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:An effective healing response is critical to healthy aging. Thus, the connection of regeneration and aging is needed to understand the complicated age-related healing process. Energy metabolism has been a common hallmark of both studies. In recent years, it become an emerging factor of skin homeostasis. Adenine nucleotide translocase-2 (ANT2) is a known cell proliferation marker and mediator of ATP import into mitochondria for energy homeostasis. Although energy homeostasis and the maintenance of mitochondrial function are critical for wound healing, the role of ANT2 in wound healing has not been elucidated. We found that ANT2 expression decreased during aging in mouse skin as well as during cellular senescence. Interestingly, overexpression of ANT2 in aged mouse skin promoted the healing of full-thickness cutaneous wounds. In addition, upregulation of ANT2 in replicative senescent human diploid dermal fibroblasts (HDFs) induced cell proliferation and migration, which are critical for the wound healing process. Furthermore, overexpression of ANT2 increased ATP production rate by activating the glycolysis pathway and also increased mitophagy, both of which are involved in energy homeostasis. Notably, ANT2-mediated upregulation of HSPA6 in aged HDFs inhibited the expression of pro-inflammatory genes that mediate cellular senescence and mitochondrial damage. This study demonstrates a new physiological role of ANT2 in skin wound healing via regulation of cell proliferation, energy homeostasis, and inflammation. Thus, our study links energy metabolism to skin homeostasis and identifies a genetic factor for improving wound healing with aging model.
Project description:Wound healing is essential to repair the skin after injury. In the epidermis, distinct stem cells (SCs) populations contribute to wound healing. However, how SCs balance proliferation, differentiation and migration to repair a wound remains poorly understood. Here we show the cellular and molecular mechanisms that regulate wound healing in mouse tail epidermis. Using a combination of proliferation kinetics experiments and molecular profiling, we identify the gene signatures associated with proliferation, differentiation and migration in different regions surrounding the wound. Functional experiments show that SC proliferation, migration and differentiation can be uncoupled during wound healing. Lineage tracing and quantitative clonal analysis reveal that, following wounding, progenitors divide more rapidly, but conserve their homeostatic mode of division, leading to their rapid depletion whereas SCs become active, giving rise to new progenitors that expand and repair the wound. These results have important implications for tissue regeneration, acute and chronic wound disorders.
Project description:To identify the candidate miRNAs that might compromise wound healing and contribute to the age-associated delay in wound repair, global miRNA profiling was performed in mouse back telogen skin of young (8-week-old) and aged (2-year-old) animals.
Project description:The full complement of hair follicles is generated during embryogenesis. Normally, no new hair is created after this time. Large full thickness skin excision wounding can result in the generation of new hair in the adult. Placodes can be observed following complete reepithelialization at wound day 14. The events leading to hair neogenesis following wounding remain poorly understood. Late healing events (from wound day 10 to wound day 14) provide a possible window of induction for hair regeneration. We used microarrays to analyse changes in gene expression during late skin healing to provide candidates for factors involved in hair neogenesis following wounding. 6 week old C57Bl/6 mice received large full thickness skin excisions. Healing wound tissue was excised at wound day 10, 12 or 14 and analyzed for gene expression.