Xin Tang1†, Jiaqi Wang1†, Jiaoling Chen1†, Wanting Liu1 , Pei Qiao1 , Huiyi Quan1 , Zhiguo Li1 , Erle Dang1 , Gang Wang1* and Shuai Shao1*

Abstract

The skin epidermis is continually infuenced by a myriad of internal and external elements. At its basal layer reside epidermal stem cells, which fuels epidermal renovation and hair regeneration with powerful self-renewal ability, as well as keeping diverse signals that direct their activity under surveillance with quick response. The importance of epidermal stem cells in wound healing and immune-related skin conditions has been increasingly recognized, and their potential for clinical applications is attracting attention. In this review, we delve into recent advancements and the various physiological and psychological factors that govern distinct epidermal stem cell populations, including psychological stress, mechanical forces, chronic aging, and circadian rhythm, as well as providing an overview of current methodological approaches. Furthermore, we discuss the pathogenic role of epidermal stem cells in immune-related skin disorders and their potential clinical applications.

Keywords Epidermal stem cells, Aging, Wound healing, Immune-related skin disorders, Regeneration

† Xin Tang, Jiaqi Wang and Jiaoling Chen contributed equally to this work.

*Correspondence:

Gang Wang

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Shuai Shao

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1 Department of Dermatology, Xijing Hospital, Fourth Military Medical University, Xi’an 710032, Shannxi, China

© The Author(s) 2024. Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modifed the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.

Received December 11, 2023; accepted February 20, 2024; published online February 26, 2024

Ryo Ichijo∗

Laboratory of Tissue Homeostasis, Department of Biosystems Science, Institute for Life and Medical Sciences, Kyoto University, 53 Shogoin

Kawara-cho, Sakyo-ku, Kyoto 606-8507, Japan.

∗Ryo Ichijo, Laboratory of Tissue Homeostasis, Department of Biosystems Science, Institute for Life and Medical Sciences, Kyoto University, Kyoto, Japan. Tel.: +81-75-751-4016,

email: 该Email地址已收到反垃圾邮件插件保护。要显示它您需要在浏览器中启用JavaScript。

In developed economies, the growing number of older individuals is a pressing issue. As a result, research progress into ageing has emphasized the significance of staying healthy in one’s later years. Stem cells have a fundamental role to play in fostering diverse cell types and necessary processes for tissue repair and regeneration. Stem cells experience the effects of ageing over time, which is caused by their functional deterioration. Changes to stem cells, their niches and signals from other tissues they interact with are crucial factors in the ageing of stem cells. Progress in single-cell RNA sequencing (scRNA-seq) technology has greatly advanced stem cell research. This review examines the mechanisms of stem cell ageing, its impact on health and investigates the potential of stem cell therapy, with a special emphasis on the skin.

 Graphical Abstract

Keywords: ageing, homeostasis, regeneration, single cell RNA sequencing, stem cell.

Samuel F. Williams , 1 Helen Wan,1 John Chittock , 1 Kirsty Brown,1 Andrew Wigley,1 Michael J. Cork 1,2,3 and Simon G. Danby 1

1 Sheffield Dermatology Research, Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield Medical School, Sheffield, UK

2 Sheffield Children’s NHS Foundation Trust, Sheffield Children’s Hospital, Western Bank, Sheffield, UK

3 Sheffield Teaching Hospitals NHS Foundation Trust, The Royal Hallamshire Hospital, Sheffield, UK Correspondence: Samuel F. Williams. Email: 该Email地址已收到反垃圾邮件插件保护。要显示它您需要在浏览器中启用JavaScript。

Abstract

Background Atopic dermatitis (AD) is characterized by skin barrier defects that are often measured by biophysical tools that observe the functional properties of the stratum corneum (SC).

Objectives To employ in vivo infrared spectroscopy alongside biophysical measurements to analyse changes in the chemical composition of the SC in relation to AD severity.

Methods We conducted an observational cross-sectional cohort study where attenuated total reflection Fourier transform infrared (ATRFTIR) spectroscopy measurements were collected on the forearm alongside surface pH, capacitance, erythema and transepidermal water loss (TEWL), combined with tape stripping, in a cohort of 75 participants (55 patients with AD stratified by phenotypic severity and 20 healthy controls). Common FLG variant alleles were genotyped.

Results Reduced hydration, elevated TEWL and redness were all associated with greater AD severity. Spectral analysis showed a reduction in 1465 cm–1 (full width half maximum) and 1340 cm–1 peak areas, indicative of less orthorhombic lipid ordering and reduced carboxylate functional groups, which correlated with clinical severity (lipid structure r=–0.59, carboxylate peak area r=–0.50).

Conclusions ATR-FTIR spectroscopy is a suitable tool for the characterization of structural skin barrier defects in AD and has potential as a clinical tool for directing individual treatment based on chemical structural deficiencies.

What is already known about this topic?

• The skin of patients with atopic dermatitis (AD) is characterized by atypical lipid levels and structure, diminished natural moisturizing factor (NMF) and filaggrin deficiency.

• As a result of these structural alterations, normal skin barrier function is reduced.
• Purpose-built probes or assays are typically used to monitor and quantify biochemical changes, such as pH, moisturization factors, hydration and transepidermal water loss (TEWL), on the epidermal surface as a result of the onset of dermatitis.

What does this study add?

• Characteristics from the mid-infrared spectra collected from participants’ skin provided molecular insight into the pathogenesis of AD.

• Lipid- and carboxylate-associated mid-infrared peaks were strongly associated with biophysical measurements, including skin hydration, NMF and TEWL.

• Peaks analysis also indicated a filaggrin deficiency, caused by genetic deposition or inflammatory action.
• Early detection of a genetic predisposition to AD would allow for preventative measures to be undertaken.

Accepted: 20 November 2023

© The Author(s) 2023. Published by Oxford University Press on behalf of British Association of Dermatologists. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (https://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact 该Email地址已收到反垃圾邮件插件保护。要显示它您需要在浏览器中启用JavaScript。

Marta Arnal‑Forné1  · Tamara Molina‑García2  · María Ortega2  · Víctor Marcos‑Garcés2,3 · Pilar Molina4  · Antonio Ferrández‑Izquierdo1,2,5 · Pilar Sepulveda1,6,7 · Vicente Bodí2,3,6,8 · César Ríos‑Navarro1,2,6 · Amparo Ruiz‑Saurí1,2,6

Accepted: 10 June 2024 / Published online: 2 July 2024

© The Author(s) 2024

Abstract

Skin represents the main barrier against the external environment, but also plays a role in human relations, as one of the prime determinants of beauty, resulting in a high consumer demand for skincare-related pharmaceutical products. Given the importance of skin aging in both medical and social spheres, the present research aims to characterize microscopic changes in human skin composition due to intrinsic aging (as opposed to aging infuenced by external factors) via histological analysis of a photoprotected body region. Samples from 25 autopsies were taken from the periumbilical area and classifed into four age groups: group 1 (0–12 years), group 2 (13–25 years), group 3 (26–54 years), and group 4 (≥55 years). Diferent traditional histological (hematoxylin–eosin, Masson’s trichrome, orcein, toluidine, Alcian blue, and Feulgen reaction) and immunohistochemical (CK20, CD1a, Ki67, and CD31) stains were performed. A total of 1879 images photographed with a Leica DM3000 optical microscope were morphometrically analyzed using Image ProPlus 7.0 for further statistical analysis with GraphPad 9.0. Our results showed a reduction in epidermis thickness, interdigitation and mitotic indexes, while melanocyte count was raised. Papillary but not reticular dermis showed increased thickness with aging. Specifcally, in the papillary layer mast cells and glycosaminoglycans were expanded, whereas the reticular dermis displayed a diminution in glycosaminoglycans and elastic fbers. Moreover, total cellularity and vascularization of both dermises were diminished with aging. This morphometric analysis of photoprotected areas reveals that intrinsic aging signifcantly infuences human skin composition. This study paves the way for further research into the molecular basis underpinning these alterations, and into potential antiaging strategies.

Keywords Skin aging · Intrinsic aging · Morphometric analysis · Human biopsies

César Ríos-Navarro 该Email地址已收到反垃圾邮件插件保护。要显示它您需要在浏览器中启用JavaScript。

* Amparo Ruiz-Saurí 该Email地址已收到反垃圾邮件插件保护。要显示它您需要在浏览器中启用JavaScript。; 该Email地址已收到反垃圾邮件插件保护。要显示它您需要在浏览器中启用JavaScript。

1 Department of Pathology, University of Valencia, Avda. Blasco Ibáñez 15. 46010, Valencia, Spain

2 Instituto de Investigación Sanitaria INCLIVA Biomedical Research Institute, Avda. Menéndez Pelayo 4acc, 46010 Valencia, Spain

3 Cardiology Department, Hospital Clínico Universitario, Valencia, Spain

4 Department of Pathology, Instituto de Medicina Legal y Ciencias Forenses, Valencia, Spain

5 Anatomic Pathology Department, Hospital Clínico Universitario, Valencia, Spain

6 Centro de Investigación Biomédica en Red (CIBER)-CV, Madrid, Spain

7 Regenerative Medicine and Heart Transplantation Unit, Instituto de Investigación Sanitaria La Fe, Valencia, Spain

8 Department of Medicine, University of Valencia, Valencia, Spain