The transient chondrocyte phenotype in osteophytic cartilage - a role of PEDF?
Ontology highlight
ABSTRACT: Pigment Epithelium-Derived Factor (PEDF) has recently been identified as a factor that is significantly upregulated in late-stage osteoarthritic cartilage in which chondrocytes are confronted with terminal differentiation and cell death. Since PEDF is known to induce cell death of endothelial cells, it may also be responsible for terminal differentiation and cell death in cartilage. Using cDNA microarray analysis, we found PEDF among the factors with the strongest differential expression and significant higher levels (118.5-fold) in osteophytic cartilage compared with articular cartilage. This study explored if PEDF interferes with the stable chondrocyte phenotype by promoting terminal differentiation or cell death.
Project description:Pigment Epithelium-Derived Factor (PEDF) has recently been identified as a factor that is significantly upregulated in late-stage osteoarthritic cartilage in which chondrocytes are confronted with terminal differentiation and cell death. Since PEDF is known to induce cell death of endothelial cells, it may also be responsible for terminal differentiation and cell death in cartilage.
Project description:Hydrostatic pressure is one of the main mechanical stimuli cartilage cells are submitted to during joint loading. If moderate hydrostatic pressure is known to be beneficial to cartilage differentiation, excessive pressure, on the other hand, induces changes in cartilage similar to those observed in osteoarthritic cartilage. Therefore, the purpose of the experiment is to identify new target genes of high hydrostatic pressure in chondrocyte precursor cells.
Project description:To investigate loss-of-function of the C/EBP family members, we used A-CEBP which exerts a dominant-negative effect against all CEBPs. DOX-inducible overexpression of A-CEBP into mouse chondrocyte cell line ATDC5 increased expressions of early differentiation markers, decreased those of late differentiation markers. In addition, A-CEBP altered many genes related with skeletal development, cartilage, cell cycle, inflammation and apoptosis. We established stable ATDC5 cells which express GFP or A-CEBP by DOX induction. We started differentiation of these cells by ITS supplement immediately after DOX induction, harvested mRNA after 3 weeks, and performed microarray analysis.
Project description:Cranial neural crest (NCC)-derived chondrocyte precursors undergo a dynamic differentiation and maturation process to establish a scaffold for subsequent bone formation, alterations in which contribute to congenital birth defects. Here, we demonstrate that transcription factor and histone methyltransferase proteins Prdm3 and Prdm16 control the differentiation switch of cranial NCCs to craniofacial cartilage. Loss of either results in hypoplastic and unorganized chondrocytes due to impaired cellular orientation and polarity. We show that PRDMs regulate cartilage differentiation by controlling the timing of Wnt/β-catenin activity in strikingly different ways: prdm3 represses while prdm16 activates global gene expression, though both by regulating Wnt enhanceosome activity and chromatin accessibility. Finally, we show that manipulating Wnt/β-catenin signaling pharmacologically or generating prdm3-/-;prdm16-/- double mutants rescues craniofacial cartilage defects. Our findings reveal upstream regulatory roles for Prdm3 and Prdm16 in cranial NCCs to control Wnt/β-catenin transcriptional activity during chondrocyte differentiation to ensure proper development of the craniofacial skeleton.
Project description:Osteoarthritis (OA) is the most common joint disease and is the leading cause of chronic disability among older people. Chondrocyte death was involved in OA pathogenesis. Ferroptosis is an iron-dependent cell death associated with peroxidation of lipids. Expression of GPX4 in the OA cartilage from OA patients were significantly lower than normal cartilage.In order to analyze the mechanism of GPX4, we conducted RNA-sequencing in mouse chondrocytes with or without GPX4 knockdown.Our results showed that Gpx4 downregulation could increase the sensitivity of chondrocytes to oxidative stress and aggravate ECM degradation in chondrocytes.
Project description:Joint injury and osteoarthritis affect millions of people worldwide, but attempts to generate articular cartilage using adult stem/progenitor cells have been unsuccessful. We hypothesized that recapitulation of the human developmental chondrogenic program using pluripotent stem cells (PSCs) may represent a superior approach for cartilage restoration. Using laser capture microdissection followed by microarray analysis, we first defined a surface phenotype (CD146low/negCD166low/negCD73+CD44lowBMPR1B+) distinguishing the earliest cartilage committed cells (pre-chondrocytes) at 5-6 weeks of development; pellet assays confirmed these cells as functional, chondrocyte-restricted progenitors. Flow cytometry, qPCR and immunohistochemistry at 17 weeks revealed that the superficial layer of peri-articular chondrocytes was enriched in cells with this surface phenotype. Isolation of cells with a similar immunophenotype from differentiating human PSCs revealed a population of CD166negBMPR1B+ putative pre-chondrocytes. Functional characterization confirmed these cells as cartilage-committed, chondrocyte progenitors. The identification of a specific molecular signature for primary cartilagecommitted progenitors may provide essential knowledge for the generation of purified, clinically relevant cartilage cells from PSCs. A total of 15 samples were analyzed. In the first comparison, there were 6 biological replicates for both the chondrogenic condensations and total limb cells. In the second comparison, three biological replicates of chondrocytes from the articular region were compared to the 6 replicates of the condensations.
Project description:Monolayer cultures of primary chondrocytes undergo morphological changes that have been broadly characterized as de-differentiation. Transcriptional profiling was used to evaluate changes in gene expression during this process. Articular cartilage was harvested from a single Standardbred horse; the chondrocytes were isolated and then maintained in monolayer culture for up to 14 days. Chondrocytes were collected on Day 1 and Day 14 of culture and snap frozen in liquid nitrogen. Total RNA was isolated, subjected to one round of linear RNA amplification, and then applied to an equine-specific cDNA microarray composed of 9322 elements. Three biological replicates were analyzed at each time point using a dye-swap experimental design. One hundred six transcripts were present at levels greater than or equal to five-fold higher in Day 1 chondrocytes relative to the cells collected at Day 14. Conversely, 68 transcripts were present at levels greater than or equal to five-fold higher in Day 14 chondrocytes. Northern blot hybridization validated the microarray data by confirming the down-regulation of steady state mRNA levels for type II procollagen and aggrecan core protein and the up-regulation of type I procollagen. Gene-by-gene and cluster analyses will be used to compare the process of “de-differentiation” in primary culture to the developmental stages of normal chondrocyte differentiation and to the fibrocartilage repair tissue that forms in osteoarthritic lesions. Keywords: articular cartilage, de-differentiation, horse, cDNA microarray This is a direct comparison between one and fourteen day cultured chondrocyte transcriptomes. Three sets of technical replicates were compared. For each comparison and its dye-swap, one Day 1 technical replicate was randomly compared to one Day 14 technical replicate.
Project description:To investigate loss-of-function of the C/EBP family members, we used A-CEBP which exerts a dominant-negative effect against all CEBPs. DOX-inducible overexpression of A-CEBP into mouse chondrocyte cell line ATDC5 increased expressions of early differentiation markers, decreased those of late differentiation markers. In addition, A-CEBP altered many genes related with skeletal development, cartilage, cell cycle, inflammation and apoptosis.
Project description:Autologous chondrocyte transplantation (ACT) is a routine technique to regenerate focal cartilage lesions. However, patients with osteoarthritis (OA) are lacking an appropriate long-lasting treatment alternative, partly since it is not known if chondrocytes from OA patients have the same chondrogenic differentiation potential as chondrocytes from donors not affected by OA. Articular chondrocytes from patients with OA undergoing total knee replacement (Mankin Score >3, Ahlbäck Score >2) and from patients undergoing ACT, here referred to as normal donors (ND), were isolated applying protocols used for ACT. Their chondrogenic differentiation potential was evaluated both in high-density pellet and scaffold (Hyaff-11) cultures by histological proteoglycan assessment (Bern Score) and immunohistochemistry for collagen types I and II. Chondrocytes cultured in monolayer and scaffolds were subjected to gene expression profiling using genome-wide oligonucleotide microarrays. Expression data were verified by using quantitative RT-PCR. Chondrocytes from ND and OA donors demonstrated accumulation of comparable amounts of cartilage matrix components, including sulphated proteoglycans and collagen types I and II. The mRNA expression of cartilage markers (COL2A1, COMP, aggrecan, CRTL1, SOX9) and genes involved in matrix synthesis (biglycan, COL9A2, COL11A1, TIMP4, CILP2) was highly induced in 3D cultures of chondrocytes from both donor groups. Genes associated with hypertrophic or OA cartilage (COL10A1, RUNX2, periostin, ALP, PTHR1, MMP13, COL1A1, COL3A1) were not significantly regulated between the two groups of donors. The expression of 661 genes, including COMP, FN1, and SOX9, were differentially regulated between OA and ND chondrocytes cultured in monolayer. During scaffold culture, the differences diminished between the OA and ND chondrocytes, and only 184 genes were differentially regulated. Only few genes were differentially expressed between OA and ND chondrocytes in Hyaff-11 culture. The risk of differentiation into hypertrophic cartilage does not seem to be increased for OA chondrocytes. Our findings suggest that the chondrogenic capacity is not significantly affected by OA and OA chondrocytes fulfill the requirements for matrix-associated ACT. Keywords: time course, cell type comparison, tissue engineered cartilage; osteoarthritis; Hyaff-11 scaffold; human chondrocytes; gene expression profiling; regenerative medicine; differentiation potential
Project description:IL-1B is an important cytokine that is often found to be up-regulated during osteoarthritic and rheumatoid joint diseases. It is viewed as a catabolic factor, inducing enzymes that allow for the degradation of the cartilage extracellular matrix and also has essential roles as an autocrine and paracrine factor in fibronectin fragment-mediated degradation. It can also reduce the synthesis of the major cartilage components, type II collagen and aggrecan. On the other hand, IL-1B also has the ability to induce the growth and morphogenic factor BMP-2. During joint diseases, IL-1B is synthesized by both synovial cells and chondrocytes. Addition of IL-1 biological antagonists such as IL-1 receptor antagonists can suppress cartilage degradation in vitro. Thus, the production of IL-1B could act as the first step in mediating a cascade of other mediators in cartilage which could be relevant to the fate of the cartilage. In order to obtain a global picture of the effect of IL-1B production on human adult articular chondrocytes, we analyzed changes in gene expression induced by IL-1B by microarray analysis. We found that IL-1B has a diverse effect on gene expression profile in chondrocytes. One of the predominant responses that we observed in adult human articular chondrocytes on exposure to IL-1B is a dramatic increase in a large set of chemokines and other genes related to the inflammatory cascade. Keywords: Gene response to IL-1B (10 ng/ml) Cartilage was obtained from adult human tissue donors with above the knee amputations due to chondrosarcoma or traumatic injury or from autopsy. Chondrocytes were isolated following established protocols, maintained in high density, and treated with IL-1B (10 ng/ml). Chondrocytes treated with buffer only served as the untreated control. The experiment was carried out in duplicate. Total RNA was extracted from these chondrocytes, labeled with fluorophores (Cy3 or Cy5) and analyzed for expression changes using the Human Operon/Qiagen v3.0 oligonucleotide array. The analysis was repeated with the fluorophore dyes exchanged between the untreated and experimental RNAs.