Project description:Understanding the dynamic changes of cells during calvarial bone repair is crucial for identifying novel therapeutic targets to enhance bone regeneration. However, the cellular changes and intercellular communication during calvarial defect repair remain poorly understood. To address this, we performed single-cell RNA sequencing on tissues collected at different time points post-defect. Our analysis revealed a significant enhancement in intercellular communication following defect, particularly among stem cells, endothelial cells, pericytes, and macrophages. Pathways related to neurogenesis were significantly enriched after defect. Furthermore, we found that inhibiting sympathetic nerves promoted calvarial bone repair. Mechanistically, sympathetic nerve inhibition enhanced angiogenesis and osteogenesis by promoting interactions between pericytes and endothelial cells, generating a novel senescenced Arg1+ macrophages, which contributed to bone repair by secreting osteogenesis-related cytokines. Besides, inhibition of sympathetic nerves promotes the generation of Shisa3+ suture cell subpopulation and enhances osteogenic differentiation capacity. Importantly, senolytics abrogated the repair benefits brought about by sympathetic nerve inhibition, underscoring the critical role of senescent macrophages in the repair process.
Project description:Living organisms are intricate systems with dynamic internal processes. Their RNA, protein, and metabolite levels fluctuate in response to variations in health and environmental conditions. Among these, RNA expression is particularly accessible for comprehensive analysis, thanks to the evolution of high throughput sequencing technologies in recent years. This progress has enabled researchers to identify unique RNA patterns associated with various diseases, as well as to develop predictive and prognostic biomarkers for therapy response. Such cross-sectional studies allow for the identification of differentially expressed genes (DEGs) between groups, but they have limitations. Specifically, they often fail to capture the temporal changes in gene expression following individual perturbations and may lead to significant false discoveries due to inherent noise in RNA sequencing sample preparation and data collection. To address these challenges, our study hypothesized that frequent, longitudinal RNA sequencing (RNAseq) analysis of blood samples could offer a more profound understanding of the temporal dynamics of gene expression in response to drug interventions, while also enhancing the accuracy of identifying genes influenced by these drugs. In this research, we conducted RNAseq on 829 blood samples collected from 84 Sprague-Dawley lab rats. Excluding the control group, each rat was administered one of four different compounds known for liver toxicity: tetracycline, isoniazid, valproate, and carbon tetrachloride. We developed specialized bioinformatics tools to pinpoint genes that exhibit temporal variation in response to these treatments.
Project description:Knee osteoarthritis (KOA), as a degenerative multifactorial disease, affects the quality of life and mental health of patients, and also brings a huge socioeconomic burden. Treating synovitis have shown promise as anti-inflammatory therapeutics in mitigating OA symptoms and disease progression. Here, by analysing synovial single-cell sequencing (scRNA-seq) data from KOA, we found that synovial fibroblasts (FLS) in OA synovium showed a distinct pro-inflammatory phenotype. We collected synovial tissue from patients with clinical OA as well as from healthy donors, and histological examination was consistent with findings in scRNA-seq. Inspired by recent cross-tissue fibroblast lineage studies, we identified by sequencing that healthy FLS in synovial tissues share transcriptome-level similarities with dermal fibroblasts (DFb). Subsequently, we revealed the local as well as systemic distribution of intra-articular injected DFbs by constructing/extracting two types of rat fibroblasts (luciferase DFbs as well as GFP DFbs). The results demonstrate that DFbs can be locally retained in the synovium for up to three weeks following targeted engrafting on it. And intra-articular injection does not result in DFbs migration to vital organs or the occurrence of histological changes in these organs. A rat model of KOA was constructed by anterior cruciate ligament transection (ACLT) in order to study the therapeutic effect of DFbs on KOA. After injection, the rats showed improvement in painful gait. In addition, histological as well as imaging results showed reduced synovitis and improvement in articular cartilage. Finally we verified the protective effect of DFbs on cytokine-stimulated chondrocytes in a co-culture system.
Project description:In order to establish a rat embryonic stem cell transcriptome, mRNA from rESC cell line DAc8, the first male germline competent rat ESC line to be described and the first to be used to generate a knockout rat model was characterized using RNA sequencing (RNA-seq) analysis.
Project description:The regeneration of craniofacial bones of the mammalian skeleton necessitates the action of both intrinsic and extrinsic inductive factors from multiple cell types, which function in a hierarchical and temporal fashion to control the differentiation of osteogenic progenitors. Single-cell transcriptomics of developing mouse cranial suture recently identified a suture mesenchymal progenitor population with tendon- or ligament-associated gene expression profile previously uncharacterized. Here, we developed a Mohawk homeobox (MkxCG;R26RtdT) reporter mouse, finding that this teno-ligamentous gene identifies a cranial suture resident cell population within the adult mouse that gives rise to calvarial osteoblasts and osteocytes overtime during homeostatic conditions. Single cell RNA-Sequencing (scRNA-Seq) demonstrated that Mkx+ suture cells demonstrate a stem-like phenotype with expression of teno-ligamentous genes. Bone injury with Mkx+ cell ablation showed delayed bone healing. Remarkably, Mkx gene played a critical role as an osteo-inhibitory factor in cranial suture cells, as knockdown or knockout resulted in increased osteogenic differentiation. Furthermore, in vivo local deletion of Mkx in Mkx floxed mice resulted in robustly increased calvarial defect repair. Finally, we observed that mechanical stretch dynamically regulates Mkx expression in turn regulating calvarial cell osteogenesis. Overall, we identify Mkx+ cells within the suture mesenchyme as a progenitor cell population for adult craniofacial bones required for bone repair and Mkx itself as mechanical stretch responsive gene which functions to prevent osteogenic differentiation within the stem cell niche.
Project description:The regeneration of craniofacial bones of the mammalian skeleton necessitates the action of both intrinsic and extrinsic inductive factors from multiple cell types, which function in a hierarchical and temporal fashion to control the differentiation of osteogenic progenitors. Single-cell transcriptomics of developing mouse cranial suture recently identified a suture mesenchymal progenitor population with tendon- or ligament-associated gene expression profile previously uncharacterized. Here, we developed a Mohawk homeobox (MkxCG;R26RtdT) reporter mouse, finding that this teno-ligamentous gene identifies a cranial suture resident cell population within the adult mouse that gives rise to calvarial osteoblasts and osteocytes overtime during homeostatic conditions. Single cell RNA-Sequencing (scRNA-Seq) demonstrated that Mkx+ suture cells demonstrate a stem-like phenotype with expression of teno-ligamentous genes. Bone injury with Mkx+ cell ablation showed delayed bone healing. Remarkably, Mkx gene played a critical role as an osteo-inhibitory factor in cranial suture cells, as knockdown or knockout resulted in increased osteogenic differentiation. Furthermore, in vivo local deletion of Mkx in Mkx floxed mice resulted in robustly increased calvarial defect repair. Finally, we observed that mechanical stretch dynamically regulates Mkx expression in turn regulating calvarial cell osteogenesis. Overall, we identify Mkx+ cells within the suture mesenchyme as a progenitor cell population for adult craniofacial bones required for bone repair and Mkx itself as mechanical stretch responsive gene which functions to prevent osteogenic differentiation within the stem cell niche.