| 1. |
- Böiers, Charlotta, et al.
(författare)
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Lymphomyeloid Contribution of an Immune-Restricted Progenitor Emerging Prior to Definitive Hematopoietic Stem Cells.
- 2013
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Ingår i: Cell Stem Cell. - : Elsevier BV. - 1934-5909 .- 1875-9777. ; 13:5, s. 535-548
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Tidskriftsartikel (refereegranskat)abstract
- In jawed vertebrates, development of an adaptive immune-system is essential for protection of the born organism against otherwise life-threatening pathogens. Myeloid cells of the innate immune system are formed early in development, whereas lymphopoiesis has been suggested to initiate much later, following emergence of definitive hematopoietic stem cells (HSCs). Herein, we demonstrate that the embryonic lymphoid commitment process initiates earlier than previously appreciated, prior to emergence of definitive HSCs, through establishment of a previously unrecognized entirely immune-restricted and lymphoid-primed progenitor. Notably, this immune-restricted progenitor appears to first emerge in the yolk sac and contributes physiologically to the establishment of lymphoid and some myeloid components of the immune-system, establishing the lymphomyeloid lineage restriction process as an early and physiologically important lineage-commitment step in mammalian hematopoiesis.
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| 2. |
- Carmeliet, Peter, et al.
(författare)
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Synergism between vascular endothelial growth factor and placental growth factor contributes to angiogenesis and plasma extravasation in pathological conditions
- 2001
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Ingår i: Nature Medicine. - : Springer Science and Business Media LLC. - 1546-170X .- 1078-8956. ; 7:5, s. 575-583
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Tidskriftsartikel (refereegranskat)abstract
- Vascular endothelial growth factor (VEGF) stimulates angiogenesis by activating VEGF receptor-2 (VEGFR-2). The role of its homolog, placental growth factor (PlGF), remains unknown. Both VEGF and PlGF bind to VEGF receptor-1 (VEGFR-1), but it is unknown whether VEGFR-1, which exists as a soluble or a membrane-bound type, is an inert decoy or a signaling receptor for PlGF during angiogenesis. Here, we report that embryonic angiogenesis in mice was not affected by deficiency of PlGF (Pgf-/-). VEGF-B, another ligand of VEGFR-1, did not rescue development in Pgf-/- mice. However, loss of PlGF impaired angiogenesis, plasma extravasation and collateral growth during ischemia, inflammation, wound healing and cancer. Transplantation of wild-type bone marrow rescued the impaired angiogenesis and collateral growth in Pgf-/- mice, indicating that PlGF might have contributed to vessel growth in the adult by mobilizing bone-marrow-derived cells. The synergism between PlGF and VEGF was specific, as PlGF deficiency impaired the response to VEGF, but not to bFGF or histamine. VEGFR-1 was activated by PlGF, given that anti-VEGFR-1 antibodies and a Src-kinase inhibitor blocked the endothelial response to PlGF or VEGF/PlGF. By upregulating PlGF and the signaling subtype of VEGFR-1, endothelial cells amplify their responsiveness to VEGF during the 'angiogenic switch' in many pathological disorders.
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| 3. |
- Danielsson, Frida, et al.
(författare)
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Majority of differentially expressed genes are down-regulated during malignant transformation in a four-stage model
- 2013
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 110:17, s. 6853-6858
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Tidskriftsartikel (refereegranskat)abstract
- The transformation of normal cells to malignant, metastatic tumor cells is a multistep process caused by the sequential acquirement of genetic changes. To identify these changes, we compared the transcriptomes and levels and distribution of proteins in a four-stage cell model of isogenically matched normal, immortalized, transformed, and metastatic human cells, using deep transcriptome sequencing and immunofluorescence microscopy. The data show that similar to 6% (n = 1,357) of the human protein-coding genes are differentially expressed across the stages in the model. Interestingly, the majority of these genes are down-regulated, linking malignant transformation to dedifferentiation. The up-regulated genes are mainly components that control cellular proliferation, whereas the down-regulated genes consist of proteins exposed on or secreted from the cell surface. As many of the identified gene products control basic cellular functions that are defective in cancers, the data provide candidates for follow-up studies to investigate their functional roles in tumor formation. When we further compared the expression levels of four of the identified proteins in clinical cancer cohorts, similar differences were observed between benign and cancer cells, as in the cell model. This shows that this comprehensive demonstration of the molecular changes underlying malignant transformation is a relevant model to study the process of tumor formation.
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| 4. |
- Li, Xuri, et al.
(författare)
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PDGF-C is a new protease-activated ligand for the PDGF alpha-receptor.
- 2000
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Ingår i: Nat Cell Biol. - : Springer Science and Business Media LLC. - 1465-7392 .- 1476-4679. ; 2:5, s. 302-9
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Tidskriftsartikel (refereegranskat)abstract
- Platelet-derived growth factors (PDGFs) are important in many types of mesenchymal cell. Here we identify a new PDGF, PDGF-C, which binds to and activates the PDGF alpha-receptor. PDGF-C is activated by proteolysis and induces proliferation of fibroblasts when overexpressed in transgenic mice. In situ hybridization analysis in the murine embryonic kidney shows preferential expression of PDGF-C messenger RNA in the metanephric mesenchyme during epithelial conversion. Analysis of kidneys lacking the PDGF alpha-receptor shows selective loss of mesenchymal cells adjacent to sites of expression of PDGF-C mRNA; this is not found in kidneys from animals lacking PDGF-A or both PDGF-A and PDGF-B, indicating that PDGF-C may have a unique function.
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| 5. |
- Li, Xuri, et al.
(författare)
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Revascularization of ischemic tissues by PDGF-CC via effects on endothelial cells and their progenitors
- 2005
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Ingår i: Journal of Clinical Investigation. - 0021-9738 .- 1558-8238. ; 115:1, s. 118-127
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Tidskriftsartikel (refereegranskat)abstract
- The angiogenic mechanism and therapeutic potential of PDGF-CC, a recently discovered member of the VEGF/PDGF superfamily, remain incompletely characterized. Here we report that PDGF-CC mobilized endothelial progenitor cells in ischemic conditions; induced differentiation of bone marrow cells into ECs; and stimulated migration of ECs. Furthermore, PDGF-CC induced the differentiation of bone marrow cells into smooth muscle cells and stimulated their growth during vessel sprouting. Moreover, delivery of PDGF-CC enhanced postischemic revascularization of the heart and limb. Modulating the activity of PDGF-CC may provide novel opportunities for treating ischemic diseases.
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| 6. |
- Pontén, Annica
(författare)
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Biological activities of novel platelet-derived growth factors, PDGF-C and PDGF-D
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Platelet-derived growth factors (PDGFs) belong to the PDGF/VEGF (vascular endothelial growth factor) family of growth factors. Members of this family share a common structural feature, a conserved PDGF/VEGF homology domain, containing eight invariant cysteine residues. PDGFs form disulphidelinked dimers and exert their biological functions by binding to, and activating two receptor tyrosine kinases, PDGFR-alpha and PDGFR-beta. For almost two decades, PDGF-A and PDGF-B were the only PDGF isoforms known to exist, but recently PDGF-C and PDGF-D were also identified. PDGF-C and PDGF-D are expressed as latent growth factors with a two-domain structure consisting of an N-terminal CUB domain, and a C-terminal PDGF/VEGF homology domain. Both factors require proteolytical removal of the CUB domain, in order to become active. PDGF-AA, PDGF-BB, PDGF-AB and PDGF-CC isoforms are able to activate PDGFR-alpha homodimers, whereas PDGF-BB and PDGF-DD activate PDGFR-beta homodimers. PDGF-AB, PDGF-BB, PDGF-CC and PDGF-DD can also activate PDGFR-alphabeta heterodimers in cells co-expressing both receptor subtypes. PDGFs are known mitogens for mesenchymal cells, and are essential in embryonic development. It is also well established that PDGFs are involved in several pathological settings, including tumor development, wound healing, fibrotic reactions, and atherosclerosis. An attractive clinical application for PDGFs is therapeutic angiogenesis, based on their ability to stimulate angiogenesis and to recruit mural cells. VEGF treatment produces extensive amounts of new blood vessels, but in order to generate functional, persistent blood vessels, recruitment of SMCs and pericytes is important. In this work, the biological activities of PDGF-C and PDGF-D were explored, including the expression pattern of PDGF-D in developing and adult tissue, overexpression of PDGF-C or PDGF-D in transgenic mice, and gene delivery of PDGF-C or PDGF-D into mouse ear using recombinant adenovirus. During mouse development PDGF-D was detected in several tissues, including myocardium, skeletal muscle, epithelium, liver, kidney, cartilage and some blood vessels. The expression pattern is different compared to PDGF-B, which is mainly expressed in growing blood vessels, suggesting distinct functions of PDGF-B and PDGF-D in PDGFR-beta signaling. In adult mice, PDGF-D was also detected in several hormoneproducing cells. Heart-specific overexpression of full-length PDGF-C, or the active form of PDGF-D (the so-called core domain), induced cardiac fibrosis, hypertrophy and cardiac failure, as well as several vascular changes, including dilation of microvessels and increased density of SMC coated vessels. In addition, PDGF-D stimulated proliferation of vSMCs, leading to thickened arterial walls. The PDGF-C transgenic mice developed sex-dependent phenotypes. In male mice, a hypertrophic response was induced, whereas females developed dilated cardiomyopathy. Adenovirally encoded PDGF-C induced capillary sprouting and PDGF-D stimulated arterialization of vessels. We suggest that PDGF-C and PDGF-D are potent modulators of vascular growth, as well as powerful mitogens for connective tissue cells.
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| 7. |
- Pontén, Annica, et al.
(författare)
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FACS-Based Isolation, Propagation and Characterization of Mouse Embryonic Cardiomyocytes Based on VCAM-1 Surface Marker Expression.
- 2013
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:12
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Tidskriftsartikel (refereegranskat)abstract
- Purification of cardiomyocytes from the embryonic mouse heart, embryonic stem (ES) or induced pluripotent stem cells (iPS) is a challenging task and will require specific isolation procedures. Lately the significance of surface markers for the isolation of cardiac cell populations with fluorescence activated cell sorting (FACS) has been acknowledged, and the hunt for cardiac specific markers has intensified. As cardiomyocytes have traditionally been characterized by their expression of specific transcription factors and structural proteins, and not by specific surface markers, this constitutes a significant bottleneck. Lately, Flk-1, c-kit and the cellular prion protein have been reported to specify cardiac progenitors, however, no surface markers have so far been reported to specify a committed cardiomyocyte. Herein show for the first time, that embryonic cardiomyocytes can be isolated with 98% purity, based on their expression of vascular cell adhesion molecule-1 (VCAM-1). The FACS-isolated cells express phenotypic markers for embryonic committed cardiomyocytes but not cardiac progenitors. An important aspect of FACS is to provide viable cells with retention of functionality. We show that VCAM-1 positive cardiomyocytes can be isolated with 95% viability suitable for in vitro culture, functional assays or expression analysis. In patch-clamp experiments we provide evidence of functionally intact cardiomyocytes of both atrial and ventricular subtypes. This work establishes that cardiomyocytes can be isolated with a high degree of purity and viability through FACS, based on specific surface marker expression as has been done in the hematopoietic field for decades. Our FACS protocol represents a significant advance in which purified populations of cardiomyocytes may be isolated and utilized for downstream applications, such as purification of ES-cell derived cardiomyocytes.
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| 8. |
- Pontén, Annica, et al.
(författare)
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Transgenic overexpression of platelet-derived growth factor-C in the mouse heart induces cardiac fibrosis, hypertrophy, and dilated cardiomyopathy
- 2003
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Ingår i: American Journal of Pathology. - 0002-9440 .- 1525-2191. ; 163:2, s. 673-682
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Tidskriftsartikel (refereegranskat)abstract
- The platelet-derived growth factors are implicated in development of fibrotic reactions and disease in several organs. We have overexpressed platelet-derived growth factor-C in the heart using the alpha-myosin heavy chain promoter and created a transgenic mouse that exhibits cardiac fibrosis followed by hypertrophy with sex-dependent phenotypes. The transgenic mice developed several pathological changes including cardiac fibroblast proliferation and deposition of collagen, hypertrophy, vascular defects, and the presence of Anitschkow cells in the adult myocardium. Male mice developed a hypertrophic phenotype, whereas female mice were more severely affected and developed dilated cardiomyopathy, leading to heart failure and sudden death. The vascular defects initially included dilation of microvessels and vascular leakage. Subsequently, a marked loss of microvessels, formation of large vascular sac-like structures, and an increased density of smooth muscle-coated vessels were observed in the myocardium. In part, the observed vascular changes may be because of an up-regulation of vascular endothelial growth factor in cardiac fibroblasts of the transgenic hearts. This unique animal model reveals that a potent mitogen for cardiac fibroblasts result in an expansion of the interstitium that induce a secondary sex-dependent hypertrophic response in the cardiomyocytes.
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| 9. |
- Walsh, Stuart, et al.
(författare)
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Cardiomyocyte cell cycle control and growth estimation in vivo- an analysis based on cardiomyocyte nuclei.
- 2010
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Ingår i: Cardiovascular Research. - : Oxford University Press (OUP). - 1755-3245 .- 0008-6363. ; 86:3, s. 365-373
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: Adult mammalian cardiomyocytes are traditionally viewed as being permanently withdrawn from the cell cycle. While some groups have reported none, others have reported extensive mitosis in adult myocardium under steady state conditions. Recently, a highly specific assay of (14)C dating in humans has suggested a continuous generation of cardiomyocytes in the adult, albeit at a very low rate. Mice represent the most commonly used animal model for these studies, but their short life-span makes them unsuitable for (14)C studies. Herein we investigate the cellular growth pattern for murine cardiomyocyte growth under steady-state conditions, addressed with new analytical and technical strategies, and we furthermore relate this to gene expression patterns. Methods and Results The observed levels of DNA synthesis in early life were associated with cardiomyocyte proliferation. Mitosis was prolonged into early life, longer than the most conservative previous estimates. DNA synthesis in neonatal life was attributable to bi-nucleation, therefore suggesting that cardiomyocytes withdraw from the cell cycle shortly after birth. No cell cycle activity was observed in adult cardiomyocytes and significant polyploidy was observed in cardiomyocyte nuclei. CONCLUSIONS: Gene analyses identified 32 genes whose expression was predicted to be particular to day 3-4 neonatal myocytes, compared to embryonic or adult cells. These cell cycle-associated genes are crucial to the understanding of the mechanisms of bi-nucleation and physiological cellular growth in the neonatal period.
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| 10. |
- Walsh, Stuart, et al.
(författare)
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Myogenic reprogramming of bone marrow derived cells in a W⁴¹Dmd(mdx) deficient mouse model
- 2011
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Ingår i: PLOS ONE. - San Francisco : Public Library of Science. - 1932-6203. ; 6:11, s. e27500-
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Tidskriftsartikel (refereegranskat)abstract
- Lack of expression of dystrophin leads to degeneration of muscle fibers and infiltration of connective and adipose tissue. Cell transplantation therapy has been proposed as a treatment for intractable muscle degenerative disorders. Several reports have demonstrated the ability of bone-marrow derived cells (BMDC) to contribute to non-haematopoietic tissues including epithelium, heart, liver, skeletal muscle and brain following transplantation by means of fusion and reprogramming. A key issue is the extent to which fusion and reprogramming can occur in vivo, particularly under conditions of myogenic deterioration.To investigate the therapeutic potential of bone marrow transplantation in monogenetic myopathy, green fluorescent protein-positive (GFP+) bone marrow cells were transplanted into non-irradiated c-kit receptor-deficient (W⁴¹) mdx mice. This model allows BMDC reconstitution in the absence of irradiation induced myeloablation. We provide the first report of BMDC fusion in a W⁴¹Dmd(mdx) deficient mouse model.In the absence of irradiation induced injury, few GFP+ cardiomyocytes and muscle fibres were detected 24 weeks post BMT. It was expected that the frequency of fusion in the hearts of W⁴¹Dmd(mdx) mice would be similar to frequencies observed in infarcted mice. Although, it is clear from this study that individual cardiomyocytes with monogenetic deficiencies can be rescued by fusion, it is as clear that in the absence of irradiation, the formation of stable and reprogrammed fusion hybrids occurs, with the current techniques, at very low levels in non-irradiated recipients.
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