Scalp hair-whorl orientation of Japanese individuals is random; hence, the trait's distribution is not genetically determined

Divergent progression pathways in male androgenetic alopecia and female pattern hair loss: Trichoscopic perspectives

BACKGROUND

Despite similarities in progressive miniaturization of hair follicles and transition of terminal hairs to vellus hairs, insufficient trichoscopic comparisons between male androgenetic alopecia (MAGA) and female pattern hair loss (FPHL) hinder our ability to select effective treatments.

AIM

Our study aimed to explore gender-specific trichoscopic characteristics of MAGA and FPHL, while formulating hypotheses regarding the progression of these conditions across clinical stages.

METHODS

We classified 126 male MAGA subjects using Hamilton-Norwood Classification and 57 FPHL subjects using adopted Sinclair Scale. Subsequently, we analyzed nine trichoscopic factors divided into three categories: hair-diameter related, hair-number per follicular unit related, and hair density related factors.

RESULTS

Of the nine quantitative trichoscopic factors, hair-diameter and hair-number per follicular unit showed strong correlations with clinical stages in both genders. Hair density, a common trichoscopic factor for hair loss evaluation, weakly correlated with clinical stages in FPHL, but not at all in MAGA. In addition, MAGA was characterized by a progressive reduction in hair-diameter, followed by a reduction in hair-number per follicular unit. FPHL, on the contrary, showed the opposite progression.

CONCLUSIONS

Trichoscopic factors vary with disease severity in a gender-specific manner. Our research highlights that MAGA and FPHL involve two distinct streams: hair-diameter decreasing by hair follicle miniaturization (Stream 1), and hair-number per follicular unit decreasing by hair follicle tri-lineage niche dysfunction (Stream 2). MAGA typically starts from Stream 1 to Stream 2, while FPHL starts from Stream 2. These diverse progression pathways underscore the importance of personalized treatment approaches.

Trichoscopic evaluation of dental pulp stem cell conditioned media for androgenic alopecia

BACKGROUND

Conditioned media (CM) derived from mesenchymal stem cells (MSC) is known to induce hair regrowth in androgenic alopecia.

OBJECTIVES

The objectives of the study were to assess the efficacy and safety of one type of MSC-CM, the CM derived from dental pulp stem cells obtained from human exfoliated deciduous teeth (SHED-CM) and to compare the efficacy of SHED-CM with and without dihydrotestosterone synthesis inhibitor (DHT-inhibitor).

METHODS

Eighty-eight male androgenic alopecia subjects with Hamilton-Norwood Classification (H-N C) I-VII were evaluated by trichoscopy to explore which trichoscopic factors statistically correlated with H-N C. After being screened, 33 subjects received six SHED-CM treatments at 1-month intervals. Clinical severity was assessed through global and trichoscopic images from baseline to 9th month.

RESULTS

SHED-CM was effective for 75% of subjects regardless of disease severity, concomitant DHT-inhibitor use, and age. Adverse effects including pain and small hemorrhages were transient and mild. We also found that clinical hair status evaluated by absolute values of three quantitative trichoscopic factors (maximum hair diameter, vellus hair rate, and multi-hair follicular unit rate) showed a good correlation with H-N C stages, and what is more-a scoring system of these three factors can be a possible predictor of SHED-CM efficacy.

CONCLUSIONS

We have shown that SHED-CM provides global and trichoscopic image improvement for androgenic alopecia, regardless of concomitant DHT-inhibitor use.

Hair Whorl Direction: The Association with Handedness, Footedness, and Eyedness

Hair whorl direction and handedness were stated to have a common genetic basis in the random recessive model. This study was carried out with a total of 317 healthy young males. The association between hair whorl swirling direction and handedness, footedness and eyedness were assessed. The direction of hair whorl was clockwise at a rate of 76.7%, and counter clock wise at a rate of 23.3%. There was no significant association between hair whorl direction and handedness, footedness, and eyedness (p > .05). The results indicate that hair whorl swirling direction is not an evident marker of functional laterality.

From cytoskeletal dynamics to organ asymmetry: a nonlinear, regulative pathway underlies left-right patterning

Consistent left-right (LR) asymmetry is a fundamental aspect of the bodyplan across phyla, and errors of laterality form an important class of human birth defects. Its molecular underpinning was first discovered as a sequential pathway of left- and right-sided gene expression that controlled positioning of the heart and visceral organs. Recent data have revised this picture in two important ways. First, the physical origin of chirality has been identified; cytoskeletal dynamics underlie the asymmetry of single-cell behaviour and patterning of the LR axis. Second, the pathway is not linear: early disruptions that alter the normal sidedness of upstream asymmetric genes do not necessarily induce defects in the laterality of the downstream genes or in organ situs Thus, the LR pathway is a unique example of two fascinating aspects of biology: the interplay of physics and genetics in establishing large-scale anatomy, and regulative (shape-homeostatic) pathways that correct molecular and anatomical errors over time. Here, we review aspects of asymmetry from its intracellular, cytoplasmic origins to the recently uncovered ability of the LR control circuitry to achieve correct gene expression and morphology despite reversals of key 'determinant' genes. We provide novel functional data, in Xenopus laevis, on conserved elements of the cytoskeleton that drive asymmetry, and comparatively analyse it together with previously published results in the field. Our new observations and meta-analysis demonstrate that despite aberrant expression of upstream regulatory genes, embryos can progressively normalize transcriptional cascades and anatomical outcomes. LR patterning can thus serve as a paradigm of how subcellular physics and gene expression cooperate to achieve developmental robustness of a body axis.This article is part of the themed issue 'Provocative questions in left-right asymmetry'.

The mane effect in the horse (Equus ferus caballus): Right mane dominance enhanced in mares but not associated with left and right manoeuvres in a reining competition

A human physical asymmetry is the near 90% clockwise occipitoparietal scalp hair-whorl direction in Europeans, an incidence that approximates the left lateralization of speech and right-handedness. Hair-whorl direction is also asymmetric in horses, Equus ferus caballus and placement is proposed to be related to temperament and lateralized skill in equitation manoeuvres. We describe a hair-whorl asymmetry in the horse, mane direction. Of 526, 3-year-old American Quarter horses, 69% of horses had mane directed to the right and 31% had mane directed to the left. The bias was larger in females, with 74% of females vs. 65% of males having mane directed to the right. Mane direction was unrelated to coat colour. The behavioural significance of mane asymmetry was investigated using judges' scores from a reining competition requiring symmetrical maneuvers of spin, circle and roll-back to either the left or to the right. There was no relation between mane asymmetry and overall reining performance and no relation between mane direction and scores for left or right manoeuvres. The results are discussed in relation to the significance of morphological asymmetries, neural function and the influence of planar cell polarity genes, such as Frizzled, that influence epidermal hair cell patterning.