Mechanical Stretch Induced Skin Regeneration: Molecular and Cellular Mechanism in Skin Soft Tissue Expansion.

Skin soft tissue expansion is one of the most basic and commonly used techniques in plastic surgery to obtain excess skin for a variety of medical uses. However, skin soft tissue expansion is faced with many problems, such as long treatment process, poor skin quality, high retraction rate, and complications. Therefore, a deeper understanding of the mechanisms of skin soft tissue expansion is needed. The key to skin soft tissue expansion lies in the mechanical stretch applied to the skin by an inflatable expander. Mechanical stimulation activates multiple signaling pathways through cellular adhesion molecules and regulates gene expression profiles in cells. Meanwhile, various types of cells contribute to skin expansion, including keratinocytes, dermal fibroblasts, and mesenchymal stem cells, which are also regulated by mechanical stretch. This article reviews the molecular and cellular mechanisms of skin regeneration induced by mechanical stretch during skin soft tissue expansion.

m6A modification of mRNA in skin diseases. / çš®è‚¤ç— ä¸­ç¼–ç RNA的m6A修饰.

N6-methyladenosine (m6A) is the predominant post-transcriptional modification for eukaryotic mRNA. It's regulated by methyltransferases, demethylases, and m6A binding proteins, and plays an important role in regulating splicing, translation, and degradation of mRNA. Skin diseases, especially immune skin diseases and skin tumors, have a complicated pathogenesis and are refractory to treatment, seriously affecting the patient quality of life. Recent studies have revealed that m6A and its regulatory proteins can affect the development of numerous skin diseases. The m6A modification was found to be involved in skin accessory development, including hair follicle and sweat gland formation. The level of m6A modification was significantly altered in a variety of skin diseases including melanoma, cutaneous squamous cell carcinoma, Merkel cell carcinoma, and psoriasis, and affected a variety of biological processes including cell proliferation and differentiation migration. The m6A and its regulatory proteins may become potential molecular markers or therapeutic targets for skin diseases, and have promising clinical applications in early diagnosis, efficacy determination, prognosis prediction, and gene therapy of skin diseases.

Generation of Skin Organoids: Potential Opportunities and Challenges.

Although several types of human skin substitutes are currently available, they usually do not include important skin appendages such as hair follicles and sweat glands, or various skin-related cells, such as dermal adipocytes and sensory neurons. This highlights the need to improve the in vitro human skin generation model for use as a tool for investigating skin diseases and as a source of cells or tissues for skin regeneration. Skin organoids are generated from stem cells and are expected to possess the complexity and function of natural skin. Here, we summarize the current literatures relating to the "niches" of the local skin stem cell microenvironment and the formation of skin organoids, and then discuss the opportunities and challenges associated with multifunctional skin organoids.

Establishment of Three Types of Immortalized Human Skin Stem Cell Lines Derived from the Single Donor.

Currently, human-skin derived cell culture is a basic technique essential for dermatological research, cellular engineering research, drug development, and cosmetic development. But the number of donors is limited, and primary cell function reduces through cell passage. In particular, since adult stem cells are present in a small amount in living tissues, it has been difficult to obtain a large amount of stem cells and to stably culture them. In this study, skin derived cells were isolated from the epidermis, dermis, and adipose tissue collected from single donor, and immortalization was induced through gene transfer. Subsequently, cell lines that could be used as stem cell models were selected using the differentiation potential and the expression of stem cell markers as indices, and it was confirmed that these could be stably cultured. The immortalized cell lines established in this study have the potential to be applied not only to basic dermatological research but also to a wide range of fields such as drug screening and cell engineering.

Magnetic-Based Cell Isolation Technique for the Selection of Stem Cells.

Magnetic-activated cell sorting (MACS) is the technology that is recently used as a magnetic-based cell isolation/purification technique. This technique enables the isolation and selection of germ, hematopoietic, and somatic stem cells including skin stem cells (SkSCs). Here, we have tried to describe the isolation of stem cells by MACS using CD34 antigen for SkSCs, again CD34 for hematopoietic stem cells (HSCs) and Thy-1 for spermatogonial stem cells (SpSCs). MACS allowed the isolation of CD34+, CD34+, and Thy-1+ human SkSCs, HSCs, and SpSCs with minimum 98% purity.

Regenerative Medicine Applications in Wound Care.

BACKGROUND: During the last two decades, a number of studies have been carried out on the application of regenerative medicine in the field of dermatology. OBJECTIVE: The aim of this research was to critically review the application of regenerative medicine in the field of dermatology. The next aim was to look in depth to see whether regenerative medicine strategies have a place in the future of wound healing in a clinical setting. More specifically, to see if these strategies would apply for burns and non-healing diabetic wounds. RESULTS: Billions of dollars have been spent worldwide on research in wound treatment and skin regeneration. Although a high number of clinical trials show promising results, there is still no commercially available treatment for use. In addition, the outcome data from the clinical trials, taking place throughout the world, are not published in a standardized manner. Standardization within clinical trials is required for: protocols, outcome, endpoint values, and length of follow-up. The lack of standardization makes it much more difficult to compare the data collected and the different types of treatment. CONCLUSION: Despite several promising results from research and early phase clinical studies, the treatment for wounds as well as skin regeneration is still considered as an unmet clinical need. However, in the past three years, more promising research has been approaching clinical trials; this could be the solution that clinicians have been waiting for. This is a multibillion dollar industry for which there should be enough incentive for researchers and industry to seek the solution.

Efficient in vivo gene editing using ribonucleoproteins in skin stem cells of recessive dystrophic epidermolysis bullosa mouse model.

The prokaryotic CRISPR/Cas9 system has recently emerged as a powerful tool for genome editing in mammalian cells with the potential to bring curative therapies to patients with genetic diseases. However, efficient in vivo delivery of this genome editing machinery and indeed the very feasibility of using these techniques in vivo remain challenging for most tissue types. Here, we show that nonreplicable Cas9/sgRNA ribonucleoproteins can be used to correct genetic defects in skin stem cells of postnatal recessive dystrophic epidermolysis bullosa (RDEB) mice. We developed a method to locally deliver Cas9/sgRNA ribonucleoproteins into the skin of postnatal mice. This method results in rapid gene editing in epidermal stem cells. Using this method, we show that Cas9/sgRNA ribonucleoproteins efficiently excise exon80, which covers the point mutation in our RDEB mouse model, and thus restores the correct localization of the collagen VII protein in vivo. The skin blistering phenotype is also significantly ameliorated after treatment. This study provides an in vivo gene correction strategy using ribonucleoproteins as curative treatment for genetic diseases in skin and potentially in other somatic tissues.

Age-related decrease in CD271(+) cells in human skin.

According to recent studies, stem cells are found in various tissues in our bodies. It has been reported that stem cells can reside in the skin tissues, including the epidermis, dermis, hair follicles and subcutaneous tissues. Homeostasis of the skin is maintained because these stem cells collaborate with each other to form new cells. We previously identified the CD271(p75NTR)(+) cell as a stem cell that was present in the epidermis, dermis and subcutaneous tissue, and further investigated the role of stem cells in wound healing and their association with skin disease. In this study, we investigated the localization of CD271(+) cells in human skin (epidermis and dermis) and its age-related changes in stem cells using CD271(+) cells. The study revealed that the number of CD271(+) cells in the epidermis and dermis decreased with aging. It is possible that such an age-related decrease in stem cells causes impaired regenerative ability and is associated with various skin diseases. If the relationship between stem cells and skin aging and diseases can be elucidated by investigations such as this study, it may lead to the development of novel anti-aging technologies and medical treatments for skin diseases in the future.

Bases moleculares da depleção de glutationa sobre a pontencialidade, diferenciação e envelhecimento de células-tronco de pele / Molecular basis of glutathione depletion upon the potenciality, differentiation potential and aging of skin stem cells

A pele está em contínua auto-renovação graças a vários nichos de células-tronco presentes neste tecido. Células progenitoras epidérmicas surgem durante o desenvolvimento embrionário e contribuem para a reposição celular da epiderme durante todo o período de vida dos mamíferos. Neste trabalho, buscou-se analisar o papel da depleção de glutationa durante a estratificação da epiderme embrionária e na manutenção da homeostase no tecido adulto. Encontramos evidências de que este tiol tem um importante papel durante a proliferação da epiderme e formação do folículo capilar. As alterações observadas na ausência de GSH foram relacionados com um padrão diferencial de fosforilação dos fatores de transcrição forkhead-homeobox- tipo-O (FOXO). Em resumo, foi estabelecida uma correlação entre o estado de GSH, a fosforilação de FOXO e o desenvolvimento da epiderme. Para melhor estudar a importância do balanço de GSH, na pele do adulto, e seu papel na manutenção deste tecido, camundongos foram tratados com um inibidor da síntese de GSH e, com N-aceti-lcisteína. Foi observado um aumento da fosforilação de Akt, padrões alterados de fosforilação FOXO e aumento da expressão de genes de genes relacionados à diferenciação. Estes resultados mostram que a via Akt/FOXO desempenha um papel importante na manutenção e diferenciação de células-tronco epidermais. O envelhecimento cronológico leva a alterações morfológicas/funcionais que conduzem à diminuição da auto-renovação, o que ocorre concomitantemente com uma diminuição dos níveis de GSH na pele. Utilizamos, também, animais idosos e avaliamos quais mecanismos eram compartilhados pelo envelhecimento e a depleção deste tiol. Observou-se que uma resposta hiperproliferativa ligada à exaustão de células-tronco pode ser o elo entre a depleção de GSH e o envelhecimento. A influência desse processo também foi investigada no compartimento dérmico, através da análise do impacto da depleção de glutationa sobre a osteogênese de células-tronco mesenquimais murinas. Quando induzidas a se diferenciarem em osso (Alizarin-Red+/Von-Kossa-stain +, aumento dos níveis de mRNA para fosfatase alcalina/osteopontina/osterix), o balanço GSH/GSSG e seu sistema antioxidante correlato é diferencialmente regulado em células-tronco mesenquimais derivadas da derme. Sendo regulado de uma forma redox-dependente através da via de MAPKs. A depleção de GSH leva à diminuição nos níveis de osteogênese em favor da adipogênese, levando ao processo comumente associado ao envelhecimento denominado "adipogenic switc". Em conclusão, os dados obtidos permitem propor um papel central para a glutationa na manutenção/comprometimento de células-tronco na pele

The skin is continuously self-renewing thanks to several stem cell niches. Epidermal progenitor cells arise during embryonic development and contribute to the replenishment of the epidermis during the lifetime of mammals. We set out to analyze the glutathione (GSH) antioxidant system during embryonic epidermis stratification and follicle development and the effect of glutathione withdrawal in this process. We found that glutathione plays an important role during epidermis proliferation and hairshaft formation. The changes observed in the absence of GSH were related to a differential phosphorylation pattern of the forkhead-homeobox-type-O (FOXO) transcription factors. In brief, a correlation between GSH status, FOXO phosphorylation and skin development was established. To further study the importance of GSH in adult skin maintenance and understand the effects of ROS in the Akt/FOXO pathway, we treated cells and mice with an inhibitor of GSH synthesis, and with N-acetyl-cysteine. Increased Akt phosphorylation, altered FOXO phosphorylation patterns and increased gene expression of differentiation-related genes were observed. Our results show that the Akt/FOXO pathway plays an important role in maintenance/differentiation of epidermal stem cells. Chronological ageing leads to morphological/functional changes causing a decline in self-renewal, as well as decreased levels of GSH. We also observed that a cell cycle hyperproliferative response was the link between stem cell exaustion in GSH-depletion and ageing. Dermal mesenchymal stem cells (MSCs), are capable of adipo-chondro- and osteogenesis. Little is known about the impact of ROS in MSC differentiation. We induced murine skin MSCs to differentiate into bone (Alizarin-Red/Von-Kossastain+, increased levels of mRNA for alkalinephosphatase/ osteopontin/osterix). In brief, the balance of GSH/GSSG and related antioxidant system is differentially regulated during this process, found to be regulated in a redox-dependent fashion through the MAPK pathway. When depleted, GSH leads to an adipogenic switch in MSC differentiation. In conclusion, our data leads us to propose a central role for glutathione in the maintenance/commitment of stem cells in skin

Follicle and melanocyte stem cells, and their application in neuroscience: A Web of Science-based literature analysis.

OBJECTIVE: To identify global research trends of follicle and melanocyte stem cells, and their application in neuroscience. DATA RETRIEVAL: We performed a bibliometric analysis of studies from 2002 to 2011 on follicle and melanocyte stem cells, and their application in neuroscience, which were retrieved from the Web of Science, using the key words follicle stem cell or melanocyte stem cell, and neural, neuro or nerve. INCLUSION CRITERIA: (a) peer-reviewed published articles on follicle and melanocyte stem cells, and their application in neuroscience, which were indexed in the Web of Science; (b) original research articles, reviews, meeting abstracts, proceedings papers, book chapters, editorial material, and news items. EXCLUSION CRITERIA: (a) articles that required manual searching or telephone access; (b) documents that were not published in the public domain; and (c) a number of corrected papers from the total number of articles. MAIN OUTCOME MEASURES: (1) Distribution of publications on follicle and melanocyte stem cells by years, journals, countries, institutions, institutions in China, and most cited papers. (2) Distribution of publications on the application of follicle and melanocyte stem cells in neuroscience by years, journals, countries, institutions, and most cited papers. RESULTS: Of the 348 publications from 2002 to 2011 on follicle and melanocyte stem cells, which were retrieved from the Web of Science, more than half were from American authors and institutes. The most prolific institutions in China for publication of papers on follicle and melanocyte stem cells were the Fourth Military Medical University and Third Military Medical University. The most prolific journals for publication of papers on follicle and melanocyte stem cells were the Journal of Investigative Dermatology, Pigment Cell & Melanoma Research. Of the 63 publications from 2002 to 2011 on the application of follicle and melanocyte stem cells in neuroscience, which were retrieved from the Web of Science, more than half were from American authors and institutes, and no papers were from Chinese authors and institutes. The most prolific journals for publication of papers on the application of follicle and melanocyte stem cells in neuroscience were the Journal of Investigative Dermatology, Pigment Cell & Melanoma Research. CONCLUSION: Based on our analysis of the literature and research trends, we found that follicle stem cells might offer further benefits in neural regenerative medicine.

THE SURVIVAL DIFFERENTIATION AND MIGRATION OF SKIN-DERIVED NEURAL STEM CELLS IN INJURED SPINAL CORD OF RAT / 解剖学报

Objective To investigate whether the skin-derived neural stem cells inducted by the culture could survive,differentiate and migrate in the lesioned site of rat spinal cord.Methods The skin of new born rat trans-gene of green fluorescence protein(GFP) was applied to be dissociated into cells,cultured and inducted to proliferate in vitro.Skin-derived neural stem cells were identified by immunocytochemistry staining.Then,skin-derived neural stem cells inducted by the culture were transplanted into the lesioned site of rat spinal cord hemisection.Thirty days and sixty days after the operation,the survival,migration and differentiation of transplanted cells were observed by immunocytochemistry staining. Results Ten days at cultured skin-dissociated cells,many cell-spheres had been formed by the proliferation of suspensive growing cells.These cell-spheres showed nestin positive staining of immunocytochemistry.It suggestes that the cell-spheres are neurospheres.In vivo,many transplanted skin-derived neural stem cells with GFP were observed in the lesioned area of spinal cord.Some transplanted cells migrated into host spinal cord tissue far away from the lesioned area.Some transplanted surviving cells showed nestin,MAP2 and GFAP positive staining of immunocytochemistry separately.Conclusion Skin-derived neural stem cells inducted by the culture may survive,migrate and differentiate into neuron-like cells and astrocyte-like cells in injured spinal cord of rat.