Elevated skin senescence in young mice causes delayed wound healing

The biomedical application of inorganic metal nanoparticles in aging and aging-associated diseases

Aging and aging-associated diseases (AAD), including neurodegenerative disease, cancer, cardiovascular diseases, and diabetes, are inevitable process. With the gradual improvement of life style, life expectancy is gradually extended. However, the extended lifespan has not reduced the incidence of disease, and most elderly people are in ill-health state in their later years. Hence, understanding aging and AAD are significant for reducing the burden of the elderly. Inorganic metal nanoparticles (IMNPs) predominantly include gold, silver, iron, zinc, titanium, thallium, platinum, cerium, copper NPs, which has been widely used to prevent and treat aging and AAD due to their superior properties (essential metal ions for human body, easily synthesis and modification, magnetism). Therefore, a systematic review of common morphological alternations of senescent cells, altered genes and signal pathways in aging and AAD, and biomedical applications of IMNPs in aging and AAD is crucial for the further research and development of IMNPs in aging and AAD. This review focus on the existing research on cellular senescence, aging and AAD, as well as the applications of IMNPs in aging and AAD in the past decade. This review aims to provide cutting-edge knowledge involved with aging and AAD, the application of IMNPs in aging and AAD to promote the biomedical application of IMNPs in aging and AAD.

Extracellular matrix modulating effects of amnion-derived mesenchymal stem cells on aging skin wounds in α-Klotho knockout mice

AIM

Wounds in the elderly are frequently recalcitrant and chronic as a result of the effects of skin aging and associated complications. The objective of this study is to utilize an α-Klotho knockout (KO) mice wound model to assess the capacity of amnion-derived mesenchymal stem cells (AMSCs) to facilitate wound healing in aging skin.

METHODS

AMSCs were applied topically to the wound after extraction and gelatinization of the conditioned medium (CM). Animal experiments were performed with two distinct mouse strains: α-Klotho KO mice and wild-type mice. Full-thickness skin defect models with a diameter of 8 mm were created by incising the skin on the left and right sides of the dorsum. On day 8 after wound creation, the mice were sacrificed, and wound tissue was collected for analysis through histological and immunohistochemical evaluations, as well as through quantitative polymerase chain reaction.

RESULTS

The topical application of CM gel to wounds of α-Klotho KO mice demonstrated that wound healing was significantly higher than that observed in control, reaching the wound closure rate of wild-type mice on day 8. Additionally, gene expression analysis of wound tissue indicated that AMSC-CM may regulate extracellular matrix formation and fibrosis. Moreover, histological analysis indicated that AMSC-CM may facilitate wound contraction of aging skin wounds of α-Klotho KO mice by inducing myofibroblast differentiation and promoting granulation and collagen formation, which are the primary components of the extracellular matrix.

CONCLUSIONS

AMSC-CM may facilitate wound healing in aging skin of α-Klotho KO mice by regulating the extracellular matrix. Geriatr Gerontol Int 2025; 25: 701-708.

Taurine is a potential therapy for rheumatoid arthritis via targeting FOXO3 through cellular senescence and autophagy

BACKGROUND

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease closely related to aging with unclear pathogenic mechanisms. This study aims to identify the biomarkers in RA, aging and autophagy using bioinformatics and machine learning and explore the binding stability of taurine to target utilizing computer-aided drug design (CADD).

METHODS

We identified differentially expressed genes (DEGs) for RA, then crossed with gene libraries for aging and autophagy to identify common genes (Co-genes). We performed Gene Ontology (GO), Kyoto Encyclopedia of the Genome (KEGG), and ClueGO analysis for Co-genes. The Co-genes were subjected to support vector machine-recursive feature elimination (SVM-RFE), Degree, and Betweenness algorithms to get hub genes, then verified by an artificial neural network (ANN). After continuing to perform least absolute shrinkage and selection operator (LASSO) and weighted gene co-expression network analysis (WGCNA) on Co-genes, the results were crossed with hub genes to obtain genes, which were imported into various validation sets for receiver operating characteristics (ROC) to identify key genes. We analyzed the microRNA/TF network, enriched pathways, and immune cell infiltration for key genes. The binding stability of taurine with the target protein was verified by CADD. Finally, we used Western blot for in vitro experimental verification.

RESULTS

We obtained 74 Co-genes enriched in RA, cellular senescence, and regulation of programmed cell death. The model prediction of hub genes works well in ANN. The key genes (MMP9, CXCL10, IL15, FOXO3) were tested in ROC with excellent efficacy. In RA, FOXO3 expression was down-regulated while MMP9, CXCL10, and IL15 expression were upregulated, and FOXO3 was negatively correlated with MMP9, CXCL10, and IL15. Two miRNAs (hsa-mir-21-5p, hsa-mir-129-2-3p) and four TFs (CTCF, KLF, FOXC1, TP53) were associated with key genes. The immune cells positively correlated with MMP9, CXCL10, and IL15 expression and negatively correlated with FOXO3 expression were Plasma cells, CD8 T cells, memory-activated CD4 T cells, and follicular helper T cells, aggregating in RA. The binding stability of taurine with FOXO3 was verified by molecular docking and molecular dynamics simulation. In vitro experiments have indicated that taurine can upregulate the expression of FOXO3 and treat RA through the FOXO3-Parkin signaling pathway.

CONCLUSIONS

MMP9, CXCL10, IL15, and FOXO3 are biomarkers of RA, cellular senescence, and autophagy. Taurine might be a promising drug against RA via targeting cellular senescence and autophagy through FOXO3.

Modelling the spatiotemporal dynamics of senescent cells in wound healing, chronic wounds, and fibrosis

Cellular senescence is known to drive age-related pathology through the senescence-associated secretory phenotype (SASP). However, it also plays important physiological roles such as cancer suppression, embryogenesis and wound healing. Wound healing is a tightly regulated process which when disrupted results in conditions such as fibrosis and chronic wounds. Senescent cells appear during the proliferation phase of the healing process where the SASP is involved in maintaining tissue homeostasis after damage. Interestingly, SASP composition and functionality was recently found to be temporally regulated, with distinct SASP profiles involved: a fibrogenic, followed by a fibrolytic SASP, which could have important implications for the role of senescent cells in wound healing. Given the number of factors at play a full understanding requires addressing the multiple levels of complexity, pertaining to the various cell behaviours, individually followed by investigating the interactions and influence each of these elements have on each other and the system as a whole. Here, a systems biology approach was adopted whereby a multi-scale model of wound healing that includes the dynamics of senescent cell behaviour and corresponding SASP composition within the wound microenvironment was developed. The model was built using the software CompuCell3D, which is based on a Cellular Potts modelling framework. We used an existing body of data on healthy wound healing to calibrate the model and validation was done on known disease conditions. The model clearly shows how differences in the spatiotemporal dynamics of different senescent cell phenotypes lead to several distinct repair outcomes. These differences in senescent cell dynamics can be attributed to variable SASP composition, duration of senescence and temporal induction of senescence relative to the healing stage. The range of outcomes demonstrated strongly highlight the dynamic and heterogenous role of senescent cells in wound healing, fibrosis and chronic wounds, and their fine-tuned control. Further specific data to increase model confidence could be used to explore senolytic treatments in wound disorders.

Relationship between gene expression associated with cellular senescence in cells from discarded wound dressings and wound healing: A retrospective cohort study

AIM

Senescent cells, inducing a senescence-associated secretory phenotype (SASP), lead to chronic inflammation in hard-to-heal wound tissue. However, eliminating senescent cells may impede normal wound healing due to their important role in the wound healing mechanism. Accordingly, we focused on wound exudates in hard-to-heal wounds, which contain many inflammation biomarkers consistent with SASP. Therefore, we hypothesized that senescent cells might be present in the exudates and induce chronic inflammation. This study investigated the relationship between gene expression associated with cellular senescence in exudates from pressure injuries and wound healing status.

METHODS

This retrospective cohort study involved patients treated by a pressure injury team. We collected viable cells from wound dressings and analyzed gene expression. Pearson's correlation coefficient was calculated between cellular senescence and SASP expression. The relationship between the gene expression of cellular senescence and the wound area reduction rate by the following week was examined using a mixed-effects model.

RESULTS

CDKN1A-related to cellular senescence-was expressed in 96.3 % of 54 samples, and CDKN1A expression and SASPs positively correlated (PLAU: r = 0.68 and TNF: r = 0.34). Low CDKN1A expression was statistically associated with a large wound area reduction rate (β = 0.83, p < 0.01).

CONCLUSIONS

Gene expression of both cellular senescence and SASP factor in wound dressings suggests the presence of cellular senescence. Senescent cells in wound dressings could be associated with delayed wound healing in the following week.

Aging, senescence, and cutaneous wound healing-a complex relationship

Cutaneous wound healing is a complex multi-step process that is highly controlled, ensuring efficient repair to damaged tissue and restoring tissue architecture. Multiple cell types play a critical role in wound healing, and perturbations in this can lead to non-healing wounds or scarring and fibrosis. Thus, the process is tightly regulated and controlled. Cellular senescence is defined as irreversible cell cycle arrest and is associated with various phenotypic changes and metabolic alterations and coupled to a secretory program. Its role in wound healing, at least in the acute setting, appears to help promote appropriate mechanisms leading to the complete restoration of tissue architecture. Opposing this is the role of senescence in chronic wounds where it can lead to either chronic non-healing wounds or fibrosis. Given the two opposing outcomes of wound healing in either acute or chronic settings, this has led to disparate views on the role of senescence in wound healing. This review aims to consolidate knowledge on the role of senescence and aging in wound healing, examining the nuances of the roles in the acute or chronic settings, and attempts to evaluate the modulation of this to promote efficient wound healing.

Urolithin A alleviates cell senescence by inhibiting ferroptosis and enhances corneal epithelial wound healing

Purpose

To analyze the therapeutic effect and mechanism of Urolithin A (UA) on delayed corneal epithelial wound healing.

Methods

The C57BL/6 mice were continuously exposed to hyperosmotic stress (HS) for 7 days followed by the removal of central corneal epithelium to establish a delayed corneal epithelial wound healing model in vivo. In vitro, the human corneal epithelial cell line (HCE-T) was also incubated under HS. UA was administered in vivo and in vitro to study its effects on corneal epithelial cells. Senescence-associated β-galactosidase (SA-β-gal) staining was performed to detect the level of cell senescence. Transcriptome sequencing (RNA-seq) was conducted to elucidate the molecular mechanism underlying the effect of UA on corneal epithelial repair. Additionally, the expression of senescence-related and ferroptosis-related genes and the levels of lipid peroxides (LPO) and malondialdehyde (MDA) were measured.

Results

Hyperosmotic stress (HS) significantly increased the proportion of SA-β-gal staining positive cells in corneal epithelial cells and upregulated the expression of p16 and p21 (p < 0.0001). Topical application of UA decreased the accumulation of senescent cells in corneal epithelial wounds and promoted epithelial wound healing. The results of RNA-seq of HS-induced corneal epithelial cells showed that the ferroptosis pathway was significantly dysregulated. Further investigation revealed that UA decreased the level of oxidative stress in HCE-T cells, including the levels of LPO and MDA (p < 0.05). Inhibition of ferroptosis significantly prevented cellular senescence in HS-induced HCE-T cells.

Conclusion

In this study, UA promoted HS-induced delayed epithelial wound healing by reducing the senescence of corneal epithelial cells through the inhibition of ferroptosis.

Targeting senescent HDF with the USP7 inhibitor P5091 to enhance DFU wound healing through the p53 pathway

OBJECTIVE

The objective of this study was to examine the potential of USP7 as a target for senolytic therapy and to investigate the molecular mechanism by which its inhibitor selectively induced apoptosis in senescent HDF and enhanced DFU wound healing.

METHODS

Clinical samples of DFU were collected to detect the expression of USP7 and aging-related proteins using immunohistochemistry and Western blot. In addition, β-galactosidase staining, qPCR, flow cytometry, ROS and MMP kits, and Western blot were used to analyze the biological functions of P5091 on senescence, cycle, and apoptosis. RNAseq was employed to further analyze the molecular mechanism of P5091. Finally, the DFU rat model was established to evaluate the effect of P5091 on wound healing.

RESULTS

The expression of USP7 and p21 were increased in DFU clinical samples. After treatment with d-glucose (30 mM, 7 days), β-galactosidase staining was deepened, proliferation rate decreased. USP7 inhibitors (P5091) could reduce the release of SASP factors, activate the production of ROS, and reduce MMP. In addition, it induced apoptosis and selectively clears senescent cells through the p53 signaling pathway. Finally, P5091 can improve diabetic wound healing in rats.

CONCLUSION

This study clarified the molecular mechanism of USP7 inhibitor (P5091) selectively inducing apoptosis of high glucose senescent HDF cells. This provides a new senolytics target and experimental basis for promoting DFU wound healing.

Modelling the spatiotemporal dynamics of senescent cells in wound healing, chronic wounds, and fibrosis

Cellular senescence is known to drive age-related pathology through the senescence-associated secretory phenotype (SASP). However, it also plays important physiological roles such as cancer suppression, embryogenesis and wound healing. Wound healing is a tightly regulated process which when disrupted results in conditions such as fibrosis and chronic wounds. Senescent cells appear during the proliferation phase of the healing process where the SASP is involved in maintaining tissue homeostasis after damage. Interestingly, SASP composition and functionality was recently found to be temporally regulated, with distinct SASP profiles involved: a fibrogenic, followed by a fibrolytic SASP, which could have important implications for the role of senescent cells in wound healing. Given the number of factors at play a full understanding requires addressing the multiple levels of complexity, pertaining to the various cell behaviours, individually followed by investigating the interactions and influence each of these elements have on each other and the system as a whole. Here, a systems biology approach was adopted whereby a multi-scale model of wound healing that includes the dynamics of senescent cell behaviour and corresponding SASP composition within the wound microenvironment was developed. The model was built using the software CompuCell3D, which is based on a Cellular Potts modelling framework. We used an existing body of data on healthy wound healing to calibrate the model and validation was done on known disease conditions. The model provides understanding of the spatiotemporal dynamics of different senescent cell phenotypes and the roles they play within the wound healing process. The model also shows how an overall disruption of tissue-level coordination due to age-related changes results in different disease states including fibrosis and chronic wounds. Further specific data to increase model confidence could be used to explore senolytic treatments in wound disorders.

Protective effects of astaxanthin on particulate matter 2.5‑induced senescence in HaCaT keratinocytes via maintenance of redox homeostasis

Particulate matter 2.5 (PM2.5) imposes a heavy burden on the skin and respiratory system of human beings, causing side effects such as aging, inflammation and cancer. Astaxanthin (ATX) is a well-known antioxidant widely used for its anti-inflammatory and anti-aging properties. However, few studies have investigated the protective effects of ATX against PM2.5-induced senescence in HaCaT cells. In the present study, the levels of reactive oxygen species (ROS) and antioxidant enzymes were measured after treatment with PM2.5. The results revealed that PM2.5 generated excessive ROS and reduced the translocation of nuclear factor erythroid 2-related factor 2 (NRF2), subsequently reducing the expression of antioxidant enzymes. However, pretreatment with ATX reversed the ROS levels as well as the expression of antioxidant enzymes. In addition, ATX protected cells from PM2.5-induced DNA damage and rescued PM2.5-induced cell cycle arrest. The levels of senescence-associated phenotype markers, such as interleukin-1β, matrix metalloproteinases, and β-galactosidase, were increased by exposure to PM2.5, however these effects were reversed by ATX. After interfering with NRF2 mRNA expression and exposing cells to PM2.5, the levels of ROS and β-galactosidase were higher compared with siControl RNA cells exposed to PM2.5. However, ATX inhibited ROS and β-galactosidase levels in both the siControl RNA and the siNRF2 RNA groups. Thus, ATX protects HaCaT keratinocytes from PM2.5-induced senescence by partially inhibiting excessive ROS generation via the NRF2 signaling pathway.

Improving dermal fibroblast-to-epidermis communications and aging wound repair through extracellular vesicle-mediated delivery of Gstm2 mRNA

Skin aging is characterized by the disruption of skin homeostasis and impaired skin injury repair. Treatment of aging skin has long been limited by the unclear intervention targets and delivery techniques. Engineering extracellular vesicles (EVs) as an upgraded version of natural EVs holds great potential in regenerative medicine. In this study, we found that the expression of the critical antioxidant and detoxification gene Gstm2 was significantly reduced in aging skin. Thus, we constructed the skin primary fibroblasts-derived EVs encapsulating Gstm2 mRNA (EVsGstm2), and found that EVsGstm2 could significantly improve skin homeostasis and accelerate wound healing in aged mice. Mechanistically, we found that EVsGstm2 alleviated oxidative stress damage of aging dermal fibroblasts by modulating mitochondrial oxidative phosphorylation, and promoted dermal fibroblasts to regulate skin epidermal cell function by paracrine secretion of Nascent Polypeptide-Associated Complex Alpha subunit (NACA). Furthermore, we confirmed that NACA is a novel skin epidermal cell protective molecule that regulates skin epidermal cell turnover through the ROS-ERK-ETS-Cyclin D pathway. Our findings demonstrate the feasibility and efficacy of EVs-mediated delivery of Gstm2 for aged skin treatment and unveil novel roles of GSTM2 and NACA for improving aging skin.

Detection of senescent cells in the mucosal healing process on type 2 diabetic rats after tooth extraction for biomaterial development

The delayed mucosal healing of tooth extraction sockets in diabetes has few known effective treatment strategies, and its underlying mechanism remains unknown. Senescent cells may play a pivotal role in this delay, given the well-established association between diabetes, senescent cells, and wound healing. Here, we demonstrated an increase in p21- or p16-positive senescent cells in the epithelial and connective tissues of extraction sockets in type 2 diabetic rats compared to those in control rats. Between 7 and 14 days after tooth extraction, a decrease in senescent cells and improvement in re-epithelialization failure were observed in the epithelium, while an increase in senescent cells and persistence of inflammation were observed in the connective tissue. These results suggest that cellular senescence may have been induced by diabetes and contributed to delayed mucosal healing by suppressing re-epithelization and persistent inflammation. These findings provide new targets for treatment using biomaterials, cells, and drugs.

Research Progress in Skin Aging and Immunity

Skin aging is a complex process involving structural and functional changes and is characterized by a decrease in collagen content, reduced skin thickness, dryness, and the formation of wrinkles. This process is underpinned by multiple mechanisms including the free radical theory, inflammation theory, photoaging theory, and metabolic theory. The skin immune system, an indispensable part of the body's defense mechanism, comprises macrophages, lymphocytes, dendritic cells, and mast cells. These cells play a pivotal role in maintaining skin homeostasis and responding to injury or infection. As age advances, along with various internal and external environmental stimuli, skin immune cells may undergo senescence or accelerated aging, characterized by reduced cell division capability, increased mortality, changes in gene expression patterns and signaling pathways, and altered immune cell functions. These changes collectively impact the overall function of the immune system. This review summarizes the relationship between skin aging and immunity and explores the characteristics of skin aging, the composition and function of the skin immune system, the aging of immune cells, and the effects of these cells on immune function and skin aging. Immune dysfunction plays a significant role in skin aging, suggesting that immunoregulation may become one of the important strategies for the prevention and treatment of skin aging.

ANT2 Accelerates Cutaneous Wound Healing in Aged Skin by Regulating Energy Homeostasis and Inflammation

An effective healing response is critical to healthy aging. In particular, energy homeostasis has become increasingly recognized as a factor in effective skin regeneration. ANT2 is a mediator of adenosine triphosphate import into mitochondria for energy homeostasis. Although energy homeostasis and mitochondrial integrity are critical for wound healing, the role played by ANT2 in the repair process had not been elucidated to date. In our study, we found that ANT2 expression decreased in aged skin and cellular senescence. Interestingly, overexpression of ANT2 in aged mouse skin accelerated the healing of full-thickness cutaneous wounds. In addition, upregulation of ANT2 in replicative senescent human diploid dermal fibroblasts induced their proliferation and migration, which are critical processes in wound healing. Regarding energy homeostasis, ANT2 overexpression increased the adenosine triphosphate production rate by activating glycolysis and induced mitophagy. Notably, ANT2-mediated upregulation of HSPA6 in aged human diploid dermal fibroblasts downregulated proinflammatory genes that mediate cellular senescence and mitochondrial damage. This study shows a previously uncharacterized physiological role of ANT2 in skin wound healing by regulating cell proliferation, energy homeostasis, and inflammation. Thus, our study links energy metabolism to skin homeostasis and reports, to the best of our knowledge, a previously unreported genetic factor that enhances wound healing in an aging model.

Nano-Architecture of Persistent Focal DNA Damage Regions in the Minipig Epidermis Weeks after Acute γ-Irradiation

Exposure to high acute doses of ionizing radiation (IR) can induce cutaneous radiation syndrome. Weeks after such radiation insults, keratinocyte nuclei of the epidermis exhibit persisting genomic lesions that present as focal accumulations of DNA double-strand break (DSB) damage marker proteins. Knowledge about the nanostructure of these genomic lesions is scarce. Here, we compared the chromatin nano-architecture with respect to DNA damage response (DDR) factors in persistent genomic DNA damage regions and healthy chromatin in epidermis sections of two minipigs 28 days after lumbar irradiation with ~50 Gy γ-rays, using single-molecule localization microscopy (SMLM) combined with geometric and topological mathematical analyses. SMLM analysis of fluorochrome-stained paraffin sections revealed, within keratinocyte nuclei with perisitent DNA damage, the nano-arrangements of pATM, 53BP1 and Mre11 DDR proteins in γ-H2AX-positive focal chromatin areas (termed macro-foci). It was found that persistent macro-foci contained on average ~70% of 53BP1, ~23% of MRE11 and ~25% of pATM single molecule signals of a nucleus. MRE11 and pATM fluorescent tags were organized in focal nanoclusters peaking at about 40 nm diameter, while 53BP1 tags formed nanoclusters that made up super-foci of about 300 nm in size. Relative to undamaged nuclear chromatin, the enrichment of DDR protein signal tags in γ-H2AX macro-foci was on average 8.7-fold (±3) for 53BP1, 3.4-fold (±1.3) for MRE11 and 3.6-fold (±1.8) for pATM. The persistent macro-foci of minipig epidermis displayed a ~2-fold enrichment of DDR proteins, relative to DSB foci of lymphoblastoid control cells 30 min after 0.5 Gy X-ray exposure. A lasting accumulation of damage signaling and sensing molecules such as pATM and 53BP1, as well as the DSB end-processing protein MRE11 in the persistent macro-foci suggests the presence of diverse DNA damages which pose an insurmountable problem for DSB repair.

Impact of senolytic treatment on immunity, aging, and disease

Cellular senescence has been implicated in the pathophysiology of many age-related diseases. However, it also plays an important protective role in the context of tumor suppression and wound healing. Reducing senescence burden through treatment with senolytic drugs or the use of genetically targeted models of senescent cell elimination in animals has shown positive results in the context of mitigating disease and age-associated inflammation. Despite positive, albeit heterogenous, outcomes in clinical trials, very little is known about the short-term and long-term immunological consequences of using senolytics as a treatment for age-related conditions. Further, many studies examining cellular senescence and senolytic treatment have been demonstrated in non-infectious disease models. Several recent reports suggest that senescent cell elimination may have benefits in COVID-19 and influenza resolution and disease prognosis. In this review, we discuss the current clinical trials and pre-clinical studies that are exploring the impact of senolytics on cellular immunity. We propose that while eliminating senescent cells may have an acute beneficial impact on primary immune responses, immunological memory may be negatively impacted. Closer investigation of senolytics on immune function and memory generation would provide insight as to whether senolytics could be used to enhance the aging immune system and have potential to be used as therapeutics or prophylactics in populations that are severely and disproportionately affected by infections such as the elderly and immunocompromised.

Senescence-associated alterations in the extracellular matrix: deciphering their role in the regulation of cellular function

The extracellular matrix (ECM) is a dynamic structural network that provides a physical scaffolding, as well as biochemical factors that maintain normal tissue homeostasis and thus its disruption is implicated in many pathological conditions. On the other hand, senescent cells express a particular secretory phenotype, affecting the composition and organization of the surrounding ECM and modulating their microenvironment. As accumulation of senescent cells may be linked to the manifestation of several age-related conditions, senescence-associated ECM alterations may serve as targets for novel anti-aging treatment modalities. Here, we will review characteristic changes in the ECM elicited by cellular senescence and we will discuss the complex interplay between ECM and senescent cells, in relation to normal aging and selected age-associated pathologies.

Immunomodulatory Nanosystems: Advanced Delivery Tools for Treating Chronic Wounds

The increasingly aging society led to a rise in the prevalence of chronic wounds (CWs), posing a significant burden to public health on a global scale. One of the key features of CWs is the presence of a maladjusted immune microenvironment characterized by persistent and excessive (hyper)inflammation. A variety of immunomodulatory therapies have been proposed to address this condition. Yet, to date, current delivery systems for immunomodulatory therapy remain inadequate and lack efficiency. This highlights the need for new therapeutic delivery systems, such as nanosystems, to manage the pathological inflammatory imbalance and, ultimately, improve the treatment outcomes of CWs. While a plethora of immunomodulatory nanosystems modifying the immune microenvironment of CWs have shown promising therapeutic effects, the literature on the intersection of immunomodulatory nanosystems and CWs remains relatively scarce. Therefore, this review aims to provide a comprehensive overview of the pathogenesis and characteristics of the immune microenvironment in CWs, discuss important advancements in our understanding of CW healing, and delineate the versatility and applicability of immunomodulatory nanosystems-based therapies in the therapeutic management of CWs. In addition, we herein also shed light on the main challenges and future perspectives in this rapidly evolving research field.

Cellular senescence in skin-related research: Targeted signaling pathways and naturally occurring therapeutic agents

Despite the growing interest by researchers into cellular senescence, a hallmark of cellular aging, its role in human skin remains equivocal. The skin is the largest and most accessible human organ, reacting to the external and internal environment. Hence, it is an organ of choice to investigate cellular senescence and to target root-cause aging processes using senolytic and senomorphic agents, including naturally occurring plant-based derivatives. This review presents different aspects of skin cellular senescence, from physiology to pathology and signaling pathways. Cellular senescence can have both beneficial and detrimental effects on the skin, indicating that both prosenescent and antisenescent therapies may be desirable, based on the context. Knowledge of molecular mechanisms involved in skin cellular senescence may provide meaningful insights for developing effective therapeutics for senescence-related skin disorders, such as wound healing and cosmetic skin aging changes.

A chronic wound model to investigate skin cellular senescence

Wound healing is an essential physiological process for restoring normal skin structure and function post-injury. The role of cellular senescence, an essentially irreversible cell cycle state in response to damaging stimuli, has emerged as a critical mechanism in wound remodeling. Transiently-induced senescence during tissue remodeling has been shown to be beneficial in the acute wound healing phase. In contrast, persistent senescence, as observed in chronic wounds, contributes to delayed closure. Herein we describe a chronic wound murine model and its cellular senescence profile, including the senescence-associated secretory phenotype.

Cellular Senescence in Aging, Tissue Repair, and Regeneration

SUMMARY

Society and our healthcare system are facing unprecedented challenges due to the expansion of the older population. As plastic surgeons, we can improve care of our older patients through understanding the mechanisms of aging that inevitably impact their outcomes and well-being. One of the major hallmarks of aging, cellular senescence, has recently become the focus of vigorous research in academia and industry. Senescent cells, which are metabolically active but in a state of stable cell cycle arrest, are implicated in causing aging and numerous age-related diseases. Further characterization of the biology of senescence revealed that it can be both detrimental and beneficial to organisms depending on tissue context and senescence chronicity. Here, we review the role of cellular senescence in aging, wound healing, tissue regeneration, and other domains relevant to plastic surgery. We also review the current state of research on therapeutics that modulate senescence to improve conditions of aging.

Multi-omics analysis of an in vitro photoaging model and protective effect of umbilical cord mesenchymal stem cell-conditioned medium

Background

Skin ageing caused by long-term ultraviolet (UV) irradiation is a complex biological process that involves multiple signalling pathways. Stem cell-conditioned media is believed to have anti-ageing effects on the skin. The purpose of this study was to explore the biological effects of UVB irradiation and anti-photoaging effects of human umbilical cord mesenchymal stem cell-conditioned medium (hUC-MSC-CM) on HaCaT cells using multi-omics analysis with a novel cellular photoaging model.

Methods

A cellular model of photoaging was constructed by irradiating serum-starved HaCaT cells with 20 mJ/cm² UVB. Transcriptomics and proteomics analyses were used to explore the biological effects of UVB irradiation on photoaged HaCaT cells. Changes in cell proliferation, apoptosis, and migration, the cell cycle, and expression of senescence genes and proteins were measured to assess the protective effects of hUC-MSC-CM in the cellular photoaging model.

Results

The results of the multi-omics analysis revealed that UVB irradiation affected various biological functions of cells, including cell proliferation and the cell cycle, and induced a senescence-associated secretory phenotype. hUC-MSC-CM treatment reduced cell apoptosis, inhibited G1 phase arrest in the cell cycle, reduced the production of reactive oxygen species, and promoted cell motility. The qRT-PCR results indicated that MYC, IL-8, FGF-1, and EREG were key genes involved in the anti-photoaging effects of hUC-MSC-CM. The western blotting results demonstrated that C-FOS, C-JUN, TGFβ, p53, FGF-1, and cyclin A2 were key proteins involved in the anti-photoaging effects of hUC-MSC-CM.

Conclusion

Serum-starved HaCaT cells irradiated with 20 mJ/cm² UVB were used to generate an innovative cellular photoaging model, and hUC-MSC-CM demonstrates potential as an anti-photoaging treatment for skin.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03137-y.