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Frontiers in Immunology 2022Fibrotic scars are common in both human and mouse skin wounds. However, wound-induced hair neogenesis in the murine wounding models often results in regenerative repair...
BACKGROUND
Fibrotic scars are common in both human and mouse skin wounds. However, wound-induced hair neogenesis in the murine wounding models often results in regenerative repair response. Herein, we aimed to uncover cellular functional heterogeneity in dermis between fibrotic and regenerative wound healing fates.
METHODS
The expression matrix of single-cell RNA sequencing (scRNA-seq) data of fibrotic and regenerative wound dermal cells was filtered, normalized, and scaled; underwent principal components analysis; and further analyzed by Uniform Manifold Approximation and Projection (UMAP) for dimension reduction with the Seurat package. Cell types were annotated, and cell-cell communications were analyzed. The core cell population myofibroblast was identified and the biological functions of ligand and receptor genes between myofibroblast and macrophage were evaluated. Specific genes between fibrotic and regenerative myofibroblast and macrophage were identified. Temporal dynamics of myofibroblast and macrophage were reconstructed with the Monocle tool.
RESULTS
Across dermal cells, there were six cell types, namely, EN1-negative myofibroblasts, EN1-positive myofibroblasts, hematopoietic cells, macrophages, pericytes, and endothelial cells. Ligand and receptor genes between myofibroblasts and macrophages mainly modulated cell proliferation and migration, tube development, and the TGF-β pathway. Specific genes that were differentially expressed in fibrotic compared to regenerative myofibroblasts or macrophages were separately identified. Specific genes between fibrotic and regenerative myofibroblasts were involved in the mRNA metabolic process and organelle organization. Specific genes between fibrotic and regenerative macrophages participated in regulating immunity and phagocytosis. We then observed the underlying evolution of myofibroblasts or macrophages.
CONCLUSION
Collectively, our findings reveal that myofibroblasts and macrophages may alter the skin wound healing fate through modulating critical signaling pathways.
Topics: Animals; Dermis; Endothelial Cells; Fibrosis; Ligands; Mice; Sequence Analysis, RNA; Wound Healing
PubMed: 35664010
DOI: 10.3389/fimmu.2022.875407 -
Developmental Cell May 2021Limb regeneration, while observed lifelong in salamanders, is restricted in post-metamorphic Xenopus laevis frogs. Whether this loss is due to systemic factors or an...
Limb regeneration, while observed lifelong in salamanders, is restricted in post-metamorphic Xenopus laevis frogs. Whether this loss is due to systemic factors or an intrinsic incapability of cells to form competent stem cells has been unclear. Here, we use genetic fate mapping to establish that connective tissue (CT) cells form the post-metamorphic frog blastema, as in the case of axolotls. Using heterochronic transplantation into the limb bud and single-cell transcriptomic profiling, we show that axolotl CT cells dedifferentiate and integrate to form lineages, including cartilage. In contrast, frog blastema CT cells do not fully re-express the limb bud progenitor program, even when transplanted into the limb bud. Correspondingly, transplanted cells contribute to extraskeletal CT, but not to the developing cartilage. Furthermore, using single-cell RNA-seq analysis we find that embryonic and adult frog cartilage differentiation programs are molecularly distinct. This work defines intrinsic restrictions in CT dedifferentiation as a limitation in adult regeneration.
Topics: Ambystoma mexicanum; Animals; Body Patterning; Cartilage; Cell Differentiation; Cellular Reprogramming; Connective Tissue Cells; Dermis; Embryo, Nonmammalian; Fibroblasts; Larva; Regeneration; Xenopus laevis
PubMed: 34004152
DOI: 10.1016/j.devcel.2021.04.016 -
Stem Cell Research & Therapy Sep 2022While rapid healing of diabetic foot ulcers (DFUs) is highly desirable to avoid infections, amputations and life-threatening complications, DFUs often respond poorly to... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
While rapid healing of diabetic foot ulcers (DFUs) is highly desirable to avoid infections, amputations and life-threatening complications, DFUs often respond poorly to standard treatment. GMP-manufactured skin-derived ABCB5 mesenchymal stem cells (MSCs) might provide a new adjunctive DFU treatment, based on their remarkable skin wound homing and engraftment potential, their ability to adaptively respond to inflammatory signals, and their wound healing-promoting efficacy in mouse wound models and human chronic venous ulcers.
METHODS
The angiogenic potential of ABCB5 MSCs was characterized with respect to angiogenic factor expression at the mRNA and protein level, in vitro endothelial trans-differentiation and tube formation potential, and perfusion-restoring capacity in a mouse hindlimb ischemia model. Finally, the efficacy and safety of ABCB5 MSCs for topical adjunctive treatment of chronic, standard therapy-refractory, neuropathic plantar DFUs were assessed in an open-label single-arm clinical trial.
RESULTS
Hypoxic incubation of ABCB5 MSCs led to posttranslational stabilization of the hypoxia-inducible transcription factor 1α (HIF-1α) and upregulation of HIF-1α mRNA levels. HIF-1α pathway activation was accompanied by upregulation of vascular endothelial growth factor (VEGF) transcription and increase in VEGF protein secretion. Upon culture in growth factor-supplemented medium, ABCB5 MSCs expressed the endothelial-lineage marker CD31, and after seeding on gel matrix, ABCB5 MSCs demonstrated formation of capillary-like structures comparable with human umbilical vein endothelial cells. Intramuscularly injected ABCB5 MSCs to mice with surgically induced hindlimb ischemia accelerated perfusion recovery as measured by laser Doppler blood perfusion imaging and enhanced capillary proliferation and vascularization in the ischemic muscles. Adjunctive topical application of ABCB5 MSCs onto therapy-refractory DFUs elicited median wound surface area reductions from baseline of 59% (full analysis set, n = 23), 64% (per-protocol set, n = 20) and 67% (subgroup of responders, n = 17) at week 12, while no treatment-related adverse events were observed.
CONCLUSIONS
The present observations identify GMP-manufactured ABCB5 dermal MSCs as a potential, safe candidate for adjunctive therapy of otherwise incurable DFUs and justify the conduct of a larger, randomized controlled trial to validate the clinical efficacy.
TRIAL REGISTRATION
ClinicalTrials.gov, NCT03267784, Registered 30 August 2017, https://clinicaltrials.gov/ct2/show/NCT03267784.
Topics: ATP Binding Cassette Transporter, Subfamily B; Animals; Dermis; Diabetes Mellitus; Diabetic Foot; Humans; Ischemia; Mesenchymal Stem Cell Transplantation; Mesenchymal Stem Cells; Mice; Neovascularization, Pathologic; Neovascularization, Physiologic; RNA, Messenger; Vascular Endothelial Growth Factor A; Wound Healing
PubMed: 36064604
DOI: 10.1186/s13287-022-03156-9 -
Nature Communications Nov 2023Tissue-resident macrophages are critical for tissue homeostasis and repair. We previously showed that dermis-resident macrophages produce CCL24 which mediates their...
Tissue-resident macrophages are critical for tissue homeostasis and repair. We previously showed that dermis-resident macrophages produce CCL24 which mediates their interaction with IL-4 eosinophils, required to maintain their M2-like properties in the T1 environment of the Leishmania major infected skin. Here, we show that thymic stromal lymphopoietin (TSLP) and IL-5 type 2 innate lymphoid cells are also required to maintain dermis-resident macrophages and promote infection. Single cell RNA sequencing reveals the dermis-resident macrophages as the sole source of TSLP and CCL24. Generation of Ccl24-cre mice permits specific labeling of dermis-resident macrophages and interstitial macrophages from other organs. Selective ablation of TSLP in dermis-resident macrophages reduces the numbers of IL-5 type 2 innate lymphoid cells, eosinophils and dermis-resident macrophages, and ameliorates infection. Our findings demonstrate that dermis-resident macrophages are self-maintained as a replicative niche for L. major by orchestrating localized type 2 circuitries with type 2 innate lymphoid cells and eosinophils.
Topics: Animals; Mice; Immunity, Innate; Eosinophils; Interleukin-5; Lymphocytes; Cytokines; Thymic Stromal Lymphopoietin; Macrophages; Leishmaniasis, Cutaneous; Dermis
PubMed: 38030609
DOI: 10.1038/s41467-023-43588-2 -
International Wound Journal Sep 2023Fish skin grafting as a new skin substitute is currently being used in clinical applications. Acceleration of the wound healing, lack of disease transmission, and low... (Review)
Review
Fish skin grafting as a new skin substitute is currently being used in clinical applications. Acceleration of the wound healing, lack of disease transmission, and low cost of the production process can introduce fish skin as a potential alternative to other grafts. An appropriate decellularization process allows the design of 3D acellular scaffolds for skin regeneration without damaging the morphology and extracellular matrix content. Therefore, the role of decellularization processes is very important to maintain the properties of fish skin. In this review article, recent studies on various decellularization processes as well as biological, physical, and mechanical properties of fish skin and its applications with therapeutic effects in wound healing were investigated.
Topics: Animals; Wound Healing; Skin Transplantation; Skin, Artificial; Extracellular Matrix; Fishes; Acellular Dermis
PubMed: 36924081
DOI: 10.1111/iwj.14158 -
Journal of Anatomy Aug 2019The structure and function of the skin relies on the complex expression pattern and organisation of extracellular matrix macromolecules, of which collagens are a... (Review)
Review
The structure and function of the skin relies on the complex expression pattern and organisation of extracellular matrix macromolecules, of which collagens are a principal component. The fibrillar collagens, types I and III, constitute over 90% of the collagen content within the skin and are the major determinants of the strength and stiffness of the tissue. However, the minor collagens also play a crucial regulatory role in a variety of processes, including cell anchorage, matrix assembly, and growth factor signalling. In this article, we review the expression patterns, key functions and involvement in disease pathogenesis of the minor collagens found in the skin. While it is clear that the minor collagens are important mediators of normal tissue function, homeostasis and repair, further insight into the molecular level structure and activity of these proteins is required for translation into clinical therapies.
Topics: Animals; Basement Membrane; Collagen; Dermis; Humans
PubMed: 31318053
DOI: 10.1111/joa.12584 -
American Journal of Physiology. Cell... Dec 2022The epidermis is a specialized epithelium that constitutes the outermost layer of the skin, and it provides a protective barrier against environmental assaults.... (Review)
Review
The epidermis is a specialized epithelium that constitutes the outermost layer of the skin, and it provides a protective barrier against environmental assaults. Primarily consisting of multilayered keratinocytes, the epidermis is continuously renewed by proliferation of stem cells and the differentiation of their progeny, which undergo terminal differentiation as they leave the basal layer and move upward toward the surface, where they die and slough off. Basal keratinocytes rest on a basement membrane at the dermal-epidermal junction that is composed of specific extracellular matrix proteins organized into interactive and mechanically supportive networks. Firm attachment of basal keratinocytes, and their dynamic regulation via focal adhesions and hemidesmosomes, is essential for maintaining major skin processes, such as self-renewal, barrier function, and resistance to physical and chemical stresses. The adhesive integrin receptors expressed by epidermal cells serve structural, signaling, and mechanosensory roles that are critical for epidermal cell anchorage and tissue homeostasis. More specifically, the basement membrane components play key roles in preserving the stem cell pool, and establishing cell polarity cues enabling asymmetric cell divisions, which result in the transition from a proliferative basal cell layer to suprabasal cells committed to terminal differentiation. Finally, through a well-regulated sequence of synthesis and remodeling, the components of the dermal-epidermal junction play an essential role in regeneration of the epidermis during skin healing. Here too, they provide biological and mechanical signals that are essential to the restoration of barrier function.
Topics: Epidermis; Epidermal Cells; Basement Membrane; Keratinocytes; Dermis; Cell Differentiation
PubMed: 36374168
DOI: 10.1152/ajpcell.00069.2022 -
International Journal of Molecular... Jul 2021We studied CD34+ stromal cells/telocytes (CD34+SCs/TCs) in pathologic skin, after briefly examining them in normal conditions. We confirm previous studies by other... (Review)
Review
We studied CD34+ stromal cells/telocytes (CD34+SCs/TCs) in pathologic skin, after briefly examining them in normal conditions. We confirm previous studies by other authors in the normal dermis regarding CD34+SC/TC characteristics and distribution around vessels, nerves and cutaneous annexes, highlighting their practical absence in the papillary dermis and presence in the bulge region of perifollicular groups of very small CD34+ stromal cells. In non-tumoral skin pathology, we studied examples of the principal histologic patterns in which CD34+SCs/TCs have (1) a fundamental pathophysiological role, including (a) fibrosing/sclerosing diseases, such as systemic sclerosis, with loss of CD34+SCs/TCs and presence of stromal cells co-expressing CD34 and αSMA, and (b) metabolic degenerative processes, including basophilic degeneration of collagen, with stromal cells/telocytes in close association with degenerative fibrils, and cutaneous myxoid cysts with spindle-shaped, stellate and bulky vacuolated CD34+ stromal cells, and (2) a secondary reactive role, encompassing dermatitis-e.g., interface (erythema multiforme), acantholytic (pemphigus, Hailey-Hailey disease), lichenoid (lichen planus), subepidermal vesicular (bullous pemphigoid), psoriasiform (psoriasis), granulomatous (granuloma annulare)-vasculitis (leukocytoclastic and lymphocytic vasculitis), folliculitis, perifolliculitis and inflammation of the sweat and sebaceous glands (perifolliculitis and rosacea) and infectious dermatitis (verruca vulgaris). In skin tumor and tumor-like conditions, we studied examples of those in which CD34+ stromal cells are (1) the neoplastic component (dermatofibrosarcoma protuberans, sclerotic fibroma and solitary fibrous tumor), (2) a neoplastic component with varying presentation (fibroepithelial polyp and superficial myxofibrosarcoma) and (3) a reactive component in other tumor/tumor-like cell lines, such as those deriving from vessel periendothelial cells (myopericytoma), epithelial cells (trichoepithelioma, nevus sebaceous of Jadassohn and seborrheic keratosis), Merkel cells (Merkel cell carcinoma), melanocytes (dermal melanocytic nevi) and Schwann cells (neurofibroma and granular cell tumor).
Topics: Animals; Antigens, CD34; Dermatitis; Dermis; Humans; Neoplasm Proteins; Skin Neoplasms; Telocytes
PubMed: 34298962
DOI: 10.3390/ijms22147342 -
The Journal of Investigative Dermatology Jan 2022This review focuses on recent advances in understanding the mechanisms involved in itch signaling in the skin and how these new findings fit into the wider picture of... (Review)
Review
This review focuses on recent advances in understanding the mechanisms involved in itch signaling in the skin and how these new findings fit into the wider picture of the expression of itch mediators and their receptors in the dermal layer. Because at present studies mostly concentrate on single cellular compartments (e.g., neural alone), we suggest that they may miss important interactions with other compartments. Therefore, to fully appreciate pruritus, we propose that studies should consider (e.g., using transcriptomic information) signal transmission within the entire neuro‒immune‒stromal triad.
Topics: Animals; Cell Communication; Dermis; Humans; Neuroimmunomodulation; Pruritus; Signal Transduction; Single-Cell Analysis; Stromal Cells; Transcriptome
PubMed: 34662564
DOI: 10.1016/j.jid.2021.08.443 -
Journal of Biomedical Optics Nov 2023Knowledge of optical properties is important to accurately model light propagation in tissue, but reference data are sparse.
SIGNIFICANCE
Knowledge of optical properties is important to accurately model light propagation in tissue, but reference data are sparse.
AIM
The aim of our study was to present skin optical properties from a large Swedish cohort including 3809 subjects using a three-layered skin model and spatially resolved diffuse reflectance spectroscopy (Periflux PF6000 EPOS).
APPROACH
Diffuse reflectance spectra (475 to 850 nm) at 0.4 and 1.2 mm source-detector separations were analyzed using an inverse Monte Carlo method. The model had one epidermis layer with variable thicknesses and melanin-related absorptions and two dermis layers with varying hemoglobin concentrations and equal oxygen saturations. The reduced scattering coefficient was equal across all layers.
RESULTS
Median absorption coefficients () in the upper dermis ranged from 0.094 at 475 nm to 0.0048 at 850 nm and similarly in the lower dermis from 0.059 to 0.0035. The reduced scattering coefficient () ranged from 3.22 to 1.20, and the sampling depth (mm) ranged from 0.23 to 0.38 (0.4 mm separation) and from 0.49 to 0.68 (1.2 mm separation). There were differences in optical properties across sex, age groups, and BMI categories.
CONCLUSIONS
Reference material for skin optical properties is presented.
Topics: Humans; Cohort Studies; Sweden; Models, Biological; Scattering, Radiation; Epidermis; Dermis; Monte Carlo Method
PubMed: 38078153
DOI: 10.1117/1.JBO.28.11.115001