Yes odalbak, that indeed is speculation, though based on the paper of Cotsarelis where he and his team removed tissue to induce regrowth. I assume they went that deep for the same reason.
In my layman's understanding, it just does not make sense to damage something that is constantly thrown out anyway and on top of that does not have anything to do with hair follicles. I think that just inducing FGF-9 is not enough; if it was, there would already be a treatment composed of just this. I think the key here is to force the body into creating scalp tissue from scratch, namely in the layer that hosts the DPs. Growth factors are not enough on their own, I am pretty sure of that. Otherwise the solution to all our problems would've already been found.
@princessRambo: Valid points under the assumption that minoxidil indeed is the only way to increase PGE2 and thus FGF9. After having read more than a dozen studies about minoxidil, I am pretty sure that minoxidil per se does not even increase PGE2 levels. That is only a side effect of its vasodilatory function. PGE2 is a product and signaler down the inflammation cascade, which is, by the way, comprised of many, many different substances. I think the diagrams showing which readings are elevated when after wounding were also posted earlier in this thread.
Anyway: The only confirmed primary function of minoxidil is vasodilation. This is not a surprise given that it is an NO compound similar to adenosine (there also exists a paper that for this reason tries to establish that minoxidil only works THROUGH adenosine, while I speculate it is either metabolised into adenosine or an agonist). As such, it will just flush everything where it does its workings. This can include pro-inflammatory substances such as PGD2, thus triggering the inflamed area to enter the next stage, where the body will upregulate PGE2 by itself. Additionally, minoxidil and adenosine in their role as neurotransmitter blockers just put all body processes to a halt where applied, including new collagen formation but also inflammationary processes in general.
FGF-9 however will also be expressed just by itself, when deep scalp tissue renews. FGF-9 will only be elevated by the body where it "makes sense", i.e., you will not find elevated levels of FGF-9 in inflamed kidneys or tonsils. So while minoxidil may be beneficial, it is not crucial, and PGE2 will also be expressed by itself after wounding. I think that FGF-9 will be elevated by the body anyway as a response to deep wounding in that area.
princessRambo said:
The indian study clearly stated they have seen new follicle growth at the 6 weeks mark, and bear in mind, they didn't even apply that much pressure as they clearly stated they only rolled until mild redness. So what can we conclude from that, the needle didn't go deep enough to draw blood, but follicular neo genesis still somehow took place.
I am fully aware of that. In this case, with small needles, the minoxidil indeed is crucial. minoxidil dissolves hard fibrotic collagen tissue where it has "access", and the small wounds give minoxidil that access. Otherwise, the minoxidil is held off by the collagen it has not yet dissolved. minoxidil acts like acid on collagen - it first needs to dissolve the top layer until it can go deeper. The small wounds (that are first filled by very soft tissue) provide channels for the minoxidil to go deeper than without. That's at least my understanding.
Edit:
Just to make my point clear: We have two papers here.
1) The indian one, which did not induce deep wounds, but used minoxidil. Worked.
2) Cotsarelis. Deep wounding, no minoxidil. Worked, as long as FGF9 expression was ensured - which is, to my knowledge at least, the case when you hit the subcutis with wounds. minoxidil by itself does not increase FGF9 anyway - as long as inflammation does not go chronic, the body is going to send PGE2 (and thus FGF9) anyway.
This image also seems to imply that follicles formed in completely new tissue in this study, i.e., they went quite deep, where the DP usually sit.
And that is exactly my point: Two ways of working here.