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- Johansson, Ulrika, 1974-, et al.
(författare)
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Formation of composite endothelial cell-mesenchymal stem cell islets : a novel approach to promote islet revascularization
- 2008
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 57:9, s. 2393-2401
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Mesenchymal stem cells (MSCs) contribute to endothelial cell (EC) migration by producing proteases, thereby paving the way into the tissues for ECs. MSCs were added to our previously described composite EC islets as a potential means to improve their capacity for islet angiogenesis. RESEARCH DESIGN AND METHODS: Human islets were coated with primary human bone marrow-derived MSCs and dermal microvascular ECs. The capacity of ECs, with or without MSCs, to adhere to and grow into human islets was analyzed. The survival and functionality of these composite islets were evaluated in a dynamic perifusion assay, and their capacity for angiogenesis in vitro was assessed in a three-dimensional fibrin gel assay. RESULTS: ECs proliferated after culture in MSC-conditioned medium, and MSCs improved the EC coverage threefold compared with EC islets alone. Islet survival in vitro and the functionality of the composite islets after culture were equal to those of control islets. The EC-MSC islets showed a twofold increase in total sprout formation compared with EC islets, and vascular sprouts emanating from the EC-MSC-islet surface showed migration of ECs into the islets and also into the surrounding matrix, either alone or in concert with MSCs. CONCLUSIONS: EC proliferation, sprout formation, and ingrowth of ECs into the islets were enhanced by MSCs. The use of composite EC-MSC islets may have beneficial effects on revascularization and immune regulation. The technique presented allows for pretreatment of donor islets with recipient-derived ECs and MSCs as a means of improving islet engraftment.
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| 2. |
- Magnusson, Peetra U, et al.
(författare)
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FGFR-1 regulates angiogenesis through cytokines interleukin-4 and pleiotrophin
- 2007
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 110:13, s. 4214-4222
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Tidskriftsartikel (refereegranskat)abstract
- The role of fibroblast growth factors (FGFs) in blood vessel formation has remained unclear. We used differentiating stem-cell cultures (embryoid bodies) and teratomas to show that FGIF receptor-1 (FGFR-1) exerts a negative regulatory effect on endothelial cell function in these models. Embryoid bodies lacking expression of FGFR-1 as a result of gene targeting (Fgfr-1(-/-)) displayed increased vascularization and a distinct, elongated vessel morphology. Teratomas derived from FGFR-1-deficient stem cells were characterized by an increased growth rate and abundant, morphologically distinct vessels. Transmission electron microscopy of the Fgfr-1(-/-) teratomas showed a compact and voluminous but functional endothelium, which anastomosed with the host circulation. The increased vascularization and altered endothelial cell morphology was dependent on secreted factor(s), based on the transfer of the Fgfr-1(+/-) vascular phenotype by conditioned medium to Fgfr-1(+/-) embryoid bodies. Antibody and transcript arrays showed down-regulation of interleukin-4 (IL-4) and up-regulation of pleiotrophin in Fgfr-1(-/-) embryoid bodies, compared with the heterozygous cultures. We used neutralizing antibodies to show that IL-4 and pleiotrophin act as negative and positive angiogenic regulators, respectively. We conclude that FGFR-1 negatively regulates endothelial cell function by altering the balance of modulatory cytokines.
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| 3. |
- Magnusson, Peetra U., et al.
(författare)
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Platelet-derived growth factor receptor-beta constitutive activity promotes angiogenesis in vivo and in vitro
- 2007
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Ingår i: Arteriosclerosis, Thrombosis and Vascular Biology. - 1079-5642 .- 1524-4636. ; 27:10, s. 2142-2149
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE - Knockout studies have demonstrated crucial roles for the platelet-derived growth factor-B and its cognate receptor, platelet-derived growth factor receptor-β (PDGFR-β), in blood vessel maturation, that is, the coverage of newly formed vessels with mural cells/pericytes. This study describes the consequences of a constitutively activating mutation of the PDGFR-β (Pdgfrb) introduced into embryonic stem cells with respect to vasculogenesis/angiogenesis in vitro and in vivo. METHODS AND RESULTS - Embryonic stem cells were induced to either form teratomas in vivo or embryoid bodies, an in vitro model for mouse embryogenesis. Western blotting studies on embryoid bodies showed that expression of a single allele of the mutant Pdgfrb led to increased levels of PDGFR-β tyrosine phosphorylation and augmented downstream signal transduction. This was accompanied by enhanced vascular development, followed by exaggerated angiogenic sprouting with abundant pericyte coating as shown by immunohistochemistry/immunofluorescence. Pdgfrb embryoid bodies were characterized by increased expression of vascular endothelial growth factor (VEGF)-A and VEGF receptor-2; neutralizing antibodies against VEGF-A/VEGF receptor-2 blocked vasculogenesis and angiogenesis in mutant embryoid bodies. Moreover, Pdgfrb embryonic stem cell-derived teratomas in nude mice were more densely vascularized than wild-type teratomas. CONCLUSION - Increased PDGFR-β kinase activity is associated with elevated expression of VEGF-A and VEGF receptor-2, acting directly on endothelial cells and resulting in increased vessel formation.
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