Epidermal Stem Cells Research Articles

Rotating cell culture system-induced injectable self-assembled microtissues with epidermal stem cells for full-thickness skin repair.

Epidermal stem cells (EpSCs) are crucial for wound healing and tissue regeneration, and traditional culture methods often lead to their inactivation. It is urgent to increase the yield of high quality EpSCs. In this study, primary EpSCs were isolated and cultured in a serum-free, feeder-free culture system. EpSCs are then expanded in a dynamic 3D environment using a rotating cell culture system (RCCS) with biodegradable porous microcarriers (MC). Over a period of 14 days, the cells self-assembled into microtissues with superior cell proliferation compared to 3D static culture. Immunofluorescence and qPCR analyses consistently showed that the stemness of the 3D microtissues was preserved, especially the COL17A1 associated with anti-aging was highly expressed in RCCS induced microtissues. In vivo experiments demonstrated that the group treated with 3D microtissues loaded with EpSCs showed enhanced early wound healing, and the injectable 3D microtissues were more conducive to maintaining cell viability and differentiation potential. Our study provides valuable insights into the dynamic 3D culture of EpSCs and introduces an injectable therapy using 3D microtissues loaded with EpSCs, which provides a new and effective approach for cell delivery and offering a promising strategy for guiding the regeneration of full-thickness skin defects.

Biochemical characterization of the feedforward loop between CDK1 and FOXM1 in epidermal stem cells

The complex network governing self-renewal in epidermal stem cells (EPSCs) is only partially defined. FOXM1 is one of the main players in this network, but the upstream signals regulating its activity remain to be elucidated. In this study, we identify cyclin-dependent kinase 1 (CDK1) as the principal kinase controlling FOXM1 activity in human primary keratinocytes. Mass spectrometry identified CDK1 as a key hub in a stem cell-associated protein network, showing its upregulation and interaction with essential self renewal-related markers. CDK1 phosphorylates FOXM1 at specific residues, stabilizing the protein and enhancing its nuclear localization and transcriptional activity, promoting self-renewal. Additionally, FOXM1 binds to the CDK1 promoter, inducing its expression.We identify the CDK1-FOXM1 feedforward loop as a critical axis sustaining EPSCs during in vitro cultivation. Understanding the upstream regulators of FOXM1 activity offers new insights into the biochemical mechanisms underlying self-renewal and differentiation in human primary keratinocytes.

Skin organoid transplantation promotes tissue repair with scarless in frostbite.

Frostbite is the most common cold injury and is caused by both immediate cold-induced cell death and the gradual development of localized inflammation and tissue ischemia. Delayed healing of frostbite often leads to scar formation, which not only causes psychological distress but also tends to result in the development of secondary malignant tumors. Therefore, a rapid healing method for frostbite wounds is urgently needed. Herein, we used a mouse skin model of frostbite injury to evaluate the recovery process after frostbite. Moreover, single-cell transcriptomics was used to determine the patterns of changes in monocytes, macrophages, epidermal cells and fibroblasts during frostbite. Most importantly, human-induced pluripotent stem cell (hiPSC) -derived skin organoids combining with gelatin-hydrogel were constructed for the treatment of frostbite. The results showed that skin organoid treatment significantly accelerated wound healing by reducing early inflammation after frostbite and increasing the proportions of epidermal stem cells. Moreover, in the later stage of wound healing, skin organoids reduced the overall proportions of fibroblasts, significantly reduced fibroblast-to-myofibroblast transition by regulating the integrin α5β1-FAK pathway, and remodeled the extracellular matrix (ECM) through degradation and reassembly mechanisms, facilitating the restoration of physiological ECM and reducing the abundance of ECM associated with abnormal scar formation. These results highlight the potential application of organoids for promoting the reversal of frostbite-related injury and the recovery of skin functions. This study provides a new therapeutic alternative for patients suffering from disfigurement and skin dysfunction caused by frostbite.

Transcription factor KROX20 marks epithelial stem cells for hair follicle formation.

Epidermal stem cells control homeostasis and regeneration of skin and hair. In the hair follicle (HF) bulge of mammals, populations of slow-cycling stem cells regenerate the HF during cyclical rounds of anagen (growth), telogen (quiescence), and catagen (regression). Multipotent epidermal cells are also present in the HF above the bulge area, contributing to the formation and maintenance of sebaceous gland and upper and middle portions of the HF. Here, we report that the transcription factor Krox20 is enriched in an epidermal stem cell population located in the upper/ middle HF. Expression analyses and lineage tracing using inducible Krox20-CreERT showed that Krox20-lineage cells migrate out of this HF region and contribute to the formation of bulge in the HF, serving as ancestors of bulge stem cells. In vivo depletion of these cells arrests HF morphogenesis. This study identifies a novel marker for an epidermal stem cell population that is indispensable for hair homeostasis.

ThP2.15 - Investigating the use of autologous stem cell therapy in the treatment of Androgenetic Alopecia

Abstract Background and Introduction Androgenetic alopecia (AGA) is the commonest form of alopecia and is characterised by progressive degeneration of hair follicles and programmed cell death, impacting individuals of both genders. This affects 80% of individuals in the Caucasian population and causes impairment of quality of life. The cause of AGA is complex and involves androgens, genetics, and hormonal miniaturisation. Dihydrotestosterone (DHT) is the primary androgen responsible for activating pathogenic pathways, resulting in the shortening of terminal follicles. Existing treatment methods are currently limited, and the development of a therapeutic approach that overcomes these limits might be of importance in plastic surgery. Method A comprehensive search is conducted on databases including Pubmed, Medline, Ovid, and Embase. Research studies are extracted and analysed using the PRISMA table. Results The bulge region serves as a vital reservoir of epidermal and melanocytic stem cells. The use of Rigenera® and autologous stem cell therapy has the capability to collect and separate these stem cells (SCs), leading to a 29% ± 5% augmentation in hair density over a span of 6 months. Additional types of multipotent stem cells, such as those found in adipose tissue, bone marrow, and human umbilical cord blood, might potentially be suitable for the purpose of hair regeneration. Possible advantages include a reduced number of biopsies, a shorter treatment duration, and not being limited by the number of donor follicles compared to surgical intervention. Conclusion Autologous stem cell therapy demonstrates potential effectiveness and warrants additional investigation to enhance the therapeutic efficacy of AGA.

Evaluation of the Composite Skin Patch Loaded with Bioactive Functional Factors Derived from Multicellular Spheres of EMSCs for Regeneration of Full-thickness Skin Defects in Rats.

Transplantation of stem cells/scaffold is an efficient approach for treating tissue injury including full-thickness skin defects. However, the application of stem cells is limited by preservation issues, ethical restriction, low viability, and immune rejection in vivo. The mesenchymal stem cell conditioned medium is abundant in bioactive functional factors, making it a viable alternative to living cells in regeneration medicine. Nasal mucosa-derived ecto-mesenchymal stem cells (EMSCs) of rats were identified and grown in suspension sphere-forming 3D culture. The EMSCs-conditioned medium (EMSCs-CM) was collected, lyophilized, and analyzed for its bioactive components. Next, fibrinogen and chitosan were further mixed and cross-linked with the lyophilized powder to obtain functional skin patches. Their capacity to gradually release bioactive substances and biocompatibility with epidermal cells were assessed in vitro. Finally, a full-thickness skin defect model was established to evaluate the therapeutic efficacy of the skin patch. The EMSCs-CM contains abundant bioactive proteins including VEGF, KGF, EGF, bFGF, SHH, IL-10, and fibronectin. The bioactive functional composite skin patch containing EMSCs-CM lyophilized powder showed the network-like microstructure could continuously release the bioactive proteins, and possessed ideal biocompatibility with rat epidermal cells in vitro. Transplantation of the composite skin patch could expedite the healing of the full-thickness skin defect by promoting endogenous epidermal stem cell proliferation and skin appendage regeneration in rats. In summary, the bioactive functional composite skin patch containing EMSCs-CM lyophilized powder can effectively accelerate skin repair, which has promising application prospects in the treatment of skin defects.

A cellular disease model toward gene therapy of TGM1-dependent lamellar ichthyosis

Lamellar Ichthyosis (LI) is a chronic disease, mostly caused by mutations in TGM1 gene, marked by impaired skin barrier formation. No definitive therapies are available and current treatments aim at symptomatic relief. LI mouse models often fail to faithfully replicate the clinical and histopathological features of human skin conditions. To develop advanced therapeutic approaches, as combined ex vivo cell and gene therapy, we established a human cellular model of LI by efficient CRISPR-Cas9-mediated gene ablation of the TGM1 gene in human primary clonogenic keratinocytes. Gene edited cells showed complete absence of Transglutaminase-1 (TG1) expression and recapitulated a hyperkeratotic phenotype with most of the molecular hallmarks of LI in vitro. Using a SINγ-RV vector expressing transgenic TGM1 under the control of its own promoter, we tested an ex vivo gene therapy approach and validate the model of LI as a platform for pre-clinical evaluation studies. Gene-corrected TGM1-null keratinocytes displayed proper TG1 expression, enzymatic activity and cornified envelopes formation, hence restored proper epidermal architecture. Single cell multiomic analysis demonstrated proviral integrations in holoclone-forming epidermal stem cells, which are crucial to epidermal regeneration. This study serves as a proof-of-concept for assessing the potential of this therapeutic approach in treating TGM1 dependent LI.

Emergence and properties of adult mammalian epidermal stem cells

In this review we discuss how the mammalian interfollicular epidermis forms during development, maintains homeostasis, and is repaired following wounding. Recent studies have provided new insights into the relationship between the stem cell compartment and the differentiating cell layers; the ability of differentiated cells to dedifferentiate into stem cells; and the epigenetic memory of epidermal cells following wounding.

Epidermal Neural Crest Stem Cell Conditioned Medium Enhances Spinal Cord Injury Recovery via PI3K/AKT-Mediated Neuronal Apoptosis Suppression

This study aimed to assess the impact of conditioned medium from epidermal neural crest stem cells (EPI-NCSCs-CM) on functional recovery following spinal cord injury (SCI), while also exploring the involvement of the PI3K-AKT signaling pathway in regulating neuronal apoptosis. EPI-NCSCs were isolated from 10-day-old Sprague-Dawley rats and cultured for 48 h to obtain EPI-NCSC-CM. SHSY-5Y cells were subjected with H2O2 treatment to induce apoptosis. Cell viability and survival rates were evaluated using the CCK-8 assay and calcein-AM/PI staining. SCI contusion model was established in adult Sprague-Dawley rats to assess functional recovery, utilizing the Basso, Beattie and Bresnahan (BBB) scoring system, inclined test, and footprint observation. Neurological restoration after SCI was analyzed through electrophysiological recordings. Histological analysis included hematoxylin and eosin (H&E) staining and Nissl staining to evaluate tissue organization. Apoptosis and oxidative stress levels were assessed using TUNEL staining and ROS detection methods. Additionally, western blotting was performed to examine the expression of apoptotic markers and proteins related to the PI3K/AKT signaling pathway. EPI-NCSC-CM significantly facilitated functional and histological recovery in SCI rats by inhibiting neuronal apoptosis through modulation of the PI3K/AKT pathway. Administration of EPI-NCSCs-CM alleviated H2O2-induced neurotoxicity in SHSY-5Y cells in vitro. The use of LY294002, a PI3K inhibitor, underscored the crucial role of the PI3K/AKT signaling pathway in regulating neuronal apoptosis. This study contributes to the ongoing exploration of molecular pathways involved in spinal cord injury (SCI) repair, focusing on the therapeutic potential of EPI-NCSC-CM. The research findings indicate that EPI-NCSC-CM exerts a neuroprotective effect by suppressing neuronal apoptosis through activation of the PI3K/AKT pathway in SCI rats. These results highlight the promising role of EPI-NCSC-CM as a potential treatment strategy for SCI, emphasizing the significance of the PI3K/AKT pathway in mediating its beneficial effects.Graphical

Biochemical role of FOXM1-dependent histone linker H1B in human epidermal stem cells

Epidermal stem cells orchestrate epidermal renewal and timely wound repair through a tight regulation of self-renewal, proliferation, and differentiation. In culture, human epidermal stem cells generate a clonal type referred to as holoclone, which give rise to transient amplifying progenitors (meroclone and paraclone-forming cells) eventually generating terminally differentiated cells. Leveraging single-cell transcriptomic data, we explored the FOXM1-dependent biochemical signals controlling self-renewal and differentiation in epidermal stem cells aimed at improving regenerative medicine applications. We report that the expression of H1 linker histone subtypes decrease during serial cultivation. At clonal level we observed that H1B is the most expressed isoform, particularly in epidermal stem cells, as compared to transient amplifying progenitors. Indeed, its expression decreases in primary epithelial culture where stem cells are exhausted due to FOXM1 downregulation. Conversely, H1B expression increases when the stem cells compartment is sustained by enforced FOXM1 expression, both in primary epithelial cultures derived from healthy donors and JEB patient. Moreover, we demonstrated that FOXM1 binds the promotorial region of H1B, hence regulates its expression. We also show that H1B is bound to the promotorial region of differentiation-related genes and negatively regulates their expression in epidermal stem cells. We propose a novel mechanism wherein the H1B acts downstream of FOXM1, contributing to the fine interplay between self-renewal and differentiation in human epidermal stem cells. These findings further define the networks that sustain self-renewal along the previously identified YAP-FOXM1 axis.

Upregulation of key factors of viral entry of corona- and influenza viruses upon TLR3-signaling in cells from the respiratory tract and clinical treatment options by 1,8-Cineol.

At the end of the 2019 coronavirus pandemic (COVID-19), highly contagious variants of coronaviruses had emerged. Together with influenza viruses, different variants of the coronavirus currently cause most colds and require appropriate drug treatment. We have investigated the expression of important factors for the replication of these viruses, namely transmembrane protease serine subtype 2 (TMPRSS2), neuropilin1 (NRP1), and angiotensin converting enzyme 2 (ACE2) or tumor necrosis factor-α (TNF-α) after toll like receptor-3 (TLR-3) stimulation using RT-qPCR and flow cytometry (FC) analysis. As model served primary fibroblasts derived from the lung and nasal cavity, as well as epidermal stem cells and fully matured respiratory epithelium. The stimulated cell cultures were treated with pharmaceuticals (Dexamethasone and Enzalutamide) and the outcome was compared with the phytomedicine 1,8-Cineol. The stimulation of TLR3 is sufficient to induce the expression of exactly those targets that were highly expressed in the corresponding culture type, specifically ACE2 and TMPRSS2 in respiratory epithelial stem cells and NRP1 in fibroblast cells. It seems this self-perpetuating cycle of infection-driven upregulation of key viral replication factors by the innate immune system represents an evolutionary advantage for viruses using these transcripts as viral replication factors. Likewise, to the standard pharmaceuticals with proven clinical efficiency, 1,8-Cineol was able to disrupt this self-perpetuating cycle. Considering the minor side effects and negligible pharmacological interactions with other drugs, it is conceivable that an adjuvant or combinatorial therapy with 1,8-Cineol for respiratory diseases caused by corona- or influenza viruses would be beneficial.

Exploring the Potential of Skin Cell Culture and the Vital Role of Skin Grafts in Regenerative Medicine and Biology

The skin is acknowledged as the biggest organ, covering the exterior of the body and serving as a physical barrier. The integumentary system is made up of three layers of tissue: the epidermis, dermis, and hypodermis. For transplantation, epidermal cell cultures have been around for a while. The epidermal stem cells can proliferate and self-renew in a manner that allows for rapid healing since they are unipotent, meaning they can only produce one type of cell. In therapeutic terms, cultured keratinocytes have been described as an autologous cell-based therapy that provides a source of autologous tissue, reducing the need for large donor sites and minimizing the risk of immune rejection. This review explores the composition and functioning of the skin’s extracellular matrix, along with strategies to incorporate ECM components into the cell culture techniques. Rebuilding skin flaws without consideration for side effects is skin grafting. The tissue lacks its circulatory supply and must receive it from the bed in which it is inserted. The skin cells have contributed to developing skin graft and tissue engineering approaches for repairing damaged skin. Similar to grafting, the skin graft is divided into sections based on the quantity of dermis involved: split-thickness skin and full-thickness skin. Transplanting autologous keratinocytes is an alternative to autologous skin grafting. In the wound bed, epidermal stem cells encourage angiogenesis. After invading the fibrin wound clot, angiogenic capillary sprouts form a microvascular network throughout the granulation tissue in a few days. In this article, authors will review the current methods and application of skin cell culture for transplantation including different cell sources, culture conditions, and transplantation techniques. The future direction of this approach is in the context of regenerative medicine and tissue engineering.

Predicting in vivo therapeutic efficacy of CelTrac1000-labeled hair follicle epidermal neural crest stem cells in models of repairing rat facial nerve defects via second near-infrared fluorescence imaging

AimsTo detect the therapeutic efficacy of CelTrac1000-labeled hair follicle epidermal neural crest stem cells (EPI-NCSCs) on repairing facial nerve defects by second near-infrared (NIR-II) fluorescence imaging. Materials and methodsFirstly, CelTrac1000-labeled EPI-NCSCs were microinjected into the acellular nerve allografts (ANAs) to bridge a 10-mm-long gap in the buccal branch of facial nerve in adult rats. Then, Celtrac1000-labeled EPI-NCSCs were detected by NIR-II fluorescence imaging system to visualize the behavior of the transplanted cells in vivo. Additionally, the effect of the transplanted EPI-NCSCs on repairing facial nerve defect was examined. Key findingsThrough 14 weeks of dynamic observation, the transplanted EPI-NCSCs survived in the ANAs in vivo after surgery. Meanwhile, the region of the NIR-II fluorescence signals was gradually limited to be consistent with the direction of the regenerative nerve segment. Furthermore, the results of functional and morphological analysis showed that the transplanted EPI-NCSCs could promote the recovery of facial paralysis and neural regeneration after injury. SignificanceOur research provides a novel way to track the transplanted cells in preclinical studies of cell therapy for facial paralysis, and demonstrates the therapeutic potential of EPI-NCSCs combined with ANAs in bridging rat facial nerve defects.

Annexin A1 protects epidermal stem cells against ultraviolet-B irradiation-induced mitochondrial dysfunction.

Ultraviolet-B (UV-B) radiation overexposure causes function impairment of epidermal stem cells (ESCs). We explored the mechanism of Annexin A1 (ANXA1) ameliorating UV-B-induced ESC mitochondrial dysfunction/cell injury. ESCs were cultured in vitro and irradiated with different doses of UV-B. Cell viability/ANXA1 protein level were assessed. After oe-ANXA1 transfection, ESCs were treated with oe-ANXA1/UV-B irradiation/CCCP/CCG-1423/3-methyladenine for 12h. Cell viability/death, and adenosine triphosphate (ATP)/reactive oxygen species (ROS) levels were determined. Mitochondrial membrane potential (MMP) changes/DNA (mtDNA) content/oxygen consumption and RhoA activation were assessed. ROCK1/p-MYPT1/MYPT1/(LC3BII/I)/Beclin-1/p62 protein levels were determined. Mitochondrial morphology was observed. Mito-Tracker Green (MTG) and LC3B levels were determined. UV-B irradiation decreased cell viability/ANXA1 expression in a dose-dependent manner. UV-B-treated ESCs exhibited reduced cell viability/ATP content/MMP level/mitochondrial respiratory control ratio/mtDNA number/RhoA activity/MYPT1 phosphorylation/MTG+LC3B+ cells/(LC3BII/I) and Beclin-1 proteins, increased cell death/ROS/p62/IL-1β/IL-6/TNF-α expression, contracted mitochondrial, disappeared mitochondrial cristae, and increased vacuolar mitochondria, which were averted by ANXA1 overexpression, suggesting that UV-B induced ESC mitochondrial dysfunction/cell injury/inflammation by repressing mitophagy, but ANXA1 promoted mitophagy by activating the RhoA/ROCK1 pathway, thus repressing UV-B's effects. Mitophagy activation ameliorated UV-B-caused ESC mitochondrial dysfunction/cell injury/inflammation. Mitophagy inhibition partly diminished ANXA1-ameliorated UV-B's effects. Conjointly, ANXA1 promoted mitophagy by activating the RhoA/ROCK1 pathway, thereby improving UV-B-induced ESC mitochondrial dysfunction/cell injury.

Study on the anti-skin aging effect and mechanism of Sijunzi Tang based on network pharmacology and experimental validation

Ethnopharmacological relevanceSi Jun Zi Tang (SJZT) is a famous traditional Chinese medicine formula composing of 4 herbal medicines (Ginseng Radix et Rhizoma, Atractylodis macrocephalae Rhizoma, Poria, and Glycyrrhizae Radix et Rhizoma) with tonifying spleen and anti-aging effects. It is also known that SJZT can be used to tone, nourish the skin and accelerate wound healing. However, due to the complexity of the formulation, the anti-aging especially anti-skin aging mechanisms as well as the key components of SJZT have not been fully investigated. Therefore, further in vitro and in vivo experimental studies are particularly needed to investigate the anti-skin ageing efficacy of SJZT. Aim of the studyThe purpose of this article was to explore the therapeutic effect and possible pharmacological mechanism of SJZT in the treatment of skin aging by topical application using network pharmacology and to validate the findings using in vitro and in vivo tests. Materials and methodsNetwork pharmacology method was applied to predict the underlying biological function and mechanism involved in the anti-skin aging effect of SJZT. Molecular docking was used to preliminarily predict the active components of SJZT-Skin Aging. UPLC QTOF MS/MS was carried out to analyze the chemical compounds. Finally, to confirm the anti-skin aging effort of SJZT, a mouse skin-aging model and UVB-induced EpiSCs (epidermal stem cells) senescence model were established. ResultsPPI network analysis and KEGG studies indicated that TP53, CDKN2A, TNF, IL6, and IL1B might be parts of the core targets associated with EpiSCs senescence. Furthermore, molecular docking suggested the top active components, glycyrrhizin, ginsenoside Rg5, ginsenoside Rh2, liquiritin, polyporenic acid C and atractylenolide II showed strong affinity to the key proteins involved in cellular senescence signaling. UPLC QTOF MS/MS analysis of SJZT confirmed the presence of these key components. In-vivo experiments revealed that SJZT could improve UVB-induced skin thickening, increase the number of collagen fibers, strengthen the structure of elastin fibers, and decrease the expression of MDA, as well as increase the expression of CAT and T-SOD in the skin tissue of mouse. And, in-vitro experiments indicated that SJZT could reduce ROS generation and oxidative stress, increase mitochondrial membrane potential, and upregulate the expression of stem cell markers. Moreover, SJZT could suppress the expression of p53, p-p53 and p21, downregulated p38 phosphorylation. Furthermore, the anti-cellular senescence effect of SJZT on EpiSCs disappeared after treatment with the p38 inhibitor adesmapimod. Taken all together, the regulation of senescence signaling in EpiSCs is an important mechanism of SJZT in combating skin aging. ConclusionThe research results indicate that SJZT has anti-skin aging effects on UVB-induced skin-aging model, possibly by mediating p38/p53 signaling pathway. These findings strongly demonstrate the great potential of SJZT as an active composite for anti-skin aging and cosmeceutical applications.

Morroniside promotes skin wound re-epithelialization by facilitating epidermal stem cell proliferation through GLP-1R-mediated upregulation of β-catenin expression.

Epidermal stem cells (EpSCs) play a vital role in skin wound healing through re-epithelialization. Identifying chemicals that can promote EpSC proliferation is helpful for treating skin wounds. This study investigates the effect of morroniside on cutaneous wound healing in mice and explores the underlying mechanisms. Application of 10‒50 μg/mL of morroniside to the skin wound promotes wound healing in mice. In vitro studies demonstrate that morroniside stimulates the proliferation of mouse and human EpSCs in a time- and dose-dependent manner. Mechanistic studies reveal that morroniside promotes the proliferation of EpSCs by facilitating the cell cycle transition from the G1 to S phase. Morroniside increases the expression of β-catenin via the glucagon-like peptide-1 receptor (GLP-1R)-mediated PKA, PKA/PI3K/AKT and PKA/ERK signaling pathways, resulting in an increase in cyclin D1 and cyclin E1 expression, either directly or by upregulating c-Myc expression. This process ultimately leads to EpSC proliferation. Administration of morroniside to mouse skin wounds increases the phosphorylation of AKT and ERK, the expressions of β-catenin, c-Myc, cyclin D1, and cyclin E1, as well as the proliferation of EpSCs, in periwound skin tissue, and accelerates wound re-epithelialization. These effects of morroniside are mediated by the GLP-1R. Overall, these results indicate that morroniside promotes skin wound healing by stimulating the proliferation of EpSCs via increasing β-catenin expression and subsequently upregulating c-Myc, cyclin D1, and cyclin E1 expressions through GLP-1R signaling pathways. Morroniside has clinical potential for treating skin wounds.

Microneedle assisted delivery of epidermal and dermal stem cells to promote hair growth

Microneedle assisted delivery of epidermal and dermal stem cells to promote hair growth

The epidermal circadian clock integrates and subverts brain signals to guarantee skin homeostasis

In mammals, the circadian clock network drives daily rhythms of tissue-specific homeostasis. To dissect daily inter-tissue communication, we constructed a mouse minimal clock network comprising only two nodes: the peripheral epidermal clock and the central brain clock. By transcriptomic and functional characterization of this isolated connection, we identified a gatekeeping function of the peripheral tissue clock with respect to systemic inputs. The epidermal clock concurrently integrates and subverts brain signals to ensure timely execution of epidermal daily physiology. Timely cell-cycle termination in the epidermal stem cell compartment depends upon incorporation of clock-driven signals originating from the brain. In contrast, the epidermal clock corrects or outcompetes potentially disruptive feeding-related signals to ensure the optimal timing of DNA replication. Together, we present an approach for cataloging the systemic dependencies of daily temporal organization in a tissue and identify an essential gate-keeping function of peripheral circadian clocks that guarantees tissue homeostasis.

Rapamycin and/or valproic acid pre-treatment protects epidermal neural crest stem cells from oxygen glucose deprivation-induced oxidative stress through NRF2 pathway

Rapamycin and/or valproic acid pre-treatment protects epidermal neural crest stem cells from oxygen glucose deprivation-induced oxidative stress through NRF2 pathway

Genetic Tools for Cell Lineage Tracing and Profiling Developmental Trajectories in the Skin

The epidermis is the body's first line of protection against dehydration and pathogens, continually regenerating the outermost protective skin layers throughout life. During both embryonic development and wound healing, epidermal stem and progenitor cells must respond to external stimuli and insults to build, maintain, and repair the cutaneous barrier. Recent advances in CRISPR-based methods for cell lineage tracing have remarkably expanded the potential for experiments that track stem and progenitor cell proliferation and differentiation over the course of tissue and even organismal development. Additional tools for DNA-based recording of cellular signaling cues promise to deepen our understanding of the mechanisms driving normal skin morphogenesis and response to stressors as well as the dysregulation of cell proliferation and differentiation in skin diseases and cancer. In this review, we highlight cutting-edge methods for cell lineage tracing, including in organoids and model organisms, and explore how cutaneous biology researchers might leverage these techniques to elucidate the developmental programs that support the regenerative capacity and plasticity of the skin.