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Concept: Sebaceous gland


The integumentary organ system is a complex system that plays important roles in waterproofing, cushioning, protecting deeper tissues, excreting waste, and thermoregulation. We developed a novel in vivo transplantation model designated as a clustering-dependent embryoid body transplantation method and generated a bioengineered three-dimensional (3D) integumentary organ system, including appendage organs such as hair follicles and sebaceous glands, from induced pluripotent stem cells. This bioengineered 3D integumentary organ system was fully functional following transplantation into nude mice and could be properly connected to surrounding host tissues, such as the epidermis, arrector pili muscles, and nerve fibers, without tumorigenesis. The bioengineered hair follicles in the 3D integumentary organ system also showed proper hair eruption and hair cycles, including the rearrangement of follicular stem cells and their niches. Potential applications of the 3D integumentary organ system include an in vitro assay system, an animal model alternative, and a bioengineered organ replacement therapy.

Concepts: Developmental biology, Stem cell, Stem cells, Organ, Skin, In vitro, Induced pluripotent stem cell, Sebaceous gland


BACKGROUND: Thuja orientalis has been traditionally used to treat patients who suffer from baldness and hair loss in East Asia. The present study sought to investigate the hair growth-promoting activity of T. orientalis hot water extract and the underlying mechanism of action. METHODS: After T. orientalis extract was topically applied to the shaved dorsal skin of telogenic C57BL/6 N mice, the histomorphometric analysis was employed to study induction of the hair follicle cycle. To determine the effect of T. orientalis extract on the telogen to anagen transition, the protein expression levels of beta-catenin and Sonic hedgehog (Shh) in hair follicles were determined by immunohistochemistry. RESULTS: We observed that T. orientalis extract promoted hair growth by inducing the anagen phase in telogenic C57BL/6 N mice. Specifically, the histomorphometric analysis data indicates that topical application of T. orientalis extract induced an earlier anagen phase and prolonged the mature anagen phase, in contrast to either the control or 1% minoxidil-treated group. We also observed increases in both the number and size of hair follicles of the T. orientalis extract-treated group. Moreover, the immunohistochemical analysis reveals earlier induction of beta-catenin and Shh proteins in hair follicles of the T. orientalis extract-treated group, compared to the control or 1% minoxidil-treated group. CONCLUSION: These results suggest that T. orientalis extract promotes hair growth by inducing the anagen phase in resting hair follicles and might therefore be a potential hair growth-promoting agent.

Concepts: Chemotherapy, Skin, Immunohistochemistry, Topical, Hair, Hair follicle, Sonic hedgehog, Sebaceous gland


BACKGROUND: Estrogen has been reported to accelerate cutaneous wound healing. This research studies the effect of young coconut juice (YCJ), presumably containing estrogen-like substances, on cutaneous wound healing in ovairectomized rats. METHODS: Four groups of female rats (6 in each group) were included in this study. These included sham-operated, ovariectomized (ovx), ovx receiving estradiol benzoate (EB) injections intraperitoneally, and ovx receiving YCJ orally. Two equidistant 1-cm full-thickness skin incisional wounds were made two weeks after ovariectomy. The rats were sacrificed at the end of the third and the fourth week of the study, and their serum estradiol (E2) level was measured by chemiluminescent immunoassay. The skin was excised and examined in histological sections stained with H&E, and immunostained using anti-estrogen receptor (ER-alpha an ER-beta) antibodies. RESULTS: Wound healing was accelerated in ovx rats receiving YCJ, as compared to controls. This was associated with significantly higher density of immunostaining for ER-alpha an ER-beta in keratinocytes, fibroblasts, white blood cells, fat cells, sebaceous gland, skeletal muscles, and hair shafts and follicles. This was also associated with thicker epidermis and dermis, but with thinner hypodermis. In addition, the number and size of immunoreactive hair follicles for both ER-alpha and ER-beta were the highest in the ovx+YCJ group, as compared to the ovx+EB group. CONCLUSIONS: This study demonstrates that YCJ has estrogen-like characteristics, which in turn seem to have beneficial effects on cutaneous wound healing.

Concepts: Wound healing, Healing, Estradiol, Skin, Dermis, Epidermis, Sebaceous gland, Coconut water


In most mammals, each hair follicle undergoes a cyclic process of growing, regressing and resting phases (anagen, catagen, telogen, respectively) called the hair cycle. Various biological factors have been reported to regulate or to synchronize with the hair cycle. Some factors involved in the extracellular matrix, which is a major component of skin tissue, are also thought to regulate the hair cycle. We have focused on an enzyme that degrades elastin, which is associated with skin elasticity. Since our previous study identified skin fibroblast elastase as neprilysin (NEP), we examined the fluctuation of NEP enzyme activity and its expression during the synchronized hair cycle of rats. NEP activity in the skin was elevated at early anagen, and decreased during catagen to telogen. The expression of NEP mRNA and protein levels was modulated similarly. Immunostaining showed changes in NEP localization throughout the hair cycle, from the follicular epithelium during early anagen to the dermal papilla during catagen. To determine whether NEP plays an important role in regulating the hair cycle, we used a specific inhibitor of NEP (NPLT). NPLT was applied topically daily to the dorsal skin of C3H mice, which had been depilated in advance. Mice treated with NPLT had significantly suppressed hair growth. These data suggest that NEP plays an important role in regulating the hair cycle by its increased expression and activity in the follicular epithelium during early anagen.

Concepts: Protein, Extracellular matrix, Skin, Hair, Hair follicle, Sebaceous gland, Goose bumps


Evolutionary modification has produced a spectrum of animal defence traits to escape predation, including the ability to autotomize body parts to elude capture. After autotomy, the missing part is either replaced through regeneration (for example, in urodeles, lizards, arthropods and crustaceans) or permanently lost (such as in mammals). Although most autotomy involves the loss of appendages (legs, chelipeds, antennae or tails, for example), skin autotomy can occur in certain taxa of scincid and gekkonid lizards. Here we report the first demonstration of skin autotomy in Mammalia (African spiny mice, Acomys). Mechanical testing showed a propensity for skin to tear under very low tension and the absence of a fracture plane. After skin loss, rapid wound contraction was followed by hair follicle regeneration in dorsal skin wounds. Notably, we found that regenerative capacity in Acomys was extended to ear holes, where the mice exhibited complete regeneration of hair follicles, sebaceous glands, dermis and cartilage. Salamanders capable of limb regeneration form a blastema (a mass of lineage-restricted progenitor cells) after limb loss, and our findings suggest that ear tissue regeneration in Acomys may proceed through the assembly of a similar structure. This study underscores the importance of investigating regenerative phenomena outside of conventional model organisms, and suggests that mammals may retain a higher capacity for regeneration than was previously believed. As re-emergent interest in regenerative medicine seeks to isolate molecular pathways controlling tissue regeneration in mammals, Acomys may prove useful in identifying mechanisms to promote regeneration in lieu of fibrosis and scarring.

Concepts: Developmental biology, Cellular differentiation, Regeneration, Skin, Hair follicle, Sebaceous gland, Salamander, Blastema


Propolis is a natural honeybee hive product with the potential for use in the treatment of dermatological conditions, such as cutaneous abrasions, burns, and acne. In this study, we investigated whether propolis stimulates hair growth in mice. Ethanol-extracted propolis, which contains various physiologically active substances such as caffeic acid and kaempferol, stimulated anagen induction in the shaved back skin. Anagen induction occurred without any detectable abnormalities in the shape of the hair follicles (HFs), hair stem cells in the bulge, proliferating hair matrix keratinocytes in the hair bulb, or in the localization of versican in the dermal papilla. Propolis treatment also stimulated migration of hair matrix keratinocytes into the hair shaft in HFs during late anagen in the depilated back skin. Organotypic culture of skin containing anagen stage HFs revealed significant stimulation of hair matrix keratinocyte proliferation by propolis. Furthermore, propolis facilitated the proliferation of epidermal keratinocytes. These results indicate that propolis stimulates hair growth by inducing hair keratinocyte proliferation.

Concepts: Skin, Epidermis, Caffeic acid, Hair, Hair follicle, Facial hair, Sebaceous gland, Propolis


Acne vulgaris is a chronic inflammatory disease with a complex pathogenesis that affects predominantly adolescents. The aim of the study was to investigate the interrelations between the presence of acne and several variables associated with somatic growth, pubertal maturation, and environmental conditions (altitude and regions of residence). A population sample of 6,200 clinically healthy boys (0-19 years) was examined and the presence of acne was determined. Height, weight, testicular volumes, penile length and circumference, as well as pubic hair were also measured. The prevalence of moderate and severe acne in the whole group was 7.74 %, while in the age group 12-19 years, it was 19.31 %. Twelve-15-year-old boys with acne were taller and heavier than the ones without. They also had increased penile length and circumference as well as larger testicular volumes. Somatometric and pubertal characteristics of 17-19-year-old boys with and without acne were similar. The prevalence of the disease did not differ between the rural and urban inhabitants. However, the acne frequency decreased with the increasing of the altitude where the boys lived. Conclusions: Our results showed that the development of acne vulgaris in male adolescents was associated with an intensive growth and pubertal maturation, while obesity per se did not play an important role. Of particular interest was the association between the prevalence of acne and the altitude of residence.

Concepts: Inflammation, Puberty, Penis, Acne vulgaris, Height, Length, Sebaceous gland, Pubic hair


BACKGROUND: Scalp dermoid cysts are subcutaneous sacs lined with a stratified squamous epithelium containing developmentally mature ectodermal tissues, including skin, hair follicles, sweat glands, and sebaceous glands. METHODS: Because they consist of developmentally mature tissues, scalp dermoid cysts are generally benign. Typically, cysts are limited to an extracranial location, and management generally involves simple surgical resection. DISCUSSION: Because of the potential for intracranial and/or intradural extension associated with some scalp dermoids, however, a comprehensive clinical evaluation incorporating MRI and CT imaging is included in the diagnostic process.

Concepts: Skin, Squamous cell carcinoma, Squamous epithelium, Sebaceous cyst, Epithelial cells, Dermoid cyst, Hair follicle, Sebaceous gland


The mammalian hair follicle unit consists of a central follicle and a series of associated structures: sebaceous glands, arrector pili muscles, Merkel cells, and sensory nerve endings. The architecture of this multicellular structure is highly polarized with respect to the body axes. Previous work has implicated Frizzled6 (Fz6)-mediated planar cell polarity (PCP) signaling in the initial specification of hair follicle orientation. Here we investigate the origin of polarity information among structures within the hair follicle unit. Merkel cell clusters appear to have direct access to Fz6-based polarity information, and they lose polarity in the absence of Fz6. By contrast, the other follicle-associated structures likely derive some or all of their polarity cues from hair follicles, and as a result, their orientations closely match that of their associated follicle. These experiments reveal the interplay between global and local sources of polarity information for coordinating the spatial arrangement of diverse multicellular structures. They also highlight the utility of mammalian skin as a system for quantitative analyses of biological polarity.

Concepts: Skin, Hair follicle, Skin anatomy, Merkel cell cancer, Merkel cell, Sebaceous gland


BACKGROUND: Follicular lymphomatoid papulosis (LyP) describes a variant of LyP with perifollicular infiltrates and some degree of folliculotropism of CD30(+) atypical lymphocytes. So far, only a few cases of follicular LyP have been described. OBJECTIVE: Our goal was to study the clinicopathologic features of follicular LyP in a series of 11 cases (9 male, 2 female; age range 7-78 years, mean age 50 years). METHODS: In all, 113 cases of LyP were reviewed to select cases showing follicular involvement. Histology was correlated with the clinical data to exclude cases of CD30(+) anaplastic large-cell lymphoma or folliculotropic mycosis fungoides. RESULTS: Six cases were classified as type C and 4 as type A, whereas the remaining case manifested epidermotropism of small lymphocytes in a background of a typical type A lesion (overlapping type A/B). Perifollicular infiltrates of CD30(+) atypical lymphoid cells were seen in all 11 cases, with infiltration of the follicular epithelium in 8 cases. Hyperplasia of the follicular epithelium was observed in 4 cases; ruptured hair follicles, in 3 cases; and follicular mucinosis, in 2 cases. In addition to hair follicle infiltration, atypical cells were recognized within sebaceous glands in 2 lesions. New findings were presence of numerous intrafollicular neutrophils in 2 patients, who clinically had pustules in addition to papules. Other histopathological features encountered included perieccrine infiltration (n = 5), focal subcutaneous involvement (n = 4), granulomatous inflammation (n = 3), epidermal hyperplasia (n = 2), and 1 each of infiltration of muscle bundles, numerous eosinophils in the infiltrate, and angiocentricity. LIMITATIONS: This was a retrospective study. CONCLUSIONS: Follicular LyP is a variant of LyP with involvement of hair follicles, mostly in the form of perifollicular infiltrate with variable degree of folliculotropism. Other changes including hyperplasia of the follicular epithelium, rupture of hair follicle, and follicular mucinosis are less common. Rarely, intrafollicular pustules can be seen in the follicular epithelium; such lesions manifest clinically as pustules.

Concepts: Lymphocyte, Anatomical pathology, Cutaneous conditions, Lymphoma, Skin, Hair follicle, Lymphomatoid papulosis, Sebaceous gland