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Hair Restoration in Androgenetic Alopecia: Looking Beyond Minoxidil,
Finasteride and Hair Transplantation
Sidharth Sonthalia1*, Deepashree Daulatabad2 and Antonella Tosti3
1Consultant Dermatologist & Dermatosurgeon SKINNOCENCE: The Skin Clinic & Research Centre, Haryana, India
2Department of Dermatology and STD, University College of Medical Sciences & GTB Hospital, New Delhi, India
3Department of Dermatology and Cutaneous Surgery, University of Miami Hospital, Miami, FL, USA
*Corresponding author: Sidharth Sonthalia, Skinnocence: The Skin Clinic and Research centre, Sushant Lok-1, Gurgaon-122009, Haryana, India, Tel:
+91-124-4014661; E-mail: sidharth.sonthalia@gmail.com
Received date: December 19, 2015; Accepted date: January 20, 2016; Published date: January 23, 2016
Copyright: ©2015 Sonthalia S, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original author and source are credited.
Abstract
Patterned hair loss (PHL) is one of the most commonly encountered problems for dermatologists. PHL at an early
age is often cosmetically unacceptable, tends to be persistent and inflicts a profound negative impact on one’s
quality of life. Androgenetic alopecia (AGA) affects both genders in a distinctive pattern of hair loss from the scalp
(MPHL for male PHL and FPHL or female PHL). The etiopathogenesis of AGA is complex, so far the major factor
emphasized to be involved has been the undesirable androgen metabolism at the hair follicle level. In this review
article, we shall dwell upon the relatively newly understood pathophysiological factors behind the genesis of AGA
apart from the hormonal factors like the Wnt/β-catenin pathway, follicular micro-inflammation, prostaglandin
imbalance, loss of extracellular matrix and oxidative stress. Based on the sound understanding of these factors we
will be elaborating upon therapies for treatment of AGA beyong minoxidil, finasteride and hair transplantation.
Amongst the therapeutic options discussed include topical 5alpha reductase (AR) inhibitors like finasteride, oral 5AR
inhibitor – dual receptor antagonist dutasteride, botanical 5AR inhibitors, oral anti-androgens and estrogens for
FPHL like spiranolactone, drospirenone etc. Wnt/β-catenin activators like topical valproic acid, hair stem cell based
therapies, prostaglandin based therapies, tetrapeptides, nutritional and anti-oxidants and many more.
Keywords: Hair restoration; Androgenetic alopecia; Minoxidil;
Finasteride; Hair transplantation
Introduction
Hair loss not only constitutes one of the most commonly
encountered problems for dermatologists, it inicts a profound
negative impact on one’s quality of life [1, 2]. Advanced patterned hair
loss (PHL), especially at an early age is oen a source of depression in
young adults. Androgenetic alopecia (AGA) aects both genders in a
distinctive pattern of hair loss from the scalp (MPHL for male PHL
and FPHL or female PHL). Bitemporal recession aects 98.6% of men
and 64.4% of women; whereas mid-frontal hair loss aects nearly two
thirds of women and three quarters of men over the age of 80 years [3].
Loss of hair from the vertex is typical of MPHL, encountered in
majority of aected men. e hallmark of the condition is progressive
and gradual miniaturization of hair follicles (HFs), accompanied by
progressive decrease in the duration of anagen and reduction of
anagen to telogen ratio. Additionally in AGA, there is a delay between
the end of the telogen phase and the beginning of the new anagen
phase; a resting phase called kenogen during which the hair follicle
remains empty. e follicular miniaturization in AGA is an
asynchronous phenomenon even within a follicular unit (FU); with
aection of secondary follicles occurring in the initial phase and the
primary follicles in the last [4]. In contrast, the miniaturization process
is synchronous in alopecia areata (AA).
e etiopathogenesis of AGA is complex. e major factor involved
in the pathogenesis of AGA is the undesirable androgen metabolism at
the hair follicle level. Elevated activity of Type II isoform of the 5-alpha
reductase (5AR) enzyme, which metabolizes testicular testosterone
circulating in the blood into dihydrotestosterone (DHT) in the
genetically predisposed hair follicles of the temporal and vertex
regions, is the most signicant factor in MPHL. Decreased aromatase
activity (the enzyme that converts ovarian testosterone circulating in
the blood into 17 beta-estradiol) leading to elevated local
concentration of testosterone seems to be operative in FPHL [5]. Hair
follicles of the temporal and vertex areas of the scalp express androgen
receptors plentifully that bind to the increased local levels of DHT,
resulting in shortening of anagen and progressive miniaturization of
thick, pigmented terminal hair into thinner, non-pigmented vellus-like
hair [6]. Finasteride (FIN), the only United States Federal Drug
administration (FDA) approved oral agent for MPHL is a specic
inhibitor of 5AR, type II isoform. Minoxidil (MNX), the other FDA
approved topical agent (for MPHL as well as FPHL) apparently acts by
increasing follicular vascularity (as a potassium channel opener),
prolonging anagen and shortening telogen, and also by converting
partially miniaturized (intermediate) hair follicles to terminal hair [7].
Hair transplantation, of course remains one of the best and sometimes
the only therapeutic option in advanced AGA.
Essentially there is a four-fold reason to explore new therapies for
AGA. Firstly, the improvement with MNX and/or FIN is limited and
tends to plateau aer one to two years of continuous use. e success
rate of treatment for AGA barely exceeds 30% using either of these
agents; which brings the second reason to the fore, i.e., a high
possibility of other pathophysiologic pathways being involved in this
condition [8]. Indeed, there is now sucient evidence supporting the
role of factors other than hormones contributing signicantly to the
pathogenesis of AGA (
vide infra
). irdly, the sexual adverse eects
(SAEs) of FIN, whether sustained actually or due to the nocebo eect
[9], and the tediousness of twice-daily application of MNX oen
Journal of Cosmetology and
Trichology Sonthalia et al., J Cosmo Trichol 2016, 2:1
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Review Article Open Access
J Cosmo Trichol
ISSN:JCTT , an Open Access Journal Volume 2 • Issue 1 • 1000105
reduce patient compliance, necessitating the development of novel
therapies. Lastly, despite the advantages of hair transplantation, many
patients who are candidates for the same prefer to avoid undergoing a
‘surgical’ procedure for hair restoration. In this review article, we shall
dwell upon the relatively newly understood pathophysiological factors
behind the genesis of AGA and discuss therapies for treatment of AGA
beyond minoxidil, nasteride and hair transplantation.
New Horizons in the Pathogenesis of AGA
Wnt/β-catenin pathway – A new yspeck in androgen-
mediated pathogenesis:
e relatively recent appreciation of the role of activation of Wnt
signaling for hair growth and wound healing [10] has literally
unleashed an altogether dierent approach to stimulating hair growth.
Hair follicle regeneration begins when signals from the mesenchyme-
derived dermal papilla cells (DPC) reach multipotent epidermal stem
cells in the bulge region [11]. Activation of Wnt/β-catenin signaling in
the epidermis leads to expansion of the stem cell compartment and
skews the keratinocytes in the interfollicular epidermis and sebaceous
glands (SGs) to dierentiate along the HF lineage. e activation of
Wnt signaling, especially Wnt10b is essential for hair follicle
development, hair cycling and hair growth [12,13]. Wnt has been
shown to be the rst trigger that stimulates DPC to induce hair growth
through induction and initiation of hair follicle formation, and
prolongation of anagen [13]. While the initiation of HF regeneration
seems to require only epidermal production of Wnt, the maintenance
and growth of these hair follicles needs subsequent interaction of Wnt
pathways between dermal and epidermal cells [12,14]. Although the
exact molecular mechanisms behind Wnt-induced hair follicular
stimulation to produce hair remain conjectural, activation of the Wnt/
β-catenin pathway seems to be contributory [14-16]. e importance
of the Wnt/β-catenin pathway in AGA is underscored by the recent
demonstration of molecular cross-talk between androgens and the
Wnt signaling in DPC, in patients with AGA. In a co-culture model
with human DPC from patients with AGA and HF stem cells, Leirós et
al.. demonstrated that androgens abrogate hair dierentiation,
evaluated by hair-specic keratin 6 expression [11]. Wnt signaling
activation restored the ability of androgen-treated DPC to induce
dierentiation. Androgen treatment revealed a profound reduction of
the cytoplasmic/total β-catenin protein ratio and upregulation of the
activity of glycogen synthase kinase-3β in DPC, indicative of canonical
Wnt pathway inhibition. us, it is becoming increasingly apparent
that androgens deregulate DPC-secreted factors involved in normal
HF stem cell dierentiation via the inhibition of the canonical Wnt
signaling pathway [11]. us, an understanding of these pathways has
clearly opened a new option of targeted treatments for AGA through
the modulation of the Wnt/β-catenin pathway. is includes drugs like
valproic acid and analogs like lithium chloride and beryllium chloride,
which have been shown to induce hair regeneration in murine model
and promote human hair growth in
in-vitro
culture model; and the
hair stimulating complex, a bioengineered human cell-derived
formulation containing Wnt7a protein that has shown promising
results in Phase I human clinical trials [10, 17-19].
Follicular micro-inammation
Follicular micro-inammation and brosis are being increasingly
recognized to play an important role in AGA, especially in the early
phases. Several studies have reported mild to moderate lympho-
histiocytic inammatory inltrate in the peri-infundibular region of
HF taken from subjects with AGA compared with controls [8]. e
term 'microinammation' has been proposed, to dierentiate the
gradual, subtle, and indolent process occurring in AGA from the
prominent inammation and brosis characteristically seen in classical
cicatricial alopecias. Morphometric studies in patients with MPHL
treated with MNX showed that 55% of those with micro-inammation
had re-growth compared to 77% in those patients without
inammation and brosis [20].
e exact trigger for this follicular micro-inammation remains
speculative. e detection of the perifollicular inltrate in the upper
follicle near the infundibulum of HF in AGA suggests the localization
of potential triggers to the peri-infundibular region; e.g.
Propionobacterium
sp.,
Malassezia
sp., or other residential ora of the
follicular infundibulum, antigens of whom may be involved in the
generation of the inammatory response [21]. e role of
keratinocytes and Langerhans cells acting as antigen presenting cells
(APC) and inducing T lymphocyte inltration and proliferation
mediated by various pro-inammatory cytokines has been suggested.
Further, perifollicular brosis (appreciable on cross-sectional scalp
biopsy of scalp with AGA as ‘brotic streamers’) seems to result from
cytokine mediated activation of collagenases, such as matrix
metalloproteinases (MMPs) [8,21], and may end with complete
destruction of the aected follicles in advanced cases. Further support
for the role of micro-inammation in AGA has come from studies that
documented signicantly superior results in improving hair growth
with combinations of MNX with antimicrobials and/or anti-
inammatory agents (like zinc pyrithione, ketoconazole,
hydrocortisone, diclofenac, tea tree oil) compared with use of MNX
alone [22].
Prostaglandin imbalance
e recent discovery by Garza et al. of prostaglandin D2 (PGD2)
and its synthetase (PGD2S) being highly expressed in the scalp of
balding men with AGA, and the temporal relationship of the increased
levels of PGD2 with the initiation of miniaturization of hair follicles in
mice has serious implications for developing targeted interventions for
treating AGA [23]. PGD2 apparently inhibits hair growth by binding
to only one of its two receptors i.e. DP-2, located in the outer root
sheath of the HF [23,24]. e opposing role of prostaglandin E2
(PGE2), a known hair growth promoter was additionally conrmed by
detection of signicantly increased levels of PGE2 in hairy non-balding
scalp. is discovery emphasizes on the role of balance between PGE2
and PGD2 in controlling hair growth, dysregulation of which may be
responsible for hair loss in AGA. Logical extrapolation would favor the
therapeutic role of supplemental PGE2, and inhibitors of PGD2
signaling by DP-2 antagonists such as indole acetic acids, phenyl acetic
acids or tetrahydroquinolines [25,26].
Oxidative stress
Apoptosis of HF cells followed by early onset of the catagen phase
by lipid peroxides that generate free radicals has been demonstrated by
Naito et al. [27]. In the DPC culture study of Bahta et al., balding DPCs
not only demonstrated slower
in-vitro
growth (compared to
nonbalding scalp DPCs) but additionally showed increased nuclear
expression of markers of oxidative stress and DNA damage including
heat shock protein-27, super oxide dismutase, catalase, and
p16(INK4a)/pRB [28]. ese ndings further suggest that DPCs of
androgenetic HFs are more sensitive to environmental oxidative stress.
Citation: Sonthalia S, Daulatabad D, Tosti A (2016) Hair Restoration in Androgenetic Alopecia: Looking Beyond Minoxidil, Finasteride and Hair
Transplantation. J Cosmo Trichol 2: 105. doi:10.4172/jctt1000105
Page 2 of 13
J Cosmo Trichol
ISSN:JCTT , an Open Access Journal Volume 2 • Issue 1 • 1000105
Indeed, pro-oxidant eects are suggested as the major mediators of
smoking and ultraviolet light induced exacerbation of AGA [21].
Loss of extracellular matrix (ECM)
In recent past, the loss of extracellular matrix (ECM) proteins in the
follicular bed contributing to progressive reduction in the size of the
hair follicle and loss of hair anchoring has gained attention as an
additional pathogenetic factor for AGA [29]. e ECM is the
extracellular part of tissue that usually provides mechanical and
structural support to the follicle cells. An appropriate amount of ECM
proteins, specically collagen type III, laminin and collagen VII is vital
to provide a good anchorage of the hair sha to the bulb [30]. In
addition, the ECM components regulate metabolic functions of the
cells surrounded by the matrix by - promoting anchorage of hair sha
in the HF, and modulating cell growth by binding and retaining
growth factors. Replenishment and re-modeling of these ECM
components by dermal broblasts is thus essential to ensure the
integrity of ECM and strong anchorage of the developing HF with the
bulb. Results from early DPC culture based studies by Randall et al.
have implicated an indirect role of androgens in altering the
production of regulatory substances such as growth factors and/or
ECM components acting via the cells of the dermal papilla, which is
their primary target [31].
In AGA, the naturally occurring tetrapeptide acetyl-N-Ser-Asp-Lys-
Pro (AcSDKP), a potent angiogenic factor has been demonstrated to
not only upregulate the synthesis of epidermal keratins, but also ECM
associated components including collagen III as well as the
glycoaminoglycans (GAGs). In the
ex vivo
-cultured hair follicles,
AcSDKP were found to promote hair sha elongation and induce
morphological and molecular modications culminating into
stimulation of hair growth [32]. Biomimetic peptides such as
acetyltetrapeptide-1 and 3, and their combination with botanical
extracts like
Trifolium pratense
ower extract, or biochanin-A (an
isoavone derived from red clover), enhance hair growth primarily by
stimulation of ECM protein synthesis in the vicinity of the hair follicle
[29]. Figure 1 summarizes salient points regarding these relatively
newer pathophysiological mechanisms implicated in AGA.
Wnt/β-catenin pathway
The activation of Wnt/β-catenin signaling essential for hair follicle development, hair cycling and hair growth
Wnt recently been shown to be the first trigger that stimulates dermal papilla cells (DPC) resulting in induction and initiation of hair follicle formation
Reduction of the cytoplasmic/total β-catenin protein ratio and upregulation of glycogen synthase kinase-3β in DPC – induced by androgens
Activators of Wnt/β-catenin signaling stimulate hair follicle (HF) formation in androgenetic alopecia (AGA)
Follicular microinflammation
Follicular microinflammation recognized to play pathogenetic role in early phases of AGA.
Mild to moderate lymphohistiocytic inflammatory infiltrate reported in the peri-infundibular region of HF of subjects with AGA, compared with controls
Potential triggers of follicular microinlammation – suspected to be localized to the peri-infundibular region; antigens of Propionobacterium sp., Malassezia sp., or other
residential flora may be involved in generating the inflammatory response.
Keratinocytes and Langerhans cells may be acting as antigen presenting cells (APC), inducing T lymphocyte infiltration and proliferation via pro-inflammatory
cytokines.
Perifollicular fibrosis contemplated to occur in later stages, plausibly a result of activation of collagenases, especially matrix metalloproteinases (MMPs); may lead to
complete destruction of HFs
Prostaglandin Imbalance
Increased expression of prostaglandin D2 (PGD2) and its synthetase (PGD2S) reported in scalp of men with AGA.
Increasing levels of PGD2 temporally related with initiation of miniaturization of HFs
PGD2 inhibits hair growth via DP-2 receptors located in the outer root sheath of the HF.
Prostaglandin E2 (PGE2) has a reverse effect and has hair growth promoting effects.
Imbalance of the levels (PGD2 > PGE2) seem to contribute to hair loss in AGA.
Oxidative Stress
Compared to non-balding scalp DPCs, the balding DPCs not only demonstrated slower in-vitro growth but aalso showed increased nuclear expression of markers of
oxidative stress and DNA damage including heat shock protein-27, super oxide dismutase, catalase, and p16(INK4a)/pRB.
Pro-oxidant effects by free radical are suspected to be the major mediators of smoking and ultraviolet light induced exacerbation of AGA.
Figure 1: Insights from the recently understood pathogenesis of AGA.
Newer Drugs for Hair Growth (Other than Topical MNX and
Oral FIN)
Topical minoxidil and nasteride (5α reductase type II inhibitor) are
the only FDA approved treatments for MPHL. Both agents arrest
progression of hair loss and stimulate partial hair regrowth. Several
other drugs are also used o-label and a plethora of novel treatments
with partially substantiated hair growth claims are making inroads in
trichologists’ prescriptions. us, the knowledge of these alternative
drugs, their mechanism, dose protocol and adverse eects is exigent
for today’s practicing dermato-trichologist. Figure 2 summaries salient
points regarding major pathogenetic mechanisms.
Citation: Sonthalia S, Daulatabad D, Tosti A (2016) Hair Restoration in Androgenetic Alopecia: Looking Beyond Minoxidil, Finasteride and Hair
Transplantation. J Cosmo Trichol 2: 105. doi:10.4172/jctt1000105
Page 3 of 13
J Cosmo Trichol
ISSN:JCTT , an Open Access Journal Volume 2 • Issue 1 • 1000105
Figure 2: Schematically outlines of the major pathogenetic mechanisms involved in AGA and important treatment options targeting the same.
Hormone Antagonists and Hormone Response
Modulators
Topical 5AR inhibition
e use of anti-androgens in a topical formulation has always been
an attractive proposition, since it is expected to deliver some ecacy of
the oral drug, with minimal risk of systemic adverse eects. In a
randomized single center, open-label, parallel-group, exploratory study
conducted in 24 healthy men with AGA subjects received either
multiple scalp applications of the topical solution of FIN (0.25%)
twice-a-day or oral FIN 1 mg once-a-day for 7 days. A strong and
comparable inhibition of plasma DHT was observed in both the
groups, but the serum levels of nasteride were signicantly lower with
the topical application group [33]. e investigators, however did not
measure the scalp DHT levels. In a retrospective assessment of 50 male
patients aged 20-40 years with AGA, who had initially been treated
with topical MNX and oral FIN for a period of two years, and aer
which the oral FIN was replaced with combination of topical 5% MNX
fortied with 0.1% FIN, 84.44% maintained a good hair density
with topical combination therapy. us, topical nasteride can be
considered for hair density maintenance aer initial improvement with
oral nasteride, thereby obviating the indenite use of oral nasteride
[34].
Oral 5AR inhibition – Dual receptor antagonist dutasteride
In contrast with FIN, dutasteride, is a dual 5AR inhibitor and is
approximately 3 times more potent than FIN at inhibiting type II 5AR
and almost 100 times more potent at inhibiting type I isoenzyme [35].
e eect of dutasteride is dose dependent. A phase II randomized
Citation: Sonthalia S, Daulatabad D, Tosti A (2016) Hair Restoration in Androgenetic Alopecia: Looking Beyond Minoxidil, Finasteride and Hair
Transplantation. J Cosmo Trichol 2: 105. doi:10.4172/jctt1000105
Page 4 of 13
J Cosmo Trichol
ISSN:JCTT , an Open Access Journal Volume 2 • Issue 1 • 1000105
placebo-controlled study of dutasteride versus nasteride showed
superiority of 2.5 mg of dutasteride over 5 mg nasteride in improving
scalp hair growth in men aged 21-45 years.[36]. e onset of hair
growth was also earlier in the dutasteride group. Improvement of hair
loss with dutasteride 0.5 mg has also been demonstrated in a lady who
failed to show any response to nasteride [37]. It has been safely
administered in women with FPHL in doses of 0.15mg per day for
three years [38]. Side eects including decreased libido, impotence and
gynecomastia are slightly higher with dutasteride than with FIN [36].
In addition, the nocebo eect, described for FIN [9] is also likely to be
encountered with dutasteride in the more educated and internet-savvy
patients. e long serum half-life of 4 weeks of dutasteride results in
persistent suppression of DHT level even aer dutasteride is ceased.
us, patients taking dutasteride should not donate blood until at least
6 months aer stopping their medication [36]. Currently, dutasteride
0.5mg dose is FDA approved for the treatment of benign prostatic
hyperplasia while its use in MPHL and FPHL remains “o-label”. It is
worth trying in patients with advanced PHL and when FIN delivers
sub-optimal.
Botanical 5AR inhibitors
Owing to the SAEs associated with FIN and dutasteride, extracts of
herbs with 5AR inhibitory eect have been explored as an alternative.
Saw palmetto berry (SPB) extract derived from the berry of the
American dwarf tree (
Serenoa repens, Sabal serrulata
) is the most
popular phytotherapeutic agent used in the treatment of AGA as well
as benign prostatic hypertrophy (BPH). e extracts from the ripe
berries of saw palmetto contain various phytosterols (e.g. β-sitosterol),
fatty acids, β-carotene and polysaccharides. SPB is being promoted as
the ‘herbal side-eect-free version of nasteride) for the treatment of
AGA. SPB acts as a multi-site inhibitor-cum-blocker of DHT [39]. It
blocks approximately 50% of the binding of DHT to ARs in the target
cells. It also blocks the nuclear uptake of DHT in target cells, and
strongly inhibits the action of the enzyme 5AR thereby reducing the
conversion of testosterone to DHT. Additionally, saw palmetto
increases activity of the 3α-hydroxysteroid-dehydrogenase, the enzyme
responsible for the metabolism of DHT into androstanediol, a weaker
androgen.
While the principle molecules responsible for the aforesaid actions
of saw palmetto are phytosterols, their activity is enhanced in their
conjugated state with fatty acids. ß-sitosterol has been suggested to
result in local reduction of testosterone (the substrate for formation of
DHT) in the microenvironment of 5AR active tissues such as the
prostate and the hair follicle. us, the pharmacodynamics of saw
palmetto dier from that of FIN in the following ways 1) dual inhibitor
of both isoforms of 5AR 2) competitive as well as non-competitive
inhibition of the enzyme, and 3) multi-site eect, in addition to 5AR
inhibition. In terms of side-eects, multiple trials on BPH have
consistently shown SPB to be free of the SAEs typical of FIN and
dutasteride [40]. In a placebo-controlled, double-blind study
conducted in 26 healthy men aged 23-64 years with mild to moderate
AGA, subjects were randomly assigned to receive the active oral sogel
(consisting of saw palmetto extract 200 mg and ß-sitosterol 50 mg as
the major ingredients, with additional components to increase the
bioavailability such as lecithin, inositol, phosphatidylcholine, niacin,
and biotin) or a matching placebo; one sogel twice daily in both the
groups for 21 weeks duration. Out of the 26 subjects, 19 completed the
study. Treatment ecacy at the nal visit as per the investigative sta
assessment of change in the patient’s scalp hair growth from baseline
(‘improved’) was reported to be 60% vs 11% in the study group vs
placebo group respectively [41]. e adverse eects in the study group
were mild and transient. ough botanical 5AR inhibitors lack the
SAEs of FIN, their ecacy in improving hair growth in AGA is inferior
to their synthetic counterparts. is has been revealed in a 2-yr long
open label study of 100 male patients with AGA, in which the hair
growth score was higher in the group that received FIN 1 mg every
day, compared to the group that received
Serenoa repens
320 mg daily
for the same period. Moreover, the eect of
Serenoa repens
over the
front area was inferior to that of FIN [42]. us, larger and gender-
specic trials with better dened ecacy end points are needed to
discern the role of saw palmetto as a treatment option for AGA.
Oral anti-androgens and estrogens for FPHL
Androgen-dependent oral drugs for FPHL include 5AR inhibitors
and anti-androgens. Owing to their propensity to cause feminization
of the male fetus, they are contra-indicated in pregnant women. Use of
these drugs in combination with oral contraceptive pills (OCPs) oers
two advantages. Not only do they provide eective contraception to
prevent teratogenic eects of anti-androgens in a woman of
reproductive age group, the estrogen component of the pill has
additional hair growth stimulatory eects. It has been suggested that
estrogens act both directly (by prolonging the anagen phase acting via
follicular estrogen receptors) and indirectly (by increasing sex
hormone binding globulin (SHBG) production, which reduces
androgen levels by binding to them) [7,43]. Cyproterone acetate (CPA)
blocks androgen receptors and inhibits gonadotropin-releasing
hormone (GnRH). In many countries including India, it is available in
combination with estradiol as an OCP [44]. e benecial role of CPA
seems to be greater in patients with evidence of hyperandrogenism. In
two studies, combination therapy of CPA with estradiol resulted in
signicant decrease in shedding and thinning of hair in patients with
FPHL [45,46]. Spironolactone, another anti-androgen oen used for
treating hirsutism and acne, has also been found to be comparably
ecacious to CPA in a trial involving 80 FPHL patients [46]. e dose
used was 200 mg daily. Drospirenone, a 17α spironolactone derivative
possesses progestagenic, anti-androgenetic, and antialdosteronic
activities, but is devoid of uid retention property. Administered in a
dose of 3 mg/day in combination with 30 µg of ethinylestradiol during
a 21-day cycle, it has become a favoured pill for women with PCOS
and is expected to have benecial eects in FPHL [7]. Flutamide, a
selective anti-androgen has found to be eective in FPHL when given
for at least a year in dose of 250 mg/day [47]. Two randomized studies
reported greater improvements with utamide than spironolactone,
FIN, and CPA [46,48]. Unfortunately, the adverse eects of this drug,
especially dose-related severe hepatic dysfunction (seen in upto
3/10,000 patients) make it an unpopular choice for many trichologists.
Wnt/β-catenin Activation
Topical valproic acid
Valproic acid (VPA), a widely used antiepileptic, is known to
activate the Wnt/β-catenin pathway, which is associated
with hair growth cycle and anagen induction [17,18]. Aer initial
encouraging results from murine-model based studies, a recent
randomized, double-blind, placebo-controlled clinical trial was
conducted in 40 men with AGA of which 27 completed the trial.
Patients with moderate AGA received either VPA (8.3%) or placebo
spray for 24 weeks. Phototrichogram analysis was employed to evaluate
the primary end-point for ecacy, i.e., change in hair count during
Citation: Sonthalia S, Daulatabad D, Tosti A (2016) Hair Restoration in Androgenetic Alopecia: Looking Beyond Minoxidil, Finasteride and Hair
Transplantation. J Cosmo Trichol 2: 105. doi:10.4172/jctt1000105
Page 5 of 13
J Cosmo Trichol
ISSN:JCTT , an Open Access Journal Volume 2 • Issue 1 • 1000105
treatment. e mean change in total hair count was signicantly
higher in the VPA group than in the placebo group [49]. Adverse
eects were mild and self-limited.
Hair stimulating complex (HSC)
Hair stimulating complex (HSC) is a bioengineered human cell-
derived formulation containing Wnt7a protein, epidermal growth
factors and follistatin, manufactured from naturally secreted growth
factors, proteins and other synergistic bioproducts that are derived
from culture of newborn cells grown in an oxygen-decient embryonic
environment. In phase I trial, intradermal application of 0.1 cc of HSC
resulted in signicantly increased hair sha thickness, hair density and
number of total terminal hair without any signicant adverse eects,
compared with placebo at 12 weeks [19]. Interestingly, the eect was
maintained aer 1 year of treatment at the HSC-treated sites. Phase II
trials are ongoing to gather more evidence in favour of HSC as a viable
therapeutic modality for PHL.
Stem cell-based therapies
Cross-species injection of antlerogenic stem cells in rabbits has
demonstrated increased number in hair follicles in the treated sites.
Moreover, these xenogenous stem cells induced an insignicant
immune response when compared with vehicle alone [50]. is
breakthrough, despite the need for substantiation with more studies,
has raised the possibility of using puried animal stem cells to promote
hair growth in humans [10]. Attempts to generate a follicular germ by
combining stem cells and dermal papillae followed by scalp
implantation of the germ have also proved fruitful with growth of a
viable hair follicle that was able to repeat the hair cycle, mingle with
the surrounding tissues and achieve piloerection [51]. ese results
invigorate the possibility of creating a functional hair follicle from
follicular stem cells, i.e., bioengineering hair for transplant. Trials are
ongoing to evaluate the possibility of creating new hair follicles by
injecting autologous dermal and/or epidermal cells.
Prostaglandin-Based erapies
Prostaglandin and prostamide analogues
Although drugs that block PGD2 signaling or enhance PGE2 are
under trial for evaluation of their ecacy and safety in AGA, other
prostaglandins also have therapeutic eects. e prostaglandin F2α
analogue latanoprost, and prostamide F2α analogue bimatoprost,
commonly used in treating glaucoma were serendipitously discovered
to be promoters of hair growth of eyelashes and eyebrows. ey result
in hair growth through modulatory action on the dermal papilla that
results in induction of the anagen phase in telogen hair follicles.
Bimatoprost is the only FDA-approved topical for hypotrichosis of the
eyelashes [52]. In anecdotal reports and few studies, these analogues
have resulted in modest hair regrowth in alopecia areata, involving the
eyebrows and eyelashes. ey are also used for cosmetic enhancement
of eyelashes. However, the use of these agents in PHL lacks robust
evidence. Following encouraging results from animal model-based
studies, a randomized comparison study that evaluated the use of
topical latanoprost 0.1% versus placebo (solutions applied daily to two
minizones of the scalp) in 16 men with Hamilton II–III patterned
alopecia revealed a signicant increase in hair density of both terminal
and vellus hair on the latanoprost-treated site at 24 weeks, compared to
baseline and to the placebo-treated site [53]. Fiy percent were dened
as having a “good clinical response” (treatment better than placebo in
at least two of the study criteria). Adverse events were limited to
folliculitis, erythema, and burning sensation on application. In
contrast, scalp injections of bimatoprost 0.03% weekly for 12 weeks
and then biweekly for 4 weeks attempted in a 59-year-old female with
FPHL failed to improve the condition [54]. us, it is premature to
comment on the ecacy of this group of drugs in PHL at present.
Direct Stimulation of Stem Cells and Dpcs
Marine protein supplements
Oral marine protein supplements (MPS) have been used for more
than 15 years as nutritional enhancers of hair growth in AGA. Viviscal®
(Hair Nourishment System; Lifes2good, Inc., Chicago, Illinois),
originally marketed under the brand name Hairgain® [Parexel Medstat
AS, Lillestrøm, Norway]) contains AminoMar C™ marine complex as
its most active principle, a proprietary blend of shark and mollusk
powder [55,56] Additional contents include an organic form of silica
derived from
Equisetum
sp. (horsetail), vitamin C derived from
Malpighia emarginata
(acerola cherry), microcrystalline cellulose
(E460), natural orange avor, magnesium stearate, hypromellose, and
glycerol [56]. Several studies, including randomized, controlled trials
have demonstrated the ecacy of Viviscal in the treatment of AGA in
men [55,57,58]. Signicant improvements, in terms of the physician-
assessed terminal hair counts as well as patient-perceived benets in
hair volume, scalp coverage, and thickness of hair shas have also been
reported in multiple double-blind, placebo-controlled studies
evaluating the ecacy of Viviscal supplement (given orally twice-a-day
for 3 months to 6 months) in women with self-perceived thinning hair
[56,59,60]. No AEs were reported in any study. Shell sh allergy is a
contraindication for this neutraceutical. e mechanism of Viviscal
seems to be the enhancement of proliferation of DPCs. It has been
postulated that Viviscal increases the alkaline phosphatase levels, a key
marker of anagen phase of the hair cycle, in DPCs [59]. Summarizing
from the above results, Viviscal may be an eective treatment option
both alone as well as a part of
a comprehensive hair restoration plan
,
e.g. in combination with MNX and/or FIN.
Platelet rich plasma
Platelet-rich plasma (PRP), an autologous preparation of plasma
with >1,000,000/μL platelets is gaining popularity across the globe as
an adjuvant treatment for PHL and to circumvent or delay the need for
hair transplantation. e platelet related growth factors (such as
platelet-derived growth factor (PDGF), transforming growth factor
(TGF), vascular endothelial growth factor (VEGF), broblast growth
factor (FGF), epidermal growth factor (EGF), and insulin-like growth
factor (IGF-1)) improve hair growth by multiple mechanisms -
stimulation of the bulge stem cells and dermal broblasts, proliferation
of dermal papilla cells, prolongation of anagen, and delaying the
progression into catagen [61]. ere are many important factors that
determine the ultimate ecacy of the therapy – e.g., the anti-coagulant
used in the collection tubes, centrifuge machine parameters (rotation
speed and total time), single-spin or double-spin method, manual
preparation or use of commercially available kits, temperature control,
addition of platelet activators etc. And more studies are warranted to
crystallize these concepts. e only adverse eect with PRP is the
procedure related pain and temporary scalp swelling. It should be
performed under topical anesthesia. Use of locoregional scalp blocks
Citation: Sonthalia S, Daulatabad D, Tosti A (2016) Hair Restoration in Androgenetic Alopecia: Looking Beyond Minoxidil, Finasteride and Hair
Transplantation. J Cosmo Trichol 2: 105. doi:10.4172/jctt1000105
Page 6 of 13
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ISSN:JCTT , an Open Access Journal Volume 2 • Issue 1 • 1000105
are an alternate option to make the procedure painless, but needs
training.
In a prospective cohort study that enrolled 18 males and 2 females
with PHL, PRP prepared by single-spin method in Regenlab SA kit was
injected in the androgen-related areas of scalp [62]. ree treatment
sessions, once-every-3-weeks and a booster session at 6 months were
delivered. At 3 months, reduction of hair loss was signicant and
hair density reached a peak at 3 months Improvement continued till
one year of the last treatment. Patients were satised with a mean
result rating of 7.1 on a scale of 1-10. In a recent randomized,
evaluator-blinded, placebo-controlled, half-head group study
compared hair regrowth with PRP versus placebo with the aid of
computerized trichograms. PRP, prepared from a small volume of
blood, was injected on half of the selected patients' scalps with PHL.
e other half was treated with placebo. ree treatments administered
at 30-day intervals protocol could be analyzed for 20 patients. Patients
were followed for 2 years. Of the 23 patients were enrolled, 3 were
excluded. At the end of the 3 treatment cycles, a signicant
improvement in the mean number of hair (mean increase of 33.6 hair
in the target area) and a mean increase in total hair density (of 45.9
hair per cm2) was observed compared with baseline values [63]. No
side eects were noted. In long term follow up, out of 20 patients, 4
(20%) reported progressive hair loss, which was more evident 16
months aer the last treatment. However, one must be aware of the
ner art of preparing and injecting PRP to optimize patient outcomes.
Readers are advised to refer to the article by Dhurat and Sukesh for
further reading on this aspect [64].
Microneedling
Microneedling involves the use of a microneedle-tipped instrument,
most commonly a dermaroller or a dermapen, available in models with
dierent or adjustable needle depths (usually ranging from 0.2-3.0
mm). Traditionally used for facial acne scars, facial rejuvenation, open
pores and striae (owing to its collagen stimulation and remodeling
eects), microneedling has recently been shown to enhance expression
of hair-related genes and stimulation of hair in mice by Jeong et al. and
Kim et al., [65,66]. A randomized evaluator blinded trial by Dhurat et
al. evaluated the eect of microneedling in 100 patients with MPHL
(grade III vertex or IV), with the Microneedling Group oered weekly
microneedling sessions along with twice daily 5% MNX lotion, and the
other group given only 5% MNX lotion twice daily. Dermaroller-MNX
treated group was statistically superior to MNX-alone treated group in
promoting hair growth in men with AGA for all 3 primary ecacy
measures of hair growth, including the mean change in hair count at
week 12 (91.4 vs 22.2 respectively), investigator evaluated visual
analogue scale scoring, and percentage of patients reporting more than
50% improvement (82% vs 4.5%) [67]. e hair re-growth induced by
microneedling is thought to result from the controlled wounding
induced by the dermaroller and the postulated mechanisms include -
release of growth factors like PDGF and EGF, direct activation of stem
cells in the hair bulge area, and increased expression of hair growth
related genes including β-catenin, Wnt3a, and Wnt10 b [65-67].
Stimulation of ECM components
Tetrapeptides
e naturally occurring tetrapeptide AcSDKP, a potent angiogenic
factor was recently shown to stimulate the growth of human
keratinocytes, broblasts and follicle DPC. In the study by Hajem et al.,
topical treatment of
ex vivo
cultured skin explants with 10 M AcSDKP
not only increased the thickness of the epidermis and upregulated
keratin synthesis, it also stimulated production of ECM components
including bronectin, collagen III and IV, as well as the
glycoaminoglycans (GAGs) [32]. In the
ex vivo
-cultured hair follicles,
AcSDKP promoted hair sha elongation and induced morphological
and molecular modications, suggestive of hair growth induction. In a
randomized placebo-controlled study by Loing et al. conducted in 30
volunteers with early AGA, daily application of a cosmetic active
ingredient prepared by combining
Trifolium pratense
ower extract
and a biomimetic peptide for 4 months yielded a signicant increase in
anagen hair count (+13%), and the anagen/telogen (A/T) ratio (+46%)
over baseline, compared to application of placebo [29]. e postulated
mechanisms for hair growth stimulation include stimulation of ECM
protein synthesis, inhibition of 5 AR activity, and reduction of
follicular micro-inammation.
Diguanosine tetraphosphate (GP4G)
In the study by Severino et al., the eects of GpG formulation, a
liposomic solution of
Artemia salina
extract, on hair follicle structures
were evaluated. A 50% increase in hair length and a 30% increase in
the number of DPC were observed [68]. e mechanism seemed to be
an increase in skin blood vessels and broblast activation modied
collagen arrangement in dermal tissues. At the molecular level, cellular
activation induced by GpG evidenced by a 38% increase in the
intracellular ATP concentration and increases in the intracellular
concentration of tri- , di- , and monophosphate nucleosides, in two cell
culture lines - Hela and broblast cells. us GpG promises to be a
novel option worth further exploration for hair regrowth in AGA.
Nutritional and antioxidant therapy
In the past decade an increasing number of reports have provided
support for nutraceuticals as eective and safe treatment options for
hair loss in general. Furthermore, there seems to be a growing trend
towards supplementation compared with prescription or over-the-
counter (OTC) medications. Isolated reports have evaluated the
inuence of various dietary supplements such as millet extracts, biotin,
pantothenic acid and other B-complex vitamins, minerals like zinc and
iron, omega-3 and omega-6 fatty acids, and anti-oxidants like lycopene
in hair loss of various origins with variable results. However, the
studies have seldom focused on their ecacy in AGA.
Biotin
Biotin, an essential vitamin is involved in vital physiological
functions like fatty acid synthesis, amino acid catabolism, and
gluconeogenesis. Additionally, it functions as a coenzyme for
mitochondrial carboxylases in hair roots. Absorption of biotin requires
the release of biotin from foods and biotin-containing peptides,
aected by the biotinidase (BTD) enzyme. An adequate intake (AI) of
30 µg/day has been suggested for adults. Genetic biotinidase
deciency, results in hair loss, in addition to a variety of systemic
symptoms such as seizures, mental retardation, dermatitis, and
aciduria, amongst others [69]. Important causes of acquired biotin
deciency include anticonvulsant therapy (especially valproate),
intestinal malabsorption and excessive alcohol consumption. Alopecia
is a common adverse eect of valproic acid, the pathogenesis of which
remains controversial. While earlier studies implicated reduced activity
of BTD leading to biotin deciency as the cause of valproate-induced
hair loss, newer studies have refuted this theory [70,71]. Irrespective of
Citation: Sonthalia S, Daulatabad D, Tosti A (2016) Hair Restoration in Androgenetic Alopecia: Looking Beyond Minoxidil, Finasteride and Hair
Transplantation. J Cosmo Trichol 2: 105. doi:10.4172/jctt1000105
Page 7 of 13
J Cosmo Trichol
ISSN:JCTT , an Open Access Journal Volume 2 • Issue 1 • 1000105
the eect of valproic acid on serum biotin levels or BTD activity,
reversal of alopecia has been reported in few patients who were on
valproic acid therapy, with oral biotin (10 mg/day) administration.
[71,72]. Although robust evidence favouring the role of oral biotin in
arresting hair loss or stimulating regrowth is lacking, it remains one of
the most prescribed nutritional supplement for any kind of hair loss.
Biotin is also a frequent component of hair mesotherapy solutions.
However, there is a clear paucity of any evidence based on robust
research favoring the role of biotin in treatment of AGA.
Zinc
e relation between zinc deciency and hair growth has been a
subject of debate for the past three decades. Zinc is a known potent
inhibitor of hair follicle regression, and also accelerates hair follicle
recovery [73]. Although, there have been arguments refuting the
relationship between zinc and hair loss [74], frank zinc deciency or at
least levels lower than control groups have indeed been documented in
almost all forms of non-cicatricial alopecia. Although, alopecia areata
(AA) and telogen euvium (TE) have been documented to be more
associated with low zinc levels [75,76], in a recent study, zinc levels
lower than the control group have also been documented in AGA [77].
In this case control study by Kil et al. that included 312 patients with
AA, MPHL, FPHL and TE, in each category of hair loss, the serum
zinc concentration was signicantly lower than that of the control
group. is included 161 patients of AGA (84 with MPHL and 77 with
FPHL). Expectedly, the ratio of the patients with serum zinc
concentration lower than the cut-o of 70 μg/dL was signicantly high
only in the AA group [77]. Zinc is also known to have some 5AR
inhibitory activity [78]. In conclusion, it is not surprising that zinc-
containing supplements have become a routine prescription by
trichologists for AGA patients as well.
Omega 3 fatty acids and antioxidants
In a recent randomized, comparative study conducted in 120
otherwise healthy female subjects with FPHL, compared to placebo, a
nutritional supplement containing omega 3 & 6 acids and antioxidants
given for 6-months resulted in statistically signicant and superior
improvement in hair growth parameters including photograph
assessment, reduction in telogen hair percentage, and increment in
non-vellus anagen hair [79]. Subjective evaluation by the women in the
supplemented group mirrored the objective results with reduction in
hair loss reported by 89.9%, improvement in hair diameter by 86.1%
and hair density by 87.3%.
Miscellaneous
Dietary supplements are popular over-the-counter products used
for hair loss by patients themselves. ese supplements contain
combinations of amino acids like L-cystine, L-lysine, L-methionine,
vitamins like biotin, calcium pantothenate and thiamine, minerals like
iron and zinc, and other substances such as Brewers yeast, in dierent
proportions. Oral supplementation with l-cystine, pantothenic acid,
thiamine nitrate, and medicinal yeast has been shown to increase the
anagen rate in apparently healthy women with telogen euvium in a
placebo-controlled study [80]. But none of these nutreceuticals have
been tested for ecacy in AGA patients. Since their general
mechanism of action seems to be induction of anagen, the use of these
multivitamin-mineral-antioxidant cocktail tablets/capsules has been
extrapolated as an adjuvant therapy in patients with AGA as well,
despite lack of evidence of ecacy in this particular type of alopecia.
Other Potential erapies for AGA
Ocinalis plant extracts – Enhancing microvascular supply
of DPC
e physiological activity of the pilosebaceous unit is linked to its
local microcirculatory system [81]. e anagen phase is accompanied
by angiogenesis. A recently launched commercial hair serum
containing extracts from 9
Ocinalis
plants:
Carthamus tinctorius
,
Prunus persica
,
Zingiber ocinalis, Panax ginseng
,
Salvia ocinalis
,
Cuscuta epithimum
,
Carum petroselinum
,
Angelica archangelica
,
Capsicum annuum
has been suggested to be a hair growth stimulator
for TE, AA as well as AGA. e primary mechanism of action seems to
be an increase in the dermal papillary blood ow and nutrients supply,
with additional antioxidant and hydrating eects [81,82]. In the study
conducted by Gori et al. in 46 subjects with AGA (40 males, 6 females),
treated with the hair serum containing ocinalis plant extracts, once-
a-day for 3 months, 25 (54%) showed clinical signs of hair follicle
reactivation (anagen phase), with an initial or an appreciable regrowth
of terminal hair [82]. e local tolerance and cosmetic acceptance was
rated good by the users.
Caeine
Caeine is evolving as a promising candidate
for hair growth stimulation. It possesses two activities of relevance for
hair growth – Indirect, via 5AR inhibition and direct, by stimulation of
hair growth parameters. Employing the hair organ culture model
wherein hair follicles from the vertex area of male AGA patients were
cultivated, Fischer et al. demonstrated that caeine in concentrations
of 0.001% and 0.005% not only counteracted the testosterone-induced
hair follicle growth suppression, but also induced signicant follicular
growth independently [83]. In their next study published recently,
Fischer et al. elaborated on caeine’s
in-vitro
eect at the cytokine
level in hair follicles cultivated from both men and women with AGA.
Caeine enhanced hair sha elongation, prolonged anagen duration
and stimulated hair matrix keratinocyte proliferation, with better
responses observed in female HFs [84]. Protein expression of TGF-β2
was reduced and IGF-1 increased in the matrix cells as well as outer
root sheath (ORS) keratinocytes in the HFs of both genders. With
discovery of such growth-promoting eects of caeine on human HFs,
the molecule has already found its way as a component of multi-
ingredient shampoos as well as some OTC as well as prescription hair
growth enhancing solutions.
Melatonin
Melatonin, the hormone secreted by the pineal gland is known to
have potent antioxidant activity. It acts as a direct radical scavenger
[21]. Melatonin’s eects on cell growth regulation have been shown in
human keratinocytes [85]. e antioxidative eects of melatonin have
been found to prevent UV-induced erythema in healthy humans,
prevent cell death of UVR irradiated leukocytes and have been
postulated to be instrumental in counteracting the detrimental eects
of environmental stressors on the aging-related parameters of skin and
hair [86,87]. Extensive research work by Fischer et al. has revealed
startling facts about the high potential of melatonin as a hair growth
agent. Human hair follicles have been shown to synthesize melatonin
and express melatonin receptors [88,89]. Human anagen hair follicles
cultivated
in vitro in a culture medium with
a melatonin concentration
of 30 μM resulted in a signicantly faster rate of hair follicle growth
compared to the culture medium alone. [90]. Currently, MEL receptors
have been identied primarily in the root sheath of the hair, and have
Citation: Sonthalia S, Daulatabad D, Tosti A (2016) Hair Restoration in Androgenetic Alopecia: Looking Beyond Minoxidil, Finasteride and Hair
Transplantation. J Cosmo Trichol 2: 105. doi:10.4172/jctt1000105
Page 8 of 13
J Cosmo Trichol
ISSN:JCTT , an Open Access Journal Volume 2 • Issue 1 • 1000105
been postulated to aect hair growth via receptor-mediated inuence
over the hair root sheaths. e hair growth eect of MEL may also
involve interaction with androgens and estrogens and their receptors,
as evidenced by the eects of MEL on inhibiting prostate enlargement.
Antiandrogenic eects of MEL on hair follicles include prolongation of
the hair cycle and decreased miniaturization.
It seems to be a promising candidate for halting hair loss and induce
growth in general hair loss as well as AGA, owing to its anti-oxidative
and antiandrogenic properties. Topically applied cosmetic hair
solution with 0.0033% melatonin content has been explored in many
studies to evaluate its ecacy in AGA in both the genders. In a detailed
analysis of ve clinical studies of MEL on hair loss, Fischer et al.
observed positive eects of topical MEL solution in the treatment of
AGA with good tolerability [91]. ese studies included both men and
women with early-stage AGA as well as generalized hair loss.
Signicant reduction in the percentage of patients with a 2- to 3-fold
positive hair-pull test, reduction of the overall severity of alopecia and
signicant increases in hair density were observed in these studies. e
duration of MEL application ranged from 3-6 months and ecacy
assessment was done by dierent methods in dierent studies
including questionnaires completed by investigators and patients, hair-
pull test, and digital soware-supported epiluminescence technique
(TrichoScan) treatment for AGA. Pharmacodynamics under once-
daily topical application in the evening showed no signicant inuence
on endogenous serum melatonin levels.
Topical roxithromycin
Roxithromycin, a macrolide antibiotic has recently been explored
for AGA based on its properties of inhibition of apoptosis of
keratinocytes (via suppressing the production of oxygen reactive
species) and suppression of the AR in human dermal broblasts
[92,93], with around 58% of the 13 men with AGA developing increase
in hair sha thickness, with no side eects following 6 months use of
3-5 mL of a 5% roxithromycin solution daily compared to the control
group in a randomized double-blinded trial [94].
Low-level laser/light therapy (LLLT)
Since the discovery of hypertrichosis as a possible paradoxical side-
eect of laser or light-based treatments for hair reduction in 2002 with
intense pulsed light therapy, this phenomenon has been estimated to
occur in 0.6% to 10% of patients treated with all laser types,
particularly when low uences are used [95,96]. e suboptimal
uencies, although too mild to induce thermolysis, are high enough to
stimulate follicular growth. e hypothesized mechanisms of action of
LLLT are increased adenosine tri-phosphate (ATP) production,
modulation of reactive oxygen species (ROS), and induction of
transcription factors. Cytochrome-c oxidase (COX) has been proposed
to be the cellular chromophore, with absorption peaks in the near
infrared light [97]. A complex biochemical process ensues following
the light-chromophore interaction leading to release of NO, which
further results in cellular proliferation, increased tissue oxygenation,
and modulation in the levels of cytokines and growth factors.
Devices based on the principle of LLLT include laser combs (e.g.,
the US-FDA approved HairMax Laser Comb®, available in three
models with 7, 9 and 12 diode-beams per comb) and machines with
helmet-like laser hoods. In a company-sponsored study of 110 male
patients, treatment with the HairMax Laser Comb® apparently resulted
in signicant increase in mean terminal hair density when compared
to a sham device [98]. Based on the favorable outcome of LLLT on hair
growth in an independent blinded study with seven patients, and
anecdotal experiences, a consensus paper by hair loss experts
suggested that while LLLT employing 650-900 nm wavelengths at 5
mW may be an eective and safe treatment option for patients with
AGA, more controlled, peer-reviewed studies validating current
devices were necessary [99-101]. In a 24-week, randomized, double-
blind, sham-device-controlled trial, Kim
et al.,
reported an increase of
hair density with the use of LLLT [102]. In a retrospective
observational study of 32 patients (21 female, 11 male) with AGA,
treated with the 655 nm-HairMax Laser Comb®, signicant
improvement was observed in 8, showed signicant, moderate
improvement in 20, and no improvement in 4, with no adverse
reactions reported in any patient [97]. Improvement was observed as
early as 3 months and was sustained up to a maximum observation
time of 24 months. Combination of LLLT with MNX and/or FIN was
suggested to have a synergistic eect in enhancing hair growth. In
another recent multicentric, randomized, sham device-controlled,
double-blind clinical trial that analyzed the ecacy of lasercomb in
103 male and 122 female subjects, whole scalp treatments were given
with a laser comb (trial groups) or sham device three times a week for
26 weeks. e mean terminal hair count of the target area at 26 weeks
in the lasercomb-treated subjects increased signicantly from baseline
(ranging from 18.4 to 25.7 per cm2), compared with minimal increase
noted in sham-treated subjects [103]. However, additional studies to
determine the long-term eects of LLLT on hair growth and to
optimize
Stem cell based treatment
Cell mediated treatments for AGA broadly include two main
approaches: the direct injection of cultured stem cells (SC) or the use
of cell secreted hair growth enhancing humoral factors. e premise of
cell-based treatment for AGA is that even till advanced stages of AGA,
the stem cell population is preserved, suggesting potential reversibility
of the condition [104]. e study of the HF stem cells (HFSCs) started
with the identication of epidermal SC in the HF bulge as quiescent
"label retaining cells". e research of these cells emerged rapidly aer
the identication of bulge cell molecular markers, such as keratin 15
and CD34 in mice and CD200 in humans, which allowed the isolation
and characterization of bulge cells from follicles [105]. Dermal Papillae
is a unique population of mesenchymal cells that regulates formation
of HF as well as the growth cycle. Although, DP cells were proposed as
the cell-based treatment for hair loss conditions like AGA,
unfortunately human DP cells are not suitable for this purpose because
they cannot be obtained in necessary amounts and rapidly lose their
ability to induce HF formation when cultured. During development
most DP cells are derived from mesoderm, however, functionally
equivalent DP cells of cephalic hair originate from neural crest (NC).
In the landmark study of Gnedeva et al., human embryonic stem cells
(hESCs) were directed to generate NC cells and then hair-inducing
DP-like cells in culture. ese hESC-derived DP-like cells (hESC-DPs)
express markers typically found in adult human DP cells and are able
to induce hair follicle formation when transplanted under the skin of
immunodecient nude mice [106]. e development of hESC-DPs
seemingly heralds a major breakthrough towards a cell-based
treatment for AGA and other hair loss disorders. Human hair follicle-
derived mesenchymal stem cells (HF-MSCs) are also capable of
dierentiating along multiple lineages. Addition of EGF and FGF to
the culture media enhance cellular pluripotency. Other cell lines
including epidermal keratinocytes, dermal broblasts and adipocytes
Citation: Sonthalia S, Daulatabad D, Tosti A (2016) Hair Restoration in Androgenetic Alopecia: Looking Beyond Minoxidil, Finasteride and Hair
Transplantation. J Cosmo Trichol 2: 105. doi:10.4172/jctt1000105
Page 9 of 13
J Cosmo Trichol
ISSN:JCTT , an Open Access Journal Volume 2 • Issue 1 • 1000105
have also been explored for cell-based treatment of hair loss. Recently,
skin derived progenitor cells (SKPs) have been expanded
in vitro
from
the dermis and share certain characteristics of DP cells. SKPs are
highly plastic even aer long-term expansion
in vitro
and can
dierentiate into multiple lineages. SKPs are also able to induce HF
formation and they can be an ample source of inductive dermal cells
for HF regeneration [107]. Adipose tissue-derived stem cells (ADSCs)
and conditioned media of ADSCs (ADSC-CM) are reported to
promote hair growth
in vitro
. In a recent retrospective, observational
study of 27 patients with FPHL treated with ADSC-CM, application of
ADSC-CM showed ecacy in treating FPHL aer 12 weeks of therapy
[108]. ere was a signicant increase in hair density as well as
hair thickness, with no severe adverse reactions. e search for more
robust sources of generating a pool of human HF is ongoing and
hopefully, stem-cell based therapies shall occupy a prominent position
in the therapeutic armamentarium of AGA.
Future potential treatments that may be eective in AGA include:
Nitric oxide (NO) gel, which has been shown to promote hair
follicle formation through stem cell development, hair regeneration,
hair sha elongation and increased growth rate in rats and mice [10].
Vitamin D3: e Vitamin D receptor (VDR) is expressed in hair
follicle keratinocytes during late anagen and catagen. Additionally,
Vitamin D3 has also been shown to modulate Wnt10b gene expression
[109]. Studies based on VD3 gene knock-out and VD3
supplementation in nude mice has revealed encouraging hair growth
promoting eects of VD3 [10].
Nestin and noggin: Studies carried on patients with alopecia areata
showed that middle anagen and early anagen hair follicles with
growing cells were found to be nestin positive, suggesting a role of
nestin-positive in the regenerating hair follicles. Noggin is an inhibitor
of the bone morphogenetic protein-4 (BMP4), which physiologically
induces selective arrest of anagen development in the secondary hair
follicles [110]. Experimentally, the administration of noggin protein
was found to induce new hair growth phase in postnatal telogen skin
in vivo
.
Conclusion
e exact pathogenesis of AGA remains elusive and seems to
involve multiple players acting at dierent levels and stages. e
understanding of newer pathogenetic mechanisms contributing to
progressive miniaturization of hair in AGA such as the androgen-
mediated suppression of Wnt/β-catenin pathway, follicular
microinammation, perifollicular paracrine prostaglandin imbalance,
and oxidative stress have enhanced the possibility of development of
targeted therapies manifold. With MNX and FIN remaining the only
two US-FDA approved treatments for AGA that oen do not produce
desirable results, quest for such therapies and new avenues like hair
follicle bioengineering was logical. Hopefully, with improved
elucidation of molecular mechanisms underlying follicular
miniaturization, development of more ecacious treatment options
would ensue.
Conict of Interest:
Dr Antonella Tosti has in the past received honoraria as consultant
from the following companies-Incyte, Khytera, P and G, DS
Laboratories, Inneov Laboratories, Polichem.
Dr Sidharth Sonthalia has in the past received honoraria as
consultant from the following companies- Sun Pharmaceuticals, Cipla
Externa, H and H pharmaceuticals and Glenmark. He is also on the
medical advisory board of the South Asian Pigmentary Disorder
Forum (SPF) of GALDERMA.
However, none of the nancial associations of Dr Tosti or Dr
Sonthalia had in any way been an inuence on the contents of the
manuscript being submitted.
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Transplantation. J Cosmo Trichol 2: 105. doi:10.4172/jctt1000105
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Citation: Sonthalia S, Daulatabad D, Tosti A (2016) Hair Restoration in Androgenetic Alopecia: Looking Beyond Minoxidil, Finasteride and Hair
Transplantation. J Cosmo Trichol 2: 105. doi:10.4172/jctt1000105
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