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23 results on '"Klingenberg, Melanie"'

8. Chemically induced hypoxia by dimethyloxalylglycine (DMOG)-loaded nanoporous silica nanoparticles supports endothelial tube formation by sustained VEGF release from adipose tissue-derived stem cells

Author

Zippusch, Sarah, primary, Besecke, Karen F W, additional, Helms, Florian, additional, Klingenberg, Melanie, additional, Lyons, Anne, additional, Behrens, Peter, additional, Haverich, Axel, additional, Wilhelmi, Mathias, additional, Ehlert, Nina, additional, and Böer, Ulrike, additional

Published
2021
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9. sj-pdf-1-jba-10.1177_08853282211046800 – Supplemental Material for Pressure-compacted and spider silk–reinforced fibrin demonstrates sufficient biomechanical stability as cardiac patch in vitro

Author

Bobylev, Dmitry, Wilhelmi, Mathias, Lau, Skadi, Klingenberg, Melanie, Mlinaric, Markus, Petená, Elena, Helms, Florian, Hassel, Thomas, Haverich, Axel, Horke, Alexander, and Böer, Ulrike

Subjects
FOS: Materials engineering, 91299 Materials Engineering not elsewhere classified
Abstract

Supplemental Material, sj-pdf-1-jba-10.1177_08853282211046800 for Pressure-compacted and spider silk–reinforced fibrin demonstrates sufficient biomechanical stability as cardiac patch in vitro by Dmitry Bobylev, Mathias Wilhelmi, Skadi Lau, Melanie Klingenberg, Markus Mlinaric, Elena Petená, Florian Helms, Thomas Hassel, Axel Haverich, Alexander Horke and Ulrike Böer in Journal of Biomaterials Applications

Published
2021
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10. Chemically induced hypoxia by dimethyloxalylglycine (dmog)-loaded nanoporous silica nanoparticles supports endothelial tube formation by sustained vegf release from adipose tissue-derived stem cells

Author

Zippusch, Sarah, Besecke, Karen F. W., Helms, Florian, Klingenberg, Melanie, Lyons, Anne, Behrens, Peter, Haverich, Axel, Wilhelmi, Mathias, Ehlert, Nina, and Böer, Ulrike

Subjects
Dewey Decimal Classification::500 | Naturwissenschaften::570 | Biowissenschaften, Biologie, Pre-vascularization, Tissue engineering, Dimethyloxalylglycine, Adipose tissue-derived stem cells, Nanoporous silica nanoparticles
Abstract

Inadequate vascularization leading to insufficient oxygen and nutrient supply in deeper layers of bioartificial tissues remains a limitation in current tissue engineering approaches to which prevascularization offers a promising solution. Hypoxia triggering pre-vascularization by enhanced vascular endothelial growth factor (VEGF) expression can be induced chemically by dimethyloxalylglycine (DMOG). Nanoporous silica nanoparticles (NPSNPs, or mesoporous silica nanoparticles, MSNs) enable sustained delivery of molecules and potentially release DMOG allowing a durable capillarization of a construct. Here we evaluated the effects of soluble DMOG and DMOG-loaded NPSNPs on VEGF secretion of adipose tissue-derived stem cells (ASC) and on tube formation by human umbilical vein endothelial cells (HUVEC)-ASC co-cultures. Repeated doses of 100 mM and 500 mM soluble DMOG on ASC resulted in 3- to 7-fold increased VEGF levels on day 9 (P

Published
2021
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12. Pressure-compacted and spider silk–reinforced fibrin demonstrates sufficient biomechanical stability as cardiac patch in vitro.

Author

Bobylev, Dmitry, Wilhelmi, Mathias, Lau, Skadi, Klingenberg, Melanie, Mlinaric, Markus, Petená, Elena, Helms, Florian, Hassel, Thomas, Haverich, Axel, Horke, Alexander, and Böer, Ulrike

Subjects
FIBRIN, SPIDER silk, TENSILE strength, SILICON surfaces
Abstract

Objective: The generation of bio-/hemocompatible cardiovascular patches with sufficient stability and regenerative potential remains an unmet goal. Thus, the aim of this study was the generation and in vitro biomechanical evaluation of a novel cardiovascular patch composed of pressure-compacted fibrin with embedded spider silk cocoons. Methods: Fibrin-based patches were cast in a customized circular mold. One cocoon of Nephila odulis spider silk was embedded per patch during the casting process. After polymerization, the fibrin clot was compacted by 2 kg weight for 30 min resulting in thickness reduction from up to 2 cm to <1 mm. Tensile strength and burst pressure was determined after 0 weeks and 14 weeks of storage. A sewing strength test and a long-term load test were performed using a customized device to exert physiological pulsatile stretching of a silicon surface on which the patch had been sutured. Results: Fibrin patches resisted supraphysiological pressures of well over 2000 mmHg. Embedding of spider silk increased tensile force 1.8-fold and tensile strength 1.45-fold (p <.001), resulting in a final strength of 1.07 MPa and increased sewing strength. Storage for 14 weeks decreased tensile strength, but not significantly and suturing properties of the spider silk patches were satisfactory. The long-term load test indicated that the patches were stable for 4 weeks although slight reduction in patch material was observed. Conclusion: The combination of compacted fibrin matrices and spider silk cocoons may represent a feasible concept to generate stable and biocompatible cardiovascular patches with regenerative potential. [ABSTRACT FROM AUTHOR]

Published
2022
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19. Immunogenicity of intensively decellularized equine carotid arteries is conferred by the extracellular matrix protein collagen type VI

Author

Boeer, Ulrike, Buettner, Falk F.R., Klingenberg, Melanie, Antonopoulos, Georgios C., Meyer, Heiko, Haverich, Axel, Wilhelmi, Mathias, Boeer, Ulrike, Buettner, Falk F.R., Klingenberg, Melanie, Antonopoulos, Georgios C., Meyer, Heiko, Haverich, Axel, and Wilhelmi, Mathias

Abstract

The limited biocompatibility of decellularized scaffolds is an ongoing challenge in tissue engineering. Here, we demonstrate the residual immunogenicity of an extensively decellularized equine carotid artery (dEAC intens) and identify the involved immunogenic components. EAC were submitted to an elaborated intensified decellularization protocol with SDS/sodium desoxycholate for 72 h using increased processing volumes (dEAC intens), and compared to dEACord prepared by an ordinary protocol (40 h, normal volumes). Matrix integrity was checked via correlative volumetric visualization which revealed only minor structural changes in the arterial wall. In dEACintens, a substantial depletion of cellular components was obvious for smooth muscle actin (100%), MHC I complexes (97.8%), alphaGal epitops (98.4% and 91.3%) and for DNA (final concentration of 0.34±0.16 ng/mg tissue). However, dEACintens still evoked antibody formation in mice after immunization with dEACintens extracts, although to a lower extent than dEACord. Mouse plasma antibodies recognized a 140 kDa band which was revealed to contain collagen VI alpha1 and alpha2 chains via mass spectrometry of both 2D electrophoretically separated and immunoprecipitated proteins. Thus, even the complete removal of cellular proteins did not yield non-immunogenic dEAC as the extracellular matrix still conferred immunogenicity by collagen VI. However, as lower antibody levels were achieved by the intensified decellularization protocol, this seems to be a promising basis for further development.

Published
2014

23. Cytotoxic Effects of Polyhexanide on Cellular Repopulation and Calcification of Decellularized Equine Carotids in vitroand in vivo

Author

Böer, Ulrike, Spengler, Claas, Klingenberg, Melanie, Jonigk, Danny, Harder, Michael, Kreipe, Hans-Heinrich, Haverich, Axel, and Wilhelmi, Mathias

Abstract

Purpose Disinfection of biological implants is indispensable for clinical safety. Here, decellularized equine carotid arteries (dECAs) were disinfected by polyhexanide (PHX), an effective, well-tolerated and nontoxic wound disinfectant and evaluated as vascular grafts for their repopulation and local biocompatibility in vivo.Methods dECAs were terminally disinfected by a combination of 0.1% PHX and 70% ethanol (dECA_PHX-ET) or exclusively ethanol (dECA-ET) and subsequently implanted as arteriovenous shunts in sheep for 14 weeks. Repopulation was determined by immunohistochemistry for endothelial- (ECs) or smooth muscle cells (SMCs) using antibodies against CD31 and smooth muscle actin. Histological evaluation was performed on HE-stained sections. Cytotoxicity of dECAs was measured directly by seeding the scaffolds with L-929 fibroblasts, which were visualized by calcein staining. Indirect cytotoxicity was determined by WST-8 viability assay by incubation of L-929 with dECA extracts.Results dECA_PHX-ET completely lacked repopulation with ECs and SMCs, showed leukocyte infiltration, strong calcification and poor neovascularization indicating insufficient biocompatibility and inflammatory graft degeneration. PHX-treatment reduced cell viability to 33.2 ± 12.6% and disturbed cell growth at direct contact. In contrast, dECA_ET had no direct cytotoxic effect and only slightly influenced cell viability (82.9 ± 12.5%), showed a substantial repopulation by ECs and SMCs including neovascularization, and were only slightly calcified.Conclusion The disinfectant polyhexanide seems to exert severe cytotoxic effects when used for the processing of decellularized matrices and may result in degenerative graft deterioration. In contrast, dECAs exclusively disinfected with ethanol were well integrated. Thus, ethanol seems to be a more suitable tool for graft processing than polyhexanide.

Published
2013
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