DNA methylation of microRNA-365-1 induces apoptosis of hair follicle stem cells by targeting DAP3

Background

DNA methylation is a crucial epigenetic alteration involved in diverse biological processes and diseases. Nevertheless, the precise role of DNA methylation in chemotherapeutic drug-induced alopecia remains unclear. This study examined the role and novel processes of DNA methylation in regulating of chemotherapeutic drug-induced alopecia.

Methods

A mouse model of cyclophosphamide (CTX)-induced alopecia was established. Hematoxylin-eosin staining and immunohistochemical staining for the Ki67 proportion and a mitochondrial membrane potential assay (JC-1) were performed to assess the structural integrity and proliferative efficiency of the hair follicle stem cells (HFSCs). Immunofluorescence staining and real-time fluorescence quantitative PCR (RT-qPCR) were performed to determine the expression levels of key HFSC markers, namely Lgr5, CD49f, Sox9, CD200, and FZD10. Differential DNA methylation levels between the normal and CTX-induced model groups were determined through simple methylation sequencing and analyzed using bioinformatics tools. The expression levels of miR-365-1, apoptosis markers, and DAP3 were detected through RT-qPCR and western blotting. In parallel, primary mouse HFSCs were extracted and used as a cell model, which was constructed using 4-hydroperoxycyclophosphamide. The luciferase reporter gene assay was conducted to confirm miR-365-1 binding to DAP3. To measure the expression of relevant indicators, superoxide dismutase (SOD) and malondialdehyde (MDA) kits were used. Methylation-specific PCR (MS-PCR) was performed to determine DNA methylation levels. The regulatory relationship within HFSCs was confirmed through plasmid overexpression of miR-365-1 and DAP3.

Result

In the alopecia areata model, a substantial number of apoptotic cells were observed within the hair follicles on the mouse backs. Immunofluorescence staining revealed that the expression of HFSC markers significantly reduced in the CTX group. Both RT-qPCR and western blotting demonstrated a noteworthy difference in DNA methyltransferase expression. Simple methylation sequencing unveiled that DNA methylation substantially increased within the dorsal skin of the CTX group. Subsequent screening identified miR-365-1 as the most differentially expressed miRNA. miR-365-1 was predicted and confirmed to bind to the target gene DAP3. In the CTX group, SOD and ATP expression markedly reduced, whereas MDA levels were significantly elevated. Cellular investigations revealed 4-HC-induced cell cycle arrest and decreased expression of HFSC markers. MS-PCR indicated hypermethylation modification of miR-365-1 in the 4-HC-induced HFSCs. The luciferase reporter gene experiment confirmed the binding of miR-365-1 to the DAP3 promoter region. miR-365-1 overexpression dramatically reduced apoptotic protein expression in the HFSCs. However, this effect was slightly reversed after DAP3 overexpression in lentivirus.

Conclusion

This study explored the occurrence of miR-365-1 DNA methylation in chemotherapeutic drug-induced alopecia. The results unveiled that miR-365-1 reduces cell apoptosis by targeting DAP3 in HFSCs, thereby revealing the role of DNA methylation of the miR-365-1 promoter in chemotherapeutic drug-induced alopecia.

Carbon Dioxide Fractional Laser Treatment Induces Lgr5+ Stem Cell Activation and Hair Regrowth Through the Canonical Wnt/β-Catenin Pathway

BACKGROUND

Different types of alopecia have negative impacts on patients. Recently, some kinds of laser or light therapies have been reported to effectively alleviate hair loss. Carbon dioxide fractional laser (CO2FL) treatment is one of the most effective laser treatments, but its beneficial effects and exact mechanism in hair regrowth have not been reported in detail. The purpose of this study was to investigate the effect and molecular mechanism further.

METHODS

C57 and Lgr5-Cre: Rosa-mTmG mouse models of hair regrowth were established by CO2FL treatment, and the parameters that induced the best effect were determined. Tissues were harvested on the day prior to the treatment day and on days 3, 5, 7, 10 and 14 after CO2FL. H&E and immunofluorescence staining, RNA sequencing (RNA-seq), quantitative real-time polymerase chain reaction (qPCR), Western blotting (WB) and related inhibitor were used to determine the molecular mechanism underlying the effect of CO2FL treatment on the hair cycle and hair regrowth. In clinical trial, five participants were treated three sessions at 1-month intervals to obverse the effects.

RESULTS

Hair regrew and covered the treatment area on the tenth day after CO2FL treatment with the best parameters, while the control group showed signs of hair growth on the 14th day. H&E and immunofluorescence staining showed that the transition of hair follicles (HFs) from telogen to anagen was accelerated, and the rapid activation and proliferation of Lgr5+ hair follicle stem cells (HFSCs) were observed in the treatment group. The RNA-seq, qPCR and WB results indicated that the Wnt pathway was significantly activated after CO2FL treatment. Improvement achieved with CO2FL treatment in clinical trial.

CONCLUSIONS

The results of this study suggest that CO2FL treatment can promote hair regrowth by activating Lgr5+ HFSCs and upregulating the Wnt/β-catenin pathway. Clinical trial results demonstrated that CO2FL treatment will be a promising therapeutic regimen for alopecia.

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Adult hair follicle stem cells differentiate into neuronal cells in explanted rat intestinal tissue

Hair follicle stem cells (HFSCs) are adult stem cells located in the outer root sheath of the follicle bulge with high neural plasticity, which promise a potential for the stem cell therapy for neurological diseases. Hirschsprung's disease (HD) is characterized by the absence of ganglia in the distant bowel. In this study, we elucidated the capacity of HFSCs to differentiate into neuronal cells in the aganglionic colon from embryonic rat. HFSCs were isolated from adult Sprague-Dawley (SD) rats and formed spheres that could be passaged. The cultured HFSCs expressed neural crest stem cells (NCSCs) markers such as SOX10, CD34, and nestin, which indicated their neural crest lineage. Subsequent differentiation assays demonstrated that these cells could give rise to neural progeny that expressed neuronal or glial markers. The aganglionic colon from the embryonic intestine was applied as in vitro explant to test the capacity of proliferation and differentiation of HFSCs. The HFSCs expressing GFP or RFP integrated in intestinal explants and maintained proliferative capacity. Moreover, the HFSCs differentiated into Tuj1- or S100β-positive cells in the cultured intestinal explants. The results proposed that the HFSCs might be an alternative source of neural stem cells for the HD therapy.

Follicular unit grafting in chronic ulcers: A valuable technique for integrated management

Chronic ulcers significantly affect the quality of life of patients and impose a high cost on the healthcare system. The therapeutic management should be comprehensive, taking into consideration the etiological diagnosis of the wound and the characteristics of the wound bed when deciding on a therapeutic proposal appropriate to the healing phase, correcting factors that delay healing. During the epithelialization phase, repair techniques with grafts are recommended to shorten re-epithelialization time, improve the quality of scar tissue, and achieve adequate pain management. Currently, due to the reported benefits of skin appendages, the technique of follicular unit auto-grafting obtained with a scalp punch is among the chosen strategies for wound repair. This is a minimally invasive, outpatient practice, whose technique has advantages over the donor site, patients recovery and well-being.

Characterization of the Newborn Epidermis and Adult Hair Follicles Using Whole-Mount Immunofluorescent Staining of Mouse Dorsal Skin

The mammalian integumentary system, including skin and its appendages, serves as a protective barrier for the body. During development, skin epidermis undergoes rapid cell division and differentiation to form multiple stratified layers of keratinocytes. Concurrently the epidermis also gives rise to hair follicles that invaginate into the dermis. In adult skin, the hair follicle undergoes cyclic regeneration fueled by hair follicle stem cells located in the bulge. Three-dimensional and high-resolution imaging of these structures using whole-mount immunofluorescent staining allows to better characterize epidermal progenitors and stem cells.

Recent progress in hair follicle stem cell markers and their regulatory roles

Hair follicle stem cells (HFSCs) in the bulge are a multipotent adult stem cell population. They can periodically give rise to new HFs and even regenerate the epidermis and sebaceous glands during wound healing. An increasing number of biomarkers have been used to isolate, label, and trace HFSCs in recent years. Considering more detailed data from single-cell transcriptomics technology, we mainly focus on the important HFSC molecular markers and their regulatory roles in this review.

Autophagy induces hair follicle stem cell activation and hair follicle regeneration by regulating glycolysis

BACKGROUND

Hair follicle stem cells (HFSCs) typically remain quiescent and are activated only during the transition from telogen to anagen to ensure that the hair follicle enters a new cycle. The metabolic behavior of stem cells in tissues is regulated by macroautophagy/autophagy, and changes in HFSC metabolism directly affect their activation and maintenance. However, the role of autophagy in the regulation of HFSC metabolism and function remains unclear.

METHODS

Back skin samples were obtained from mice at different hair follicle cycle stages, and immunofluorescence staining was used to monitor autophagy in HFSCs. Mouse and human hair follicles were treated with rapamycin (Rapa, an autophagy activator) or 3-methyladenine (3-MA, an autophagy inhibitor). The effects of autophagy on the hair follicle cycle and HFSC were investigated by imaging, cell proliferation staining, and HFSC-specific marker staining. The influence and mechanism of autophagy on HFSC metabolism were explored using RNA sequencing, real-time polymerase chain reaction, immunohistochemical staining, and detection of lactate and glucose concentrations. Finally, the influence of autophagy-induced glycolysis on HFSC and the hair follicle cycle was verified by stem cell characteristics and in vivo functional experiments.

RESULTS

Autophagy in HFSC was highest during the transition from telogen to anagen. Inhibiting autophagy with 3-MA led to early entry into catagen and prolonged telogen, whereas Rapa promoted autophagy and hair growth. Autophagy activated HFSC by increasing the expression and activity of HFSC lactate dehydrogenase (Ldha), thereby transforming HFSC metabolism into glycolysis. Inhibition of Ldha expression counteracted the effects of autophagy.

CONCLUSIONS

Autophagy activated HFSC by promoting the transition from HFSC metabolism to glycolysis, ultimately initiating the hair follicle cycle and promoting hair growth.

Exosomes for hair growth and regeneration

Exosomes are lipid bilayer vesicles, 30-200 nm in diameter, that are produced by cells and play essential roles in cell-cell communication. Exosomes have been studied in several medical fields including dermatology. Hair loss, a major disorder that affects people and sometimes causes mental stress, urgently requires more effective treatment. Because the growth and cycling of hair follicles are governed by interactions between hair follicle stem cells (HFSCs) and dermal papilla cells (DPCs), a better understanding of the mechanisms responsible for hair growth and cycling through exosomes may provide new insights into novel treatments for hair loss. In this review, we focused on the comprehensive knowledge and recent studies on exosomes in the field of hair development and regeneration. We classified exosomes of several cellular origins for the treatment of hair loss. Exosomes and their components, such as microRNAs, are promising drugs for effective hair loss treatment.

Photobiomodulation Facilitates Rat Cutaneous Wound Healing by Promoting Epidermal Stem Cells and Hair Follicle Stem Cells Proliferation

BACKGROUND

Cutaneous wound healing represents a common fundamental phenomenon requiring the participation of cells of distinct types and a major concern for the public. Evidence has confirmed that photobiomodulation (PBM) using near-infrared (NIR) can promote wound healing, but the  cells involved and the precise molecular mechanisms remain elusive.

METHODS

Full-thickness skin defects with a diameter of 1.0 cm were made on the back of rats and randomly divided into the control group, 10 J, 15 J, and 30 J groups. The wound healing rate at days 4, 8, and 12 postoperatively was measured. HE and Masson staining was conducted to reveal the histological characteristics. Immunofluorescence staining was performed to label the epidermal stem cells (ESCs) and hair follicle stem cells (HFSCs). Western blot was performed to detect the expressions of proteins associated with ESCs and HFSCs. Cutaneous wound tissues were collected for RNA sequencing. Gene ontology and the Kyoto Encyclopedia of Genes and Genomes analysis was performed, and the hub genes were identified using CytoHubba and validated by qRT-PCR.

RESULTS

PBM can promote reepithelialization, extracellular matrix deposition, and wound healing, increase the number of KRT14+/PCNA+ ESCs and KRT15+/PCNA+ HFSCs, and upregulate the protein expression of P63, Krt14, and PCNA. Three hundred and sixty-six differentially expressed genes (DEGs) and 7 hub genes including Sox9, Krt5, Epcam, Cdh1, Cdh3, Dsp, and Pkp3 were identified. These DEGs are enriched in skin development, cell junction, and cadherin binding involved in cell-cell adhesion etc., while these hub genes are related to skin derived stem cells and cell adhesion.

CONCLUSION

PBM accelerates wound healing by enhancing reepithelialization through promoting ESCs and HFSCs proliferation and elevating the expression of genes associated with stem cells and cell adhesion. This may provide a valuable alternative strategy to promote wound healing and reepithelialization by modulating the proliferation of skin derived stem cells and regulating genes related to cell adhesion.

Distinct mechanisms for sebaceous gland self-renewal and regeneration provide durability in response to injury

Sebaceous glands (SGs) release oils that protect our skin, but how these glands respond to injury has not been previously examined. Here, we report that SGs are largely self-renewed by dedicated stem cell pools during homeostasis. Using targeted single-cell RNA sequencing, we uncovered both direct and indirect paths by which resident SG progenitors ordinarily differentiate into sebocytes, including transit through a Krt5+PPARγ+ transitional basal cell state. Upon skin injury, however, SG progenitors depart their niche, reepithelialize the wound, and are replaced by hair-follicle-derived stem cells. Furthermore, following targeted genetic ablation of >99% of SGs from dorsal skin, these glands unexpectedly regenerate within weeks. This regenerative process is mediated by alternative stem cells originating from the hair follicle bulge, is dependent upon FGFR2 signaling, and can be accelerated by inducing hair growth. Altogether, our studies demonstrate that stem cell plasticity promotes SG durability following injury.

Hair follicle stem cell proliferation and differentiation are achieved by miR-1285-3P through targeted regulation of NOTCH pathway

The purpose of this experiment is to understand how miR-1285-3P regulates the NOTCH signaling pathway by targeting, thereby affecting the proliferation and differentiation of hair follicle stem cells. The cultured Inner Mongolia hair follicle stem cells were used in this experiment, and they were divided into control group, blank transfection group and miR-1285-3P transfection group. Among them, the control group was left untreated; the blank group was given miR-NC transfection; at the same time, the miR-1285-3P transfection group was given miR-1285-3P mimics for transfection. Compared with the control group (97.24 ± 6.81) and blank gro transfection up (97.32 ± 7.20), the cell proliferation ability of the miR-1285-3P transfection group (49.31 ± 3.39) was significantly lower. Compared with the other two groups, The proliferation ability of cells in the miR-1285-3P transfection group was decreased (P < 0.05); compared with the S-phase hair follicle stem cells in the control group (19.23 ± 1.29) and blank transfection group (19.38 ± 1.45), the miR-1285-3P transfection group (15.26 ± 1.26) decreased more significantly (P < 0.05). For hair follicle stem cells in each group, the proportion of cells in the G0-G1 phase was significantly different between the blank transfection group (63.18 ± 2.78) and the control group (64.29 ± 2.09), and the blank transfection group had a higher proportion (P < 0.05). In the process of miR-1285-3P targeting and regulating NOTCH signaling pathway, the proliferation and differentiation ability of hair follicle stem cells is affected. When NOTCH signaling pathway is activated, the differentiation of hair follicle stem cells is accelerated.

Hepatocyte growth factor-modified hair follicle stem cells ameliorate cerebral ischemia/reperfusion injury in rats

BACKGROUND

Hair follicle stem cells (HFSCs) are considered as a promising cell type in the stem cell transplantation treatment of neurological diseases because of their rich sources, easy access, and the same ectoderm source as the nervous system. Hepatocyte growth factor (HGF) is a pleiotropic cytokine that shows neuroprotective function in ischemic stroke. Here we assessed the therapeutic effects of HFSCs on ischemic stroke injury and the synthetic effect of HGF along with HFSCs.

METHODS

Rat HFSCs were intravenously transplanted into a middle cerebral artery ischemia/reperfusion (I/R) rat model. Neurological scoring and TTC staining were performed to assess the benefits of HFSC transplantation. Inflammatory cytokines, blood-brain barrier integrity and angiogenesis within penumbra were estimated by Western blot and immunohistochemistry. The differentiation of HFSCs was detected by immunofluorescence method 2 weeks after transplantation.

RESULTS

HFSC transplantation could significantly inhibit the activation of microglia, improve the integrity of blood-brain barrier and reduce brain edema. Moreover, the number of surviving neurons and microvessels density in the penumbra were upregulated by HFSC transplantation, leading to better neurological score. The combination of HFSCs and HGF could significantly improve the therapeutic benefit.

CONCLUSION

Our results indicate for the first time that HGF modified HFSCs can reduce I/R injury and promote the neurological recovery by inhibiting inflammatory response, protecting blood-brain barrier and promoting angiogenesis.

Effects of Hair Follicle Stem Cells Coupled With Polycaprolactone Scaffold on Cutaneous Wound Healing in Diabetic Male Rats

INTRODUCTION

Chronic wounds are debilitating complications of diabetes mellitus. The present study was conducted to investigate the effect of the hair follicle stem cells (HFSCs) by polycaprolactone scaffold on the healing of incisional cutaneous wounds on streptozotocin-induced diabetic male rats.

METHODS

The wound model was obtained by a biopsy punch of the skin of the animals' back. The animals were randomly divided into five groups as follows: (1) Sham (nondiabetic, not treated), (2) Control (diabetic, not treated), (3) Scaffold (diabetic, treated with polycaprolactone nanofiber scaffold), (4) HFSCs (diabetic, treated with HFSCs), and (5) Scaffold + HFSCs (diabetic, treated with combination of Scaffold and HFSCs). The wounds were photographed in the course of the treatment and their healing rate was assessed. The samples were collected from the wound sites 7, 14, and 28 d after their development. Angiogenesis was surveyed by examining messenger RNA expression and the protein synthesis levels of vascular endothelial growth factor receptor 2 (VEGFR2) and platelet/endothelial cell adhesion molecule-1/cluster of differentiation 31. The histological changes were investigated using hematoxylin and eosin and Masson's trichrome staining. Furthermore, the wound breaking strength was measured on the 28th day by tensiometry.

RESULTS

The application of the VEGFR2 as a substrate promotes the expression of CD31 in HFSCs and Scaffold + HFSCs groups compared to controls (P < 0.0001). HFSCs and scaffold also rescue the diabetes-induced dysfunction as assessed based on the parameters, such as viability, proliferation, colony formation, cellular adhesion, and chemotactic migration. HFSCs augment the levels of VEGFR2 and promote the restoration of the wound healing in diabetic groups. Furthermore, the maximum biomechanical stress significantly increased in the experimental diabetic groups (Scaffold: 1.38 ± 0.09, HFSCs: 2.13 ± 0.8, Scaffold + HFSCs: 2.38 ± 0.11) compared to the diabetes control group (1.16 ± 0.12). Using of HFSCs and scaffold on diabetic wounds leads to an accelerated wound closure, notably.

CONCLUSIONS

Thus, the current data showed that HFSCs and scaffold form excellent biomaterial in the treatment of diabetic wounds.

miR-27a Targeting PIK3R3 Regulates the Proliferation and Apoptosis of Sheep Hair Follicle Stem Cells

Micro RNAs are regulatory factors in tissue development, organ formation, cell growth, apoptosis and other biological processes. In particular, several miRNAs are related to the development of hair follicles. Here, we investigated the effect of the targeting of PIK3R3 by miR-27a on the AKT/MTOR pathway and on the proliferation and apoptosis of hair follicle stem cells (HFSCs) in sheep. Knockdown of the expression of PIK3R3 was found to significantly inhibit the proliferation and promote the apoptosis of HFSCs. Similarly, a miR-27a mimic significantly inhibited the proliferation and promoted the apoptosis of HFSCs. The miR-27a mimic was also shown to significantly inhibit the expression of PIK3R3, AKT, and MTOR and the phosphorylation of AKT and MTOR, while a miR-27a inhibitor increased the expression of these genes. The presence of an miR-27a binding site in the 3' UTR of PIK3R3 was identified by a bioinformatics analysis, and the interaction was verified with a dual-luciferase reporter assay. The expression of PIK3R3 mRNA and protein was negatively correlated with the presence of miR-27a, which suggests that this interaction may be involved in the biological impacts on proliferation and apoptosis. Thus, this study demonstrates that miR-27a plays a potential role in the proliferation and apoptosis of sheep hair follicle stem cells by targeting PIK3R3, which can be used to design new methods to improve sheep wool.

Regulation of signaling pathways in hair follicle stem cells

Hair follicle stem cells (HFSCs) reside in the bulge region of the outer root sheath of the hair follicle. They are considered slow-cycling cells that are endowed with multilineage differentiation potential and superior proliferative capacity. The normal morphology and periodic growth of HFSCs play a significant role in normal skin functions, wound repair and skin regeneration. The HFSCs involved in these pathophysiological processes are regulated by a series of cell signal transduction pathways, such as lymphoid enhancer factor/T-cell factor, Wnt/β-catenin, transforming growth factor-β/bone morphogenetic protein, Notch and Hedgehog. The mechanisms of the interactions among these signaling pathways and their regulatory effects on HFSCs have been previously studied, but many mechanisms are still unclear. This article reviews the regulation of hair follicles, HFSCs and related signaling pathways, with the aims of summarizing previous research results, revealing the regulatory mechanisms of HFSC proliferation and differentiation and providing important references and new ideas for treating clinical diseases.

Low-level laser treatment promotes skin wound healing by activating hair follicle stem cells in female mice

The aim of the study was to explore the effect and mechanism of a low-level laser on hair follicle stem cells in full-thickness skin wound healing in mice. Full-thickness skin defects were generated by a 5-mm punch biopsy tool on the backs of depilated C57/BL6N mice, which were randomly divided thereafter into a low-dose laser treatment group (LLLT-Low), a high-dose laser treatment group (LLLT-High), and a control group (control). From the day of modeling to the day before the skin samples were taken, the wound area and wound edge of the mice in the LLLT-Low and LLLT-High groups were irradiated with a laser comb every 24 h, and the energy density was 1 J/cm2 and 10 J/cm2, respectively. The control group was irradiated with an ordinary fluorescent lamp. At 0, 3, 5, 10, and 14 days after modeling, pictures of each wound were taken, and the percent wound closure was analyzed. At 3, 5, 10, and 14 days after modeling, the samples were observed by hematoxylin and eosin (HE) and immunofluorescence (IF) staining. Whole transcriptome sequencing (RNA-Seq) was performed on the samples on day 10. Gene Ontology (GO) analysis was performed, and the results were validated by Western blot analysis and enzyme-linked immunosorbent assay (ELISA). The analysis of the percent of wound closure showed that healing was accelerated (significantly from 5 to 10 days) in the LLLT-Low group, but there was no clear change in the LLLT-High group. HE staining showed that the LLLT-Low group had an increasing number of hair follicles and a tendency to migrate to the center of the wound. There was no significant increase in the number of hair follicles and no obvious migration in the LLLT-High group. Immunofluorescence staining showed that the total number of CK15 + hair follicle stem cells in the LLLT-Low group was higher than that in the control group and LLLT-High group at all time points. The number and farthest migration distance of CK15 + hair follicle stem cells increased significantly with time, and after 5 days, they were significantly higher than those in the control group and LLLT-High group. RNA-Seq and Western blot analysis showed that the expression of related genes in hair follicle stem cells, including CK15, in the LLLT-Low group was upregulated. GO analysis and ELISA showed that the expression of many cytokines, represented by IL34, in the LLLT-Low group was upregulated. Low-level laser treatment can promote the proliferation, differentiation, and migration of CK15 + hair follicle stem cells by upregulating the cytokine IL34, thereby promoting skin wound healing in mice.

Basal Cells in the Epidermis and Epidermal Differentiation

A definite identification of epidermal stem cells is not known and the mechanism of epidermal differentiation is not fully understood. Toward both of these quests, considerable information is available from the research on lineage tracing and clonal growth analysis in the basal layer of the epidermis, on the hair follicle and the interfollicular epidermal stem cells, and on Wnt signaling along with its role in the developmental patterning and cell differentiation. In this paper, literature on the aforementioned research has been collated and analyzed. In addition, models of the basal layer cellular composition and the epidermal differentiation have been presented. Graphical Abstract.

PlncRNA-1 stimulates hair follicle stem cell differentiation in wound healing via the EZH2/ZEB1/MAPK1 axis

BACKGROUND

Hair follicles have been reported to contribute to epidermal healing, with differentiation of hair follicle stem cells (HFSCs) aiding in wound re-epithelialization. This study is aimed to delineate the molecular mechanistic actions by which prostate cancer-upregulated long noncoding RNA 1 (PlncRNA-1) accelerates the proliferation and differentiation of HFSCs in wound healing.

METHODS

HFSCs were obtained from the scalps of five volunteers, in which the expression of PlncRNA-1 and downstream regulatory genes was identified. Effects of PlncRNA-1 overexpression and ZEB1 knockdown on the proliferation and differentiation of HFSCs were examined. A wound mouse model was further established for in vivo experiments to substantiate in vitro findings.

RESULTS

PlncRNA-1 is highly expressed in HFSCs and accelerates the proliferation and differentiation of HFSCs. PlncRNA-1 recruits EZH2 to ZEB1 promoter region and augments the H3K27me3 methylation, thereby downregulating the expression of ZEB1. Without such suppression, ZEB1 could repress MAPK1 expression and restrict HFSC proliferation and differentiation. Further, PlncRNA-1 overexpression accelerates wound healing and epidermal regeneration in vivo.

CONCLUSIONS

PlncRNA-1 inhibits ZEB1 and activates MAPK1 signaling through upregulating EZH2, thereby enhancing the proliferation and differentiation of HFSCs and wound healing.

Mechanotransductive Differentiation of Hair Follicle Stem Cells Derived from Aged Eyelid Skin into Corneal Endothelial-Like Cells

Corneal endothelial insufficiency is one of the leading causes of blindness. The main contemporary treatment for corneal blindness is endothelial keratoplasty, which, however, is unsatisfactory as a medical therapy due to the lack of donor corneas and graft rejection. Therefore, autologous stem cell-based corneal endothelial tissue substitutes may be a promising alternative to conventional grafts in the future. To address the age of most patients suffering from corneal endothelial deficiencies, we investigated the presence and potential of hair-derived stem cells from older tissue donors. Our studies revealed the presence of pluripotency- and neural crest-associated markers in tissue sections from blepharoplasty patients aged 50 to 80 years. In vitro outgrowths from eyelid hair follicles on collagen-coated tissue culture plates revealed a weak decrease in stem-cell potency. In contrast, cells within the spheres that spontaneously formed from the adherent cell layer retained full stem-cell potency and could be differentiated into cells of the ecto- meso and endodermal lineages. Although these highly potent hair follicle derived stem cells (HFSC) were only very slightly expandable, they were able to recognize the biomimicry of the Descemet’s-like topography and differentiate into corneal endothelial-like cells. In conclusion, HFSCs derived from epidermal skin of eyelid biopsies are a promising cell source to provide autologous corneal endothelial replacement for any age group of patients.

Transcription Factor DLX5 Promotes Hair Follicle Stem Cell Differentiation by Regulating the c-MYC/microRNA-29c-3p/NSD1 Axis

Introduction

Adult stem cell function has been one of the most intensively explored areas of biological and biomedical research, with hair follicle stem cells serving as one of the best model systems. This study explored the role of the transcription factor DLX5 in regulating hair follicle stem cell (HFSC) differentiation.

Methods

HFSCs were isolated, characterized, and assessed for their expression of DLX5, c-MYC, NSD1, and miR-29c-3p using RT-qPCR, Western blot analysis, or immunofluorescence. Next, the ability of HFSCs to proliferate as well as differentiate into either sebaceous gland cells or epidermal cells was determined. The binding of DLX5 to the c-MYC promoter region, the binding of c-MYC to the miR-29c-3p promoter region, and the binding of miR-29c-3p to the 3′-UTR of NSD1 mRNA were verified by luciferase activity assay and ChIP experiments.

Results

DLX5 was highly expressed in differentiated HFSCs. DLX5 transcriptionally activated c-MYC expression to induce HFSC differentiation. c-MYC was able to bind the miR-29c-3p promoter and thus suppressed its expression. Without miR-29c-3p mediated suppression, NSD1 was then able to promote HFSC differentiation. These in vitro experiments suggested that DLX5 could promote HFSC differentiation via the regulation of the c-MYC/miR-29c-3p/NSD1 axis.

Discussion

This study demonstrates that DLX5 promotes HFSC differentiation by modulating the c-MYC/miR-29c-3p/NSD1 axis and identifies a new mechanism regulating HFSC differentiation.

N1-acetylspermidine is a determinant of hair follicle stem cell fate

Stem cell differentiation is accompanied by increased mRNA translation. The rate of protein biosynthesis is influenced by the polyamines putrescine, spermidine and spermine, which are essential for cell growth and stem cell maintenance. However, the role of polyamines as endogenous effectors of stem cell fate and whether they act through translational control remains obscure. Here, we investigate the function of polyamines in stem cell fate decisions using hair follicle stem cell (HFSC) organoids. Compared to progenitor cells, HFSCs showed lower translation rates, correlating with reduced polyamine levels. Surprisingly, overall polyamine depletion decreased translation but did not affect cell fate. In contrast, specific depletion of natural polyamines mediated by spermidine/spermine N1-acetyltransferase (SSAT; also known as SAT1) activation did not reduce translation but enhanced stemness. These results suggest a translation-independent role of polyamines in cell fate regulation. Indeed, we identified N1-acetylspermidine as a determinant of cell fate that acted through increasing self-renewal, and observed elevated N1-acetylspermidine levels upon depilation-mediated HFSC proliferation and differentiation in vivo. Overall, this study delineates the diverse routes of polyamine metabolism-mediated regulation of stem cell fate decisions.

This article has an associated First Person interview with the first author of the paper.

Summary: Reduced protein synthesis is required for stem cell functions. Here, we delineate a complex interplay of polyamines and mRNA translation that determines hair follicle stem cell fate decisions.

Silencing MAP3K1 expression inhibits the proliferation of goat hair follicle stem cells

The Yangtze River Delta White Goat is the only goat breed in the world that can produce superior-quality brush hair. Previous studies have shown that some genes are expressed differentially in the skin tissues between the goats produced superior-quality and normal-quality brush hair. Studies also have shown that different gene play varied roles in regulating the proliferation and apoptosis of hair follicle stem cells. However, the biological function of MAP3K1 (mitogen-activated protein kinase kinase kinase 1) gene in hair follicle stem cells is not fully understood. This study aims to investigate the role of MAP3K1 knockdown during the proliferation and apoptosis of hair follicle stem cells. RT-qPCR and Western blot were used to detect mRNA gene and protein expression level, CCK-8 and EdU assays were used to detect cell proliferation, and cell cycle and apoptosis were detected by flow cytometry. The results showed that the MAP3K1 expression level was significantly higher in the skin tissue of produced superior-quality brush hair than that in produced normal-quality brush hair. Moreover, functional studies indicated that si-MAP3K1 significantly inhibits the proliferation of hair follicle stem cells that came from a superior goat and promotes its apoptosis. Based on aforementioned assays, we speculated that MAP3K1 might play a regulatory effect in superior-quality brush hair traits.

DNMT1-mediated methylation inhibits microRNA-214-3p and promotes hair follicle stem cell differentiate into adipogenic lineages

Background

Dysfunction of the DNA methylation was associated with stem cell reprogramming. Moreover, DNA methyltransferase 1 (DNMT1) deficiency was involved in the differentiation of hair follicle stem cell (HFSc), but the molecular mechanisms remain unknown.

Methods

HFSc from human scalp tissues were isolated and cultured. The oil red O staining was used to observe the adipogenesis. The interaction relationship between microRNA (miR)-214-3p and mitogen-activated protein kinase 1 (MAPK1) was accessed by dual-luciferase reporter gene assay. The methylation level of miR-214-3p promoter was detected by methylation-specific PCR and the enrichment of DNMT1 in miR-214-3p promoter by chromatin immunoprecipitation assay. A mouse model of trauma was established to observe the skin regeneration at 0, 6, and 14 days.

Results

Expression of DNMT1 and MAPK1 was increased in the HFSc, while the expression of miR-214-3p was reduced. Moreover, DNMT1 inhibited the expression of miR-214-3p by promoting the promoter methylation of miR-214-3p. Overexpression of DNMT1 could reduce the expression of miR-214-3p, but increase the expression of MAPK1 and the extent of extracellular signal regulated kinase (ERK)1/2 phosphorylation, leading to enhanced adipogenic differentiation. Importantly, DNMT1 promoted skin regeneration in vivo. Conversely, overexpression of miR-214-3p could reverse the effects of DNMT1 on adipogenesis of HFSc.

Conclusion

DNMT1 promotes adipogenesis of HFSc by mediating miR-214-3p/MAPK1/p-ERK1/2 axis. This study may provide novel biomarkers for the potential application in stem cell therapy.

Transplanted hair follicle stem cells migrate to the penumbra and express neural markers in a rat model of cerebral ischaemia/reperfusion

BACKGROUND

Ischaemic stroke has become the main cause of death and severe neurological disorders, for which effective restorative treatments are currently limited. While stem cell transplantation offers therapeutic potential through neural regeneration, this approach is associated with the challenges of limited applicable sources. Hair follicle stem cells (HFSCs) are multipotential cells that can differentiate into ectodermal and mesodermal lineages and proliferate for long periods. The therapeutic potentials of HFSCs have not been investigated in ischaemic stroke models, and therefore, in this study, we aimed to determine whether they could survive and migrate to ischaemic areas after a stroke attack.

METHODS

A rat model of middle cerebral artery ischaemia/reperfusion was established and intravenously administered HFSCs. The potential of HFSCs to migrate and differentiate into neuron-like cells as well as their ability to reduce the infarct size was evaluated. Rat brain tissue samples were collected 2 weeks after cell transplantation and analysed via TTC staining, immunofluorescence and immunohistochemistry methods. The data were statistically analysed and presented as the means ± standard deviations.

RESULTS

Intravenously administrated rat HFSCs were able to migrate to the penumbra where they expressed neuron-specific markers, reduced the infarct volume and promoted neurological recovery.

CONCLUSION

HFSC transplantation has therapeutic potential for ischaemic stroke and is, therefore, worthy of further investigation toward possible clinical development for treating stroke patients.

Hair follicle stem cells differentiation into bone cells on collagen scaffold

The hair follicle is a dynamic structure which contains different niches for stem cells, therefore; it has been considered as valuable and rich sources of stem cells, due to easy access, multipotency and non-oncogenic properties. In the present study, the differentiation capacities of hair follicle stem cells into bone cells on the natural collagen scaffolds were investigated. The stem cells were extracted from the hair follicle bulge area of male Wistar rats' whisker and cultured until 3rd passage, then osteogenic differentiations were induced by culturing the cells in the specific osteogenic medium. After 3 weeks, the differentiation parameters, including morphological changes, levels of calcification and expression of the bone specific genes were detected. The hydrogel preparation and scaffold fabrication was carried out using the extracted collagen and was studied by scanning electron microscope. Comparison of the stem cells' growth and changes on the scaffold and non-scaffold conditions showed that, in the both situation, the cells revealed differentiation signs of osteocytes, including large and cubic morphology with a star-shaped nucleus. Staining by Alizarin-red and Von-Kossa methods showed the presence of red and black calcium mass on the scaffold. Expression of the osteopontin and alkaline phosphatase genes confirmed the differentiation. Considerable porosity in the surface of the scaffold was recorded by scanning electron microscopy, which made it convenient for cells' attachment and growth. The data showed that the bulge stem cells possess significant capacity for osteoblastic differentiation and collagen scaffolds were found to be an appropriate matrix for growth and differentiation of the cell.

Experimentally Induced Epithelial-Mesenchymal Transition of Human Hair Follicle Stem Cells as a Model of Scarring Alopecia Ex Vivo

Primary cicatricial alopecia is characterized by a permanent "scarring" alopecia. This condition is characterized by the irreversible loss of hair follicles (HF) as a result of apoptosis and epithelial-mesenchymal transition (EMT) of epithelial stem cells localized in the HF bulge.We here report the procedure for experimentally induced EMT in healthy human epidermal stem cells (eSCs) using full-length HF organ culture ex vivo. The present model can be used to recapitulate the complex processes observed in scarring alopecia patient tissues, to further investigate the mechanisms involved in EMT transformation of HFeSCs, and to test substances that could prevent and/or rescue HFeSCs from EMT for the management of scarring alopecias.

A crucial role of fibroblast growth factor 2 in the differentiation of hair follicle stem cells toward endothelial cells in a STAT5-dependent manner

Fibroblast growth factor (FGF2) is reported to affect the proliferation, differentiation, and survival abilities of stem cells. In this study, we hypothesize that FGF2 might promote the differentiation of hair follicle stem cell (HFSCs) into endothelial cells (ECs), in a manner dependent on STAT5 activation. We first treated human HFSCs with recombinant human FGF2 to determine the involvement of FGF2 in the differentiation of HFSCs. Then the expression of EC-specific markers including von Willebrand factor (vWF), VE-cadherin, CD31, FLT-1, KDR and Tie2 was evaluated using immunofluorescence and flow cytometry, while the expression of HFSC-specific markers such as K15, K19, Lgr5, Sox9 and Lhx2 was determined by flow cytometry. Next, in vitro tube formation was performed to confirm the function of FGF2, and low-density lipoprotein (LDL) uptake by ECs and HFSCs was studied by Dil-acetylated LDL assay. In addition, we transduced FGF2-treated HFSCs with constitutive-active or dominant-negative STAT5A adenovirus vectors. FGF2 up-regulated the expression of EC-specific markers, and promoted the differentiation of HFSCs into ECs, tube formation and LDL uptake. The phosphorylated STAT5 was translocated into the nucleus of HFSCs after FGF2 treatment, but this translocation was blocked by the dominant-negative STAT5A mutant. FGF2 increased the differentiation potential through the activation of STAT5 in vivo. Taken together, we find that FGF2 promotes the differentiation of HFSCs into ECs via activated STAT5, which gives a new perspective on the role of FGF2 in the development of ischemic vascular disease.

BMP2-mediated PTEN enhancement promotes differentiation of hair follicle stem cells by inducing autophagy

The proliferation and differentiation of hair follicle stem cells (HFSCs) is regulated by several signaling pathways, including BMP and PTEN. Therefore, this study intended to clarify the potential effects of two such regulators, BMP2 and PTEN, on HFSC differentiation. HFSCs were subjected to BMP2, noggin (BMP2 ligand inhibitor), rapamycin (Rapa, autophagy inducer), 3-methyladenine (3-MA, autophagy inhibitor), or shRNA against PTEN. The differentiation of HFSCs was evaluated using oil red O staining and autophagy was assessed using the transmission electron microscope. Then expression of epidermal differentiation marker (K10 and involucrin), adipogenic markers (PPAR-γ2, aP2, perilipin2, and Adipoq), keratinocyte-specific marker (K15), proliferation-related markers (PCNA and Ki67) and autophagy-related factors (Atg5, Atg7, Atg12, Beclin-1 and LC3-II/LC3-I) was examined by RT-qPCR and Western blot analysis. Next, HFSCs were treated with 3-MA, or shRNA against Atg5 or Atg7 to verify the effect of autophagy on differentiation of BMP2-treated HFSCs. Finally, the effect of BMP2 on HFSC differentiation was verified by a mouse wound model. HFSCs overexpressing BMP2 exhibited elevated expression of epidermal differentiation marker, adipogenic markers and autophagy-related factors but inhibited expression of keratinocyte-specific marker and proliferation-related markers. Furthermore, we found that PTEN promoted the differentiation of BMP2-treated HFSCs by inducing autophagy. In vivo experiments further confirmed the roles of BMP2/PTEN on differentiation of HFSCs. Taken together, BMP2 up-regulated PTEN and consequently induced autophagy to facilitate HFSC differentiation.

Context-dependent effect of sPLA2-IIA induced proliferation on murine hair follicle stem cells and human epithelial cancer

BACKGROUND

Tissue stem cells (SCs) and cancer cells proliferation is regulated by many common signalling mechanisms. These mechanisms temporally balance proliferation and differentiation events during normal tissue homeostasis and repair. However, the effect of these aberrant signalling mechanisms on the ultimate fate of SCs and cancer cells remains obscure.

METHODS

To evaluate the functional effects of Secretory Phospholipase A₂-IIA (sPLA₂-IIA) induced abnormal signalling on normal SCs and cancer cells, we have used K14-sPLA₂-IIA transgenic mice hair follicle stem cells (HFSCs), DMBA/TPA induced mouse skin tumour tissues, human oral squamous cell carcinoma (OSCC) and skin squamous cell carcinoma (SCC) derived cell lines.

FINDINGS

Our study demonstrates that sPLA₂-IIA induces rapid proliferation of HFSCs, thereby altering the proliferation dynamics leading to a complete loss of the slow cycling H2BGFP positive HFSCs. Interestingly, in vivo reversion study by JNK inhibition exhibited a significant delay in post depilation hair growth, confirming that sPLA₂-IIA promotes HFSCs proliferation through JNK/c-Jun signalling. In a different cellular context, we showed increased expression of sPLA₂-IIA in human OSCC and mouse skin cancer tissues. Importantly, a xenograft of sPLA₂-IIA knockdown cells of OSCC and SCC cell lines showed a concomitant reduction of tumour volume in NOD-SCID mice and decreased JNK/c-Jun signalling.

INTERPRETATION

This study unravels how an increased proliferation induced by a common proliferation inducer (sPLA₂-IIA) alters the fate of normal SCs and cancer cells distinctively through common JNK/c-Jun signalling. Thus, sPLA₂-IIA can be a potential target for various diseases including cancer. FUND: This work was partly supported by the Indian Council of Medical Research (ICMR-3097) and ACTREC (42) grants.

Human Hair Follicle Associated-Pluripotent (hHAP) Stem Cells Differentiate to Cardiac Muscle Cells

Human hair follicle-associated pluripotent (hHAP) stem cells were isolated from the upper parts of human hair follicles. hHAP stem cells were suspended in DMEM containing 10% fetal bovine serum (FBS) where they differentiated to cardiac muscle cells as well as neurons, glial cells, keratinocytes, and smooth muscle cells. The methods of this chapter are appropriate for use of human hair follicles to produce hHAP stem cells in sufficient quantities for future heart, nerve, and spinal cord regeneration in the clinic.

Synchronous profiling and analysis of mRNAs and ncRNAs in the dermal papilla cells from cashmere goats

Background

Dermal papilla cells (DPCs), the “signaling center” of hair follicle (HF), delicately master continual growth of hair in mammals including cashmere, the fine fiber annually produced by secondary HF embedded in cashmere goat skins. Such unparalleled capacity bases on their exquisite character in instructing the cellular activity of hair-forming keratinocytes via secreting numerous molecular signals. Past studies suggested microRNA (miRNAs) and long non-coding RNAs (lncRNAs) play essential roles in a wide variety of biological process, including HF cycling. However, their roles and related molecular mechanisms in modulating DPCs secretory activities are still poorly understood.

Results

Here, we separately cultivated DPCs and their functionally and morphologically distinct dermal fibroblasts (DFs) from cashmere goat skins at anagen. With the advantage of high throughput RNA-seq, we synchronously identified 2540 lncRNAs and 536 miRNAs from two types of cellular samples at 4th passages. Compared with DFs, 1286 mRNAs, 18 lncRNAs, and 42 miRNAs were upregulated, while 1254 mRNAs, 53 lncRNAs and 44 miRNAs were downregulated in DPCs. Through overlapping with mice data, we ultimately defined 25 core signatures of DPCs, including HOXC8 and RSPO1, two crucial activators for hair follicle stem cells (HFSCs). Subsequently, we emphatically investigated the impacts of miRNAs and lncRNAs (cis- and trans- acting) on the genes, indicating that ncRNAs extensively exert negative and positive effects on their expressions. Furthermore, we screened lncRNAs acting as competing endogenous RNAs (ceRNAs) to sponge miRNAs and relief their repressive effects on targeted genes, and constructed related lncRNAs-miRNAs-HOXC8/RSPO1 interactive lines using bioinformatic tools. As a result, XR_310320.3-chi-miR-144-5p-HOXC8, XR_311077.2-novel_624-RSPO1 and others lines appeared, displaying that lncRNAs might serve as ceRNAs to indirectly adjust HFSCs status in hair growth.

Conclusion

The present study provides an unprecedented inventory of lncRNAs, miRNAs and mRNAs in goat DPCs and DFs. We also exhibit some miRNAs and lncRNAs potentially participate in the modulation of HFSCs activation via delicately adjusting core signatures of DPCs. Our report shines new light on the latent roles and underlying molecular mechanisms of ncRNAs on hair growth.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5861-4) contains supplementary material, which is available to authorized users.

Up-regulated lncRNA5322 elevates MAPK1 to enhance proliferation of hair follicle stem cells as a ceRNA of microRNA-19b-3p

Hair follicle stem cells (HFSCs), located in the bulge region of the follicle, maintain hair follicle growth and cycling. Long non-coding RNAs (lncRNAs), non-protein coding transcripts, are widely known to play critical roles in differentiation and proliferation of stem cells. Therefore, the current study aimed to explore the regulatory roles of lncRNA5322 in HFSCs proliferation and the underlying regulatory mechanisms. Initially, the expression patterns of lncRNA5322 and microRNA-19b-3p (miR-19b-3p) in HFSCs were detected. Subsequently, gain-and loss-of-functions analyses were conducted to explore the roles of lncRNA5322, miR-19b-3p and mitogen-activated protein kinase 1 (MAPK1) in cell proliferation, colony formation and apoptosis of HFSCs, with the expression of cyclin-dependent kinase (CDK)1 and CDK2 examined. Also, the interaction relationships among lncRNA5322, miR-19b-3p and MAPK1 were explored. Furthermore, a mouse model was established to detect the roles of lncRNA5322, miR-19b-3p, and MAPK1 in wound contraction and epidermal regeneration. Over-expressed lncRNA5322 was found to promote proliferation, colony formation ability but inhibit apoptosis of HFSCs, in addition to up-regulation of the expression of CDK1 and CDK2. LncRNA5322 was found to act as a ceRNA of miR-19b-3p which directly targeted MAPK1. Furthermore, up-regulation of lncRNA5322 enhanced wound contraction and epidermal regeneration in vivo by increasing the expression of MAPK1 through functioning as a ceRNA of miR-19b-3p. In summary, the results in this study suggested that lncRNA5322 serves as a ceRNA of miR-19b-3p to elevate the expression of MAPK1, ultimately promoting HFSCs proliferation, wound contraction and epidermal regeneration of mouse model.

The balance of Bmp6 and Wnt10b regulates the telogen-anagen transition of hair follicles

BACKGROUND

The periodic growth of hair follicles is regulated by the balance of activators and inhibitors. The BMP signaling pathway plays an important role during hair follicle regeneration, but the exact BMP protein that controls this process has not been revealed.

METHODS

The expression of BMP6 was determined via in situ hybridization and immunofluorescence. The in vivo effect of BMP6 overexpression was studied by using a previously established adenovirus injection model. The hair follicle regeneration was assessed by gross observation, H&E staining and 5-bromo-2-deoxyuridine (BrdU) tracing. The expression patterns of BMP6 signaling and Wnt10b signaling in both AdBMP6-treated and AdWnt10b-treated skins were determined by in situ hybridization and immunofluorescence.

RESULTS

BMP6 was expressed differently in the stages of hair follicle cycle. The telogen-anagen transition of hair follicles was inhibited by adenovirus-mediated overexpression of BMP6. In the in vivo model, the BMP6 signaling was inhibited by Wnt10b and the Wnt10b signaling was inhibited by BMP6. The activation of hair follicle stem cells (HFSCs) was also competitively regulated by Wnt10b and BMP6.

CONCLUSIONS

Combined with previously reported data of Wnt10b, our findings indicate that BMP6 and Wnt10b are major inhibitors and activators respectively and their balance regulates the telogen-anagen transition of hair follicles. To the best of our knowledge, our data provide previously unreported insights into the regulation of hair follicle cycling and provide new clues for the diagnosis and therapies of hair loss.

Murine Hair Follicle Derived Stem Cell Transplantation onto the Cornea Using a Fibrin Carrier

The goal of this protocol is to establish a procedure for cultivating stem cells on a fibrin carrier to allow for eventual transplantation to the eye. The ability to transfer stem cells to a patient is critical for treatment for a variety of disorders and wound repair. We took hair follicle stem cells from the vibrissae of transgenic mice expressing a dual reporter gene under the control of the Tet-on system and the keratin 12 promoter (Meyer- Blazejewska et al., 2011 ). A clonal growth assay was performed to enrich for stem cells. Once holoclones formed they were transferred onto a fibrin carrier and cultivated to obtain a confluent epithelial cell layer. Limbal stem cell deficient (LSCD) mice were used as the transplant recipient in order to test for successful grafting and eventual differentiation into a corneal epithelial phenotype.

Hair Follicle Stem Cell Isolation and Expansion

Stem cells are widely used for numerous clinical applications including limbal stem cell deficiency. Stem cell derived from the bulge region of the hair follicle have the ability to differentiate into a variety of cell types including interfollicular epidermis, hair follicle structures, sebaceous glands and corneal epithelial cells when provided the appropriate cues. Hair follicle stem cells are being studied as a valuable source of autologous stem cells to treat disease. The protocol described below details the isolation and expansion of these cells for eventual clinical application. We used a dual-reporter mouse model to visualize both isolation and eventual differentiation of these cells in a limbal stem cell-deficient mouse model.

Regeneration of Mouse Skin Melanocyte Stem Cells In Vivo and In Vitro

Coordinated regeneration of melanocyte stem cells (McSCs) and hair follicle stem cells (HSCs) contributes to generation of pigmented hairs. Synchronous regeneration of McSCs with activation of HSCs occurs not only during initiation of a new hair cycle in vivo but also during reconstitution of hair follicles in vitro. The duration of the quiescent state of these stem cells becomes longer and longer in lifespan of mammals, leading to a decreased regenerative ability to form hair follicles. Here, we describe methods to activate McSCs during hair follicle regeneration in vivo, and isolate melanocytes from neonatal mouse skin to generate an immortalized cell line of melanocyte progenitors in vitro, aiming to use them for studying melanogenesis and future clinical application.

Stem Cells and Tissue Engineering: Regeneration of the Skin and Its Contents

In this review, the authors discuss the stages of skin wound healing, the role of stem cells in accelerating skin wound healing, and the mechanism by which these stem cells may reconstitute the skin in the context of tissue engineering.

In vitro culture of rat hair follicle stem cells on rabbit bladder acellular matrix

Background

The aim of this work was to create a xenogeneic cell scaffold complex with rabbit bladder acellular matrix and rat hair follicle stem cells, to study the feasibility of construct tissue engineer bladder through biocompatibility of hair follicle stem cells and heterogeneous bladder acellular matrix.

Material and Methods

New Zealand rabbit bladder acellular matrix was prepared. Scanning electron microscope and Masson staining were used to analyse the acellular material. Two-steps precipitation method was used to place the third generation of hair follicle stem cells onto the surface of the bladder acellular matrix. The in vitro cell growth on the scaffold complex was regularly monitored through an inverted microscope. Cell growth curve was established and histological examination and scanning electron microscopic were used to analyse the progresses of the cell growth on the matrix material.

Results

The prepared bladder acellular matrix was white, translucent and membranous. It possessed a fibrous network and collagen structure without any significant cell residues as displayed by the scanning electron microscope, and Masson staining. After 48 h of culture, observation by inverted microscope showed that the hair follicle stem cells grew well around the bladder acellular matrix. After 1 week of culture, scanning electron microscopy showed that the hair follicle stem cells spread and adhered on the surface of the scaffold.

Conclusions

The in vitro culture of rat hair follicle stem cells and the rabbit bladder acellular matrix possessed a good biocompatibility, which provides a good experiment support for hair follicle stem cells to repair the bladder defects disease.

sPLA2 -IIA Overexpression in Mice Epidermis Depletes Hair Follicle Stem Cells and Induces Differentiation Mediated Through Enhanced JNK/c-Jun Activation

Secretory phospholipase A2 Group-IIA (sPLA2 -IIA) catalyzes the hydrolysis of the sn-2 position of glycerophospholipids to yield fatty acids and lysophospholipids. sPLA2 -IIA is deregulated in various cancers; however, its role in hair follicle stem cell (HFSC) regulation is obscure. Here we report a transgenic mice overexpressing sPLA2 -IIA (K14-sPLA2 -IIA) showed depletion of HFSC pool. This was accompanied with increased differentiation, loss of ortho-parakeratotic organization and enlargement of sebaceous gland, infundibulum and junctional zone. The colony forming efficiency of keratinocytes was significantly reduced. Microarray profiling of HFSCs revealed enhanced level of epithelial mitogens and transcription factors, c-Jun and FosB that may be involved in proliferation and differentiation. Moreover, K14-sPLA2 -IIA keratinocytes showed enhanced activation of EGFR and JNK1/2 that led to c-Jun activation, which co-related with enhanced differentiation. Further, depletion of stem cells in bulge is associated with high levels of chromatin silencing mark, H3K27me3 and low levels of an activator mark, H3K9ac suggestive of alteration in gene expression contributing toward stem cells differentiation. Our results, first time uncovered that overexpression of sPLA2 -IIA lead to depletion of HFSCs and differentiation associated with altered histone modification. Thus involvement of sPLA2 -IIA in stem cells regulation and disease pathogenesis suggest its prospective clinical implications. Stem Cells 2016;34:2407-2417.

Expression of pluripotency markers in Arbas Cashmere goat hair follicle stem cells

In our previous work, we found that the Inner Mongolia Arbas Cashmere goat hair follicle stem cells (gHFSCs) can be successfully differentiated into adipocyte, chondrocyte, and osteocyte lineages. In this study, we further examined the expression of the pluripotency and stemness markers Oct4, Nanog, Sox2, AKP, and TERT in gHFSCs by immunocytochemistry, flow cytometry, real-time PCR, and Western blot. Immunofluorescent staining showed that the gHFSCs were positive for all five markers. Fluorescence-activated cell sorting (FACS) further analyzed the positive expression of Oct4, Nanog, and Sox2 in the gHFSCs. Compared with Arbas Cashmere goat adipose-derived stem cells (gADSCs) at the mRNA expression level, Oct4 was relatively highly expressed in gHFSCs, 41.36 times of the gADSCs, and Nanog was 5.61, AKP was 2.74, and TERT was 2.10 times, respectively (p < 0.01). Western blot indicated that all markers are expressed at the protein level in the gHFSCs. When compared with gADSCs, using α-tubulin as a reference protein, gray intensity analysis showed that the expression of Oct4, Nanog, AKP, and TERT were, respectively, 5.94, 10.78, 1.33, and 1.39 times of gADSCs. Additionally, mRNA and protein expression of Sox2 were detected in the gHFSCs but not in the gADSCs. The protein expression pattern of these markers was consistent with the mRNA results.

Isolation and characterization of hair follicle stem cells from Arbas Cashmere goat

In this study, highly purified hair follicle stem cells from Arbas Cashmere goat (gHFSCs) were isolated using enzyme digestion and adhesion to type IV collagen. The biological characteristics of the gHFSCs were identified by morphological observation, growth curve, markers assay and differentiation in vitro. The gHFSCs were in small cell size with typical cobblestone morphology, good adhesion and high refractive index. Immunocytochemistry staining showed the cells were expressing Krt15, Krt19, CD34, Itgβ1 and Krt14. Cell growth curve indicated that cultured gHFSCs had strong proliferation ability. Krt14 and CD34 were high expressed at the mRNA level, respectively, 39.68 and 24.37 times of the Cashmere goat keratinocytes, and krt15 expression was 5.62 times and itgβ1 expression was 1.81 times higher (p < 0.01). Western blot detected the expression of all the above markers. After osteogenic induction, the cells were positive for Von Kossa staining and expressed Osteocalcin. Sulfated proteoglycans in cartilaginous matrices were positively stained by Alcian blue after chondrogenic induction and COL2A1 was expressed. In myogenic induction, Hoechst 33342 staining evidenced cytoplasm fusion and positive expression of MyoG was detected by immunocytochemistry.

Foxi3 Deficiency Compromises Hair Follicle Stem Cell Specification and Activation

The hair follicle is an ideal system to study stem cell specification and homeostasis due to its well characterized morphogenesis and stereotypic cycles of stem cell activation upon each hair cycle to produce a new hair shaft. The adult hair follicle stem cell niche consists of two distinct populations, the bulge and the more activation-prone secondary hair germ (HG). Hair follicle stem cells are set aside during early stages of morphogenesis. This process is known to depend on the Sox9 transcription factor, but otherwise the establishment of the hair follicle stem cell niche is poorly understood. Here, we show that that mutation of Foxi3, a Forkhead family transcription factor mutated in several hairless dog breeds, compromises stem cell specification. Further, loss of Foxi3 impedes hair follicle downgrowth and progression of the hair cycle. Genome-wide profiling revealed a number of downstream effectors of Foxi3 including transcription factors with a recognized function in hair follicle stem cells such as Lhx2, Runx1, and Nfatc1, suggesting that the Foxi3 mutant phenotype results from simultaneous downregulation of several stem cell signature genes. We show that Foxi3 displays a highly dynamic expression pattern during hair morphogenesis and cycling, and identify Foxi3 as a novel secondary HG marker. Absence of Foxi3 results in poor hair regeneration upon hair plucking, and a sparse fur phenotype in unperturbed mice that exacerbates with age, caused by impaired secondary HG activation leading to progressive depletion of stem cells. Thus, Foxi3 regulates multiple aspects of hair follicle development and homeostasis. Stem Cells 2016;34:1896-1908.

Vital roles of stem cells and biomaterials in skin tissue engineering

Tissue engineering essentially refers to technology for growing new human tissue and is distinct from regenerative medicine. Currently, pieces of skin are already being fabricated for clinical use and many other tissue types may be fabricated in the future. Tissue engineering was first defined in 1987 by the United States National Science Foundation which critically discussed the future targets of bioengineering research and its consequences. The principles of tissue engineering are to initiate cell cultures in vitro, grow them on scaffolds in situ and transplant the composite into a recipient in vivo. From the beginning, scaffolds have been necessary in tissue engineering applications. Regardless, the latest technology has redirected established approaches by omitting scaffolds. Currently, scientists from diverse research institutes are engineering skin without scaffolds. Due to their advantageous properties, stem cells have robustly transformed the tissue engineering field as part of an engineered bilayered skin substitute that will later be discussed in detail. Additionally, utilizing biomaterials or skin replacement products in skin tissue engineering as strategy to successfully direct cell proliferation and differentiation as well as to optimize the safety of handling during grafting is beneficial. This approach has also led to the cells’ application in developing the novel skin substitute that will be briefly explained in this review.

Arterial grafts exhibiting unprecedented cellular infiltration and remodeling in vivo: the role of cells in the vascular wall

OBJECTIVE

To engineer and implant vascular grafts in the arterial circulation of a pre-clinical animal model and assess the role of donor medial cells in graft remodeling and function.

APPROACH AND RESULTS

Vascular grafts were engineered using Small Intestinal Submucosa (SIS)-fibrin hybrid scaffold and implanted interpositionally into the arterial circulation of an ovine model. We sought to demonstrate implantability of SIS-Fibrin based grafts; examine the remodeling; and determine whether the presence of vascular cells in the medial wall was necessary for cellular infiltration from the host and successful remodeling of the implants. We observed no occlusions or anastomotic complications in 18 animals that received these grafts. Notably, the grafts exhibited unprecedented levels of host cell infiltration that was not limited to the anastomotic sites but occurred through the lumen as well as the extramural side, leading to uniform cell distribution. Incoming cells remodeled the extracellular matrix and matured into functional smooth muscle cells as evidenced by expression of myogenic markers and development of vascular reactivity. Interestingly, tracking the donor cells revealed that their presence was beneficial but not necessary for successful grafting. Indeed, the proliferation rate and number of donor cells decreased over time as the vascular wall was dominated by host cells leading to significant remodeling and development of contractile function.

CONCLUSIONS

These results demonstrate that SIS-Fibrin grafts can be successfully implanted into the arterial circulation of a clinically relevant animal model, improve our understanding of vascular graft remodeling and raise the possibility of engineering mural cell-free arterial grafts.

Neuronal differentiation of rat hair follicle stem cells: the involvement of the neuroprotective factor Seladin-1 (DHCR24)

Background: The seladin-1 (selective Alzheimer disease indicator-1), also known as DHCR24, is a gene found to be down-regulated in brain region affected by Alzheimer disease (AD). Whereas, hair follicle stem cells (HFSC), which are affected in with neurogenic potential, it might to hypothesize that this multipotent cell compartment is the predominant source of seladin-1. Our aim was to evaluate seladin-1 gene expression in hair follicle stem cells. Methods: In this study, bulge area of male Wistar rat HFSC were cultured and then characterized with Seladin-1 immunocytochemistry and flow cytometry on days 8 to 14. Next, 9-11-day cells were evaluated for seladin-1 gene expression by real-time PCR. Results: Our results indicated that expression of the seladin-1 gene (DHCR24) on days 9, 10, and 11 may contribute to the development of HFSC. However, the expression of this gene on day 11 was more than day 10 and on 10^th day was more than day 9. Also, we assessed HFSC on day 14 and demonstrated these cells were positive for β-ш tubulin, and seladin-1 was not expressed in this day. Conclusion: HFSC express seladin-1 and this result demonstrates that these cells might be used to cell therapy for AD in future.

Smad1 and 5 but not Smad8 establish stem cell quiescence which is critical to transform the premature hair follicle during morphogenesis toward the postnatal state

Hair follicles (HFs) are regenerative miniorgans that offer a highly informative model system to study the regulatory mechanisms of hair follicle stem cells (hfSCs) homeostasis and differentiation. Bone morphogenetic protein (BMP) signaling is key in both of these processes, governing hfSCs quiescence in the bulge and differentiation of matrix progenitors. However, whether canonical or noncanonical pathways of BMP signaling are responsible for these processes remains unresolved. Here, we conditionally ablated two canonical effectors of BMP signaling, Smad1 and Smad5 during hair morphogenesis and postnatal cycling in mouse skin. Deletion of Smad1 and Smad5 (dKO) in the epidermis during morphogenesis resulted in neonatal lethality with lack of visible whiskers. Interestingly, distinct patterns of phospho-Smads (pSmads) activation were detected with pSmad8 restricted to epidermis and pSmad1 and pSmad5 exclusively activated in HFs. Engraftment of dKO skin revealed retarded hair morphogenesis and failure to differentiate into visible hair. The formation of the prebulge and bulge reservoir for quiescent hfSCs was precluded in dKO HFs which remained in prolonged anagen. Surprisingly, in postnatal telogen HFs, pSmad8 expression was no longer limited to epidermis and was also present in dKO bulge hfSCs and matrix progenitors. Although pSmad8 activity alone could not prevent dKO hfSCs precocious anagen activation, it sustained efficient postnatal differentiation and regeneration of visible hairs. Together, our data suggest a pivotal role for canonical BMP signaling demonstrating distinguished nonoverlapping function of pSmad8 with pSmad1 and pSmad5 in hfSCs regulation and hair morphogenesis but a redundant role in adult hair progenitors differentiation.

Human Hair Follicle Cells with the Cell Surface Marker CD34 Can Regenerate New Mouse Hair Follicles and Located in the Outer Root Sheath of Immunodeficient Nude Mice

BACKGROUND AND OBJECTIVES

The bulge region of hair follicle has been reported as a putative reservoir of hair follicle stem cells. The purpose of this study was to compare hair follice CD34 negative (CD34-) cell with CD34 positive (CD34+) cell and to evaluate the ability to regenerate new hair of immunodeficient nude mouse.

METHODS AND RESULTS

In this report, we isolated the cells with CD34, known as bulge-negative cell surface marker from cultured human hair follicle cells using by magnetic cell sorting (MACS), injected the cells to immunodeficient nude mouse. To determine immunological characterization, human hair follicle CD34+ cells and CD34- cells were assessed by flow cytometry. The localization of injected-CD34+ cells was assessed on formalin-fixed, paraffin-embedded mouse skin samples by in situ hybridization technique. Our findings show that the human hair follicle cells with cell surface marker CD34 were located in the outer root sheath of nude mouse after transplantation and the cells were able to regenerate new hair follicle in immunodeficient nude mouse. CD34- cells also were able to regenerate follicles in the mouse, however, CD34+ cells were able to regenerate much more hair follicle than CD34- cells.

CONCLUSIONS

Therefore, the results of this study add new insight into the investigation of CD34 stem cell-related molecule in human hair follicles and suggest that not all human hair follicle stem cells reside in bulge region, but in a lager niche.

Wnt/β-catenin signaling in dermal condensates is required for hair follicle formation

Broad dermal Wnt signaling is required for patterned induction of hair follicle placodes and subsequent Wnt signaling in placode stem cells is essential for induction of dermal condensates, cell clusters of precursors for the hair follicle dermal papilla (DP). Progression of hair follicle formation then requires coordinated signal exchange between dermal condensates and placode stem cells. However, it remains unknown whether continued Wnt signaling in DP precursor cells plays a role in this process, largely due to the long-standing inability to specifically target dermal condensates for gene ablation. Here we use the Tbx18(Cre) knockin mouse line to ablate the Wnt-responsive transcription factor β-catenin specifically in these cells at E14.5 during the first wave of guard hair follicle formation. In the absence of β-catenin, canonical Wnt signaling is effectively abolished in these cells. Sox2(+) dermal condensates initiate normally; however by E16.5 guard hair follicle numbers are strongly reduced and by E18.5 most whiskers and guard hair follicles are absent, suggesting that active Wnt signaling in dermal condensates is important for hair follicle formation to proceed after induction. To explore the molecular mechanisms by which Wnt signaling in dermal condensates regulates hair follicle formation, we analyze genome-wide the gene expression changes in embryonic β-catenin null DP precursor cells. We find altered expression of several signaling pathway genes, including Fgfs and Activin, both previously implicated in hair follicle formation. In summary, these data reveal a functional role of Wnt signaling in DP precursors for embryonic hair follicle formation and identify Fgf and Activin signaling as potential effectors of Wnt signaling-regulated events.