Project description:One of the keys to achieving skin regeneration lies within understanding the heterogeneity of neonatal fibroblasts, which support skin regeneration. However, the molecular underpinnings regulating the cellular states and fates of these cells are not fully understood. To investigate this, we performed a parallel multi-omics analysis by processing neonatal murine skin for single-cell ATAC-sequencing (scATAC-seq) and single-cell RNA-sequencing (scRNA-seq) separately. Our approach revealed that fibroblast clusters could be sorted into papillary and reticular lineages based on transcriptome profiling, as previously published. However, scATAC-seq analysis of neonatal fibroblast lineage markers, such as, Dpp4/CD26, Corin, and Dlk1 along with markers of myofibroblasts, revealed accessible chromatin in all fibroblast populations despite their lineage specific transcriptome profiles. These results suggests that accessible chromatin does not always translate to gene expression and that many fibroblast lineage markers reflect a fibroblast state, which includes neonatal papillary, reticular, and myofibroblasts. This analysis also provides a possible explanation as to why these marker genes can be promiscuously expressed in different fibroblast populations under different conditions. Our scATAC-seq analysis also revealed that the functional lineage restriction between dermal papilla and adipocytes fates are regulated by distinct chromatin landscapes. Finally, we have developed a webtool for our multi-omics analysis: https://skinregeneration.org/scatacseq-and-scrnaseq-data-from-thompson-et-al-2021-2/.
Project description:Fibroblasts are the main dermal cell type and are essential for the architecture and function of human skin. Important differences have been described between fibroblasts localized in distinct dermal layers, and these cells are also known to perform varied functions. However, this phenomenon has not been analyzed comprehensively yet. Here we have used single-cell RNA sequencing to analyze >15,000 cells from a sun-protected area in young and old donors. Our results define four main fibroblast subpopulations that can be spatially localized and functionally distinguished. Importantly, intrinsic aging reduces this fibroblast ‘priming’, generates distinct expression patterns of skin aging-associated genes, and substantially reduces the interactions of dermal fibroblasts with other skin cell types. Our work thus provides comprehensive evidence for a functional specialization of human dermal fibroblasts and suggests that the age-related loss of fibroblast priming contributes to human skin aging.
Project description:Skin fibrotic disease representsa major global healthcare burden, characterized by fibroblast hyperproliferation and excessive accumulation of extracellular matrix.Fibroblasts are found to be heterogeneous in multiple fibrotic diseases,but the fibroblast heterogeneity of skin fibrotic diseases remains unknown.In this study, we performed single-cell RNA-seq in keloid, a paradigm of skin fibrotic diseases, andnormal scardermis tissues.Our results indicate that keloid and normal scar fibroblasts could be divided into 4 subpopulations: secretory-papillary, secretory-reticular, mesenchymal and pro-inflammatory.The percentage of mesenchymal fibroblast subpopulationincreased significantly in keloid compared to normal scar. Interestingly, we also found increasing mesenchymal fibroblast subpopulation in scleroderma, another skin fibrotic disease.Function studies showed that the mesenchymal fibroblasts promoted collagen synthesis of the other fibroblasts in keloid partiallythrough secreting POSTN. These findings will help us understandskin fibroticpathogenesis in depth,and provided potential target cells for fibrotic diseases therapies.
Project description:Single cell RNA-seq was performed on healthy mouse skin fibroblasts. This data along with single cell transcriptomics datasets of fibroblasts from other healthy tissues was used to construct a steady state mouse fibroblast atlas.
Project description:Skin fibrotic disease representsa major global healthcare burden, characterized by fibroblast hyperproliferation and excessive accumulation of extracellular matrix.Fibroblasts are found to be heterogeneous in multiple fibrotic diseases,but the fibroblast heterogeneity of skin fibrotic diseases remains unknown.In this study, we performed single-cell RNA-seq in keloid, a paradigm of skin fibrotic diseases, andnormal scardermis tissues.Our results indicate thatkeloid and normal scar fibroblasts could be divided into 4 subpopulations: secretory-papillary, secretory-reticular, mesenchymal and pro-inflammatory.The percentage of mesenchymal fibroblast subpopulationincreased significantly in keloid compared to normal scar. Interestingly, we also found increasing mesenchymal fibroblast subpopulation in scleroderma, another skin fibrotic disease.Function studies showed that the mesenchymal fibroblasts promoted collagen synthesis of the other fibroblasts in keloid partiallythrough secreting POSTN. These findings will help us understandskin fibroticpathogenesis in depth,and provided potential target cells for fibrotic diseases therapies.
Project description:In adult mammals, skin wound healing has evolved to favor rapid repair through the formation of fibrotic scar. These dermal scars are dysfunctional and may lead to chronic disfigurement and disability, yet the biologic mechanisms that drive fibrosis and prevent tissue regeneration remain unknown. Here, we report that reindeer (Rangifer tarandus) antler velvet exhibits regenerative wound healing, whereas identical full-thickness injury in dorsal back skin of the same animal forms fibrotic scar. This regenerative capacity is retained even following ectopic transplantation of velvet to a scar-forming site, demonstrating that this latent regenerative capacity is innate to velvet cells and independent of local factors derived from the growing antler. Single cell RNA-sequencing of uninjured skin revealed a marked divergence in resting fibroblast transcriptional states and immunomodulatory function. Uninjured velvet fibroblast shared a striking resemblance with human fetal fibroblasts whereas uninjured back skin fibroblasts exhibited an overrepresentation of pro-inflammatory genes resembling adult human fibroblasts. Identical skin injury resulted in site-specific fibroblast polarization; back fibroblasts exacerbated the inflammatory response, whereas velvet fibroblasts adopted an immunosuppressive state and reverted back to a regeneration-competent ground state. Consequently, velvet wounds exhibited an accelerated adoption of anti-inflammatory immune states and an expedited resolution of immune response. This study demonstrates reindeer as a novel comparative mammalian model to study both adult skin regeneration (velvet) and scar formation (back skin) within the same animal. Our study underscores the importance of fibroblast heterogeneity in shaping local immune cell functions that ultimately polarize wound healing outcomes. Purposeful, acute modulation of fibroblast-mediated immune signaling represents an important therapeutic avenue to mitigate scar and improve wound healing.
Project description:In adult mammals, skin wound healing has evolved to favor rapid repair through the formation of fibrotic scar. These dermal scars are dysfunctional and may lead to chronic disfigurement and disability, yet the biologic mechanisms that drive fibrosis and prevent tissue regeneration remain unknown. Here, we report that reindeer (Rangifer tarandus) antler velvet exhibits regenerative wound healing, whereas identical full-thickness injury in dorsal back skin of the same animal forms fibrotic scar. This regenerative capacity is retained even following ectopic transplantation of velvet to a scar-forming site, demonstrating that this latent regenerative capacity is innate to velvet cells and independent of local factors derived from the growing antler. Single cell RNA-sequencing of uninjured skin revealed a marked divergence in resting fibroblast transcriptional states and immunomodulatory function. Uninjured velvet fibroblast shared a striking resemblance with human fetal fibroblasts whereas uninjured back skin fibroblasts exhibited an overrepresentation of pro-inflammatory genes resembling adult human fibroblasts. Identical skin injury resulted in site-specific fibroblast polarization; back fibroblasts exacerbated the inflammatory response, whereas velvet fibroblasts adopted an immunosuppressive state and reverted back to a regeneration-competent ground state. Consequently, velvet wounds exhibited an accelerated adoption of anti-inflammatory immune states and an expedited resolution of immune response. This study demonstrates reindeer as a novel comparative mammalian model to study both adult skin regeneration (velvet) and scar formation (back skin) within the same animal. Our study underscores the importance of fibroblast heterogeneity in shaping local immune cell functions that ultimately polarize wound healing outcomes. Purposeful, acute modulation of fibroblast-mediated immune signaling represents an important therapeutic avenue to mitigate scar and improve wound healing.