Human induced pluripotent stem cells (iPSCs) are a potential source of hepatocytes for liver transplantation to treat end-stage liver disease. In vitro differentiation of human iPSCs into hepatic ...cells has been achieved using a multistage differentiation protocol, but whether these cells are functional and capable of engrafting and regenerating diseased liver tissue is not clear. We show that human iPSC-derived hepatic cells at various differentiation stages can engraft the liver in a mouse transplantation model. Using the same differentiation and transplantation protocols, we also assessed the ability of human iPSCs derived from each of the three developmental germ layer tissues (that is, ectoderm, mesoderm, and endoderm) to regenerate mouse liver. These iPSC lines, with similar but distinct global DNA methylation patterns, differentiated into multistage hepatic cells with an efficiency similar to that of human embryonic stem cells. Human hepatic cells at various differentiation stages derived from iPSC lines of different origins successfully repopulated the liver tissue of mice with liver cirrhosis. They also secreted human-specific liver proteins into mouse blood at concentrations comparable to that of proteins secreted by human primary hepatocytes. Our results demonstrate the engraftment and liver regenerative capabilities of human iPSC-derived multistage hepatic cells in vivo and suggest that human iPSCs of distinct origins and regardless of their parental epigenetic memory can efficiently differentiate along the hepatic lineage.
Patient‐specific induced pluripotent stem cells (iPSCs) represent a potential source for developing novel drug and cell therapies. Although increasing numbers of disease‐specific iPSCs have been ...generated, there has been limited progress in iPSC‐based drug screening/discovery for liver diseases, and the low gene‐targeting efficiency in human iPSCs warrants further improvement. Using iPSC lines from patients with alpha‐1 antitrypsin (AAT) deficiency, for which there is currently no drug or gene therapy available, we established a platform to discover new drug candidates and correct disease‐causing mutation with a high efficiency. A high‐throughput format screening assay, based on our hepatic differentiation protocol, was implemented to facilitate automated quantification of cellular AAT accumulation using a 96‐well immunofluorescence reader. To expedite the eventual application of lead compounds to patients, we conducted drug screening utilizing our established library of clinical compounds (the Johns Hopkins Drug Library) with extensive safety profiles. Through a blind large‐scale drug screening, five clinical drugs were identified to reduce AAT accumulation in diverse patient iPSC‐derived hepatocyte‐like cells. In addition, using the recently developed transcription activator‐like effector nuclease technology, we achieved high gene‐targeting efficiency in AAT‐deficiency patient iPSCs with 25%‐33% of the clones demonstrating simultaneous targeting at both diseased alleles. The hepatocyte‐like cells derived from the gene‐corrected iPSCs were functional without the mutant AAT accumulation. This highly efficient and cost‐effective targeting technology will broadly benefit both basic and translational applications. Conclusions: Our results demonstrated the feasibility of effective large‐scale drug screening using an iPSC‐based disease model and highly robust gene targeting in human iPSCs, both of which are critical for translating the iPSC technology into novel therapies for untreatable diseases. (HEPATOLOGY 2013;57:2458–2468)
The Rare Isotope Science Project (RISP) of the Institute for Basic Science (IBS) has been developing a heavy-ion accelerator, called the Rare isotope Accelerator complex for ON-line experiments ...(RAON). For accelerator operation, The RISP control system adopts the Experimental Physics and Industrial Control System (EPICS) to control and monitor all accelerator software and hardware 1. The signal archiving system is a core system for accelerator operation, and research for improving reliability and integrity is important. Signal archiver method using the EPICS framework has three significant modes of operation. First is the classic channel archiver using the file base method, and the second is the Relational DataBase (RDB) archiver using a relational database. But classic channel archiver has the problem that the index file contains information on a data block corresponding to PV data mismatch with real data. Also, the RDB archiver has a problem in the performance of file I/O. The RAON control group has built a signal archiving system using an archive appliance that solves the current problems from several archiving methods. This paper describes the result of the Superconducting Radio Frequency (SRF) archiving system based on the archiver appliance.
Neovessel formation is a complex process governed by the orchestrated action of multiple factors that regulate EC specification and dynamics within a growing vascular tree. These factors have been ...widely exploited to develop therapies for angiogenesis-related diseases such as diabetic retinopathy and tumor growth and metastasis. WNT signaling has been implicated in the regulation and development of the vascular system, but the detailed mechanism of this process remains unclear. Here, we report that Dickkopf1 (DKK1) and Dickkopf2 (DKK2), originally known as WNT antagonists, play opposite functional roles in regulating angiogenesis. DKK2 induced during EC morphogenesis promoted angiogenesis in cultured human endothelial cells and in in vivo assays using mice. Its structural homolog, DKK1, suppressed angiogenesis and was repressed upon induction of morphogenesis. Importantly, local injection of DKK2 protein significantly improved tissue repair, with enhanced neovascularization in animal models of both hind limb ischemia and myocardial infarction. We further showed that DKK2 stimulated filopodial dynamics and angiogenic sprouting of ECs via a signaling cascade involving LRP6-mediated APC/Asef2/Cdc42 activation. Thus, our findings demonstrate the distinct functions of DKK1 and DKK2 in controlling angiogenesis and suggest that DKK2 may be a viable therapeutic target in the treatment of ischemic vascular diseases.
Human induced pluripotent stem cells (iPSCs) are potential renewable sources of hepatocytes for drug development and cell therapy. Differentiation of human iPSCs into different developmental stages ...of hepatic cells has been achieved and improved during the last several years. We have recently demonstrated the liver engraftment and regenerative capabilities of human iPSC-derived multistage hepatic cells in vivo. Here we describe the in vitro and in vivo activities of hepatic cells derived from patient specific iPSCs, including multiple lines established from either inherited or acquired liver diseases, and discuss basic and clinical applications of these cells for disease modeling, drug screening and discovery, gene therapy and cell replacement therapy.
Capsiate, a nonpungent capsaicin analogue, and its dihydroderivative dihydrocapsiate are the major capsaicinoids of the nonpungent red pepper cultivar CH-19 Sweet. In this study, we report the ...biological actions and underlying molecular mechanisms of capsiate on angiogenesis and vascular permeability. In vitro, capsiate and dihydrocapsiate inhibited vascular endothelial growth factor (VEGF)-induced proliferation, chemotactic motility, and capillary-like tube formation of primary cultured human endothelial cells. They also inhibited sprouting of endothelial cells in the rat aorta and formation of new blood vessels in the mouse Matrigel plug assay in response to VEGF. Moreover, both compounds blocked VEGF-induced endothelial permeability and loss of vascular endothelial (VE)-cadherin-facilitated endothelial cell-cell junctions. Importantly, capsiate suppressed VEGF-induced activation of Src kinase and phosphorylation of its downstream substrates, such as p125(FAK) and VE-cadherin, without affecting autophosphorylation of the VEGF receptor KDR/Flk-1. In vitro kinase assay and molecular modeling studies revealed that capsiate inhibits Src kinase activity via its preferential docking to the ATP-binding site of Src kinase. Taken together, these results suggest that capsiate could be useful for blocking pathologic angiogenesis and vascular permeability caused by VEGF.
Recent advances in induced pluripotent stem (iPS) cell research have significantly changed our perspective on regenerative medicine. Patient‐specific iPS cells have been derived not only for disease ...modeling but also as sources for cell replacement therapy. However, there have been insufficient data to prove that iPS cells are functionally equivalent to human embryonic stem (hES) cells or are safer than hES cells. There are several important issues that need to be addressed, and foremost are the safety and efficacy of human iPS cells of different origins. Human iPS cells have been derived mostly from cells originating from mesoderm and in a few cases from ectoderm. So far, there has been no report of endoderm–derived human iPS cells, and this has prevented comprehensive comparative investigations of the quality of human iPS cells of different origins. Here we show for the first time reprogramming of human endoderm‐derived cells (i.e., primary hepatocytes) to pluripotency. Hepatocyte‐derived iPS cells appear indistinguishable from hES cells with respect to colony morphology, growth properties, expression of pluripotency‐associated transcription factors and surface markers, and differentiation potential in embryoid body formation and teratoma assays. In addition, these cells are able to directly differentiate into definitive endoderm, hepatic progenitors, and mature hepatocytes. Conclusion: The technology to develop endoderm–derived human iPS cell lines, together with other established cell lines, will provide a foundation for elucidating the mechanisms of cellular reprogramming and for studying the safety and efficacy of differentially originated human iPS cells for cell therapy. For the study of liver disease pathogenesis, this technology also provides a potentially more amenable system for generating liver disease‐specific iPS cells. (HEPATOLOGY 2010;51:1810–1819)
This paper develops a computationally efficient method to bound the impact of multiple uncertain parameters in a dynamic load model. Load model trajectory sensitivity is first conducted on regional ...dynamics only (e.g., a large industrial load bus and its model for adequately representing the bus voltage dynamics) to identify critical and correlated load parameters. Systemwide trajectory sensitivity on the entire power system model is then evaluated for this reduced set of parameters, and finally, the impact of multiple uncertain parameters on the representation of power system dynamics is bounded. To reinforce this reasoning, we elaborate on the conceptual meaning of the load model trajectory sensitivity, its implication, and its applicability to the entire power grid analysis. This research also develops a fluctuation index of trajectory sensitivity to effectively rank and select the model parameters based on the impact of their perturbations on the system's dynamic performance. Case studies for the Korean power system demonstrate the validity and efficacy of the developed methods for adequately bounding the uncertainty impacts with reference to the comprehensive time-domain dynamic simulation approach.
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