The length and size of hair are dependent on the anagen, growth stage, of the hair cycle. It also depends on the amount of oxygen and nutrients that are being delivered to the hair follicle through derma papillae with subcutaneous blood flow. However, at the cornerstone of these processes, lies the blood flow. We looked closely at the relationship between blood flow, hair growth and hair loss. While the link is straightforward, as numerous studies support the view that better blood flow leads to better hair and reduction of hair loss, we examined this relationship below, explaining the mechanics and biology to better equip you in understanding your hair in your hair growing journey.
The hair follicles are situated in the lower art of the dermis, except in the scalp where the hair follicles are around in the upper part of the subcutaneous tissue. The lower third of the hair follicles is enveloped by a rich vascular plexus – the hair root is essentially enveloped in blood vessels.
Hair follicles reconstitute themselves though the hair cycle, which also suggests the presence of intrinsic stem cells. In contrast to the previous belief that stem cells reside in the bulbar – i.e. bottom – region of hair follicles, stem cells were detected in the bulge area, a contiguous part of outer root sheath, that provides the insertion point for arrector pili muscle and marks the bottom of the permanent portion of hair follicles. Later, studies successively demonstrated that these bulge stem cells has high proliferative capacity and multipotency to regenerate not only hair follicles but also sebaceous glands and epidermis. The genesis of these stems cells are directly responsible for new hair formation and support of hair follcicles [link]
The gene overview
Aside from that, some cell growth factors, such as VEGF, FGF-5S, IGF-1 and KGF, induce the proliferation of cells in the hair follicle and surrounding vascular system also maintaining follicles in the growth phase. On the other hand, negative factors, like FGF-5, terminate the anagen phase, sometimes prematurely. We look at two of them closely.
Blood vessel grow gene
Vascular endothelial growth factor (VEGF) is a signal protein produced by cells that stimulates the formation of blood vessels.
“A few scientific studies have suggested that people with hair loss may have fewer blood vessels. But no one had actually measured how closely blood vessel growth is correlated with hair growth, or what might cause scalp vessels to grow in the first place.” – researchers concluded when compared two groups of mice, one normal and one genetically programmed to produce an abundance of VEGF.
The VEGF-enhanced mice with artificially increased amount of blood vessels, grew hair faster and thicker in the first two weeks of life than did the control mice. When normal mice were treated with an antibody that blocks VEGF activity and then shaved, their hair grew back slower and was thinner than their untreated counterparts.
Longer growth stage gene
In addition to blood flow, science had recently found a number of genes that directly affect the length of anagen stage and transition into catagen (shedding stage) of a hair follicle. Namely, FGF-5S, fibroblast growth factor 5, a molecule whose normal function is. to regulate one step in the progression of the follicle through the hair growth cycle.
FGF-5 inhibits hair growth by blocking the activation of dermal papilla cells, turning them from anagen into catagen. However, if inhibited, anagen stage can be extended. The FGF-5 inhibtor was found in an extract of Sanguisorba officinalis’ root, which, interestingly, in some folk medicine also have been found to have impact on blood. The root of the plant’s name itself means “blood” (Latin: sanguine means blood). Blocking FGF5 in the human scalp extends the hair cycle, resulting in less hair fall, faster hair growth rate and increased hair growth.
Catch-22 of ageing
As we age, many men and some women fall victims to androgenic alopecia, which relates to the sensitivity to androgens in scalp. The hair follicles fall into a culprit – known as follicle miniaturisation: the hair follicle decreases in size and therefore requires less blood supply. In turn, the less blood supply there is, the slower hair growth as with the absence of adequate blood flow, nutrients – whether applied topically or consumed as part of supplements or balanced nutrition – do not reach the hair follicle, therefore “starving” the hair root from much needed fuel even further. If it does sound like a downward spiral – it is.
Unsurprisingly, amongst the popular remedies against hair loss are:
* Inversion method to physically instils higher blood flow to scalp
* Scalp massages to stimulate blood flow
* Caffeine, popular stimulant in hair growth serums
* Derma rolling to prompt micro wounding and production of collagen as well as improved blood flow
* Castor oil with its main active ingredient being ricinoleic acid, which activating receptors in hair follicles
All these aid the proliferation of stem cells to support new hair growth, as well as strengthening existing hair follicles. Hair miniaturisation commonly associated with ageing, have also been repeatedly reported to go into remission after topical stimulants for blood flow have been introduced.
Hair growth effect of minoxidil, https://europepmc.org/abstract/med/11915519
FGF5 as a regulator of the hair growth cycle: Evidence from targeted and spontaneous mutations
Waremochi extract has an inhibitory effect on FGF-5 activity and improves hair loss by prolonging the growth period, https://www.jstage.jst.go.jp/article/nishinihonhifu/69/1/69_1_81/_article/-char/ja/
Subcutaneous blood flow in early male pattern baldness