Project description:Runx1 is a transcription factor that plays a key role in determining the proliferative and differential state of multiple cell types, during both development and adulthood. Here, we report how runx1 is specifically upregulated at the injury site during zebrafish heart regeneration, but unexpectedly, absence of runx1 results in enhanced regeneration. Using single cell sequencing, we found that the wild-type injury site consists of Runx1-positive endocardial cells and thrombocytes that express smooth muscle and collagen genes without differentiating into myofibroblasts. Both these populations are absent in runx1 mutants, resulting in a less collagenous and fibrinous scar. The reduction in fibrin in the mutant is further explained by reduced myofibroblast formation and by upregulation of components of the fibrin degradation pathway, including plasminogen receptor Annexin 2A as well as downregulation of plasminogen activator inhibitor serpine1 in myocardium and endocardium, resulting in increased levels of Plasminogen. In addition, this we also find enhanced myocardial proliferation as well as increased myocardial survival in the mutant. Our findings suggest that Runx1 controls the regenerative response of multiple cardiac cell-types and that targeting Runx1 is a novel therapeutic strategy to induce endogenous heart repair.
Project description:Runx1 is a transcription factor that plays a key role in determining the proliferative and differential state of multiple cell types, during both development and adulthood. Here, we report how Runx1 is specifically upregulated at the injury site during zebrafish heart regeneration, and that absence of runx1 results in increased myocardial survival and proliferation, and overall heart regeneration, accompanied by decreased fibrosis. Using single cell sequencing, we found that the wild-type injury site consists of Runx1-positive endocardial cells and thrombocytes that induce expression of smooth muscle and collagen genes. Both these populations cannot be identified in runx1 mutant wounds that contain less collagen and fibrin. The reduction in fibrin in the mutant is further explained by reduced myofibroblast formation and upregulation of components of the fibrin degradation pathway, including plasminogen receptor annexin 2A as well as downregulation of plasminogen activator inhibitor serpine1 in myocardium and endocardium, resulting in increased levels of plasminogen. Our findings suggest that Runx1 controls the regenerative response of multiple cardiac cell types and that targeting Runx1 is a novel therapeutic strategy for inducing endogenous heart repair.
Project description:Runx1 is strongly induced in the heart after acute injury and in chronic disease settings. Its expression negatively correlates with outcomes, and past work has shown a protective effect when Runx1 is inhibited through a variety of experimental means. We sought to establish the cell type(s) responsible for Runx1-dependent adverse remodeling following infarction. Using immunostaining for RUNX1 along with existing single cell RNA sequencing data sets, we established which cell types express Runx1 and prioritized two from this list – cardiomyocytes and fibroblasts. Cre drivers for the respective cell populations were paired with a Runx1 floxed allele to generate inducible, cell-type specific knockout mice. Following myocardial infarction induced by permanent ligation, mice were assessed for functional recovery by echocardiography and histological measurements, including scar size, cardiomyocyte dimension, and cell proliferation. Detailed transcriptomic analysis was used to assess mechanism of action. In contrast to existing literature, we did not observe a measurable impact of cardiomyocyte-specific loss of Runx1 on heart function or histology following myocardial infarction when compared to Cre-positive controls. On the other hand, loss of Runx1 in the Postn-expressing activated fibroblast population resulted in a protective effect on heart function seen as early as 3 days post-infarction and maintained until the 56-day experimental endpoint. These functional benefits were accompanied by smaller scars, reduced cardiomyocyte hypertrophy, and a reduction of activated fibroblasts progressing to an SMA-positive myofibroblast. Overall, we demonstrate Runx1 expression in activated fibroblasts drives adverse remodeling phenotypes following myocardial infarction.
Project description:Hypertrophic scarring (HS) is characterized by excessive extracellular matrix deposition, matrix metalloprotein gene activation, and fibroblast invasive growth. However, the methylation level of hypertrophic scarring is poorly understood. Genome wide DNA methylation profiling of normal skin and hypertrophic scar. The Illumina Infinium Methylation EPIC BeadChip (850K) was used to obtain DNA methylation profiles across approximately 853,307 CpGs in liquid based scar samples. Samples included 6 normal skin, and 6 hypertrophic scar.
Project description:Excessive repair after burn or trauma will lead to the formation of pathological scar. TGF-β1 is a powerful growth factor after wound healing. It is considered to be a key regulator of HS and various fibrotic diseases. MicroRNAs (miRNAs) can widely participate in the pathophysiological processes of various diseases by participating in post transcriptional gene regulation. At present, there is no research report on miR-361 and hypertrophic scar. This study found that miR-361 in HS is down-regulated. MiR-361 can inhibit the proliferation of HS fibroblasts and promote their apoptosis by inhibiting TGF-β1. Moreover, miR-361 can inhibit the formation of rabbit ear scar by inhibiting the expression of TGF-β1.
Project description:To test the ability of the Automated Spatially Targeted Optical Micro Proteomics (AutoSTOMP) protocol to selectively biotinylate structures of interest within tissue sections we first examined a rat myocardial infarction model. In this model, trauma caused by ligation and infiltrating immune cells causes fibroblast activation and deposition of scar tissue that ultimately impairs cardiac function. Macrophages are thought to play a role in inflammatory regulation and damaged cell turnover in the tissue. We decide to grab the proteome of the macrophage rich regions.
Project description:Dipeptidyl peptidase 4 (Dpp4) plays a pivotal role in fibrotic and nonfunctional scar development following skin injury and is present in a subset of fibroblasts implicated in scar formation. Simultaneously, heterogeneous vascular endothelial cells (ECs) retain their capacity to drive tissue regeneration and repair within scarred areas. Effective strategies for inhibiting scar-associated fibroblasts and regulating EC subtypes in the scar microenvironment remain unclear. Here, we engineered CAR-Trem2-Ms capable of targeting DPP4+ fibroblasts and modulating EC phenotypes within the scar microenvironment to effectively prevent and treat scarring. Furthermore, compared to those in normal control samples, DPP4 expression levels were higher in both clinical scar databases and samples from scar patients. We transferred a CAR gene specifically targeting Dpp4+ fibroblasts into macrophages, which were then induced into CAR-Trem2-Ms with 1,25-dihydroxycholecalciferol (an active form of VD, VD3). Hydrogel micropore micro
Project description:Dipeptidyl peptidase 4 (Dpp4) plays a pivotal role in fibrotic and nonfunctional scar development following skin injury and is present in a subset of fibroblasts implicated in scar formation. Simultaneously, heterogeneous vascular endothelial cells (ECs) retain their capacity to drive tissue regeneration and repair within scarred areas. Effective strategies for inhibiting scar-associated fibroblasts and regulating EC subtypes in the scar microenvironment remain unclear. Here, we engineered CAR-Trem2-Ms capable of targeting DPP4+ fibroblasts and modulating EC phenotypes within the scar microenvironment to effectively prevent and treat scarring. Furthermore, compared to those in normal control samples, DPP4 expression levels were higher in both clinical scar databases and samples from scar patients. We transferred a CAR gene specifically targeting Dpp4+ fibroblasts into macrophages, which were then induced into CAR-Trem2-Ms with 1,25-dihydroxycholecalciferol (an active form of VD, VD3). Hydrogel micropore microneedles (mMNs) were employed to deliver CAR-Trem2-Ms to effectively alleviate scar formation. Single-cell transcriptome sequencing and analysis revealed that CAR-Trem2-Ms could modify EC phenotypes and regulate fibrosis by suppressing the profibrotic gene Lrg1. CAR-Trem2-Ms effectively inhibited fibrosis in fibroblasts induced by high EC LRG1 expression in vitro, further revealing the underlying mechanism by which CAR-Trem2-Ms exert their antifibrotic effects. Our findings offer a promising approach for treating post-traumatic scarring and provide novel insights into the pathological mechanisms underlying fibrosis.
Project description:The adult mammalian heart heals after myocardial infarction (MI) by deposition of scar tissue, leading to downstream arrhythmia, remodelling and heart failure1. In contrast, adult zebrafish and neonatal mouse hearts are capable of regenerating after injury. Macrophages are key mediators of tissue repair and appear to be required for both regeneration and healing by scar formation, but the mechanisms underlying these distinct roles are poorly understood2-4. Here we investigated how macrophages differentially influence the mode of repair by determining their responses in scar-free versus scar-induced healing, comparing ventricular resection with cryo-injured adult zebrafish hearts and neonatal versus adult mouse hearts after MI. Unbiased transcriptomics revealed molecular programmes implicating macrophages in the initiation and resolution of inflammation to dictate the kinetics of scarring during zebrafish regeneration and the activation of direct and indirect pathways to drive fibrosis in the adult mouse heart. Most notably we observed up-regulation of collagen isoforms in both zebrafish and mouse macrophages following injury. Adoptive transfer of macrophages, from resected zebrafish hearts into cryo-injured hosts and splenic monocyte-derived macrophages from adult mouse donors into neonatal hearts, enhanced scar formation and induced fibrosis, respectively, via cell autonomous production of collagen. In zebrafish, macrophage-specific targeting of collagen 4a binding protein and cognate collagen 4a1 followed by transfer led to significantly reduced scarring in cryo-injured hosts, as further evidence of a direct macrophage contribution to collagen deposition and scar formation. These findings contrast with the current model of scarring, whereby collagen is laid down exclusively by myofibroblasts, and implicate macrophages as critical regulators of heart repair.