This survey of recent literature relates to assessing hair damage, reducing dye allergy, increasing and inhibiting hair growth, cleansing and conditioning hair, and more. The papers are presented as food for thought in the early stages of the product development process, and may warrant deeper investigation.
Monoethanolamine-based vs. ammonia-based colorant hair damage
A.D. Bailey, G. Zhang and B.P. Murphy; J Cosmet Sci 65(1) 1-9;
According to the authors of this paper, the number of permanent hair color products utilizing 2-aminoethanol [monoethanolamine (MEA)] in place of ammonia is increasing. The focus of this work was understanding the relative hair damage caused by each, particularly at the upper use limits of MEA. Fourier transform infrared spectroscopy measurements of cysteic acid levels were paired with scanning electron microscopy photomicrographs to visualize cuticle damage and protein loss.
All methods showed greater damage from MEA-based formulations—up to 85%, in the most extreme case, versus ammonia. The authors, therefore, suggest minimizing the volatility of ammonia to reduce its odor rather than replacing it with high levels of MEA.
Microscopic changes in Iranian hair from coloring, waving and ironing
S. Talghini and M. Ranjkesh, Pak J Biol Sci 16(20) 1184-8; Oct 15, 2013
This study examined the microscopic changes to hair caused by coloring, waving and hair ironing. For the study, 154 Iranian women were recruited and categorized in four groups: a control group (n = 35) who had not treated hair within six months; a dyed hair group (n = 49); a waved hair group (n = 35); and an ironed-hair group (n = 35).
Hair samples from all groups were examined microscopically and compared with the controls. The rate of abnormal hair structure findings was 17.1% in the control group; 53.1% in the dyed hair group; 45.7% in the waved hair group; and 54.3% in the ironed hair group.
p-Phenylenediamine with methoxymethyl side chain for reduced sensitization
C. Goebel, J. Troutman, J. Hennen, H. Rothe, H. Schlatter, G.F. Gerberick and B. Blömeke; Toxicol Appl Pharmacol; 274(3) 480-7 (Feb 1, 2014)
The sensitizing capacity of p-phenylenediamine (PPD) and p-toluylenediamine (PTD, i.e., 2-methyl-PPD), used in oxidative hair dyes, are well-established. [For more on this, see Page 10 of this issue.] However, modification of their molecular structure may impair their color performance.
Here, the authors introduced a methoxymethyl side chain to the primary intermediate 2-methoxymethyl-p-phenylenediamine (ME-PPD), and found it provided excellent hair-coloring performance while significantly reducing sensitizing properties, compared with PPD and PTD.
Determining pheomelanin/eumelanin ratio in red hair
E.N. Chikvaidze, T.M. Partskhaladze and T.V. Gogoladze; Magn Reson Chem; doi: 10.1002/mrc.4075, e-pub ahead of print; Apr 22, 2014
In this paper, the authors assess the electron spin resonance (ESR) spectra of red hair samples. At a low microwave power, two spectra were observed: a singlet spectrum from eumelanin and a triplet spectrum from pheomelanin. At high microwave power, however, only the triplet spectra was detected, due to saturation of the eumelanin singlet.
Using different ratios of black to red hair, additional ESR spectra were plotted, and the researchers found a linear relationship between the two parameters. This minimally invasive method is therefore proposed to measure pheomelanin content in hair as well as skin—which could be of interest because pheomelanin acts as a pro-oxidant upon exposure to UV radiation.
MicroRNAs in growth arrest/cell death of H2O2-treated dermal papilla cells identified
O.Y. Kim, H.J. Cha, K.J. Ahn, I.S. An, S. An and S. Bae; Mol Med Rep, doi: 10.3892/mmr.2014.2158, e-pub ahead of print; Apr 16, 2014
MicroRNAs (miRNAs) are small, non-coding RNAs that control biological processes by interfering with the translation of target genes. According to these researchers, studies suggest miRNAs are involved in cellular responses to H2O2, and such reactive oxygen species are involved in hair malignancies.
In the present study, miRNA expression was profiled in human dermal papilla cells treated with H2O2, and bioinformatic analyses showed that H2O2 response pathways related to growth arrest and apoptosis were affected. According to the authors, identifying miRNAs and their targets may offer therapeutic strategies for H2O2 -induced hair follicle disorders.
Minoxidil suppresses androgen receptor functions
C.L. Hsu, J.S. Liu, A.C. Lin, C.H. Yang, W.H. Chung and W.G. Wu; Oncotarget; Apr 8, 2014
According to this research, minoxidil has been used for more than 20 years to treat androgenetic alopecia but its mechanism is unknown. These authors hypothesized it may influence the androgen-androgen receptor (AR) or its downstream signaling.
Tests described here revealed that minoxidil suppressed AR-related functions, in turn decreasing AR transcriptional activity and reducing the expression of AR targets at the protein level, among other activities. These findings suggest minoxidil could treat cancer and age-related diseases, opening a new avenue for its applications.
6-Gingerol inhibits hair growth
Y. Miao, Y.B. Sun, W.J. Wang, Z.D. Zhang, J.D. Jiang, Z.H. Li and Z.Q. Hu; Public Library of Science [in Chinese], 29(6) 448-52; Nov 2013
In the presented work, the authors investigated the hair growth effects of 6-gingerol, the main active in ginger, in vitro and in vivo. In vitro, hair follicles were co-cultured with three concentrations of 6-gingerol for five days, and hair elongation was measured. Effects of the 6-gingerol on dermal papilla cells (DPC) were measured using the MTT Assay, and the expression of antibodies in DPCs were measured using Western blotting. In vivo, the influence of 6-gingerol on hair growth was measured by topical application of the 6-gingerol to the dorsal skin of rats.
Overall, in vitro, hair shaft lengths were reduced with higher concentrations of 6-gingerol. Also, the ingredient inhibited the proliferation of DPCs (p < 0.05). In vivo, hair length and density decreased significantly with just 1 mg/mL of 6-gingerol.
Placental growth factor for hair growth
S.Y. Yoon, J.S. Yoon, S.J. Jo, C.Y. Shin, J.Y. Shin, J.I. Kim, O. Kwon and K.H. Kim; J Dermatol Sci. 74(2) 125-34, May 2014
In this work, dermal papilla were isolated from human hair follicles and subcultured, and at passages 1, 3 and 5 (n = 4), their gene expression profiles were compared using mRNA sequencing. Among the growth factors down-regulated in later passages was placental growth factor (PlGF), which was selected to further elucidate its effects on hair growth.
PlGF was shown to enhance hair shaft elongation ex vivo in hair organ cultures. It also significantly accelerated hair follicle growth and prolonged anagen hair growth in an in vivo model of depilation-induced hair regeneration. The authors suggest PlGF may therefore serve as a therapeutic target for the treatment of alopecia.
Topical valproic acid increases hair count
S.J. Jo, H. Shin, Y.W. Park, S.H. Paik, W.S. Park, Y.S. Jeong, H.J. Shin and O.J. Kwon; Dermatol 41(4) 285-91; Apr 2014
According to this research, valproic acid (VPA), a widely used anticonvulsant, has been found to activate pathways associated with hair growth and anagen induction. To assess its topical efficacy, a randomized, double-blind, placebo-controlled clinical trial was carried out. Male patients with moderate androgenetic alopecia (AGA) underwent treatment with either sodium valproate, 8.3%, or a placebo spray for 24 weeks. The primary end-point for efficacy was the change in hair count during treatment, assessed by phototrichogram analysis.
The mean change in total hair count was significantly higher in the VPA group than in the placebo group (p = 0.047). Therefore, the authors propose VPA as a treatment option for AGA.
The role of prostaglandin D2 in male pattern baldness
A. Nieves and L.A. Garza; Exp Dermatol; 23(4) 224-7; Apr 2014
As described in this work, the most diverse lipids in the body are found in the skin, and their bioactivity is under-explored. Prostaglandin D2 (PGD2), in particular, has been identified at elevated levels in the scalps of men with AGA. In relation, the enzyme prostaglandin D2 synthase (PTGDS or lipocalin-PGDS) produces PGD2, and is responsive in multiple other organs as well. PGD2 has two known receptors, GPR44 and PTGDR, and the former has been connected with the decrease in hair growth by PGD2.
According to these authors, the elucidation of these interactions opens new opportunities to develop treatments for AGA, for example, by inhibiting the activity of PTGDS, PGD2 or GPR44.
M.R. Deeksha and P.K. Sharma; Recent Pat Inflamm Allergy Drug Discov; 8(1) 48-58; Jan 2014
Today’s shampoo products provide cleansing with added benefits such as conditioning, smoothing and maintaining hair health. These authors reviewed various types of shampoos, the nature of their ingredients and their claimed effects. Shampoos were evaluated in terms of physical appearance, detergency, surface tension, foam quality, pH and viscosity, as well as solids content, flow properties, dirt dispersion, cleansing action, stability, wetting time and preparation methods. Patents and commercial value also are considered.
Shampoo compositions and deposition
C. Lepilleur, A. Giovannitti-Jensen and C Kyer; J Cosmet Sci; 64(6) 411-27; Nov-Dec 2013
This study aimed to determine factors affecting the performance of cationic polymers in shampoo systems. Tests were conducted by varying the levels of three surfactants (sodium lauryl ether sulfate, sodium lauryl sulfate and cocamidopropyl betaine) in formulations containing various cationic polymers—such as cassia derivatives of different charge densities, cationic guar and cationic hydroxyethyl cellulose.
Results indicated that formulation compositions dramatically affected silicone and cationic polymer deposition. Three specific parameters were most important to deposition, namely ionic strength, surfactant (micelle) charge and total amount of surfactant.
Hair follicle stem cell research: Current knowledge and future challenges
T.S. Purba, I.S. Haslam, E. Poblet, F. Jiménez, A. Gandarillas, A. Izeta and R. Paus; BioEssays (36)5 513–525 (May 2014)
In this work, the authors explain that epithelial hair follicle stem cells (eHFSCs) generate, maintain and renew the hair follicle (HF), supplying cells to produce the keratinized hair shaft and aiding in the re-epithelialization of injured skin. However, human eHFSCs are much less understood than their murine counterparts, and it is unclear which murine eHFSC markers really apply to the human HF. Here, the authors review human eHFSC biology and related molecular markers, and consider unmet key challenges remaining to transfer emerging concepts from murine epithelial stem cell biology to human HF physiology and pathology.