Hyperactivation of sympathetic nerves drives depletion of melanocyte stem cells.

Empirical and anecdotal evidence has associated stress with accelerated hair greying (formation of unpigmented hairs)1,2, but so far there has been little scientific validation of this link. Here we report that, in mice, acute stress leads to hair greying through the fast depletion of melanocyte stem cells. Using a combination of adrenalectomy, denervation, chemogenetics3,4, cell ablation and knockout of the adrenergic receptor specifically in melanocyte stem cells, we find that the stress-induced loss of melanocyte stem cells is independent of immune attack or adrenal stress hormones. Instead, hair greying results from activation of the sympathetic nerves that innervate the melanocyte stem-cell niche. Under conditions of stress, the activation of these sympathetic nerves leads to burst release of the neurotransmitter noradrenaline (also known as norepinephrine). This causes quiescent melanocyte stem cells to proliferate rapidly, and is followed by their differentiation, migration and permanent depletion from the niche. Transient suppression of the proliferation of melanocyte stem cells prevents stress-induced hair greying. Our study demonstrates that neuronal activity that is induced by acute stress can drive a rapid and permanent loss of somatic stem cells, and illustrates an example in which the maintenance of somatic stem cells is directly influenced by the overall physiological state of the organism.

Effect of Electrode Surface Chemistry on Ion Structuring of Imidazolium Ionic Liquids.

Surface chemistry plays a critical role in the ion structuring of ionic liquids (ILs) at the interfaces of electrodes and controls the overall energy storage performance of the system. Herein, we functionalized the gold (Au) colloid probe of an atomic force microscope with -COOH and -NH2 groups to explore the effect of different surface chemical properties on the ion structuring of an IL. Aided by colloid-probe atomic force microscopy (AFM), the ion structuring of an imidazolium IL, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6], abbreviated as BP hereafter), on the Au electrode surface and the ion response to the change in the surface chemistry are investigated. AFM morphologies, contact angles, and approaching force-distance curves of the BP IL on the functionalized Au surfaces exhibited that the IL forms a more obvious layering structure on the -COOH-terminated Au surface (Au-COOH), while it forms heterogeneous and aggregating droplets on the -NH2 surface (Au-NH2). The formed uniform and aggregation-free ion layers in the vicinity of the Au-COOH surface are due to the π-π+ stacking interaction between the delocalized π+ electrons from the imidazolium ring in the IL [BMIM]+ cation and the localized π electrons from the sp2 carbon on the -COOH group. The in situ observation of nano-friction and torsional resonance frequency at the IL-electrode interfaces further demonstrated the ion structuring of the IL at Au-COOH, which results in a more sensitive electrochemical response associated with a faster capacitive process.

[Detection and significance of epidermal growth factor receptor mutation in esophageal, esophagogastric junction and gastric cancers].

OBJECTIVE: Tyrosine kinase inhibitors (TKIs) of the epidermal growth factor receptor (EGFR) have been reported to be effective in the treatment of esophageal and esophagogastric junction cancers. The aim of this study was to detect the frequency of EGFR mutation and expression in Chinese patients with esophageal, esophagogastric junction and gastric cancers, and to clarify the value of EGFR mutation and expression in predicting the efficacy of TKI in the treatment of these tumors. METHODS: In this study, 180 tumor samples with histologically confirmed esophageal cancer (39 cases), cancer of the esophagogastric junction (92 cases) and gastric cancer (49 cases) were collected. Twenty-nine different EGFR mutations in exons 18-21 were assessed by real-time PCR-optimized oligonucleotide probe method. EGFR protein expression was evaluated by immunohistochemistry (IHC) in 89 tumor samples. RESULTS: The mutation analysis for EGFR (exons 18-21) showed no mutations in any of the hotspots of the gene in the 180 tumor samples analyzed. EGFR expression was negative in 12 tumor samples, 1+ in 31 tumor samples, 2+ in 24 tumor samples, and 3+ in 22 tumor samples. EGFR expression was 2+ or 3+ in 12 (92.3%) of the 13 esophageal squamous cell carcinomas, 29 (47.5%) of the 61 esophagogastric junction cancers, and 5 (33.3%) of the 15 gastric adenocarcinomas. CONCLUSIONS: Our results indicate that EGFR mutation in exons 18-21 is absent in the examined samples of esophageal, esophagogastric junction and gastric cancers. More studies are warranted to explore the predictive biological markers for the therapeutic response to EGFR TKI.

A ROCK inhibitor promotes keratinocyte survival and paracrine secretion, enhancing establishment of primary human melanocytes and melanocyte-keratinocyte co-cultures.

Primary melanocytes isolated from skin and expanded in culture have been widely used for laboratory research and clinical applications. The conventional method to isolate primary melanocytes from skin usually requires about 3-4 weeks of culture for melanocytes to grow sufficiently to passage. Considering that melanocytes comprise only 3%-7% of epidermal cells in normal human skin, it would be extremely helpful to increase the isolation efficiency and shorten the initial culture time to quickly meet various application needs. Here, we report that adding Y-27632, a Rho kinase inhibitor, into the initial culture medium for 2 days can dramatically increase the yield of melanocytes. We found that Y-27632 can promote keratinocyte attachment and survival in the melanocyte culture system, resulting in not only better recovery, but also increased proliferation of melanocytes by a paracrine signaling pathway. More specifically, Y-27632 significantly induced keratinocyte expression of stem cell factor, which played an important role in enhancing the growth of melanocytes. In summary, Y-27632 could profoundly enhance the yield of primary melanocytes in the initial culture through paracrine effects on keratinocytes.

Pre-aggregation of scalp progenitor dermal and epidermal stem cells activates the WNT pathway and promotes hair follicle formation in in vitro and in vivo systems.

BACKGROUND: Billions of dollars are invested annually by pharmaceutical companies in search of new options for treating hair loss conditions; nevertheless, the challenge remains. One major limitation to hair follicle research is the lack of effective and efficient drug screening systems using human cells. Organoids, three-dimensional in vitro structures derived from stem cells, provide new opportunities for studying organ development, tissue regeneration, and disease pathogenesis. The present study focuses on the formation of human hair follicle organoids. METHODS: Scalp-derived dermal progenitor cells mixed with foreskin-derived epidermal stem cells at a 2:1 ratio aggregated in suspension to form hair follicle-like organoids, which were confirmed by immunostaining of hair follicle markers and by molecular dye labeling assays to analyze dermal and epidermal cell organization in those organoids. The hair-forming potential of organoids was examined using an in vivo transplantation assay. RESULTS: Pre-aggregation of dermal and epidermal cells enhanced hair follicle formation in vivo. In vitro pre-aggregation initiated the interactions of epidermal and dermal progenitor cells resulting in activation of the WNT pathway and the formation of pear-shape structures, named type I aggregates. Cell-tracing analysis showed that the dermal and epidermal cells self-assembled into distinct epidermal and dermal compartments. Histologically, the type I aggregates expressed early hair follicle markers, suggesting the hair peg-like phase of hair follicle morphogenesis. The addition of recombinant WNT3a protein to the medium enhanced the formation of these aggregates, and the Wnt effect could be blocked by the WNT inhibitor, IWP2. CONCLUSIONS: In summary, our system supports the rapid formation of a large number of hair follicle organoids (type I aggregates). This system provides a platform for studying epithelial-mesenchymal interactions, for assessing inductive hair stem cells and for screening compounds that support hair follicle regeneration.

Y-27632 preserves epidermal integrity in a human skin organ-culture (hSOC) system by regulating AKT and ERK signaling pathways.

BACKGROUND: The human skin organ culture (hSOC) developed a century ago has been widely used to study various aspects of human skin development, differentiation, function, disease as well as skin appendages biology, however, maintaining the integrity of epidermal structure in long-term culture, has remained a challenge. OBJECTIVES: Here we tried to establish a culture system using supplemented William's E medium in the presence of a ROCK inhibitor Y-27632 to maintain epidermal architecture in the long-term hSOC and to investigate the underlying mechanisms. METHODS: Human breast skins, cut into 5 mm × 5 mm pieces, were cultured in supplemented William's E medium in the presence of 30µM Y-27632. The cultured skin tissues were collected at different time points for analysis of epidermal cell proliferation and differentiation by real time qRT-PCR and immunofluorescence (IF) staining. The keratinocyte suspension assay and in vivo treatment of Y-27632 on mouse were also carried out to study that the regulation of Y-27632 on keratinocyte proliferation and differentiation. RESULTS: We found Y-27632 not only enhanced both basal cell proliferation and expression of suprabasal cell differentiation markers, but also maintained the balance of keratinocyte proliferation and differentiation through activation of AKT pathways on one hand and inhibition of ERK pathways on the other hand. The AKT inhibitor MK-2206 blocked the epidermal preservation effect of Y-27632, while the MEK/ERK inhibitor U0126 enhanced the preservation of epidermal structure in the hSOC. CONCLUSIONS: Y-227632 can maintain skin epidermal integrity through regulation of AKT and ERK activity in the hSOC.