Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.1 (alkaline phosphatase)
 47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fibroblast-like cells emerging from cultured human pancreatic endocrine and exocrine tissue have been reported. Although a thorough phenotypic characterization of these cells has not yet been carried out, these cells have been hypothesized to be contaminating fibroblasts, mesenchyme and/or possibly beta-cell progenitors. In this study, we expanded fibroblast-like cells from adult human exocrine pancreas following islet isolation and characterized these cells as mesenchymal stem cells (MSCs) based on their cell surface antigen expression and ability to differentiate into mesoderm. Analysis by flow cytometry demonstrated that pancreatic MSCs express cell surface antigens used to define MSCs isolated from bone marrow such as CD13, CD29, CD44, CD49b, CD54, CD90 and CD105. In addition, utilizing protocols used to differentiate MSCs isolated from other somatic tissues, we successfully differentiated pancreatic MSCs into: (1) osteocytes that stained positive for alkaline phosphatase, collagen, mineralization (calcification) and expressed osteocalcin, (2) adipocytes that contained lipid inclusions and expressed fatty acid binding protein 4 and (3) chondrocytes that expressed aggrecan. We also demonstrated that pancreatic MSCs are multipotent and capable of deriving cells of endodermal origin. Pancreatic MSCs were differentiated into hepatocytes that stained positive for human serum albumin and expressed endoderm and liver-specific genes such as GATA 4 and tyrosine aminotransferase. In addition, preliminary protocols used to differentiate these cells into insulin-producing cells resulted in the expression of genes necessary for islet and beta-cell development such as Pax4 and neurogenin 3. Therefore, multipotent MSCs residing within the adult exocrine pancreas could represent a progenitor cell, which when further manipulated could result in the production of functional islet beta-cells.
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PMID:Expansion of mesenchymal stem cells from human pancreatic ductal epithelium. 1640 34

Chondrogenesis is a critical step in palatogenesis. All-trans retinoic acid (atRA), a vitamin A derivative, is a known teratogenic effector of cleft palate. Here, we evaluated the effects of atRA on the osteo-/chondrogenic differentiation of mouse embryonic palate mesenchymal (MEPM) cells. MEPM cells, in a high-density micromass environment, undergo active chondrogenesis in a manner analogous to that of limb-derived mesenchymal cells, and served as a valid model system to investigate the mechanisms regulating chondrogenesis during palatogenesis. atRA-treated MEPM micromass expressed relatively higher levels of osteoblastic gene markers (alkaline phosphatase and collagen type I) and lower levels of chondrocytic gene markers (collagen type II and aggrecan). As transforming growth factor-beta3 (TGF-beta3) is an essential growth factor for chondrogenesis of embryonic mesenchymal cells both in in vivo and in vitro conditions, we thereby explored the effects of atRA on TGF-beta3 signaling pathway. atRA led to an increase in mRNA expression of TGF-beta3 and an instantaneous decrease in TGF-beta type II receptor (TbetaRII) as determined by real-time RT-PCR. Further study showed that atRA inhibited phosphorylation of Smad2 and Smad3 and increased Smad7 expression. Activation of the Smad pathways by transfection with Smad7deltaC mutant or constitutively active TbetaRII retroviral vector abolished atRA-induced inhibition of chondrogenesis as indicated by Alcian blue staining, indicating that Smad signaling is essential for this response. Taken together, these data for the first time demonstrated a role for RA-induced hypochondrogenesis through regulation of the TGF-beta3 pathway and suggested a role for TbetaRII /Smad in retinoid-induced cleft palate.
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PMID:All-trans retinoic acid inhibited chondrogenesis of mouse embryonic palate mesenchymal cells by down-regulation of TGF-beta/Smad signaling. 1641 76

This article addresses the stability of chondrogenic phenotype and the transdifferentiation potential of bone marrow-derived mesenchymal stem cells (MSCs) at distinct stages of differentiation. Differentiated MSCs were expected to maintain cartilage-like gene expression pattern in the absence of any chondrogenic growth factor or in the presence of osteogenic signals. MSCs encapsulated in alginate beads were treated with transforming growth factor (TGF)-beta 3 for 3, 6, or 14 days and then cultured in absence of TGF-beta for the remainder of the 2-week culture period. Additionally, cells were cultured in osteogenic medium after TGF-beta-mediated chondroinduction. Gene expression of col2a1, aggrecan, COMP, alkaline phosphatase (AP), and correlating protein synthesis was analyzed. After short-term stimulation with TGF-beta, MSCs maintained a chondrogenic phenotype. Chondrogenic gene expression and protein synthesis directly correlated with the extent of stimulation time and the concentration of TGF-beta. Pretreatment with TGF-beta could prevent AP mRNA expression of encapsulated MSCs. TGF- beta stimulation within the first 3 days of culture seems to be crucial for the expression of a chondrogenic phenotype. Fully differentiated and encapsulated MSCs are not able to transdifferentiate into osteoblasts. These findings give rise to a better understanding of the behavior of cartilage grafts affected by local factors of osteochondral transplantation sites in vivo.
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PMID:Mesenchymal stem cells maintain TGF-beta-mediated chondrogenic phenotype in alginate bead culture. 1684 38

Mesenchymal stem cells (MSCs) are pluripotent progenitor cells with the ability to generate cartilage, bone, muscle, tendon, ligament, and fat. However, recent evidence indicates that a major drawback of current cartilage- and intervertebral disc-tissue engineering is that human MSCs isolated from some arthritic patients (a clinically relevant source of stem cells) express type X collagen (a marker of chondrocyte hypertrophy associated with endochondral ossification) and osteogenic markers. Some studies have attempted to use growth factors to inhibit type X collagen expression, but none has addressed the possible effect of the chemical composition of the substratum on chondrocyte hypertrophy and osteogenesis. Here, we examine the growth and differentiation potential of human MSCs cultured on nitrogen (N)-rich plasma polymer layers (N-doped plasma-polymerized ethylene, containing up to 36% nitrogen; PPE:N). We show that PPE:N almost completely suppresses the expression not only of type X collagen, but also of osteogenic marker genes such as alkaline phosphatase, bone sialoprotein, and osteocalcin. In contrast, neither aggrecan nor type I collagen expression were significantly affected. These results indicate that PPE:N coatings may be suitable surfaces for inducing MSCs to a chondrocyte or disc-like phenotype for tissue engineering of cartilage or intervertebral discs, in which hypertrophy and osteogenesis are suppressed.
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PMID:Suppression of genes related to hypertrophy and osteogenesis in committed human mesenchymal stem cells cultured on novel nitrogen-rich plasma polymer coatings. 1699 97

Chondrocytes and adipocytes are two differentiated cell types which are both derived from mesenchymal cells. The purpose of this study was to investigate whether peroxisome proliferator-activated receptor-gamma (PPARgamma), a transcription factor involved in lineage determination during adipogenesis, is able to induce adipogenic differentiation in growth plate chondrocytes. Isolated epiphyseal chondrocytes were infected with a PPARgamma adenovirus or treated with the PPARgamma agonist ciglitazone. Both of these treatments resulted in lipid droplet accumulation and expression of the adipogenic markers aP2, lipoprotein lipase, and adipsin in chondrocytes. Proteoglycan matrix synthesis was decreased in the PPARgamma-infected cells, as was the expression of the chondrogenic genes Col2a1 and aggrecan. Growth plate cells transfected with a PPARgamma expression plasmid under the control of the collagen alpha1(II) promoter also demonstrated a similar adipogenic changes. Terminal differentiation of growth plate chondrocytes induced by thyroid hormone was also inhibited by overexpression of PPARgamma and ciglitazone treatment, with decreased expression of alkaline phosphatase and Runx2/Cbfa1 genes. These in vitro data suggest that PPARgamma is able to promote adipogenic differentiation in growth plate chondrocytes, while negatively regulating chondrogenic differentiation and terminal differentiation.
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PMID:Peroxisome Proliferator-Activated Receptor-gamma Promotes Adipogenic Changes in Growth Plate Chondrocytes In Vitro. 1725 68

Since IGF-I is an important chondrocyte growth factor, we sought to examine the intracellular mechanisms by which it exerts two of its pivotal effects, stimulation of proliferation and differentiation. We used the mesenchymal chondrogenic cell line RCJ3.1C5.18, which progresses spontaneously to differentiated growth plate chondrocytes. This differentiation process could be enhanced by exogenous IGF-I. Pharmacological inhibition of the phosphatidylinositol-3 (PI-3) kinase by LY294002, mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK)1/2 by U0126, the protein kinase (PK) A pathway by H-89 or KT5720, and the PKC pathway by bisindolylmaleimide suppressed IGF-I-stimulated cell proliferation. In contrast, IGF-I-enhanced early cell differentiation, as assessed by collagen type II and aggrecan gene expression, was not affected by MAPK/ERK1/2 pathway inhibition, but significantly diminished by inhibition of the PI-3 kinase, the PKC and the PKA pathway. Moreover, terminal differentiation of chondrocytes in response to IGF-I, as assessed by gene expression of alkaline phosphatase, Indian hedgehog, and collagen type X, were only interrupted by PI-3 kinase pathway inhibition. In conclusion, IGF-I exerts its differential effect on chondrocyte proliferation vs differentiation through the use of at least four partially interacting intracellular signaling pathways, whose activity is temporarily regulated. When chondrocytes progress from proliferating cells to early and terminal differentiating cells, they progressively inactivate IGF-I-related intracellular signaling pathways. This mechanism might be essential for the complex and cell stage-specific anabolic action of IGF-I in the growth plate.
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PMID:Signaling mechanisms leading to regulation of proliferation and differentiation of the mesenchymal chondrogenic cell line RCJ3.1C5.18 in response to IGF-I. 1744 38

There are increasing reports regarding differentiation of bone marrow stromal cells (BMSC) from human and various species of animals including pigs. The phenotype and function of BMSC along a mesenchymal lineage differentiation are well characterized by specific transcription factors and marker genes. However, it is not fully clear whether multilineage differentiation (osteogenesis, chondrogenesis, and adipogenesis) of BMSC is associated with a specific gene expression pattern. In the present study, we investigated the gene expression pattern of representative transcription factors and marker genes along those three mesenchymal lineages during a particular lineage differentiation of porcine BMSC by means of real-time PCR measurement. In an osteogenic medium, the mRNA levels of cbfa1, osterix, alkaline phosphatase, type 1 collagen, osteonectin, bone sialoprotein, and osteocalcin were induced stepwise. Meanwhile, sox9, specific to chondrogenic differentiation, was inhibited but not PPARgamma2 specific to adipogenic differentiation. In an adipogenic medium, adipogenic differentiation was confirmed by upregulation of PPARgamma2 and aP2 and downregulation of osteogenic genes and sox9. Chondrogenic differentiation was induced in cell pellet culture by expression of sox9, type 2 collagen, and aggrecan. Cbfa1 and PPARgamma2 were inhibited in chondrogenic medium. These results indicate that the differentiation potential of BMSC to a particular mesenchymal lineage relies upon specific gene expression pattern, namely upregulation of genes specific for this lineage and suppression of other lineage differentiation.
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PMID:Multilineage differentiation of porcine bone marrow stromal cells associated with specific gene expression pattern. 1767 6

Tissue engineering (TE) has emerged as a promising new therapy for the treatment of damaged tissues and organs. Adult stem cells are considered as an attractive candidate cell type for cell-based TE. Mesenchymal stem cells (MSC) have been isolated from a variety of tissues and tested for differentiation into different cell lineages. While clinical trials still await the use of human MSC, horse tendon injuries are already being treated with autologous bone marrow-derived MSC. Given that the bone marrow is not an optimal source for MSC due to the painful and risk-containing sampling procedure, isolation of stem cells from peripheral blood would bring an attractive alternative. Adherent fibroblast-like cells have been previously isolated from equine peripheral blood. However, their responses to the differentiation conditions, established for human bone marrow MSC, were insufficient to fully confirm their multilineage potential. In this study, differentiation conditions were optimized to better evaluate the multilineage capacities of equine peripheral blood-derived fibroblast-like cells (ePB-FLC) into adipogenic, osteogenic, and chondrogenic pathways. Adipogenic differentiation using rabbit serum resulted in a high number of large-size lipid droplets three days upon induction. Cells' expression of alkaline phosphatase and calcium deposition upon osteogenic induction confirmed their osteogenic differentiation capacities. Moreover, an increase of dexamethasone concentration resulted in faster osteogenic differentiation and matrix mineralization. Finally, induction of chondrogenesis in pellet cultures resulted in an increase in cartilage-specific gene expression, namely collagen II and aggrecan, followed by protein deposition after a longer induction period. This study therefore demonstrates that ePB-FLC have the potential to differentiate into adipogenic, osteogenic, and chondrogenic mesenchymal lineages. The presence of cells with confirmed multilineage capacities in peripheral blood has important clinical implications for cell-based TE therapies in horses.
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PMID:Multilineage differentiation potential of equine blood-derived fibroblast-like cells. 1769 29

Elevated concentrations of interleukin (IL)-6 and soluble IL-6 receptor (sIL-6Ralpha) in synovial fluid have been implicated in joint cartilage destruction. We examined the effect of IL-6 and sIL-6Ralpha on cell growth, alkaline phosphatase (ALPase) activity, and the expression of Sox-9, type II collagen, aggrecan core, link protein, BMP-7, and BMP receptors in human chondrocytes. Cell proliferation increased slightly in the presence of both IL-6 and sIL-6Ralpha, whereas ALPase activity decreased markedly. The expression of Sox-9 and aggrecan core did not change in the presence or absence of IL-6 and sIL-6Ralpha, whereas the expression of type II collagen, link protein, BMP-7, and BMP receptors increased in the presence of both IL-6 and sIL-6Ralpha. These results suggest that IL-6 and sIL-6Ralpha suppress the differentiation of chondrocytes and induce the repair of arthrodial cartilage through an increase in the expression of cartilage matrix proteins, BMP-7, and BMP receptors in the cells.
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PMID:Effects of IL-6 and soluble IL-6 receptor on the expression of cartilage matrix proteins in human chondrocytes. 1788 2

In order to ensure that MSCs designed for in vivo cartilage repair do not untowardly differentiate into osteoblasts and mineralize in situ, we tested whether siRNA-induced suppression of cbfa1/Runx2 affected the osteogenic and chondrogenic differentiation potential of the murine cell line C3H10T1/2. Anti-cbfa1/Runx2 siRNA decreased the levels of cbfa1/Runx2 mRNA and protein by 65-80%, and also markedly reduced the expression of osteoblast-related genes such as Dlx5, osterix, collagen type I, alkaline phosphatase (AP), osteocalcin, SPARC/osteonectin and osteopontin, leading to a temporal expression of AP enzyme activity and mineralization potential delayed by at least some 7-9 days. Furthermore, siRNA-transfected cells, grown under chondrogenic conditions did not display biologically significant changes in the expression of aggrecan, collagen type II or type X, or histology when grown in micropellets or monolayer cultures. Finally, when cells were propagated in osteogenic medium and injected into the tibial muscles of SCID mice, no overtly mineralized bone tissue emerged. These experiments indicate that a major transient reduction of cbfa1/Runx2 expression in MSCs is sufficient to delay osteoblastic differentiation, both in vitro and in vivo, while chondrogenesis seemed to be sustained.
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PMID:Transient down-regulation of cbfa1/Runx2 by RNA interference in murine C3H10T1/2 mesenchymal stromal cells delays in vitro and in vivo osteogenesis, but does not overtly affect chondrogenesis. 1831 48


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