Chronic skin wounds affect 2.2 million patients who are elderly and/or diabetic (UK), yet current treatments remain inadequate due to limited understanding of the molecular and cellular correlates of poor healing. Indeed, our group first demonstrated that cellular senescence contributes to delayed wound repair in vivo. Thus, clearance of senescent cells could present a targeted therapeutic strategy to promote skin repair. In this study, we aimed to spatially characterize immunosenescence within human chronic wounds and in vivo models of delayed wound repair to discern which cell types drive pathological senescence. We also synthesized a senescence radiopharmaceutical, [18F]FPyGal, to enable live tracking of tissue senescence across the wound healing continuum. Flow cytometry and spatial proteomic imaging (MACSima platform) characterized immunosenescence in selected tissues (including skin and wounds) in vivo [young/aged (C57BL/6J) and diabetic (db/db) mice] and in patient chronic wounds. High-performance liquid chromatography validated synthesis of [18F]FPyGal, which was injected (IV) into mice to assess biodistribution via positron emission tomography/computed tomography imaging. We show that both lymphoid and myeloid populations are highly senescent in aged and diabetic mouse wounds. This profiling also revealed that diabetic unwounded skin retains highly senescent populations, indicating intrinsic skin senescence in diabetes. Interestingly, we identified a highly senescent CD4+CD8+ T-cell subset, providing functional insight into undercharacterized wound-lymphoid populations. These findings extend to human chronic wounds, where increased immunosenescence is linked to clinical outcome. Optimization of [18F]FPyGal synthesis generated a radiochemical purity of > 98%. Initial in vivo testing confirmed limited adverse effects of [18F]FPyGal, enabling future wound validation These data reveal a previously unappreciated role for immunosenescence in delayed wound repair, presenting an exciting avenue for therapeutic targeting. Successful synthesis of the [18F]FPyGal radiotracer will enable future temporospatial studies elucidating how local and systemic tissue senescence contribute to cutaneous wound pathology.

Human skin hosts a diverse and unique microbiota, playing crucial roles in health, protection and immunity. While ageing alters skin microbiota composition, the causal relationship between these changes and the ageing process remains poorly understood. This study investigates the bidirectional relationship between skin ageing and microbiota. Healthy volunteers recruited for this study were categorized as young (18–30 years) and elderly (> 60 years). Swabs from the forehead, forearm and foot were used for bacterial isolation and metagenomic profiling using Nanopore sequencing. Age-related biophysical parameters were measured using DermaLab Combo®. Bacterial profiling revealed important age-associated differences. Younger individuals exhibited higher sebum content and a greater abundance of lipophilic Cutibacterium on the forehead, whereas Corynebacterium was more abundant in the elderly. The forearm displayed a more diverse and evenly distributed microbial community, with Staphylococcus being more prevalent in young volunteers’ arms. Additionally, there was an increase in potentially opportunistic pathogens, such as Escherichia and Corynebacterium. Staphylococcus dominated both age group’s microbiomes on the feet, with a moderate increase in the younger group. Alpha and beta diversities showed considerable disparities between groups in different body sites. Biophysical properties varied more between body location within individuals than between age groups, highlighting the influence of intrapersonal differences. Ongoing whole-genome analyses aim to further explore bacterial pathways linked to age. By combining the power of long-read sequencing with biophysical measures we were able to explore age-related bacterial changes across skin regions. PromethION sequencing provided unprecedented insight into the skin’s strain-level diversity. Our findings suggest that microbial changes may be both a cause and a consequence of biophysical changes in the skin. For further explorations, whole-genome studies are being conducted to unveil the mechanisms behind microbiome alterations on the skin, paving the way for groundbreaking advances in understanding and addressing skin ageing.

Abstract Introduction and aims Chronic wounds affect over 2.2 million patients in the UK, yet effective therapies remain lacking owing to limited understanding of the cellular mechanisms underlying impaired healing. Our group was the first to mechanistically demonstrate that cellular senescence contributes to delayed wound repair in vivo, and that targeting CXCR2 dampens senescence and promotes tissue regeneration. Thus, in the present study, we integrated spatial transcriptomics and immune profiling to define the senescent wound microenvironment in both human tissue and murine models to uncover cellular and molecular drivers of senescence in human chronic wounds and inform therapeutic targets. Methods Spatial transcriptomics (Xenium, 10X Genomics) and protein multiplex imaging (MACSima, Miltenyi Biotec) were conducted on human and murine chronic wound tissue. Immunohistochemistry of selected makers further validated transcriptomic findings. Complimentary in vivo studies were conducted in diabetic mice, with wound healing outcomes and immune cell senescence assessed via histology and flow cytometry. Results Transcriptomic analysis revealed significant upregulation of interleukin (IL)1β and CXCL5 in high-senescent wounds, implicating inflammatory chemokine signalling in sustaining the senescent niche. Both IL1β and CXCL5 show strong colocalization and enrichment within a myeloid cluster spatially adjacent to the leading edge of the wound. CellChat analysis confirmed strong predicted ligand–receptor interactions between this myeloid cluster and basal keratinocytes, indicating macrophage priming and paracrine crosstalk driving cellular dysfunction and chronic inflammation. In vivo blockade of IL1β reduced immune cell senescence and significantly improved wound healing, reinforcing its central role in modulating wound inflammation and repair. Conclusions Our data validate senescence as a hallmark of chronic wound dysfunction, where immunosenescence drives sustained inflammation and impaired healing. IL1β-driven immune–epithelial crosstalk emerged as a key mechanism in this process, identifying IL1β as a promising therapeutic target. These findings provide a foundation for precision therapies aimed at targeting senescence to improve wound healing outcomes in patients.

This study aimed to evaluate the effects of comorbidities, neoadjuvant chemotherapy, haemoglobin levels, and nutritional status on a novel model of ex-vivo wound healing. Human skin samples were obtained from surgical waste of patients undergoing plastic and reconstructive procedures. Ex vivo wounds were created using punch biopsies, cultured over a 48-hour healing time course, and analysed for mean healed area (%). Patient records were reviewed for comorbidities, smoking status, preoperative chemoradiotherapy, and haemoglobin and albumin levels. Data analysis was conducted using univariate and multivariate regression analyses to identify predictors of wound healing outcomes. A total of 64 ex vivo donor skin samples were analysed, with a mean area healed at 48 hours of 69.3% ± 20.3% and a median of 71.7%. Smoking, obesity, nutrition, haemoglobin, neoadjuvant chemotherapy, diabetes, autoimmune disease, or preoperative immunosuppressant use were not significant predictors of mean area healed at 48 hours (all p values > 0.05). However, concurrent autoimmune disease and immunosuppressant use significantly reduced the mean area healed (p = 0.048; 95% CI: [-1.86, -0.01]). The ex vivo model examined real patient samples, offering insights into wound healing variability. No significant effects of smoking, obesity, nutrition, haemoglobin, or neoadjuvant chemotherapy were observed on healing outcomes. However, autoimmune disease and immunosuppressant use significantly reduced healing. Larger, diverse cohorts with extended follow-up are needed to address subgroup limitations. This model highlights the complexity of wound healing and its potential to bridge laboratory findings with clinical practice, enabling personalised medicine.

This study aimed to assess the association between clinical risk factors, treatment-related variables, and postoperative wound complications in breast reconstructive surgery. This retrospective cohort study included patients undergoing reconstructive breast surgery at a single centre between August 2017 and January 2024. Data on risk factors, including obesity, smoking status, age, diabetes mellitus, hypertension, preoperative haemoglobin levels, nutritional status, and preoperative use of immunosuppressants, chemotherapy, and targeted anticancer therapy eg: Herceptin were collected. Wound healing outcomes were classified using the breast reconstruction specific Clavien-Dindo classification. Relationships were evaluated using an ordered multivariate logistic regression. A total of 215 patients were included (mean age 51.4 ± 10.1 years). Preoperative therapies included chemotherapy (48.6%), radiotherapy (37.7%), oestrogen receptor blockers (15.5%), aromatase inhibitors (18.8%), and targeted anticancer drugs (15.6%). Obesity was identified as a strong predictor of higher-grade complications according to the Clavien-Dindo classification (OR = 3.17 [95% CI: 1.77–5.67], p < 0.001). Preoperative targeted anticancer drugs (OR = 0.36 [95% CI: 0.15–0.84], p = 0.018), nutrition scores (OR = 1.16 [95% CI: 1.04–1.30], p = 0.007), and immunosuppressant use (OR = 3.43 [95% CI: 1.01–10.90], p = 0.036) were also significant predictors of higher-grade complications (p<0.05) . The model was statistically significant (p = 0.0013). Targeted anticancer therapies, obesity, nutrition, and immunosuppressant use significantly influence wound complication severity. Preoperative optimisation and individualised risk stratification are crucial to reducing surgical wound complications. Future research should explore underlying mechanisms using ex vivo models and develop standardised wound reporting criteria for breast reconstruction.

The skin microbiome is dominated by a few key genera, among which Staphylococcus is one of the most well characterized. Recent studies have examined the roles of various Staphylococcus species such as Staphylococcus epidermidis and Staphylococcus hominis within broader skin microbial communities. However, these investigations often rely on isolates from multiple individuals and hence limit their ability to capture intra-community interactions. In this study, we focused on the axillary micro-biome of a single healthy individual to characterize the genetic and functional diversity of resident Staphylococcus isolates. Using a low-cost, high-throughput DNA extraction and long-read whole-genome sequencing pipeline, we generated complete genomes for 93 isolates spanning 7 genetically distinct lineages across 3 major skin species. These comprised one dominant and three additional lineages of S. epidermidis, two of S. hominis and one of Staphylococcus capitis. Functional and metabolic analyses revealed species-and strain-specific features, suggesting potential metabolic cross-feeding and specialization within this community, including within strains of S. epidermidis. These findings highlight the metabolic complexity and potential interdependence of staphylococci inhabiting a single skin site and the need for strain-level resolution of the community. The strains form part of the York Skin Microbiome (YSM) collection, a growing open biobank of genetically diverse skin isolates from matched individuals.

This study investigates a series of phosphate-glass fibers (PGFs) in the system P2O5-CaO-MgO-Na2O-Fe2O3 with various Fe contents (0, 0.1, 0.5, 1, and 2 wt %) prepared via electrospinning of polyphosphate coacervate gels. This method is preferable over the traditional high-temperature melt-spinning technique used for PGF production as it represents a more cost-effective and sustainable route. Structural analysis performed via Fourier transform Infrared spectroscopy shows that PGFs are mainly formed by polyphosphate chains containing Q1 and Q2 units. Thermal analysis demonstrates that the amorphous nature of the PGFs can be preserved up to calcination temperatures in the range 450-520 °C, with crystallization temperatures increasing with the iron content. Dissolution studies were performed by immersing the PGFs in deionized water and analyzing the species released (P, Ca, Mg, Fe, and Na) via microwave plasma atomic emission spectroscopy at regular intervals up to 72 hours (h). Results show that both iron and phosphate anion release increases with iron loading, suggesting that the phosphate network is weakened by an increasing amount of iron. Given that PGFs are particularly advantageous in wound healing due to their fibrous morphology, their cytocompatibility was assessed by seeding human keratinocytes (HaCaTs) in contact with the dissolution products of PGFs after 24 h of immersion at three different ratios of dissolution products to cell medium (1:100, 3:100, and 5:100). No cytotoxicity was observed for any of the ratios studied. Moreover, the dissolution products of some PGFs resulted in an enhanced growth of HaCaTs, with the best result being observed when using dissolution products from PGFs containing 0.1 wt % of Fe and a dissolution product-cell medium ratio of 5:100. Dissolution products from PGFs with an Fe content up to 0.5 wt % have also demonstrated antibacterial activity against the bacterium Escherichia coli (E. coli). A preliminary test on the efficacy of PGFs in wound healing via ex vivo studies on human skin has demonstrated that the PGFs in direct contact with the wound promote 84% wound closure.

Biomaterials capable of promoting wound healing and preventing infections remain in great demand to address the global unmet need for the treatment of chronic wounds. Phosphate-based glasses (PG) have shown potential as bioresorbable materials capable of inducing tissue regeneration, while being replaced by regenerated tissue and releasing therapeutic species. In this work, phosphate-glass-based fibers (PGF) in the system P2O5-CaO-Na2O added with 1, 2, 4, 6, and 10 mol % of the therapeutic metallic ions (TMI) Ag+, Zn2+, and Fe3+ were manufactured via electrospinning of coacervate gels. Coacervation is a sustainable, cost-effective, water-based method to produce PG. All TMI are effective in promoting wound closure (re-epithelialization) in living human skin ex vivo, where the best-performing system is PGF containing Ag+. In particular, PGF with ≥4 mol % of Ag+ is capable of promoting 84% wound closure over 48 h. These results are confirmed by scratch test migration assays, with the PGF-Ag systems containing ≥6 mol % of Ag+, demonstrating significant wound closure enhancement (up to 72%) after 24 h. The PGF-Ag systems are also the most effective in terms of antibacterial activity against both the Gram-positive Staphylococcus aureus and the Gram-negative Escherichia coli. PGF doped with Zn2+ shows antibacterial activity only against S. aureus in the systems containing Zn2+ ≥ 10 mol %. In addition, PGF doped with Fe3+ rapidly accelerates ex vivo healing in patient chronic wound skin (>30% in 48 h), demonstrating the utility of doped PGF as a potential therapeutic strategy to treat chronic wounds.

Our skin is home to a diverse community of commensal microorganisms integral to cutaneous function. However, microbial dysbiosis and barrier perturbation increase the risk of local and systemic infection. Staphylococcus aureus is a particularly problematic bacterial pathogen, with high levels of antimicrobial resistance and direct association with poor healing outcome. Innovative approaches are needed to selectively kill skin pathogens, such as S aureus, without harming the resident microbiota. In this study, we provide important data on the selectivity and efficacy of an S aureus-targeted- targeted endolysin (XZ.700) within the complex living skin/wound microbiome. Initial cross-species comparison using Nanopore long-read sequencing identified the translational potential of porcine rather than murine skin for human-relevant microbiome studies. We therefore performed an interventional study in pigs to assess the impact of endolysin administration on the microbiome. XZ.700 selectively inhibited endogenous porcine S aureus in vivo, restoring microbial diversity and promoting multiple aspects of wound repair. Subsequent mechanistic studies confirmed the importance of this microbiome modulation for effective healing in human skin. Taken together, these findings strongly support further development of S aureus-targeted- targeted endolysins for future clinical management of skin and wound infections.

Our skin is home to a diverse community of commensal microorganisms integral to cutaneous function. However, microbial dysbiosis and barrier perturbation increase the risk of local and systemic infection. Staphylococcus aureus is a particularly problematic bacterial pathogen, with high levels of antimicrobial resistance and direct association with poor healing outcome. Innovative approaches are needed to selectively kill skin pathogens, such as S. aureus, without harming the resident microbiota. Here we provide important data on the selectivity and efficacy of an S. aureus-targeted endolysin (XZ.700) within the complex living skin/wound microbiome. Initial cross-species comparison using Nanopore long-read sequencing identified the translational potential of porcine, rather than murine, skin for human-relevant microbiome studies. We therefore performed an interventional study in pigs to assess the impact of endolysin administration on the microbiome. XZ.700 selectively inhibited endogenous porcine S. aureus in vivo, restoring microbial diversity and promoting multiple aspects of wound repair. Subsequent mechanistic studies confirmed the importance of this microbiome modulation for effective healing in human skin. Taken together, these findings strongly support further development of S. aureus-targeted endolysins for future clinical management of skin and wound infections.

This study investigates the effects of environmentally-relevant concentrations of fluoxetine (FLX, commercial name: Prozac) on wound healing. Pollution of water systems with pharmaceutical and personal care products, including antidepressants such as FLX and other selective serotonin reuptake inhibitors, is a growing environmental concern. Environmentally-relevant FLX concentrations are known to impact physiological functions and behaviour of aquatic animals, however, the effects of exposure on humans are currently unknown. Using a combination of human skin biopsies and a human keratinocyte cell line, we show that exposure to environmental FLX promotes wound closure. We show dose-dependent increases in wound closure with FLX concentrations from 125 ng/l. Using several -omics and pharmaceutical approaches, we demonstrate that the mechanisms underlying enhanced wound closure are increased cell proliferation and serotonin signalling. Transcriptomic analysis revealed 350 differentially expressed genes after exposure. Downregulated genes were enriched in pathways related to mitochondrial function and metabolism, while upregulated genes were associated with cell proliferation and tissue morphogenesis. Kinase profiling showed altered phosphorylation of kinases linked to the MAPK pathway. Consistent with this, phosphoproteomic analyses identified 235 differentially phosphorylated proteins after exposure, with enriched GO terms related to cell cycle, division, and protein biosynthesis. Treatment of skin biopsies and keratinocytes with ketanserin, a serotonin receptor antagonist, reversed the increase in wound closure observed upon exposure. These findings collectively show that exposure to environmental FLX promotes wound healing through modulating serotonin signalling, gene expression and protein phosphorylation, leading to enhanced cell proliferation. Our results justify a transition from the study of behavioural effects of environmental FLX in aquatic animals to the investigation of effects of exposure on wound healing in aquatic and terrestrial animals, including direct impacts on human health.

Naked mole-rats (NMRs) (Heterocephalus glaber) are long-lived mammals that possess a natural resistance to cancer and other age-related pathologies, maintaining a healthy life span >30 years. In this study, using immunohistochemical and RNA-sequencing analyses, we compare skin morphology, cellular composition, and global transcriptome signatures between young and aged (aged 3‒4 vs. 19‒23 years, respectively) NMRs. We show that similar to aging in human skin, aging in NMRs is accompanied by a decrease in epidermal thickness; keratinocyte proliferation; and a decline in the number of Merkel cells, T cells, antigen-presenting cells, and melanocytes. Similar to that in human skin aging, expression levels of dermal collagens are decreased, whereas matrix metalloproteinase 9 and matrix metalloproteinase 11 levels increased in aged versus in young NMR skin. RNA-sequencing analyses reveal that in contrast to human or mouse skin aging, the transcript levels of several longevity-associated (Igfbp3, Igf2bp3, Ing2) and tumor-suppressor (Btg2, Cdkn1a, Cdkn2c, Dnmt3a, Hic1, Socs3, Sfrp1, Sfrp5, Thbs1, Tsc1, Zfp36) genes are increased in aged NMR skin. Overall, these data suggest that specific features in the NMR skin aging transcriptome might contribute to the resistance of NMRs to spontaneous skin carcinogenesis and provide a platform for further investigations of NMRs as a model organism for studying the biology and disease resistance of human skin.