351
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Alzheimer's-associated PLCγ2 is a signaling node required for both TREM2 function and the inflammatory response in human microglia. Nat Neurosci 2020; 23:927-938. [PMID: 32514138 DOI: 10.1038/s41593-020-0650-6] [Citation(s) in RCA: 127] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 05/01/2020] [Indexed: 02/08/2023]
Abstract
Human genetic data indicate that microglial dysfunction contributes to the pathology of Alzheimer's disease (AD), exemplified by the identification of coding variants in triggering receptor expressed on myeloid cells 2 (TREM2) and, more recently, in PLCG2, a phospholipase-encoding gene expressed in microglia. Although studies in mouse models have implicated specific Trem2-dependent microglial functions in AD, the underlying molecular mechanisms and translatability to human disease remain poorly defined. In this study, we used genetically engineered human induced pluripotent stem cell-derived microglia-like cells to show that TREM2 signals through PLCγ2 to mediate cell survival, phagocytosis, processing of neuronal debris, and lipid metabolism. Loss of TREM2 or PLCγ2 signaling leads to a shared signature of transcriptional dysregulation that underlies these phenotypes. Independent of TREM2, PLCγ2 also signals downstream of Toll-like receptors to mediate inflammatory responses. Therefore, PLCγ2 activity regulates divergent microglial functions via distinct TREM2-dependent and -independent signaling and might be involved in the transition to a microglial state associated with neurodegenerative disease.
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352
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Deczkowska A, Weiner A, Amit I. The Physiology, Pathology, and Potential Therapeutic Applications of the TREM2 Signaling Pathway. Cell 2020; 181:1207-1217. [DOI: 10.1016/j.cell.2020.05.003] [Citation(s) in RCA: 143] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 04/15/2020] [Accepted: 04/30/2020] [Indexed: 12/20/2022]
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353
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Qin Z, Gu M, Zhou J, Zhang W, Zhao N, Lü Y, Yu W. Triggering receptor expressed on myeloid cells 2 activation downregulates toll-like receptor 4 expression and ameliorates cognitive impairment in the Aβ 1-42 -induced Alzheimer's disease mouse model. Synapse 2020; 74:e22161. [PMID: 32412103 DOI: 10.1002/syn.22161] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 04/18/2020] [Accepted: 05/04/2020] [Indexed: 01/15/2023]
Abstract
Increasing evidence suggests that changes in the triggering receptor expressed on myeloid cells 2 (TREM2) is closely correlated with the pathological development of Alzheimer's disease (AD). However, the biological function and related role of this change remain poorly understood. Higher TREM2 expression has been reported in the brain of AD patients than in normal controls. Here, levels of TREM2 gene and protein levels were observed to be higher in both cortex and hippocampus of the Aβ1-42 -induced AD mice than in those of the wild type mice. Together with in vitro experimental data, we found that the anti-inflammatory role of TREM2 was, to some extent, limited and potentially counteracted by the hyperactive toll-like receptor 4 (TLR4) in the AD mice. In this context, Interleukin 4 (IL-4), as an agonist of TREM2, was administered to the AD mice to persistently activate TREM2. Interestingly, TREM2 activation in IL-4-treated AD mice led to an elevation in lysosomes and microtubule-associated protein 1 light chain 3 (LC3) II/I expression, demonstrating that the level of microglia autophagy was increased. Increased autophagy significantly downregulated the expression levels of caspase recruitment domain-containing protein 9 (CARD9) and TLR4, potentially weakening the CARD9-TLR4 pathway and suppressing the TLR4-mediated pro-inflammatory effect in IL-4-treated AD mice. Furthermore, data acquired from Morris water maze testing indicated that IL-4 administration could ameliorate cognitive impairment in the AD mice. In conclusion, the findings from in vitro and in vivo experiments suggest that TREM2 might represent a potential drug target to treat neuroinflammation in AD.
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Affiliation(s)
- Zhangjin Qin
- Department of Human Anatomy, Institute of Neuroscience, Chongqing Medical University, Chongqing, China.,Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Min Gu
- Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Jian Zhou
- Department of Human Anatomy, Institute of Neuroscience, Chongqing Medical University, Chongqing, China
| | - Wenbo Zhang
- Department of Human Anatomy, Institute of Neuroscience, Chongqing Medical University, Chongqing, China.,Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Nan Zhao
- Department of Human Anatomy, Institute of Neuroscience, Chongqing Medical University, Chongqing, China
| | - Yang Lü
- Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Weihua Yu
- Department of Human Anatomy, Institute of Neuroscience, Chongqing Medical University, Chongqing, China
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354
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Gutierrez E, Lütjohann D, Kerksiek A, Fabiano M, Oikawa N, Kuerschner L, Thiele C, Walter J. Importance of γ-secretase in the regulation of liver X receptor and cellular lipid metabolism. Life Sci Alliance 2020; 3:3/6/e201900521. [PMID: 32354700 PMCID: PMC7195048 DOI: 10.26508/lsa.201900521] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 04/16/2020] [Accepted: 04/17/2020] [Indexed: 12/12/2022] Open
Abstract
Inhibition of the Alzheimer associated γ-secretase impairs the regulation of cellular lipid droplet homeostasis. Presenilins (PS) are the catalytic components of γ-secretase complexes that mediate intramembrane proteolysis. Mutations in the PS genes are a major cause of familial early-onset Alzheimer disease and affect the cleavage of the amyloid precursor protein, thereby altering the production of the amyloid β-peptide. However, multiple additional protein substrates have been identified, suggesting pleiotropic functions of γ-secretase. Here, we demonstrate that inhibition of γ-secretase causes dysregulation of cellular lipid homeostasis, including up-regulation of liver X receptors, and complex changes in the cellular lipid composition. Genetic and pharmacological inhibition of γsecretase leads to strong accumulation of cytoplasmic lipid droplets, associated with increased levels of acylglycerols, but lowered cholesteryl esters. Furthermore, accumulation of lipid droplets was augmented by increasing levels of amyloid precursor protein C-terminal fragments, indicating a critical involvement of this γ-secretase substrate. Together, these data provide a mechanism that functionally connects γ-secretase activity to cellular lipid metabolism. These effects were also observed in human astrocytic cells, indicating an important function of γ-secretase in cells critical for lipid homeostasis in the brain.
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Affiliation(s)
| | - Dieter Lütjohann
- Institute of Clinical Chemistry and Clinical Pharmacology, University of Bonn, Bonn, Germany
| | - Anja Kerksiek
- Institute of Clinical Chemistry and Clinical Pharmacology, University of Bonn, Bonn, Germany
| | - Marietta Fabiano
- Department of Neurology, University Hospital Bonn, Bonn, Germany
| | - Naoto Oikawa
- Department of Neurology, University Hospital Bonn, Bonn, Germany
| | - Lars Kuerschner
- Life and Medical Sciences Institute, University of Bonn, Bonn, Germany
| | - Christoph Thiele
- Life and Medical Sciences Institute, University of Bonn, Bonn, Germany
| | - Jochen Walter
- Department of Neurology, University Hospital Bonn, Bonn, Germany
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355
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Scearce-Levie K, Sanchez PE, Lewcock JW. Leveraging preclinical models for the development of Alzheimer disease therapeutics. Nat Rev Drug Discov 2020; 19:447-462. [PMID: 32612262 DOI: 10.1038/s41573-020-0065-9] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/26/2020] [Indexed: 02/06/2023]
Abstract
A large number of mouse models have been engineered, characterized and used to advance biomedical research in Alzheimer disease (AD). Early models simply damaged the rodent brain through toxins or lesions. Later, the spread of genetic engineering technology enabled investigators to develop models of familial AD by overexpressing human genes such as those encoding amyloid precursor protein (APP) or presenilins (PSEN1 or PSEN2) carrying mutations linked to early-onset AD. Recently, more complex models have sought to explore the impact of multiple genetic risk factors in the context of different biological challenges. Although none of these models has proven to be a fully faithful reproduction of the human disease, models remain essential as tools to improve our understanding of AD biology, conduct thorough pharmacokinetic and pharmacodynamic analyses, discover translatable biomarkers and evaluate specific therapeutic approaches. To realize the full potential of animal models as new technologies and knowledge become available, it is critical to define an optimal strategy for their use. Here, we review progress and challenges in the use of AD mouse models, highlight emerging scientific innovations in model development, and introduce a conceptual framework for use of preclinical models for therapeutic development.
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356
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Abstract
Microglia exhibit differing functions and phenotypes depending on life stage and the context of health or disease. Recently, in Nature Neuroscience, Marschallinger et al. (2020) described a new state of microglia, namely "lipid-droplet-accumulating microglia" (LDAM), that contributes to neuronal inflammation and age-related neurodegeneration.
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Affiliation(s)
- Eun Sun Jung
- Department of Biochemistry and Biomedical Sciences, Seoul National University, College of Medicine, Seoul 03080, South Korea; Neuroscience Research Institute, Seoul National University, College of Medicine, Seoul 03080, South Korea; SNU Dementia Research Center, Seoul National University, College of Medicine, Seoul 03080, South Korea
| | - Inhee Mook-Jung
- Department of Biochemistry and Biomedical Sciences, Seoul National University, College of Medicine, Seoul 03080, South Korea; Neuroscience Research Institute, Seoul National University, College of Medicine, Seoul 03080, South Korea; SNU Dementia Research Center, Seoul National University, College of Medicine, Seoul 03080, South Korea.
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357
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Schlepckow K, Monroe KM, Kleinberger G, Cantuti‐Castelvetri L, Parhizkar S, Xia D, Willem M, Werner G, Pettkus N, Brunner B, Sülzen A, Nuscher B, Hampel H, Xiang X, Feederle R, Tahirovic S, Park JI, Prorok R, Mahon C, Liang C, Shi J, Kim DJ, Sabelström H, Huang F, Di Paolo G, Simons M, Lewcock JW, Haass C. Enhancing protective microglial activities with a dual function TREM2 antibody to the stalk region. EMBO Mol Med 2020; 12:e11227. [PMID: 32154671 PMCID: PMC7136959 DOI: 10.15252/emmm.201911227] [Citation(s) in RCA: 147] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 02/12/2020] [Accepted: 02/17/2020] [Indexed: 01/07/2023] Open
Abstract
Triggering receptor expressed on myeloid cells 2 (TREM2) is essential for the transition of homeostatic microglia to a disease-associated microglial state. To enhance TREM2 activity, we sought to selectively increase the full-length protein on the cell surface via reducing its proteolytic shedding by A Disintegrin And Metalloproteinase (i.e., α-secretase) 10/17. We screened a panel of monoclonal antibodies against TREM2, with the aim to selectively compete for α-secretase-mediated shedding. Monoclonal antibody 4D9, which has a stalk region epitope close to the cleavage site, demonstrated dual mechanisms of action by stabilizing TREM2 on the cell surface and reducing its shedding, and concomitantly activating phospho-SYK signaling. 4D9 stimulated survival of macrophages and increased microglial uptake of myelin debris and amyloid β-peptide in vitro. In vivo target engagement was demonstrated in cerebrospinal fluid, where nearly all soluble TREM2 was 4D9-bound. Moreover, in a mouse model for Alzheimer's disease-related pathology, 4D9 reduced amyloidogenesis, enhanced microglial TREM2 expression, and reduced a homeostatic marker, suggesting a protective function by driving microglia toward a disease-associated state.
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Affiliation(s)
- Kai Schlepckow
- German Center for Neurodegenerative Diseases (DZNE) MunichMunichGermany
| | | | - Gernot Kleinberger
- Metabolic BiochemistryBiomedical Center (BMC)Faculty of MedicineLudwig‐Maximilians‐Universität MünchenMunichGermany
- Present address:
ISAR Bioscience GmbHPlaneggGermany
| | | | - Samira Parhizkar
- Metabolic BiochemistryBiomedical Center (BMC)Faculty of MedicineLudwig‐Maximilians‐Universität MünchenMunichGermany
| | - Dan Xia
- Denali Therapeutics Inc.South San FranciscoCAUSA
| | - Michael Willem
- Metabolic BiochemistryBiomedical Center (BMC)Faculty of MedicineLudwig‐Maximilians‐Universität MünchenMunichGermany
| | - Georg Werner
- Metabolic BiochemistryBiomedical Center (BMC)Faculty of MedicineLudwig‐Maximilians‐Universität MünchenMunichGermany
| | - Nadine Pettkus
- Metabolic BiochemistryBiomedical Center (BMC)Faculty of MedicineLudwig‐Maximilians‐Universität MünchenMunichGermany
| | - Bettina Brunner
- German Center for Neurodegenerative Diseases (DZNE) MunichMunichGermany
| | - Alice Sülzen
- German Center for Neurodegenerative Diseases (DZNE) MunichMunichGermany
| | - Brigitte Nuscher
- Metabolic BiochemistryBiomedical Center (BMC)Faculty of MedicineLudwig‐Maximilians‐Universität MünchenMunichGermany
| | - Heike Hampel
- Metabolic BiochemistryBiomedical Center (BMC)Faculty of MedicineLudwig‐Maximilians‐Universität MünchenMunichGermany
| | - Xianyuan Xiang
- Metabolic BiochemistryBiomedical Center (BMC)Faculty of MedicineLudwig‐Maximilians‐Universität MünchenMunichGermany
- Graduate School of Systemic NeuroscienceLudwig‐Maximilians‐Universität MünchenMunichGermany
| | - Regina Feederle
- German Center for Neurodegenerative Diseases (DZNE) MunichMunichGermany
- Munich Cluster for Systems Neurology (SyNergy)MunichGermany
- Helmholtz Center MunichGerman Research Center for Environmental HealthInstitute for Diabetes and ObesityCore Facility Monoclonal Antibody DevelopmentMunichGermany
| | - Sabina Tahirovic
- German Center for Neurodegenerative Diseases (DZNE) MunichMunichGermany
| | | | | | - Cathal Mahon
- Denali Therapeutics Inc.South San FranciscoCAUSA
| | | | - Ju Shi
- Denali Therapeutics Inc.South San FranciscoCAUSA
- Present address:
Jazz PharmaceuticalsPalo AltoCAUSA
| | - Do Jin Kim
- Denali Therapeutics Inc.South San FranciscoCAUSA
| | | | - Fen Huang
- Denali Therapeutics Inc.South San FranciscoCAUSA
| | | | - Mikael Simons
- German Center for Neurodegenerative Diseases (DZNE) MunichMunichGermany
- Munich Cluster for Systems Neurology (SyNergy)MunichGermany
- Institute of Neuronal Cell Biology (TUM‐NZB)MunichGermany
| | | | - Christian Haass
- German Center for Neurodegenerative Diseases (DZNE) MunichMunichGermany
- Metabolic BiochemistryBiomedical Center (BMC)Faculty of MedicineLudwig‐Maximilians‐Universität MünchenMunichGermany
- Munich Cluster for Systems Neurology (SyNergy)MunichGermany
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358
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Gordon S, Plüddemann A, Mukhopadhyay S. Plasma membrane receptors of tissue macrophages: functions and role in pathology. J Pathol 2020; 250:656-666. [PMID: 32086805 DOI: 10.1002/path.5404] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Accepted: 02/18/2020] [Indexed: 12/11/2022]
Abstract
The cells of the mononuclear phagocyte system (MPS) constitute a dispersed organ, which is distributed throughout the body. Macrophages in different tissues display distinctive mosaic phenotypes as resident and recruited cells of embryonic and bone marrow origin, respectively. They help to maintain homeostasis during development and throughout adult life, yet contribute to the pathogenesis of many disease processes, including inflammation, innate and adaptive immunity, metabolic disorders, and cancer. Heterogeneous tissue macrophage populations display a wide variety of surface molecules to recognise and respond to host, microbial, and exogenous ligands in their environment; their receptors mediate the uptake and destruction of effete and dying host cells and pathogens, as well as contribute trophic and secretory functions within every organ in the body. Apart from local cellular interactions, macrophage surface molecules and products serve to mobilise and coordinate systemic humoral and cellular responses. Their use as antigen markers in pathogenesis and as potential drug targets has lagged in clinical pathology and human immunotherapy. In this review, we summarise the properties of selected surface molecules expressed on macrophages in different tissues and disease processes, to provide a functional basis for diagnosis, further research, and treatment. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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Affiliation(s)
- Siamon Gordon
- College of Medicine, Graduate Institute of Biomedical Sciences, Chang Gung University, Taoyuan City, Taiwan.,Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Annette Plüddemann
- Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK
| | - Subhankar Mukhopadhyay
- Peter Gorer Department of Immunobiology, Medical Research Council Centre for Transplantation, King's College London, London, UK
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359
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360
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Reich M, Paris I, Ebeling M, Dahm N, Schweitzer C, Reinhardt D, Schmucki R, Prasad M, Köchl F, Leist M, Cowley SA, Zhang JD, Patsch C, Gutbier S, Britschgi M. Alzheimer's Risk Gene TREM2 Determines Functional Properties of New Type of Human iPSC-Derived Microglia. Front Immunol 2020; 11:617860. [PMID: 33613545 PMCID: PMC7887311 DOI: 10.3389/fimmu.2020.617860] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 12/29/2020] [Indexed: 12/17/2022] Open
Abstract
Microglia are key in the homeostatic well-being of the brain and microglial dysfunction has been implicated in neurodegenerative disorders such as Alzheimer's disease (AD). Due to the many limitations to study microglia in situ or isolated for large scale drug discovery applications, there is a high need to develop robust and scalable human cellular models of microglia with reliable translatability to the disease. Here, we describe the generation of microglia-like cells from human induced pluripotent stem cells (iPSC) with distinct phenotypes for mechanistic studies in AD. We started out from an established differentiation protocol to generate primitive macrophage precursors mimicking the yolk sac ontogeny of microglia. Subsequently, we tested 36 differentiation conditions for the cells in monoculture where we exposed them to various combinations of media, morphogens, and extracellular matrices. The optimized protocol generated robustly ramified cells expressing key microglial markers. Bulk mRNA sequencing expression profiles revealed that compared to cells obtained in co-culture with neurons, microglia-like cells derived from a monoculture condition upregulate mRNA levels for Triggering Receptor Expressed On Myeloid Cells 2 (TREM2), which is reminiscent to the previously described disease-associated microglia. TREM2 is a risk gene for AD and an important regulator of microglia. The regulatory function of TREM2 in these cells was confirmed by comparing wild type with isogenic TREM2 knock-out iPSC microglia. The TREM2-deficient cells presented with stronger increase in free cytosolic calcium upon stimulation with ATP and ADP, as well as stronger migration towards complement C5a, compared to TREM2 expressing cells. The functional differences were associated with gene expression modulation of key regulators of microglia. In conclusion, we have established and validated a work stream to generate functional human iPSC-derived microglia-like cells by applying a directed and neuronal co-culture independent differentiation towards functional phenotypes in the context of AD. These cells can now be applied to study AD-related disease settings and to perform compound screening and testing for drug discovery.
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Affiliation(s)
- Marvin Reich
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland.,In Vitro Toxicology and Biomedicine, Department inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, Konstanz, Germany
| | - Iñaki Paris
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland.,Achucarro Basque Center for Neuroscience, Science Park of the UPV/EHU, Leioa, Spain
| | - Martin Ebeling
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Nadine Dahm
- Roche Pharma Research and Early Development, Therapeutic Modalities, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Christophe Schweitzer
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Dieter Reinhardt
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Roland Schmucki
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Megana Prasad
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Fabian Köchl
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Marcel Leist
- In Vitro Toxicology and Biomedicine, Department inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, Konstanz, Germany
| | - Sally A Cowley
- James Martin Stem Cell Facility, Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Jitao David Zhang
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Christoph Patsch
- Roche Pharma Research and Early Development, Therapeutic Modalities, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Simon Gutbier
- Roche Pharma Research and Early Development, Therapeutic Modalities, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Markus Britschgi
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
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