Suchergebnisse

Acknowledgments: This study was supported by Instituto de Salud Carlos III (ISCiii) of Spain, co-financed by FEDER funds from European Union, through grants PI18/01557 (to AG), PI18/01556 (to JV), and CIBERNED (CB06/05/1116 to AG and CB06/05/0094 to JV); by Junta de Andalucia through Consejería de Economía y Conocimiento grants UMA18-FEDERJA-211 (to AG), PY18-RT-2233 (to AG) and US-1262734 (to JV) co-financed by Programa Operativo FEDER 2014-2020 and Consejeria de Salud grant PI-0276-2018 (to JAGL). ; Oligodendrocytes (OLs) are highly specialized cells of the central nervous system responsible for myelin production and metabolic support of neurons. Defects in OLs are crucial in several neurodegenerative diseases including multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS). Scarce access to primary samples and lack of efficient protocols to generate OLs from human pluripotent stem cells (hPSCs) are hampering our understanding of OL biology and the development of novel therapies. To promote the conversion of hPSCs into OLs, we have screened for a number of transcription factors (TFs) previously reported to be involved in OL generation. We found that the overexpression of SOX10 was sufficient to generate O4+ oligodendrocyte precursor cells (OPCs) from hPSCs only 10 days after SOX10 induction. Generated OPCs expressed mature OL proteins as MBP or MOG. At the transcriptome level, generated OPCs resembled primary OPCs. To test the functionality of generated OPCs, O4+ cells were co-cultured together with neurons, finding that O4+ cells were able to myelinate the neurons. Moreover, O4+ cells were injected intracerebrally in newborn shiverer RAG2-/- mice, finding that generated OLs extended within the corpus callosum and generated functional myelin, demonstrating the functionality of generated cells also in vivo. The protocol also describes an alternative for viral transduction, by incorporating an inducible SOX10 in the safe harbor locus AAVS1, yielding ~100% pure OPCs. O4+ OPCs can be co-cultured with maturing hPSC-derived neurons in 96/384-well- format plates, allowing the screening of pro-myelinating compounds. We have developed a novel methodology for a fast (20 days from hPSC stage) and efficient generation of functional OLs, which allow testing of compounds involved in myelination. This technology will allow further studies to better understand human OL biology and the screening of potential compounds involved in myelination in a human setting. ; Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.

The need to track and evaluate the fate of transplanted cells is an important issue in regenerative medicine. In order to accomplish this, pre-labelling cells with magnetic resonance imaging (MRI) contrast agents is a well-established method. Uptake of MRI contrast agents by non-phagocytic stem cells, and factors such as cell homeostasis or the adverse effects of contrast agents on cell biology have been extensively studied, but in the context of nanoparticle (NP)-specific parameters. Here, we have studied three different types of NPs (Endorem (R), magnetoliposomes [MLs], and citrate coated C-200) to label relatively larger, mesenchymal stem cells (MSCs) and, much smaller yet faster proliferating, multipotent adult progenitor cells (MAPCs). Both cell types are similar, as they are isolated from bone marrow and have substantial regenerative potential, which make them interesting candidates for comparative experiments. Using NPs with different surface coatings and sizes, we found that differences in the proliferative and morphological characteristics of the cells used in the study are mainly responsible for the fate of endocytosed iron, intracellular iron concentration, and cytotoxic responses. The quantitative analysis, using high-resolution electron microscopy images, demonstrated a strong relationship between cell volume/surface, uptake, and cytotoxicity. Interestingly, uptake and toxicity trends are reversed if intracellular concentrations, and not amounts, are considered. This indicates that more attention should be paid to cellular parameters such as cell size and proliferation rate in comparative cell-labeling studies. ; The authors are grateful to Guerbet, Roissy, France, for the generous gift of Endorem (R). The technical assistance of Marc Jans, Manja Muitjens, and Pieter Berckmans is gratefully acknowledged. We would like to thank Jesse Trekker for the assistance with ICP-OES measurements. This work was financially supported by the European commission project EC-FP7-NMP-2008-Large 'ViBRANT' (228933), the Flemish Government for the SBO-IWT-80017 'iMAGiNe' and the SBO-IWT-060838 'BRAINSTIM', and by the KU Leuven Program Financing 'IMIR'. AKA is grateful for receiving financial support for a PhD fellowship (DBOF) from the KU Leuven.

Transplantation of mesenchymal stem cells (MSCs) into injured or diseased tissuefor the in situ delivery of a wide variety of MSC-secreted therapeutic proteinsis an emerging approach for the modulation of the clinical course of several diseases and traumata. From an emergency point-of-view, allogeneic MSCs have numerous advantages over patient-specific autologous MSCs since off-the-shelf cell preparations could be readily available for instant therapeutic intervention following acute injury. Although we confirmed the in vitro immunomodulatory capacity of allogeneic MSCs on antigen-presenting cells with standard coculture experiments, allogeneic MSC grafts were irrevocably rejected by the host's immune system upon either intramuscular or intracerebral transplantation. In an attempt to modulate MSC allograft rejection in vivo, we transduced MSCs with an interleukin-13 (IL13)-expressing lentiviral vector. Our data clearly indicate that prolonged survival of IL13-expressing allogeneic MSC grafts in muscle tissue coincided with the induction of an alternatively activated macrophage phenotype in vivo and a reduced number of alloantigen-reactive IFN- and/or IL2-producing CD8(+) T cells compared to nonmodified allografts. Similarly, intracerebral IL13-expressing MSC allografts also exhibited prolonged survival and induction of an alternatively activated macrophage phenotype, although a peripheral T cell component was absent. In summary, this study demonstrates that both innate and adaptive immune responses are effectively modulated in vivo by locally secreted IL13, ultimately resulting in prolonged MSC allograft survival in both muscle and brain tissue. ; We thank A. Liston and S. Humblet-Baron (VIB Translational Immunology Lab, KU Leuven, Belgium) for sharing their optimized staining protocols for intracellular cytokine analysis by flow cytometry. This work was supported by research grants G.0130.11 and G.0136.11 (granted to A.V.d.L., Z.N.B. and P.P.), G.0131.11 (granted to Z.N.B. and P.P.), G.0834.11 (granted to S.H. and P.P.) and G.0851.11 (granted to C.V. and Z.N.B.) of the Research Foundation Flanders (FWO Vlaanderen, Belgium) and in part by a Methusalem research grant from the Flemish government (granted to H.G.). C.J.H. and E.Lu. hold a PhD studentship from the FWO Vlaanderen. C.G. and D.L.B. hold a PhD studentship from the Flemish Institute for Science and Technology (IWT Vlaanderen).

Tools for rapid and efficient transgenesis in "safe harbor" loci in an isogenic context remain important to exploit the possibilities of human pluripotent stem cells (hPSCs). We created hPSC master cell lines suitable for FLPe recombinase-mediated cassette exchange (RMCE) in the AAVS1 locus that allow generation of transgenic lines within 15 days with 100% efficiency and without random integrations. Using RMCE, we successfully incorporated several transgenes useful for lineage identification, cell toxicity studies, and gene overexpression to study the hepatocyte lineage. However, we observed unexpected and variable transgene expression inhibition in vitro, due to DNA methylation and other unknown mechanisms, both in undifferentiated hESC and differentiating hepatocytes. Therefore, the AAVS1 locus cannot be considered a universally safe harbor locus for reliable transgene expression in vitro, and using it for transgenesis in hPSC will require careful assessment of the function of individual transgenes. ; L.O. was funded by IWT/OZM/090838, IACS BPAMER3/08/04, and Government of Aragon FMI048/08; M.P. by FWO 1288714N; and R.S. by the Dutch Diabetes Foundation. R.B., N.H., J.V., K.C., and Q.C. were supported by IWT fellowships SB-121393, SB-121396, SB-101230, SB-091228, and SB-093228, respectively. B.Z.S. was financed by FP7-PEOPLE-2011-IIF (Proposal No. 298785) and W.G. by the China Scholarship Council. S.B.-W. and T.C. were supported by the FP7-HEMIBIO (266777). Funding to C.M.V. was from FWO G.0667.07 and G.0975.11; KU Leuven (EIW-B4855-EF/05/11, ETH-C1900-PF, EME-C2161-GOA/11/012), IWT-HEPSTEM, BELSPO-IUAP-DEVREPAIR, FP7-HEMIBIO (266777). We thank Prof. P. Collas and Dr. B. Izzi for their discussions related to the DNA methylation studies; Dr. D. Franckaert, Dr. S. Schlenner, and Dr. A. Van Nieuwenhuijze for their availability to operate the sorter as well as M. Welters and R. Van Rossom for technical assistance.

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disorder due to selective loss of motor neurons (MNs). Mutations in the fused in sarcoma (FUS) gene can cause both juvenile and late onset ALS. We generated and characterized induced pluripotent stem cells (iPSCs) from ALS patients with different FUS mutations, as well as from healthy controls. Patient-derived MNs show typical cytoplasmic FUS pathology, hypoexcitability, as well as progressive axonal transport defects. Axonal transport defects are rescued by CRISPR/Cas9-mediated genetic correction of the FUS mutation in patient-derived iPSCs. Moreover, these defects are reproduced by expressing mutant FUS in human embryonic stem cells (hESCs), whereas knockdown of endogenous FUS has no effect, confirming that these pathological changes are mutant FUS dependent. Pharmacological inhibition as well as genetic silencing of histone deacetylase 6 (HDAC6) increase α-tubulin acetylation, endoplasmic reticulum (ER)–mitochondrial overlay, and restore the axonal transport defects in patient-derived MNs. ; We thank Sarah Debray and Joni Vanneste for their help with iPSC culturing. We thank Balazs Toth for the initial guidance with the patch clamp experiments. We thank Franziska Bursch for helping with the patch clamp experiments. We thank Steven Boeynaems, Elke Bogaert and Benjamin Gille for guidance with the data analysis. We thank Dr Haibo Wang and Prof Muralidhar L. Hegde for warm help and nice discussions. This work was supported by the KU Leuven (C1 and "Opening the Future" Fund), the "Fund for Scientific Research Flanders" (FWO-Vlaanderen), the Agency for Innovation by Science and Technology (IWT; SBO-iPSCAF), the Belgian Government (Interuniversity Attraction Poles Programme P7/16 initiated by the Belgian Federal Science Policy Office), the Thierry Latran Foundation, the "Association Belge contre les Maladies neuro-Musculaires" (ABMM), the FWO-Vlaanderen under the frame of E-RARE-2, the ERA-Net for Research on Rare Diseases (PYRAMID), the EU Joint Programme - Neurodegenerative Disease Research (JPND) projects (STRENGTH and RiMod-FTD), the ALS Liga België (A Cure for ALS) and the Flemish governmentinitiated Flanders Impulse Program on Networks for Dementia Research (VIND). W.G. is supported by the China Scholarship Council (CSC). W.R. is supported through the E.von Behring Chair for Neuromuscular and Neurodegenerative Disorders, Geneeskundige Stichting Koningin Elisabeth (G.S.K.E.) and the European Research Council under the European's Seventh Framework Programme (FP7/2007-2013)/ ERC grant agreement No. 340429. W.B. is a postdoctoral fellow of FWO. P.V.D holds a senior clinical investigatorship of FWO-Vlaanderen. F.W. and S.P. are supported in part by the Deutsche Gesellschaft für Muskelkranke and the Initiative Therapieforschung ALS e.V. including the contribution of Elmar Siger in memory of his wife Ingrid. D.B. thanks ANR (LabEx Revive, Investissement d'Avenir, ANR-10-LABX-73) and the Association Française contre les Myopathies (AFM grant 16465) for their financial support. C.L. is a PhD fellow supported by ANR-10-LABX-73.

Hazard assessment, based on new approach methods (NAM), requires the use of batteries of assays, where individual tests may be contributed by different laboratories. A unified strategy for such collaborative testing is presented. It details all procedures required to allow test information to be usable for integrated hazard assessment, strategic project decisions and/or for regulatory purposes. The EU-ToxRisk project developed a strategy to provide regulatorily valid data, and exemplified this using a panel of > 20 assays (with > 50 individual endpoints), each exposed to 19 well-known test compounds (e.g. rotenone, colchicine, mercury, paracetamol, rifampicine, paraquat, taxol). Examples of strategy implementation are provided for all aspects required to ensure data validity: (i) documentation of test methods in a publicly accessible database; (ii) deposition of standard operating procedures (SOP) at the European Union DB-ALM repository; (iii) test readiness scoring accoding to defined criteria; (iv) disclosure of the pipeline for data processing; (v) link of uncertainty measures and metadata to the data; (vi) definition of test chemicals, their handling and their behavior in test media; (vii) specification of the test purpose and overall evaluation plans. Moreover, data generation was exemplified by providing results from 25 reporter assays. A complete evaluation of the entire test battery will be described elsewhere. A major learning from the retrospective analysis of this large testing project was the need for thorough definitions of the above strategy aspects, ideally in form of a study pre-registration, to allow adequate interpretation of the data and to ensure overall scientific/toxicological validity.

Hazard assessment, based on new approach methods (NAM), requires the use of batteries of assays, where individual tests may be contributed by different laboratories. A unified strategy for such collaborative testing is presented. It details all procedures required to allow test information to be usable for integrated hazard assessment, strategic project decisions and/or for regulatory purposes. The EU-ToxRisk project developed a strategy to provide regulatorily valid data, and exemplified this using a panel of > 20 assays (with > 50 individual endpoints), each exposed to 19 well-known test compounds (e.g. rotenone, colchicine, mercury, paracetamol, rifampicine, paraquat, taxol). Examples of strategy implementation are provided for all aspects required to ensure data validity: (i) documentation of test methods in a publicly accessible database; (ii) deposition of standard operating procedures (SOP) at the European Union DB-ALM repository; (iii) test readiness scoring accoding to defined criteria; (iv) disclosure of the pipeline for data processing; (v) link of uncertainty measures and metadata to the data; (vi) definition of test chemicals, their handling and their behavior in test media; (vii) specification of the test purpose and overall evaluation plans. Moreover, data generation was exemplified by providing results from 25 reporter assays. A complete evaluation of the entire test battery will be described elsewhere. A major learning from the retrospective analysis of this large testing project was the need for thorough definitions of the above strategy aspects, ideally in form of a study pre-registration, to allow adequate interpretation of the data and to ensure overall scientific/toxicological validity.

Hazard assessment, based on new approach methods (NAM), requires the use of batteries of assays, where individual tests may be contributed by different laboratories. A unified strategy for such collaborative testing is presented. It details all procedures required to allow test information to be usable for integrated hazard assessment, strategic project decisions and/or for regulatory purposes. The EU-ToxRisk project developed a strategy to provide regulatorily valid data, and exemplified this using a panel of > 20 assays (with > 50 individual endpoints), each exposed to 19 well-known test compounds (e.g. rotenone, colchicine, mercury, paracetamol, rifampicine, paraquat, taxol). Examples of strategy implementation are provided for all aspects required to ensure data validity: (i) documentation of test methods in a publicly accessible database; (ii) deposition of standard operating procedures (SOP) at the European Union DB-ALM repository; (iii) test readiness scoring accoding to defined criteria; (iv) disclosure of the pipeline for data processing; (v) link of uncertainty measures and metadata to the data; (vi) definition of test chemicals, their handling and their behavior in test media; (vii) specification of the test purpose and overall evaluation plans. Moreover, data generation was exemplified by providing results from 25 reporter assays. A complete evaluation of the entire test battery will be described elsewhere. A major learning from the retrospective analysis of this large testing project was the need for thorough definitions of the above strategy aspects, ideally in form of a study pre-registration, to allow adequate interpretation of the data and to ensure overall scientific/toxicological validity. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s00204-020-02802-6) contains supplementary material, which is available to authorized users.