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Wang W.,Helmholtz Center Geesthacht | Kratz K.,Helmholtz Center Geesthacht | Kratz K.,Helmholtz Virtual Institute Multifunctional Materials in Medicine | Behl M.,Helmholtz Center Geesthacht | And 18 more authors.
Clinical Hemorheology and Microcirculation | Year: 2015

Polyether ether ketone (PEEK) as a high-performance, thermoplastic implant material entered the field of medical applications due to its structural function and commercial availability. In bone tissue engineering, the combination of mesenchymal stem cells (MSCs) with PEEK implants may accelerate the bone formation and promote the osseointegration between the implant and the adjacent bone tissue. In this concept the question how PEEK influences the behaviour and functions of MSCs is of great interest. Here the cellular response of human adipose-derived MSCs to PEEK was evaluated and compared to tissue culture plate (TCP) as the reference material. Viability and morphology of cells were not altered when cultured on the PEEK film. The cells on PEEK presented a high proliferation activity in spite of a relatively lower initial cell adhesion rate. There was no significant difference on cell apoptosis and senescence between the cells on PEEK and TCP. The inflammatory cytokines and VEGF secreted by the cells on these two surfaces were at similar levels. The cells on PEEK showed up-regulated BMP2 and down-regulated BMP4 and BMP6 gene expression, whereas no conspicuous differences were observed in the committed osteoblast markers (BGLAP, COL1A1 and Runx2). With osteoinduction the cells on PEEK and TCP exhibited a similar osteogenic differentiation potential. Our results demonstrate the biofunctionality of PEEK for human MSC cultivation and differentiation. Its clinical benefits in bone tissue engineering may be achieved by combining MSCs with PEEK implants. These data may also provide useful information for further modification of PEEK with chemical or physical methods to regulate the cellular processes of MSCs and to consequently improve the efficacy of MSC-PEEK based therapies. © 2015 IOS Press and the authors.

Krueger K.,Charité - Medical University of Berlin | Terne C.,Charité - Medical University of Berlin | Terne C.,Helmholtz Virtual Institute Multifunctional Materials in Medicine | Werner C.,Leibniz Institute of Polymer Research | And 4 more authors.
Analytical Chemistry | Year: 2013

For physical and chemical characterization of polymers, a wide range of analytical methods is available. Techniques like NMR and X-ray are often combined for a detailed characterization of polymers used in medical applications. Over the past few years, MALDI mass-spectrometry has been developed as a powerful tool for space-resolved analysis, not least because of its mass accuracy and high sensitivity. MALDI imaging techniques combine the potential of mass-spectrometric analysis with imaging as additional spatial information. MALDI imaging enables the visualization of localization and distribution of biomolecules, chemical compounds, and other molecules on different surfaces. In this study, surfaces of polymeric dialyzer membranes, consisting of polysulfone (PS) and polyvinylpyrrolidone (PVP), were investigated, regarding chemical structure and the compound's distribution. Flat membranes as well as hollow fiber membranes were analyzed by MALDI imaging. First, analysis parameters like laser intensity and laser raster step size (spatial resolution in resulting image) were established in accordance with polymer's characteristics. According to the manufacturing process, luminal and abluminal membrane surfaces are characterized by differences in chemical composition and physical characteristics. The MALDI imaging demonstrated that the abluminal membrane surface consists more of polysulfone than polyvinylpyrrolidone, and the luminal membrane surface displayed more PVP than PS. The addition of PVP as hydrophilic modifier to polysulfone-based membranes increases the biocompatibility of the dialysis membranes. The analysis of polymer distribution is a relevant feature for characterization of dialysis membranes. In conclusion, MALDI imaging is a powerful technique for polymer membrane analysis, regarding not only detection and identification of polymers but also localization and distribution in membrane surfaces. © 2013 American Chemical Society.

Wang W.,Free University of Berlin | Xu X.,Free University of Berlin | Li Z.,Free University of Berlin | Lendlein A.,Free University of Berlin | And 3 more authors.
Clinical Hemorheology and Microcirculation | Year: 2014

Mesenchymal stem cells (MSCs) are an ideal cell source for tissue engineering and regenerative medicine as they possess self-renewal properties and multilineage differentiation potential. They can be isolated from various tissues and expanded easily through normal cell culture techniques. Genetic modifications of MSCs to further improve their therapeutic efficacy have been widely studied and extensively researched. Compared to viral gene delivery methods, non-viral methods generate less toxicity and immunogenicity and thus represent a promising and effective tool for the genetic engineering of MSCs. In the last decades, various non-viral gene delivery strategies have been developed and some of them have been applied for MSC transfection. This paper gives an overview of the techniques, influencing factors and potential applications of non-viral methods used for the genetic engineering of MSCs. © 2014-IOS Press and the authors.

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