Dimitra Thomaidou | Neural Stem Cells and Neuro-Imaging Group

Head of the Group

Contact:

210 6478833 | .img@.img |  CV

RESEARCH INTERESTS

Direct lineage reprogramming has emerged as a promising, fast approach for manipulating cell fate to obtain customized functional neuronal cell types. A step further, utilization of endogenous brain cells that can be directly reprogrammed into neurons, remains a challenge with important clinical applications for the treatment of neurodegeneration.
Our group is interested in studying the transcriptional and epigenetic mechanisms governing direct lineage reprogramming to induced neurons (iNs), as well as, exploiting the mode of action of novel genes and miRNAs in promoting neuronal trans-differentiation of somatic cell types.  To this end, we are using transgenic mice expressing in their CNS fluorescent proteins in a subtype-specific manner and recombinant viral vectors expressing neurogenic molecules of interest in order to:
A) Explore the regenerative potential of neurogenic genes and neurogenesis-modulating miRNAs in directing the reprogramming of activated astroglia both in vitro and in vivo following traumatic brain injury towards a neuronal phenotype and
B) Follow, by intravital whole animal 2-photon imaging, astroglia-microglia dynamics,, interactions and reprogramming properties in real time in whole anaesthetized mice, following acute and chronic brain injury and inflammation.

RESEARCH PROGRAMS

Generation of neurons by in vitro direct reprogramming of mouse and human cortical astrocytes and embryonic fibroblasts


Recent studies demonstrate that various cell types, including brain astrocytes and skin fibroblasts, can be reprogrammed to neural precursor cells (NPCs) and neurons via challenging certain genes levels. Our aim is to investigate whether in lineage distant somatic cell types residing inside and outside the CNS can be turned into NPCs and neurons upon forced expression of factors that induce neurogenesis during development. To this end we have demonstrated that: a) the neurogenic molecule CEND1 can reprogram mouse astrocytes towards GABA+ neurons and acts synergistically with NEUROG2 to trans-differentiate them towards proliferating NPCs and subtype-specific neurons, b) CEND1 and NEUROG2 possess a broader neurogenic potential, inducing neuronal reprogramming of MEFs , c) CEND1 is a key downstream player in NEUROG2-induced astrocytic reprogramming participating in a positive feedback loop leading to neurogenesis and d) Double over-expression of CEND1 and NEUROG2 results in activation of Wnt/ beta-catenin signaling pathway driving astrocytes to acquire NSC multipotent character. Taken together, our results demonstrate that CEND1 is not only a potent inducer of neuronal differentiation in neural precursor cells as previously shown (Katsimpardi et al., 2008), but has a neurogenic capacity in different cell contexts. Currently we are expanding our studies to exploiting the mechanisms of direct cell reprogramming of human primary astrocytes to functional neurons through neurogenic molecules forced expression.

Members involved
Katerina Aravantinou-Fatorou

Relevant publications
Aravantinou-Fatorou  K, Ortega, F,  Chroni-Tzartou D., Antoniou, Poulopoulou C., N., Politis P.K., Berninger B. Matsas R and Thomaidou D. (2015) Cend1 and Neurogenin2 reprogram mouse astrocytes and embryonic fibroblasts to induced neural precursor cells and differentiated neurons, Stem Cell Reports; 5(3): 405-18.

Direct reprogramming of reactive astrocytes to differentiated neurons in vitro and in vivo following forced expression of neurogenic miRNAs

miRNAs have emerged as critical post-transcriptional modulators of gene expression by simultaneously targeting multiple genes, thus they appear as attractive candidates to regulate direct cell reprogramming through fine-tuning the expression levels of neurogenic factors. Our efforts are focusing towards the identification of miRNAs that are potent to induce direct cell reprogramming of primary astrocytes to induced-neurons (iNs) in vitro and in vivo and elucidation of their mechanisms of action at the transcriptional and epigenetic level. To this end we are using neurogenic miRNA-mimics and recombinant viral vectors expressing selected neurogenic miRNAs along with fluorescent proteins to: a) in vitro explore the coding and non-coding transcriptome and DNA methylation profile of reprogrammed astrocytes with next generation sequencing and epigenome profiling and b) assess the capacity of certain neurogenic miRNAs to instruct direct neuronal reprogramming of astrocytes following their in vivo forced expression in animal models of brain trauma.

Members involved
Elsa Papadimitriou, Pari Koutsoudaki, Irini Thanou, Argyro Lambrou

Relevant publications

Thomaidou  D. (2014) Neural Stem Cells transplantation in an animal model of traumatic brain injury; Methods Mol. Biol., 1210: 9-21.

Study of Neurovascular Unit (NVU) interactions and dynamics after acute and chronic brain injury: an open window into the brain through intravital 2-photon imaging

The term “Neurovascular Unit” (NVU) is used to describe the integrated system of vascular and neuronal cells and the surrounding glia working in concert to enable proper brain homeostasis and function. The NVU is affected in many CNS conditions and plays a role in their pathology thus study of the cellular interactions in the pathological NVU could contribute to the identification of numerous potential targets for treatment in the context of CNS neurodegeneration/ neuroinflammation. The dynamics of such processes can be adequately captured by in vivo 2-photon imaging, which allows the study of cellular responses to environmental stimuli and cell-cell interactions in the living brain in real time. Accordingly, to explore the dynamic interactions of the NVU following acute and chronic brain injury, we are monitoring by intravital 2-photon imaging the morphological changes of perivascular astrocytes, as well as their dynamic interactions with perivascular microglia and blood vessels under physiological conditions and during LPS-induced systemic inflammation or laser-induced acute brain injury, using transgenic mice expressing fluorescent proteins under astroglia-, microglia- and pericyte-specific promoters

Members involved
Pari Koutsoudaki, Katerina Aravantinou, Evangelia  Xingi  (Light Microscopy Unit), Ioanna Giaglissi, Ioanna Tzioti

Effect of chemical brain lesion on adult neurogenesis occurring in neurogenic and non-neurogenic brain areas

Adult mammalian brain neural stem/progenitor cells have a spatially restricted distribution and neurogenesis takes place only in specific brain areas. However recently, it has been proposed that a low level of neurogenesis also occurs in “non-neurogenic regions”, such as the striatum and to a lesser extent the cortex. Importantly, brain lesions have succeeded to unmask neurogenic activity in such regions in laboratory rodents. To this end we are investigating whether disturbance of the adult mouse SVZ, through stereotaxic intraventricular injections of mitotoxic/chemotherapeutic agents activates cells of neighboring non-neurogenic regions to acquire a neural progenitor potential. Our current data support the hypothesis that administration of mitotoxic/chemotherapeutic agents in the cerebrospinal fluid (CSF) is responsible for SVZ disruption and ectopic presence of newborn neurons in non-neurogenic areas. The fact that several mitotoxic factors are widely used as chemotherapeutic agents and that patients undergoing chemotherapy exhibit progressive cognitive deficits, raises the question whether these treatments lead to disruption of neurogenesis. Therefore, further study of this SVZ-disorganization model will shed light into important questions related to NPCs and parenchymal brain cells’ response to chemotherapeutic treatment.

Members involved
Irini Thanou (PhD), Pari Koutsoudaki

Role of extracellular HSP-90 (eHSP-90) on Breast Cancer Stem Cells proliferation properties (Collaboration with Prof. Evangelia Patsavoudi, Technological Educational Institute of Athens)

In recent years, increasing evidence indicates that cancer originates from a small fraction of tumor initiating cells with the abilities of self-renewal, unlimited propagation, multipotent differentiation and giving rise to all types of differentiated cells of the tumor population. These cells are called cancer stem cells (CSCs). Of major importance is the resistance that these cells appear to exhibit to the conventional methods of cancer therapy such as chemotherapy and radiotherapy. Cytoplasmic HSP90 has been implicated in the development and progression of cancer. Additionally, increasing evidence reveals an extracellular chaperoning activity for HSP90 during cancer cell invasion and metastasis. In this collaborative study with the group of Dr Patsavoudi we explore the presence of HSP90 in breast CSC and we show for the first time that eHSP90 is over-expressed in mammosphere cultures that are derived from breast cancer cell lines thus indicating that eHSP90 represents a potential novel BCSC marker. Moreover, we present evidence that eHSP90 is functionally involved in BCSC activity in vitro and in vivo, as selective neutralization of eHSP90, using the monoclonal antibody mAb 4C5, has the capacity to inhibit stem cell activity in vitro and significant regression of mammosphere-derived tumors in vivo both in prophylactic and therapeutic 4C5 administration protocols.

Relevant publications

Stivarou T, Stellas D, Vartzi G, Thomaidou D and Patsavoudi E (2016) MAb 4C5 targeting eHSP90, inhibits breast cancer stem cell derived tumor growth in vitro and in vivo. Cancer Biol. Ther.; 2; 17(8):799-812.
Thomaidou D and Patsavoudi E. (2015) Extracellular HSP90 in cancer invasion and metastasis: from translational research to clinical prospects, J. Analyt. Oncol.(Invited Review) 4(4):178-190.

Implications of δ-opioid receptor activation and RGS4 in STAT5B activation in neural stem cells proliferation/ differentiation – (Collaboration with Dr Zafiroula Georgoussi, National Centre for Scientific Research “Demokritos”)

The Regulator of G protein Signaling 4 (RGS4) is a multitask protein that negatively modulates opioid receptor signaling. Previously the group of Dr Georgoussi, has showed that the δ-opioid receptor (δ-OR) forms a multiprotein signaling complex consisting of Gi/Go proteins and the Signal Transducer and Activator of Transcription 5B (STAT5B) that leads to neuronal differentiation and neurite outgrowth upon δ-ΟR activation. In this collaborative project we have investigated the role of RGS4 in signaling pathways regulating neurotropic events using primary neuronal and adult NSC cultures derived from RGS4 knock-out (KO) mice. It has been demonstrated that RGS4 interacts directly with STAT5B independently of δ-ΟR presence. An intruiging finding is that RGS4 implicated in neuronal sprouting and enhanced proliferation of NSCs, with concomitant increase in the mRNA levels of the anti-apoptotic STAT5B target genes bcl2 and bcl-xl. These observations suggest that RGS4 is implicated in opioid dependent neuronal differentiation and neurite outgrowth via a “non-canonical” signaling pathway regulating STAT5B-directed responses.

Members Involved

Elsa Papadimitriou

Relevant Publications 
Pallaki P, Papadimitriou E, Georganta E.M, Serafimidis I, Papakonstantinou M.P, Agalou A, Koutloglou S, Symeonof A, Tserga A, Papanikolaou V, Thomaidou D, Gaitanou M. and Georgoussi Z. (2017) A novel regulatory role of RGS4 in STAT5B activation and its effect on neural precursors proliferation and neurite outgrowth Neuropharmacology; 117:408-421.

FUNDING

  • Fondation Santé- 2017: “Elucidation of miRNA-mediated transcription and epigenetic mechanisms controlling trans-differentiation of astrocytes to induced neurons” (PI).
  • Ministry of Education Insfrastructure 2014-2020 Grant BIOIMAGING-GR 2017-2020: BioImaging-GR: A Greek Research Infrastructure for Visualizing and Monitoring Fundamental Biological Processes, Coordinated by N. Tavernarakis (PI). For more information about funding see the link below Bioimaging funding
  • Stavros Niarchos Foundation Grant 2016-2020: Development of innovative biological products and services for infectious and neurodegenerative diseases, Coordinated by R. Matsas & V. Miriagou (PI).
  • Greek Ministry of Education 2012-2015: EXCELLENCE II GRANT 3713 –ASTRO-TRACE: Astroglia activation and reprogramming in brain injury and repair: an open window into the brain through intravital imaging (PI).
  • IKYDA-2014 Greek German Grant, 2014-2015: Astroglia activation and reprogramming in brain injury and repair: analysis by in vivo imaging (2P-LSM) of the brain (PI).
  • General Secretariat for Research and Technology – European Social Fund (ESF) and the Greek State, Action “KRIPIS” of the Operational Strategic Reference Framework, NSFR 2007-2013 GRANT InfeNeuTra – MIS450598: Infectious and neurodegenerative diseases in the 21st century: study of basic mechanisms for the development of the translational research and cutting edge technologies aiming to effective diagnosis prevention and therapy, Coordinated by K. Karagouni (PI).
  • Institut Pasteur International Network and Carnot Foundation 2013 Grant for organization of RIIP Regional Course: Digital image processing/analysis tools in Light Microscopy: From the basics and beyond, Organized by H. Boleti, D. Thomaidou , J.C. Olivo -Marin.
  • EPEAK Archimidis Grant HEATSTEMAB, 2012-2014: Study of Heat Shock Protein 90 in Cancer Stem Cells properties, Coordinated by E. Patsavoudi (PI).
  • EU FP7 Program Grant 264083 NEUROSIGN 2010-2013: Development of a Centre of Excellence in Neurosignalling, Coordinated by S. Tzartos – (WP leader responsible for Insfrastructure Acquisition and In Vivo Imaging).
  • Institut Pasteur Paris Grand Program Horizontal (GPH), 2004-2008. Stem Cells: Control of Stem Cells Neurogenesis in the Adult Brain, Coordinated by J.M. Heard (PI).
  • Greek General Secretariat of Research and Technology Human Networks of Scientific and Technological Training Program, 2004-2005. Applications of light microscopy in Biomedical Research and Diagnosis (co-PI with H. Boleti).
  • Greek General Secretariat of Research and Technology (GSRT) and British Council Program of Greek-English Collaboration. 2005-2007 Elucidation of the function of the neurogenic gene bm88 in a mouse knock-out model (PI).
  • Greek General Secretariat for Research and Technology Programme EPAN, 2004-2006: Neural Stem Cell Therapies for Neurodegenerative Diseases: Determination of a “molecular signature” for neuronal fate, YB26, Coordinated by R. Matsas (PI).

TEACHING and TRAINING ACTIVITIES

Dimitra Thomaidou has the following record in educational activities:

Teaching in undergraduate and postgraduate courses at the University of Athens/Department of Biology, Medical School, Nursery School, University of Patras/Medical School, University of Alexandroupolis Molecular Biology School and Athens International Master’s Programme in Neurosciences that launched in 2017 as part of the Network of European Neuroscience Schools (NENS).

Teaching and providing laboratory training of post-graduate students of EPEAK post-graduate courses on “Molecular Medicine” and “Clinical Biochemistry-Molecular Diagnosis”.

Training of numerous under-graduate and post-graduate students of HPI and other Greek Universities/Research Institutes in Confocal & Multiphoton Microscopy and Live Cell Imaging technologies.

The following workshops have been organized or co-organized by our group:

2013 International Digital image processing/analysis tools in Light Microscopy: From the basics and beyond”, supported by the Institut Pasteur International Network (RIIP) and the Carnot Foundation (2013) HPI, Athens.
2013 EU-REGPOT ‘NeuroSign’ European training workshop on: Live Cell Imaging and Electrophysiology, HPI, Athens.
2012 EU-REGPOT ‘NeuroSign’ European training workshop on: Animal models of neurodegeneration and assessment of motor and cognitive function, HPI, Athens
2004 -2005 Workshops on Modern light microscopy techniques in biomedical research” HPI, Athens.
2003 FENS/IBRO Winter School: NEURAL STEM CELLS from specification and nervous system patterning to therapies for neurodegenerative diseases,  Kitzbuhel, Austria.

Chapters in Books

Thomaidou D. (2014) Neural Stem Cells transplantation in an animal model of traumatic brain injury, in “Stem Cell and Tissue Repair: Methods and Protocols”. Published by Springer, Chryssa Kioussi editor (Chapter 2).

Thomaidou D., Politis PK., and Matsas R. (2010) Neurogenesis in the Central Nervous System: Cell cycle progression / exit and differentiation of neuronal progenitors, in “Cell Cycle Regulation and Differentiation in Cardiovascular and Neural Systems”, published by Springer Verlag., Antonio Giordano and Umberto Galderisi editors (Chapter 8).

SELECTED PUBLICATIONS

Picture

Pallaki P, Papadimitriou E, Georganta E.M, Serafimidis I, Papakonstantinou M.P, Agalou A, Koutloglou S, Symeonof A, Tserga A, Papanikolaou V, Thomaidou D, Gaitanou M. and Georgoussi Z. (2017) A novel regulatory role of RGS4 in STAT5B activation and its effect on neural precursors proliferation and neurite outgrowth Neuropharmacology; 117:408-421.

2017
Picture

Stivarou T, Stellas D, Vartzi G, Thomaidou D and Patsavoudi E (2016) MAb 4C5 targeting eHSP90, inhibits breast cancer stem cell derived tumor growth in vitro and in vivo. Cancer Biol. Ther.; 2; 17(8):799-812.

2016
Picture

Aravantinou-Fatorou  K, Ortega, F,  Chroni-Tzartou D., Antoniou, Poulopoulou C., N., Politis P.K., Berninger B.  Matsas R and Thomaidou D. (2015) Cend1 and Neurogenin2 reprogram mouse astrocytes and embryonic fibroblasts to induced neural precursor cells and differentiated neurons, Stem Cell Reports; 5(3): 405-18.

Thomaidou D and Patsavoudi E. (2015) Extracellular HSP90 in cancer invasion and metastasis: from translational research to clinical prospects, J. Analyt. Oncol.(Invited Review)  4(4):178-190.

2015
Picture

Thomaidou  D. (2014) Neural Stem Cells transplantation in an animal model of traumatic brain injury; Methods Mol. Biol., 1210: 9-21.

2014
Picture

Ziavra D., Makri G, Giompres P., Taraviras S., Thomaidou D, Matsas R, Mitsacos A, Kouvelas ED (2012). “Embryonic Stem Cells transplanted in the striatum of a mouse model of Parkinson’s disease differentiate to neuronal phenotypes and reduce rotational deficit CNS Neurol. Disord. Drug Targets. 11(7):829-35.

2012
Picture

Elkouris M, Balaskas N, Poulou M, Politis PK, Panayiotou E, Malas S, Thomaidou D, Remboutsika E (2011). Sox1 maintains the undifferentiated state of cortical neural progenitor cells via the suppression of Prox1-mediated cell cycle exit and neurogenesis. Stem Cells 29: 89-98.

2011
Picture

Lavdas AΑ., Chen J., Papastefanaki F., Schachner M. Matsas R., and Thomaidou D. (2010). Transplantation of Schwann cells over-expressing L1 enhance functional recovery in a mouse spinal cord compression model Exp. Neurol. 221:206-216.

Makri G., Lavdas A., Katsimpardi L., Thomaidou D.* and Matsas R.* (2010). Transplantation of embryonic neural stem/ precursor cells overexpressing BM88/Cend1 enhances the generation of neuronal cells in the injured mouse cortex. Stem Cells, 28: 127-139. *joint senior authors

2010
Picture

Katsimpardi L., Gaitanou M., Malnou C., Charneau P., Lledo PM., Matsas R. and Thomaidou D. (2008) BM88/Cend1 expression levels are critical for proliferation and differentiation of subventricular zone-derived   neural precursor cells. Stem Cells, 26: 1796-807.

Politis PK, Thomaidou D, Matsas R. (2008) Coordination of cell cycle exit and differentiation of neuronal progenitors. Cell Cycle. Mar 15;7(6):691-7.

2008
Picture

Georgopoulou, N., Hurel, C., Politis P., Gaitanou, M Matsas R. and Thomaidou D. (2006) BM88 is a dual function molecule inducing cell cycle exit and neuronal differentiation of neuroblastoma cells via cyclin D1 down-regulation and pRb hypophosphorylation  JBC, 281: 33606-33620.

2006
Picture

Koutmani Y., Hurel, C.  Patsavoudi E., Haeck M., Gotz M.,  Thomaidou D.* and Matsas R. * *equal contribution. (2004) “BM88 is a marker of proliferating neuroblasts that will differentiate into the neuronal lineage”, Eur. J. Neurosci. 20:2509-23.

2004

SCIENCE and SOCIETY

Communicating science to the public is an important for all members of our group. To this end we are participating in several dissemination activities including:

  • European Researchers’ Night
  • Athens Science Festival
  • Brain Awarness Week (public events organized by the Hellenic Society for Neurosciences and the Dana Alliance for Brain Research)
  • Lectures to high school students organized in HPI

GROUP MEMBERS / COLLABORATORS

Dimitra Thomaidou

Head of the Group
Email: .img@.img

Katerina Aravantinou-Fatorou

Post-doctoral Fellow
Email: .img@.img

Elsa Papadimitriou

Post-doctoral Fellow
Email: .img@.img

Irini Thanou

PhD Student
Nursery School University of Athens
Email: .img@.img

Ioanna Tsioti

MSc Student in Biomedical Sciences
Medical Department, University of Ioannina

Argyro Lambrou

BSc Student
Biology Department University of Athens

TITLE 09

COLLABORATORS

Prof. Dr. Frank  Kirchhoff, University of Saarland, Germany : Intravital Imaging of the CNS
Prof. Dr. Katerina  Akassoglou , UCSF, USA: Intravital Imaging of Astroglia Dynamics
Prof. Dr. Benedikt  Berninger, University of Mainz, Germany: Astrocytic Reprogramming
Prof. Dr. Federico Calegari, Technical University Dresden, Germany: In vivo Astrocytic Activation
Dr. Jean-Christophe Olivo-Marin, Institut Pasteur Paris: Digital Image Processing
Dr. Pierre-Marie Lledo, Institut Pasteur Paris:  Adult Neurogenesis
Dr. Pierre Charneau, Institut Pasteur Paris: Viral Vecterology
Dr. Pablo Navarro-Gil, Institut Pasteur Paris: Epigenetic regulation of cell reprogramming
Dr. Eric Batsché, Institut Pasteur Paris: Epigenetic regulation of cell reprogramming
Dr. Jean-Yves Coppée, Institut Pasteur Paris: Next Generation Sequencing
Dr. Federico Luzzati, University of Turin: Adult neurogenesis, Aastrocytic Activation
Dr. Francis Szele, University of Oxford: Adult Neurogenesis
Pari Koutsoudaki, Medical School, University of Athens

ALUMNI

Yassemi Koutmani, Laboratory Technician, Biomedical Research Foundation, Academy of Athens
Lida Katsimpardi| Researcher, Department of Neuroscience, Institute Pasteur Paris
Georgia Makri, Post-Doc in Johns Hopkins University (2010-2015)

Top