Project description:Our knowledge of transcriptional heterogeneities in epithelial stem/progenitor cell compartments is limited. Epidermal basal cells sustain cutaneous tissue maintenance and drive wound healing. Previous studies have probed basal cell heterogeneity in stem/progenitor potential, but a comprehensive dissection of basal cell dynamics during differentiation is lacking. Using single-cell RNA-sequencing coupled with RNAScope and fluorescence lifetime imaging, we identify three non-proliferative and one proliferative basal cell transcriptional states in homeostatic skin that differ in metabolic preference and become spatially partitioned during wound re-epithelialization. Pseudotemporal trajectory and RNA velocity analyses produce a quasi-linear differentiation hierarchy where basal cells progress from Col17a1high/Trp63high state to early response state, proliferate at the juncture of these two states, or become growth arrested before differentiating into spinous cells. Wound healing induces plasticity manifested by dynamic basal-spinous interconversions at multiple basal states. Our study provides a systematic view of epidermal cellular dynamics supporting a revised “hierarchical-lineage” model of homeostasis.
Project description:Tissue repair processes maintain proper organ function following mechanical or infection related damage. In addition to anti-bacterial properties, MAIT cells express a tissue repair transcriptomic program and promote skin wound healing when expanded. Herein, we use a human‑like full‑thickness skin excision mouse model to assess the underlying mechanisms of MAIT cell tissue repair function. Single-cell RNAseq analysis suggests that skin MAIT cells already express a repair program at steady state. Following skin excision, MAIT cells promote keratinocyte proliferation thereby accelerating healing. Using skin grafts, parabiosis and adoptive transfer experiments, we show that MAIT cells migrate into the wound from other tissues in a TCR independent but CXCR6 dependent manner. Amphiregulin secreted by MAIT cells following excision promotes wound healing. The repair function is independent of sustained TCR stimulation. Overall, our study provides mechanistic insight into MAIT cell wound healing function in the skin.
Project description:Skin has distinct characteristics depending on the anatomical site; however, the cell and molecular differences, and their functional implications, have been little described. RNA-sequencing of healthy adult mouse skin from the abdomen, back, and face/cheek has revealed that dermis from different sites is distinct, and that this aligns with their diverse embryonic origins (abdominal dermis develops from lateral plate mesoderm, dorsal dermis from paraxial mesoderm, and cheek dermis from neural crest). The functional implications for wound repair are evident from the differences in extracellular matrix and cell migration observed in tissue and dermal fibroblasts from these sites, and the histological and transcriptional variations during a wound response.
Project description:The expression profile during wound repair of cutaneous excisional wound (2x2 cm) was studied. The tissue was sampled from the centre of the open wound (day 3/7/14) or centre of the wound scar (day 21/35/70). The microarray slide were scanned in low intensity scan and high intensity scan mode. Wound tissue (day 3, day 7, day 14, day 21, day 35, day 70, n = 4 per interval) vs. control - uninjured skin (day 0, n=4 ). In each interval two biological replicates of four were labeled with flip dyes.
Project description:Repair after damage is essential for tissue homeostasis. Post-menstrual repair of the uterine endometrium is a unique cyclical manifestation of rapid, scar-free, tissue repair taking ~3-5 days. Skin repair post-wounding is slower (~2 weeks) and, in the case of chronic wounds, takes months/years to restore integrity. Herein, the unique ‘rapid-repair’ endometrial environment is translated to the ‘slower-repair’ skin environment. Menstrual fluid (MF), the milieu of post-menstrual endometrial repair, facilitates healing of endometrial and keratinocyte ‘wounds’ in vitro, promoting cellular adhesion and migration, stimulates keratinocyte migration in an ex vivo human skin-reconstruct model and promotes re-epithelialization in an in vivo porcine wound model. Proteomic analysis of MF identified a large number of proteins; several proteins were selected for further investigation, with the endometrium demonstrated as the source of these factors. Functionally, they promote repair of endometrial and keratinocyte wounds by promoting migration, differing significantly from currently available wound-repair treatments, which mainly promote proliferation. Development of these and other menstrual fluid factors into a ‘migration-inducing’ treatment paradigm will provide novel therapies for tissue repair.
Project description:Impaired skin wound healing is a significant global health issue, especially among the elderly. Wound healing is a well-orchestrated process involving the sequential phases of inflammation, proliferation, and tissue remodeling. Although wound healing is a highly dynamic and energy-requiring process, the role of metabolism remains largely unexplored. By combining transcriptomics and metabolomics of human skin biopsy samples, we mapped the core bioenergetic and metabolic changes in normal acute as well as chronic wounds in elderly subjects. We found upregulation of glycolysis, the tricarboxylic acid cycle, glutaminolysis, and β-oxidation in the later stages of acute wound healing and in chronic wounds. To ascertain the role of these metabolic pathways on wound healing, we targeted each pathway in a wound healing assay as well as in a human skin explant model using metabolic inhibitors and stimulants. Enhancement or inhibition of glycolysis and, to a lesser extent, glutaminolysis had a far greater impact on wound healing than similar manipulations of oxidative phosphorylation and fatty acid β-oxidation. These findings increase the understanding of wound metabolism and identify glycolysis and glutaminolysis as potential targets for therapeutic intervention.
Project description:During wounding healing, different pools of stem cells (SCs) During homeostasis, different compartments of the epidermis are sustained by distinct pools of stem cells (SC) whereas, upon wounding, these different SCs contribute to skin repair. However, how SCs become activated and drive the tissue remodeling essential for skin repair is still poorly understood. Here, by developing a mouse model allowing lineage tracing and basal cell lineage ablation while leaving the basic organization of the skin intact, we monitor SC fate and tissue dynamics during regeneration using confocal and intravital imaging. Analysis of basal cell rearrangements shows dynamic transitions from a solid-like homeostatic state to a fluid-like state allowing tissue remodelling during repair, as predicted by a minimal mathematical modelling of the spatiotemporal dynamics and fate behaviour of the basal cells population. The basal cell layer progressively returns to a solid-like state with re-epithelialization and the restoration of barrier function. Bulk, single-cell RNA and epigenetic profiling of SCs together with functional experiments uncover a common regenerative state regulated by the EGFR/AP1 axis activated during tissue fluidization that is essential for skin SC activation and tissue repair.