Energy metabolism in human pluripotent stem cells and their differentiated counterparts

Background: Human pluripotent stem cells have the ability to generate all cell types present in the adult organism, therefore harboring great potential for the in vitro study of differentiation and for the development of cell-based therapies. Nonetheless their use may prove challenging as incomplete differentiation of these cells might lead to tumoregenicity. Interestingly, many cancer types have been reported to display metabolic modifications with features that might be similar to stem cells. Understanding the metabolic properties of human pluripotent stem cells when compared to their differentiated counterparts can thus be of crucial importance. Furthermore recent data has stressed distinct features of different human pluripotent cells lines, namely when comparing embryo-derived human embryonic stem cells (hESCs) and induced pluripotent stem cells (IPSCs) reprogrammed from somatic cells. Methodology/Principal Findings: We compared the energy metabolism of hESCs, IPSCs, and their somatic counterparts. Focusing on mitochondria, we tracked organelle localization and morphology. Furthermore we performed gene expression analysis of several pathways related to the glucose metabolism, including glycolysis, the pentose phosphate pathway and the tricarboxylic acid (TCA) cycle. In addition we determined oxygen consumption rates (OCR) using a metabolic extracellular flux analyzer, as well as total intracellular ATP levels by high performance liquid chromatography (HPLC). Finally we explored the expression of key proteins involved in the regulation of glucose metabolism. Conclusions/Findings: Our results demonstrate that, although the metabolic signature of IPSCs is not identical to that of hESCs, nonetheless they cluster with hESCs rather than with their somatic counterparts. ATP levels, lactate production and OCR revealed that human pluripotent cells rely mostly on glycolysis to meet their energy demands. Furthermore, our work points to some of the strategies which human pluripotent stem cells may use to maintain high glycolytic rates, such as high levels of hexokinase II and inactive pyruvate dehydrogenase (PDH). © 2011 Varum et al

DNA Damage Responses in Human Induced Pluripotent Stem Cells and Embryonic Stem Cells

BACKGROUND: Induced pluripotent stem (iPS) cells have the capability to undergo self-renewal and differentiation into all somatic cell types. Since they can be produced through somatic cell reprogramming, which uses a defined set of transcription factors, iPS cells represent important sources of patient-specific cells for clinical applications. However, before these cells can be used in therapeutic designs, it is essential to understand their genetic stability.\ud \ud METHODOLOGY/PRINCIPAL FINDINGS: Here, we describe DNA damage responses in human iPS cells. We observe hypersensitivity to DNA damaging agents resulting in rapid induction of apoptosis after γ-irradiation. Expression of pluripotency factors does not appear to be diminished after irradiation in iPS cells. Following irradiation, iPS cells activate checkpoint signaling, evidenced by phosphorylation of ATM, NBS1, CHEK2, and TP53, localization of ATM to the double strand breaks (DSB), and localization of TP53 to the nucleus of NANOG-positive cells. We demonstrate that iPS cells temporary arrest cell cycle progression in the G(2) phase of the cell cycle, displaying a lack of the G(1)/S cell cycle arrest similar to human embryonic stem (ES) cells. Furthermore, both cell types remove DSB within six hours of γ-irradiation, form RAD51 foci and exhibit sister chromatid exchanges suggesting homologous recombination repair. Finally, we report elevated expression of genes involved in DNA damage signaling, checkpoint function, and repair of various types of DNA lesions in ES and iPS cells relative to their differentiated counterparts.\ud \ud CONCLUSIONS/SIGNIFICANCE: High degrees of similarity in DNA damage responses between ES and iPS cells were found. Even though reprogramming did not alter checkpoint signaling following DNA damage, dramatic changes in cell cycle structure, including a high percentage of cells in the S phase, increased radiosensitivity and loss of DNA damage-induced G(1)/S cell cycle arrest, were observed in stem cells generated by induced pluripotency.\ud \u

The missing link between awareness and use in the uptake of pro-internationalization incentives

We investigate the process by which firms become participants in official programmes of public support designed to promote outward internationalization. This study builds on previous research that has established the distinct factors associated with firms’ awareness and use of public support measures. These earlier studies have also shown that deficiencies within programmes manifest in low participation rates. However, scholars have not extended this reasoning to focus on the underlying processes involved, and have paid little attention to the steps through which firms elect to use public support, and how support operates upon, and within, the firm. In particular, the link between awareness of public incentives towards internationalization and the use of these incentives has been overlooked. General failure to understand this link is a potential source of policy inefficiency, reducing the effectiveness of those public programmes that employ incentives. We pose three research questions to examine the concept of such a link: (1) Do firms select public incentives that compensate for a lack of resources or capabilities in their possession? (2) Do firms react primarily to internal or external exigencies, for example, internal financial constraints or, rather, are they responding to unfolding circumstances, such as the more demanding market conditions experienced on internationalization? And (3) do firms use public support to “externalize” the increased risk to which they are exposed as internationalization proceeds, and thereby protect their external activities and investments from loss? The process that firms go through to apply for any type of public support is normally two-staged. Firms first become aware of incentives and then decide whether or not to use them. This process can be handled empirically using a Heckman Selection Model, which we apply to explore our research questions using survey data collected from a sample of Portuguese firms. We find that the greater are the internal limitations of these firms with respect to resources and capabilities and the more demanding are the conditions in which internationalization takes place, then the greater is the use made of public support. We find that awareness of the availability of support is promoted by firms’ in-house resources and capabilities and, at the same time, is positively associated with more demanding conditions of internationalization. The use of public support appears to be associated with the opportunity cost to the firm of public incentives, and with the increased risk inherent with internationalization. These results point to the existence of important sources of inefficiency within the process of application for policy measures, particularly with respect to the link between awareness and use. The use of public support is inversely associated with the opportunity cost to the firm of the resources deployed to apply for public incentives and, for firms with greater resources and capabilities, associated positively with the increased inherent risk of internationalization. We find evidence that it is the firms with greater resources and capabilities that predominate in the application for public incentives, allowing us to infer from the data that the typical recipient pursues more risky modes of entry, or selects locations with higher levels of risk, because of the availability of public support. These results point to the possible existence of important sources of inefficiency within the process of application for policy measures, particularly with respect to the link between awareness and use. This behaviour is quite distinct from the search for return on commercial investments and, therefore, is indicative of the possibility of social loss within this public policy intervention

Technological innovation policy in China: the lessons, and the necessary changes ahead

China has now moved considerably away from being an imitative latecomer to technology toward to being an innovation-driven economy. The key lessons from China’s experience are that (1) there is synergy between External Knowledge and Indigenous Innovation because the process of learning the tacit knowledge required in using the foreign technology fully is made easier by strong in-house R&D capability; (2) the open innovation approach is very important because it allows multiple driving forces—the state, the private sector and MNEs—with each playing a changing role over time; and (3) the commencement of foreign technology transfer and investment in indigenous innovation should go hand in hand. Without the numerous well-funded programs to build up the innovation infrastructure to increase the absorptive capacity of Chinese firms, foreign technology would have remained static technology embedded in imported machines and would not have strengthened indigenous technological capability. However, China could still end up in the middle-income trap, unless it undertakes a series of critical reforms in its innovation regime in order to keep moving up growth trajectories that are increasingly skill-intensive and technology-intensive

Using the Ideas Café to explore trust in autonomous vehicles

Trust has been shown to play a key role in our ability to safely use autonomous vehicles; hence the authors used the Ideas Café to explore the factors affecting trust in autonomous vehicles. The Ideas Café is an informal collaborative event that brings the public together with domain experts for exploratory research. The authors structured the event around factors affecting trust in the technology, privacy and societal impact. The event followed a mixed methods approach using: table discussions, spectrum lines and line ups. 36 participants attended the Ideas Café event held at the Coventry Transport Museum in June 2017. Table discussions provided the key findings for Thematic Analysis as part of Grounded Theory; which found, contrary to current research trends, designing for the technology’s integration with society as equally important for trust as the vehicle design itself. The authors also reported on the emergent high level interface guidelines