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  • 1
    Language: English
    In: Journal of Materials Science: Materials in Medicine, 2014, Vol.25(3), pp.857-871
    Description: Cultivation and proliferation of stem cells in three-dimensional (3-D) scaffolds is a promising strategy for regenerative medicine. Mesenchymal stem cells with their potential to differentiate in various cell types, cryopreserved adhesion-based in fabricated scaffolds of biocompatible materials can serve as ready-to-use transplantation units for tissue repair, where pores allow a direct contact of graft cells and recipient tissue without further preparation. A successful cryopreservation of adherent cells depends on attachment and spreading processes that start directly after cell seeding. Here, we analyzed different cultivation times (0.5, 2, 24 h) prior to adhesion-based cryopreservation of human mesenchymal stem cells within alginate–gelatin cryogel scaffolds and its influence on cell viability, recovery and functionality at recovery times (0, 24, 48 h) in comparison to non-frozen control. Analysis with confocal laser scanning microscopy and scanning electron microscopy indicated that 2 h cultivation time enhanced cryopreservation success: cell number, visual cell contacts, membrane integrity, motility, as well as spreading were comparable to control. In contrast, cell number by short cultivation time (0.5 h) reduced dramatically after thawing and expanded cultivation time (24 h) decreased cell viability. Our results provide necessary information to enhance the production and to store ready-to-use transplantation units for application in bone, cartilage or skin regenerative therapy.
    Keywords: Biomedical Engineering -- Analysis ; Biomedical Engineering -- Usage ; Stem Cells -- Analysis ; Stem Cells -- Usage ; Electron Microscopy -- Analysis ; Electron Microscopy -- Usage;
    ISSN: 0957-4530
    E-ISSN: 1573-4838
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  • 2
    Language: English
    In: Biomaterials, August 2014, Vol.35(26), pp.7374-7385
    Description: Cardiomyocytes (CMs) from induced pluripotent stem (iPS) cells mark an important achievement in the development of pharmacological, toxicological and developmental assays and in the establishment of protocols for cardiac cell replacement therapy. Using CMs generated from murine embryonic stem cells and iPS cells we found increased cell–matrix interaction and more matured embryoid body (EB) structures in iPS cell-derived EBs. However, neither suspension-culture in form of purified cardiac clusters nor adherence-culture on traditional cell culture plastic allowed for extended culture of CMs. CMs grown for five weeks on polystyrene exhibit signs of massive mechanical stress as indicated by α-smooth muscle actin expression and loss of sarcomere integrity. Hydrogels from polyacrylamide allow adapting of the matrix stiffness to that of cardiac tissue. We were able to eliminate the bottleneck of low cell adhesion using 2,5-Dioxopyrrolidin-1-yl-6-acrylamidohexanoate as a crosslinker to immobilize matrix proteins on the gels surface. Finally we present an easy method to generate polyacrylamide gels with a physiological Young's modulus of 55 kPa and defined surface ligand, facilitating the culture of murine and human iPS-CMs, removing excess mechanical stresses and reducing the risk of tissue culture artifacts exerted by stiff substrates.
    Keywords: Cell Culture ; Cell Adhesion ; Cardiomyocyte ; Hydrogel ; Cross-Linking ; Cell Viability ; Medicine ; Engineering
    ISSN: 0142-9612
    E-ISSN: 1878-5905
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  • 3
    Language: English
    In: Journal of Nanoparticle Research, 2011, Vol.13(12), pp.6789-6803
    Description: Gold nanoparticles are very attractive for biomedical products. However, there is a serious lack of information concerning the biological activity of nanosized gold in human tissue cells. An influence of nanoparticles on stem cells might lead to unforeseen consequences to organ and tissue functions as long as all cells arising from the initial stem cell might be subsequently damaged. Therefore the effect of negatively charged gold nanoparticles (9 and 95 nm), which are certified as reference material for preclinical biomedical research, on the adipogenic differentiation of human mesenchymal stem cells (hMSCs) is investigated here. Bone marrow hMSCs are chosen as differentiation model since bone marrow hMSCs are well characterized and their differentiation into the adipogenic lineage shows clear and easily detectable differentiation. In this study effects of gold nanoparticles on adipogenic differentiation are analyzed regarding fat storage and mitochondrial activity after different exposure times (4–21 days). Using time lapse microscopy the differentiation progress under chronically gold nanoparticle treatment is continuously investigated. In this preliminary study, chronically treatment of adipogenic differentiating hMSCs with gold nanoparticles resulted in a reduced number and size of lipid vacuoles and reduced mitochondrial activity depending on the applied concentration and the surface charge of the particles.
    Keywords: Gold nanoparticles ; Human mesenchymal stem cells ; Adipogenic differentiation ; Toxicity ; Cellular uptake ; Health effects
    ISSN: 1388-0764
    E-ISSN: 1572-896X
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  • 4
    In: Scanning, November 2016, Vol.38(6), pp.625-633
    Description: To purchase or authenticate to the full-text of this article, please visit this link: http://onlinelibrary.wiley.com/doi/10.1002/sca.21310/abstract Byline: Alisa Katsen-Globa, Norbert Puetz, Michael M. Gepp, Julia C. Neubauer, Heiko Zimmermann Summary One of the often reported artefacts during cell preparation to scanning electron microscopy (SEM) is the shrinkage of cellular objects, that mostly occurs at a certain time-dependent stage of cell drying. Various methods of drying for SEM, such as critical point drying, freeze-drying, as well as hexamethyldisilazane (HMDS)-drying, were usually used. The latter becomes popular since it is a low cost and fast method. However, the correlation of drying duration and real shrinkage of objects was not investigated yet. In this paper, cell shrinkage at each stage of preparation for SEM was studied. We introduce a shrinkage coefficient using correlative light microscopy (LM) and SEM of the same human mesenchymal stem cells (hMSCs). The influence of HMDS-drying duration on the cell shrinkage is shown: the longer drying duration, the more shrinkage is observed. Furthermore, it was demonstrated that cell shrinkage is inversely proportional to cultivation time: the longer cultivation time, the more cell spreading area and the less cell shrinkage. Our results can be applicable for an exact SEM quantification of cell size and determination of cell spreading area in engineering of artificial cellular environments using biomaterials. SCANNING 38:625-633, 2016. [c] 2016 Wiley Periodicals, Inc. Article Note: Conflicts of interest: None.
    Keywords: Light Microscopy Lm ; Scanning Electron Microscopy Sem ; Cell Shrinkage ; Cell Spreading Area ; Hexamethyldisilazane Hmds
    ISSN: 0161-0457
    E-ISSN: 1932-8745
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  • 5
    Language: English
    In: Biomaterials, 2010, Vol.31(8), pp.2388-2398
    Description: Specific transport of anti-cancer drugs into tumor cells may result in increased therapeutic efficacy and decreased adverse events. Expression of αvβ3 integrin is enhanced in various types of cancer and monoclonal antibodies (mAbs) directed against αvβ3 integrins hold promise for anti-cancer therapy. DI17E6 is a monoclonal antibody directed against αv integrins that inhibits growth of melanomas and and inhibits angiogenesis due to interference with αvβ3 integrins. Here, DI17E6 was covalently coupled to human serum albumin nanoparticles. Resulting nanoparticles specifically targeted αvβ3 integrin positive melanoma cells. Moreover, doxorubicin loaded DI17E6 nanoparticles showed increased cytotoxic activity in αvβ3-positive melanoma cells than the free drug. Therefore, DI17E6-coupled human serum albumin nanoparticles represent a potential delivery system for targeted drug transport into αvβ3-positive cells.
    Keywords: Albumin ; Chemotherapy ; Drug Delivery ; Ecm (Extracellular Matrix) ; Integrin ; Nanoparticles ; Medicine ; Engineering
    ISSN: 0142-9612
    E-ISSN: 1878-5905
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  • 6
    Language: English
    In: Cryobiology, December 2011, Vol.63(3), pp.175-185
    Description: ► We established a surface-based protocol for bulk vitrification of hESCs. ► It results in very high recovery rates and maintains pluripotency. ► Method is easy to handle and allows exact incubation times. ► Slow rate protocol of adherent hESCs results in disturbed membrane integrity. ► Efficiency of slow rate protocol is significantly lower and depends on colony size. Human embryonic stem cells (hESCs) are candidates for many applications in the areas of regenerative medicine, tissue engineering, basic scientific research as well as pharmacology and toxicology. However, use of hESCs is limited by their sensitivity to freezing and thawing procedures. Hence, this emerging science needs new, reliable preservation methods for the long-term storage of large quantities of functional hESCs remaining pluripotent after post-thawing and culturing. Here, we present a highly efficient, surface based vitrification method for the cryopreservation of large numbers of adherent hESC colonies, using modified cell culture substrates. This technique results in much better post-thaw survival rate compared to cryopreservation in suspension and allows a quick and precise handling and storage of the cells, indicating low differentiation rates.
    Keywords: Adherent Cryopreservation ; Human Embryonic Stem Cells ; Vitrification ; Biology
    ISSN: 0011-2240
    E-ISSN: 1090-2392
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  • 7
    In: Engineering in Life Sciences, November 2012, Vol.12(6), pp.584-587
    Description: Miniaturization and parallelization of cell culture procedures are in focus of research in order to develop test platforms with low material consumption and increased standardization for toxicity and drug screenings. The cultivation in hanging drops (s) is a convenient and versatile tool for biological applications and represents an interesting model system for the screening applications due to its uniform shape, the advantageous gas supply, and the small volume. However, its application has so far been limited to non#x02010;adherent and aggregate forming cells. Here, we describe for the first time the proof‐of‐principle regarding the adherent cultivation of human embryonic stem cells in . For this microcarriers were added to the droplet as dynamic cultivation surfaces resulting in a maintained pluripotency and proliferation capacity for 10 days. This enables the technique to be extended to the cultivation of adherence‐dependent stem cells. Also, the possible automation of this method by implementation of liquid handling systems opens new possibilities for miniaturized screenings, the improvement of cultivation and differentiation conditions, and toxicity and drug development.
    Keywords: Hanging Drop ; High‐Throughput Screening ; Hescs ; Microcarrier
    ISSN: 1618-0240
    E-ISSN: 1618-2863
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  • 8
    Language: English
    In: Cryobiology, 2010, Vol.61(3), pp.393-394
    Keywords: Biology
    ISSN: 0011-2240
    E-ISSN: 1090-2392
    Source: ScienceDirect Journals (Elsevier)
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  • 9
    Language: English
    In: Journal of Materials Science: Materials in Medicine, 2018, Vol.29(7), pp.1-13
    Description: The surface charge of a biomaterial represents a promising tool to direct cellular behavior, which is crucial for therapeutic approaches in regenerative medicine. To expand the understanding of how the material surface charge affects protein adsorption and mesenchymal stem cell behavior, differently charged surfaces with zeta potentials spanning from −25 mV to +15 mV were fabricated by the conjugation of poly(amidoamine) to alginate-based hydrogels. We showed that the increase of the biomaterials surface charge resulted in enhanced quantities of biologically available, surface-attached proteins. Since different surface charges were equalized after protein adsorption, mesenchymal stem cells interacted rather with diverse protein compositions instead of different surface features. Besides an enhanced cell attachment to increasingly positively charged surfaces, the cell spreading area and the expression of adhesion-related genes integrin α5 and tensin 1 were found to be increased after adhesion. Moreover, first results indicate a potential impact of the surface charge on mesenchymal stem cell differentiation towards bone and fat cells. The improved understanding of surface charge-related cell behavior has significant impact on the design of biomedical devices and artificial organs.
    Keywords: Biological Products ; Biomedical Engineering ; Stem Cells ; Integrins ; Adsorption ; Cell Differentiation;
    ISSN: 0957-4530
    E-ISSN: 1573-4838
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  • 10
    Language: English
    In: Cryobiology, 2010, Vol.61(3), pp.408-408
    Keywords: Biology
    ISSN: 0011-2240
    E-ISSN: 1090-2392
    Source: ScienceDirect Journals (Elsevier)
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