Project description:Regulation of transcription occurs in a cell type specific manner orchestrated by epigenetic mechanisms including DNA methylation. Methylation changes may also play a key role in lineage specification during stem cell differentiation. To further our understanding of epigenetic regulation in chondrocytes we characterised DNA methylation changes during chondrogenesis of mesenchymal stem cells (MSCs) by Infinium 450K methylation array. Significant DNA hypomethylation was identified during chondrogenesic differentiation including changes at many key cartilage gene loci. Integration with chondrogenesis gene expression data revealed an enrichment of significant CpGs in upregulated genes, while characterisation of significant CpG loci indicated their predominant localisation to enhancer regions. Comparison with methylation profiles of other tissues, including healthy and diseased adult cartilage, identified chondrocyte-specific regions of hypomethylation and the overlap with differentially methylated CpGs in osteoarthritis. Taken together we have associated DNA methylation levels with the chondrocyte phenotype. The consequences of which has potential to improve cartilage generation for tissue engineering purposes and also to provide context for observed methylation changes in cartilage diseases such as osteoarthritis
Project description:Epigenetic mechanisms are known to regulate gene expression during chondrogenesis. In this study, we have characterised the epigenome during in vitro differentiation of human mesenchymal stem cells (hMSCs) into chondrocytes. Chromatin immunoprecipitation followed by next-generation sequencing (ChIP-seq) was used to assess a range of N-terminal post-transcriptional modifications (marks) to histone H3 lysines (H3K4me3, H3K4me1, H3K27ac, H3K27me3 and H3K36me3) in both hMSCs and differentiated chondrocytes. Chromatin states were characterised using histone ChIP-seq and cis-regulatory elements were identified in chondrocytes.
Project description:Cartilage tissue engineering seeks to replace degenerated or damaged cartilage following disease or injury. Mesenchymal stem/stromal cells (MSCs) provide an attractive cell source for cartilage repair; however, the underlying molecular pathways that drive chondrogenesis of these pools of adult stem cells remains poorly understood. Here, we generated a rich data set of high throughput RNA sequencing of human MSCs throughout chondrogenesis at six different time points. Our data is consisted of 18 libraries with three individual donors as biological replicates, each library possessing a sequencing depth of 100 million reads. We also performed flow cytometric, histological, and biochemical analyses in parallel to validate the quality of our in vitro engineered cartilage. Differential gene expression and gene ontology analyses identified dynamic changes in multiple biological pathways, namely downregulation in cell cycle and proliferation, and upregulation in extracellular matrix synthesis. Weighted gene correlation network analysis also identified an important chondrogenic gene subset, whose functional characterization promises to further harness the potential of MSCs for cartilage tissue engineering. Furthermore, we created a graphic user interface encyclopedia built with the goal of producing an open resource of transcriptomic regulation for additional data-mining and pathway analysis of the process of MSC chondrogenesis. The tool can be accessed at: http://msc-browser.guilaklab.com
Project description:Long non-coding RNAs profiling of human mesenchymal stem cells comparing undifferentiated HMSCs with differentiated HMSCs during chondrogenesis. The chondrogenic differentiation of HMSCs was induced by chondrogenic medium. The chondrogenic marker genes (Col2a1, Sox9 and ACAN) has been detected upregulating during this process by Q-PCR. The aim of this study is to determine key lncRNAs regulating the chondrogenic differentiation process.
Project description:Limb development is a well-established model for understanding cell fate decisions, and the formation of skeletal elements is coordinated through a sequence of events that control chondrogenesis spatiotemporally. It has been established that epigenetic control participates in cartilage maturation. Our research has shown for the first time that the inhibition of DNA methylation in interdigital tissue with 5-azacytidine results in the formation of an ectopic digit. This discovery suggested that DNA methylation dynamics could regulate the fate of cells between chondrogenesis and cell death during autopod development. We sequenced WGBS libraries from in-vivo interdigital tissue treated with 5-azacytidine or DMSO to identify genome-wide methylation changes during the early stages of 5-azacytidine-induced chondrogenesis.
Project description:Assessing the quality of tissue engineered (TE) cartilage has historically been performed by endpoint measurements including marker gene expression. Until the adoption of promoter-driven reporter constructs capable of quantitative and real time non-destructive expression analysis, temporal gene expression assessments along a timeline could not be performed on TE constructs. We further exploit this technique to utilize microRNA (miRNA or miR) through the use of firefly luciferase reporter (Luc) containing a 3' UTR perfect complementary target sequence to the mature miR-145-5p. We report the development and testing of a firefly luciferase (Luc) reporter responsive to miR-145-5p for longitudinal tracking of miR-145-5p expression throughout MSC chondrogenic differentiation. Plasmid reporter vectors containing a miR-145-5p responsive reporter (Luc reporter with a perfect complementary target sequence to the mature miR-145-5p sequence in the 3'UTR), a Luc reporter driven by a truncated Sox9 (one of the targets of miR-145-5p) promoter, or the Luc backbone (control) vector without a specific miRNA target were transfected into MSCs by electroporation. Transfected MSCs were mixed with untransfected MSC to generate chondrogenic pellets. Pellets were imaged by bioluminescent imaging (BLI) and harvested along a preset time line. The imaging signals from miR-145-5p responsive reporter and Sox9 promoter-driven reporter showed correlated time-courses (measured by BLI and normalized to Luc-control reporter; Spearman r=0.93, p=0.0002) during MSC chondrogenic differentiation. Expression analysis by qRT-PCR suggests an inverse relationship between miR-145-5p and Sox9 gene expression during MSC chondrogenic differentiation. Non-destructive cell-pellet imaging is capable of supplementing histological analyses to characterize TE cartilage. The miR-145-5p responsive reporter is relatively simple to construct and generates a consistent imaging signal responsive to miR-145-5p during MSC chondrogenesis in parallel to certain molecular and cellular events.