Hair Restoration Blog

Minoxidil (Rogaine) is one of the two proven treatments for hair loss along with hair transplant. Although minoxidil mechanism of action for hair growth is not fully understood, there have been several suggested mechanisms such as:

• Nitric oxide chemical agonist effect impactig scalp blood vessels
• Potassium channel opener causing hyperpolarization of follicles cell membrane
• Vasodilation possibly due to its nitric oxide effect

This new study is done in Department of Immunology of Kyungpook National University in Korea. The result of the study was published in The Journal of Dermatological Science shows a new mechanism for minoxidil as activator of β-catenin pathway in human dermal papilla cells, one of the two stem cells involved in development and growth of hair. The investigators announced that this mechanism could be an explanation for anagen prolongation effect of minoxidil.

The length of the actively growing hair in anagen phase (growth phase) is responsible for hair length. The investigators indicated that maintenance of β-catenin activity in the dermal papilla cells (DPCs) enables hair follicles to keep growing actively. Minoxidil or Rogain promotes hair growth in male patterned baldness suggesting that minoxidil can prolong the growth phase in hair life cycle.

The study is done in mouse model with application of 3% minoxidil for ten days. DPCs were transfected with β-catenin responsive TCF reporter plasmid. They showed that extension of anagen phase was significantly promoted after minoxidil application. The researchers concluded that minoxidil extends the anagen phase by activating β-catenin activity in the DPCs and that can be one of the main pathways in its hair growth or hair loss prevention mechanism.

Studies like this increase our understanding of hair loss and hair growth and over time can help hair restoration field to have more options to fight hair loss in a more efficient way.

Q:

Hello Doctor Mohebi,

I hope all is well and that Orlando was a success.

I am now creeping on 3 weeks post operation and just as you expected the en masse shedding commenced at right around the 2 week mark.  The good news is that I still have a sizable number left, which goes to show a large number of grafts are the way to go, but I did have a couple of more questions I thought were valuable and perhaps worthy of your blog.

1)  Even though I am at my 3rd week post op and many hairs have already been shed, many more seem to be sticking around — at least for now.  I am wondering if there’s any kind of benchmark to assess when I can expect the shedding to stop.  I would like to be able to clip all of my hair short so as to not have to keep “covering up” with hats and the alike, but I am not sure how much more shedding will take place.  Should I just wait til new hairs start to grow (1-3 months post operation, as I’ve been told) or is it relatively safe to assume that most of the hair which has not been shed after approximately a month will stick around (hang in there)?

2) For a more long-term question, what happens to the new transplants that have fallen out?  Given that telogen effluvium has taken place, I am assuming that the new hair will sprout once anagen takes place.  But here’s the dilemma:  If the front of my head contains transplants that ALL FALL OUT (for the sake of the argument, as you have stated that 90% or so of patients experience this) then that would suggest that all of this hair would be hitting CTR+ALT+DEL (or restart!) at about the same time.  If that is true, then all this hair should be hitting catagen and then telogen again at relatively about the same time, say between 2-3 years for most people.  Am I then to assume that my forehead will become synchronously thin at about 3 years only to become very full again a few months later????

Thanks Doctor.

Anonymously Yours,

A:

These are very clever questions and I will happily post them on our Hair Restoration Blog for others to see.  I will try to answer your questions in the order you asked them.

Hair Shedding After Hair Transplant

Losing hair shafts of newly transplanted hair generally occurs in most transplant cases and only a small percentage of them will continue growing the transplanted hair from the day of surgery.  Even if you are one of those lucky people who never loses their hair after surgery, you still may lose a significant number of hair shafts and only some of them will continue growing without going through shock loss.  It is not always easy to predict the timing of hair shedding in transplanted grafts, but if you have kept them for the first month after hair restoration surgery, it is likely that they will not shed.

As far as clipping your hair, you could have done it at any time after the first week following your hair transplantation.  Just be careful about the length of hair on the donor area.  You don’t want to expose your wound on the back and clipping your hair short tends to do this.  The transplanted hairs are part of your scalp at this stage and you cannot dislodge them even if you try.

Are all transplanted hairs entering the resting phase at the same time?

When hair shafts fall out due to telogen, the follicles enter their resting (or telogen) phase.  In this phase the grafts lose their shafts, the follicles shrink and become dormant for a short period of time (usually 4-6 weeks).  Following telogen comes another anagen phase in which new hairs sprout from the same transplanted hair follicles.  The initial hair grown is short and fine almost similar to vellus hair, but unlike vellus hair, it becomes longer and thicker over time.

For some reason, the biologic timer of your hair follicles are not quite synchronized.  The shedding of the transplanted hair won’t happen at the same time and therefore you won’t have to experience baldness again in the transplanted area a few years from now.  You should have some of your hair growing while a small portion of them remain in resting phase the whole time.

This type of “hair test” is done by a hair transplant surgeon or dermatologist to find out the rate of telogen hiar. It’s a simple procedure. The doctor pulls hair to find out the number of hair follicles in the resting phase. The way the test works is that the doctor grasps a couple of hair shafts between the pointing finger and thumb, then pulls them ever so softly. There are two classifications of hairs: Anagen, which are growing hairs that ought to remain in place; and telogen: hairs that should pull out rather easily.

By keeping track of the number of pulled hairs, a person can approximately calculate, in the telogen state, the hair follicle percentage. For example, if a person pulls on 10 hairs and then 2 come out, then the telogen hair follicles frequency is 20%.  If extracted hair follicles percentage is up to 25%, that is still considered OK, but if it’s over 35%, it is not normal and shows that there’s a disproportionate amount of hair in the resting phase.  This condition is often seen in Telogen Effluvium (TE).

Even though this hair-pulling test seems simple, a person may come to the wrong conclusions if they do not carry out the test properly and he or she does not have a full comprehension of the test’s limitations. The biggest concern is that the test results may be affected by what the patient did with her hair in the preceding hours. When the patient washes her hair, it will cause many of the telogen hairs to fall out.

There are several factors which can increase the accuracy of the hair pull test. The hair pull test can be ratcheted up to another level by conducting the “unit area trichogram”. This type of test requires that a couple hair follicle samples are grabbed from the scalp utilizing rubber-covered forceps; both telogen and anagen hairs are yanked. These hairs are to be placed on a glass slide and inspected using a microscope. After that, the dermatologist is to count up the telogen hairs and the anagen hairs as well.  The test can help the doctor in differentiating a variety of hair loss conditions.