Nanomechanical Characterization of Osteogenic Differentiation of Mesenchymal Stem Cells on Bioactive Peptide Nanofiber Hydrogels

Stem cell differentiation is known to be influenced by the mechanical properties of the surrounding extracellular matrix (ECM); however, little is known about the mechanical phenotypes of differentiating stem cells within the ECM. Here, this study uses osteoinductive, ECM-mimetic peptide nanofibers to investigate the changes in the mechanical properties of rat mesenchymal stem cells (rMSCs) during osteogenic differentiation. In addition, octafluorocyclobutane (C4F8)-coated atomic force microscopy (AFM) cantilevers are developed to minimize tip–sample adhesion during the nanomechanical characterization of rMSCs, and osteogenic differentiation is monitored through molecular analysis in conjunction with AFM measurements. rMSCs cultured on osteoinductive peptide nanofibers differentiate at substantially higher rates, form osteogenic cell clusters, deposit calcium to the surrounding matrix, and strikingly increase their Young's moduli throughout the osteogenic differentiation process compared to controls. These results show that the elasticity profiles of differentiating rMSCs may change significantly depending on environmental factors and especially the degree of biomineralization, and that the natural elasticity responses of cells cultured on scaffolds may be considerably different from those observed on non-bioactive surfaces. This is important for the identification of cell elasticity as a biophysical marker of osteogenic differentiation of MSCs, and indicates that biomineralization might have a predominant role on cell mechanics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

Climate change promotes parasitism in a coral symbiosis.

Coastal oceans are increasingly eutrophic, warm and acidic through the addition of anthropogenic nitrogen and carbon, respectively. Among the most sensitive taxa to these changes are scleractinian corals, which engineer the most biodiverse ecosystems on Earth. Corals' sensitivity is a consequence of their evolutionary investment in symbiosis with the dinoflagellate alga, Symbiodinium. Together, the coral holobiont has dominated oligotrophic tropical marine habitats. However, warming destabilizes this association and reduces coral fitness. It has been theorized that, when reefs become warm and eutrophic, mutualistic Symbiodinium sequester more resources for their own growth, thus parasitizing their hosts of nutrition. Here, we tested the hypothesis that sub-bleaching temperature and excess nitrogen promotes symbiont parasitism by measuring respiration (costs) and the assimilation and translocation of both carbon (energy) and nitrogen (growth; both benefits) within Orbicella faveolata hosting one of two Symbiodinium phylotypes using a dual stable isotope tracer incubation at ambient (26 °C) and sub-bleaching (31 °C) temperatures under elevated nitrate. Warming to 31 °C reduced holobiont net primary productivity (NPP) by 60% due to increased respiration which decreased host %carbon by 15% with no apparent cost to the symbiont. Concurrently, Symbiodinium carbon and nitrogen assimilation increased by 14 and 32%, respectively while increasing their mitotic index by 15%, whereas hosts did not gain a proportional increase in translocated photosynthates. We conclude that the disparity in benefits and costs to both partners is evidence of symbiont parasitism in the coral symbiosis and has major implications for the resilience of coral reefs under threat of global change

Measuring the deliverable and impressible dimensions of service experience

Service innovation has become a priority within the field of innovation management and is increasingly focused on creating memorable experiences that can result in customer loyalty. Studies of experience design suggest individual service elements to be managed when staging an experience, whereas conceptual models in the literature emphasize the holistic way in which an experience is perceived. In short, service experience is greater than the sum of its parts. Therefore, successful innovation management requires the ability to understand and measure the mechanisms by which service innovations impact customers' experiences. Our research addresses this need by identifying dimensions of service experience and developing a tool for their measurement. Using a three stage process of systematic literature review, rigorous scale development and reduction, and validation, we identify six dimensions of the service experience and develop scales to measure each one. This results in a model of service innovation that highlights the levers through which a company's service innovation efforts can result in memorable experiences and ultimately new service success

Tailoring magnetic PLGA nanoparticles suitable for doxorubicin delivery

One of the main problems of current cancer chemotherapy is the lack of selectivity of anti-cancer drugs to tumor cells, which leads to systemic toxicity and adverse side effects. In order to overcome these limitations, researches on controlled drug delivery systems have gained much attention. Nanoscale-based drug delivery systems provide tumor targeting. Among many types of nanocarriers, superparamagnetic nanoparticles with their biocompatible polymer coatings can be targeted to an intented site by an external magnetic field. Thus, the drug can be carried to the targeted site safely. The aim of this study is to prepare poly(dl-lactic-co-glycolic acid) (PLGA)-coated magnetic nanoparticles and load anti-cancer drug, doxorubicin to them. For this purpose, magnetite (Fe3O4) iron oxide nanoparticles were synthesized as a magnetic core material (MNP) and then coated with oleic acid. Oleic acid-coated MNP (OA-MNP) was encapsulated into PLGA. Effects of different OA-MNP/PLGA ratios on magnetite entrapment efficiency were investigated. Doxorubicin-loaded magnetic polymeric nanoparticles (DOX-PLGA-MNP) were prepared. After the characterization of prepared nanoparticles, their cytotoxic effects on MCF-7 cell line were studied. PLGA-coated magnetic nanoparticles (PLGA-MNP) had a proper size and superparamagnetic character. The highest magnetite entrapment efficiency of PLGA-MNP was estimated as 63 % at 1:8 ratio. Cytotoxicity studies of PLGA-MNP did not indicate any notable cell death between the concentration ranges of 2 and 125 mu g/ml. Drug loading efficiency was estimated as 32 %, and it was observed that DOX-PLGA-MNP showed significant cytotoxicity on MCF-7 cells compared to PLGA-MNP. The results showed that prepared nanoparticles have desired size and superparamagnetic characteristics without serious toxic effects on cells. These nanoparticles may be suitable for targeted drug delivery applications

The Customer Contact Model for Organization Design

The literature on organization design has been dominated by descriptive models in its dealing with structure and operations. This paper takes an alternative view advocating the use of a normative model to be used in the design of service organizations. This model sees the extent of customer contact with the service organization as a major variable affecting system performance and advocates reconfiguring the structure of the service organization to reflect this impact. The discussion describes a taxonomy used to classify firms along the contact dimension and develops 13 propositions which convey critical distinctions between high and low contact services. Application of the model for managerial decision making involves the use of decoupling and the paper identifies factors which favor/disfavor decoupling in light of existing and desired service delivery objectives.organizational design, decoupling, customer contact, service systems

Tailoring the magnetic behavior of polymeric particles for bioapplications

In this study, magnetic polymeric nanoparticles were prepared use in for targeted drug delivery. First, iron oxide (Fe3O4) magnetic nanoparticles (MNPs) were synthesized by coprecipitation with ferrous and ferric chloride salts. Then, to render the MNPs hydrophobic, the surfaces were covered with oleic acid. Finally, the hydrophobic MNPs (H-MNPs) were encapsulated with polymer. The emulsion evaporation technique was used for the preparation of polymer-coated H-MNP. Poly(DL-lactide-co-glycolide) (PLGA) and chitosan-modified PLGA were used as polymers. The polymeric nanoparticles were characterized and compared. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, small-angle X-ray scattering, size distribution, zeta potential, magnetic properties, and magnetite entrapment efficiency measurements were performed to investigate the properties of the nanoparticles. The XTT assay was performed to understand the biocompatibility (i.e., toxicity) of MNPs and magnetic polymeric nanoparticles to MCF-7 cells