subject each time there are new developments.  You should also not try to test your own topical version as even the experts are having a hard time developing the appropriate version.  According to Dr. Christiano:

“Though she thinks men might have the same success with an ointment, she said the trick is that it has to penetrate properly. Compared with the paper-thin skin of mice, human skin is “much thicker, and it’s oily, and it’s deep, and it’s got a fat layer — so there’s a lot to think about when making a good topical formula.”

It is well worth watching the video in the above article just to see the funky haired mice.

— In a first, myself as well as all of this blog’s commentators missed the important International Society of Hair Restoration Surgery (ISHRS)’s 24th Annual Congress that ran from September 28th through October 1st in Las Vegas.  I did not even see any threads on the conference in any of the hair loss forums out there, which is strange.  I usually cover the 2-3 most important hair loss related conferences in the world every year in separate posts, but this time I forgot to do so.  You can find the detailed ISHRS 24th Congress final program guide here.  As usual, there were way too many interesting presentations.  For our purposes, the most important ones were:

  • Dr. Angela Christiano: “JAK Inhibitors, Hair Regeneration and
    Genetic Testing”.
  • Dr. Pantelis Rompolas: “Potency and Contribution of Stem Cells to Hair Follicle Regeneration”.
  • Dr. Rodney Sinclair: “Advancing our Understanding of the Biology of Androgenetic Alopecia and Changing the way we use Minoxidil to Treat it”.
  • Dr. Angela Christiano and Dr. Ken Washenik led a discussion titled “Biotechnology in Hair Regeneration”.

On Twitter, Dr. Alan Bauman told me that while Dr. Christiano did not provide any data on JAK inhibitors for androgenetic alopecia (AGA), she did hint that JAK inhibitors seem to stimulate the anagen phase of the hair growth cycle.  Fingers crossed as usual when it comes to this subject.  I was surprised at the number of presentations on body hair transplants (BHT), with Dr. Arvind Poswal discussing long-term ten-year plus results of his BHT patients.  Also surprising were the number of presentations on platelet-rich plasma (PRP).

— In stark contrast to the above omission, in the past week at least 10 (!) people either commented under a blog post or e-mailed me about cosmetics behemoth L’oréal (France) and Poietis (France) partnering to bioprint hair follicles via laser. This news item was extremely well covered across the global media and there are hundreds of articles on the internet about this interesting subject matter.  The end goal “holy grail” of this research will be to implant the new hair follicles into balding regions.  Below is the official company video outlining the technology and the goals behind this partnership:

— Unfortunately, it seems like Replicel has not fulfilled the contractual obligations of its partnership with Shiseido (although the former disputes this allegation).  In any event, it is unlikely that this will stop Shiseido from proceeding with its plans.

Cassiopeia (Italy) updates us on its topical anti-androgen product Breezula (formerly called CB-03-01).  Also see my past post on this subject.  It seems like even if phase 2 and phase 3 clinical trials succeed, this product will not come to market before 2021.

— Samumed’s Dr. Osman Kibar’s presentation (a small part of it is on hair loss) at a recent conference organized by the UK’s Royal Society of Medicine.  He received many compliments on Twitter for his presentation.

Cellmid has better than expected quarterly sales of its FGF5 inhibiting product Evolis in Australia.

Kerastem completes enrollment in Phase 2 clinical trials.

Spex has a brand new updated website, which is worth a visit.

— Former baseball great Jose Canseco just announced today that he will get a hair transplant with Dr. Parsa Mohebi next week.

— Sportscaster Joe Buck’s hair transplant addiction nearly cost him his voice and his career.

The benefits of going bald.  I would much rather have none of those benefits and hair instead:-)

Men’s vanity involves hair transplants.

And now on to medical items of interest:

— The National Geographic is a highly reputable magazine so I believe them when they say that ending blindness is no longer just a dream.

Rapamycin could make your dog (and maybe humans too) live longer.

Microsoft aims to cure cancer in ten years.  In the end it is just a programming error.

— A very interesting new endeavor: “Human Cell Atlas project aims to map the human body’s 35 trillion cells“.

Teeth regeneration advances.

Building a bionic spine.

3D printing continues to revolutionize the field of prosthetic limbs.

First “three person baby” born in Mexico (doctors went there from the USA so as to escape strict regulations).  Baby’s parents were Jordanian.  Medicine will hopefully soon become very multinational.

Stem cells regenerate damaged monkey heart.

— Yet more evidence that turmeric is very good for you, but only when added to food that is then cooked.

Endurance training causes positive genetic changes.

— Not sure if I believe half the stuff in the below video, but it is well presented with 100 percent thumbs up likes thus far: K. Comella: “Reversing Aging with Stem Cells”: