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Ursula Theocharidis

Bio: Ursula Theocharidis is an academic researcher from Ruhr University Bochum. The author has contributed to research in topics: Neural stem cell & Stem cell. The author has an hindex of 6, co-authored 10 publications receiving 284 citations.

Papers
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Journal ArticleDOI
TL;DR: It is concluded that neural stem/progenitor cell subpopulations reside in neurospheres that are distinguishable by their responsiveness to FGF‐2 and EGF which is differentially regulated by CS‐carbohydrate structures.
Abstract: The neural stem cell niche of the embryonic and adult forebrain is rich in chondroitin sulfate glycosaminoglycans (CS-GAGs) that represent complex linear carbohydrate structures on the cell surface of neural stem/progenitor cells or in their intimate environment. We reported earlier that the removal of CS-GAGs with the bacterial enzyme chondroitinase ABC (ChABC) reduced neural stem/progenitor cell proliferation and self-renewal, whereas this treatment favored astroglia formation at the expense of neurogenesis. Here, we studied the consequences of CS-deglycanation further and revealed that CS-GAGs are selectively required for neurosphere formation, proliferation, and self-renewal of embryonic cortical neural stem/progenitor cells in response to fibroblast growth factor (FGF)-2. Consistently, the FGF-2-dependent activation of the MAPKinase in neural stem/progenitor cells was diminished after ChABC treatment, but unaltered after epidermal growth factor (EGF) stimulation. Upon EGF treatment, fewer radial glia were brain lipid-binding protein (BLBP)-positive, whereas more were glutamate aspartate transporter (GLAST)-positive after CS-GAG removal. Only in this latter situation, GLAST-positive radial glia cells extended processes that supported neuronal migration from differentiating neurospheres. CS-deglycanation also selectively increased astrocyte numbers and their migration in response to EGF. Thus, our approach revealed that CS-GAGs are essential for FGF-2-mediated proliferation and maintenance of neuron-generating neural stem/progenitor cells. Simultaneously, CS-GAGs act as a brake on the EGF-dependent maturation, migration, and gliogenesis of neural stem/progenitor cells. We conclude that neural stem/progenitor cell subpopulations reside in neurospheres that are distinguishable by their responsiveness to FGF-2 and EGF which is differentially regulated by CS-carbohydrate structures.

103 citations

Journal ArticleDOI
TL;DR: The present review focuses on glioblastoma multiforme (GBM) and points out that extracellular matrix (ECM) molecules and their complementary receptors influence the behavior of NSCs/CSCs as well as brain tumor progression.

71 citations

Journal ArticleDOI
TL;DR: The current state of research suggesting that tenascin‐C plays an important modulatory role with regard to neural stem and glial progenitor cell proliferation and differentiation is discussed and tenascIn‐C and/or ‐derived peptides may be promising tools for the construction of synthetic stem cell environments.

57 citations

Book ChapterDOI
TL;DR: Increasing evidence is summarized that the extracellular matrix (ECM) of the stem cell environment is of crucial importance for the biology of this cellular compartment.
Abstract: Neural stem cells (NSCs) derive from the neuroepithelium of the neural tube, develop into radial glial cells, and recede at later developmental stages. In the adult, late descendants of these embryonic NSCs reside in discretely confined areas of the central nervous system, the stem cell niches. The best accepted canonical niches are the subventricular zone of the lateral ventricle and the subgranular zone of the dentate gyrus of the hippocampus. Stem cell niches provide a privileged environment to NSCs that supports self-renewal and maintenance of this cellular compartment. While numerous studies have highlighted the importance of transcription factors, morphogens, cytokines, and growth factors as intrinsic and extrinsic factors of stem cell regulation, less attention has been paid to the molecular micromilieu that characterizes the stem cell niches. In this chapter, we summarize increasing evidence that the extracellular matrix (ECM) of the stem cell environment is of crucial importance for the biology of this cellular compartment. A deeper understanding of the molecular composition of the ECM, the complementary receptors, and the signal transduction pathways engaged may prove highly relevant for harnessing NSCs in the context of biotechnological applications.

53 citations

Journal ArticleDOI
TL;DR: Estimation of the expression pattern of Tnc variants after cortical lesions and after treatment of astrocytes with various cytokines suggests that TGFbeta1 could mediate, at least in part, the injury-induced upregulation of these isoforms.

33 citations


Cited by
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Journal ArticleDOI
TL;DR: The complex ECM structure is emphasized as to provide a better understanding of its dynamic structural and functional multipotency and the implication of the various families of ECM macromolecules in health and disease is presented.

1,379 citations

Journal ArticleDOI
TL;DR: A number of distinct features of the brain tumor microenvironment are discussed, including brain-resident cell types, the blood-brain barrier, and various aspects of the immune-suppressive environment.

1,011 citations

Journal ArticleDOI
TL;DR: The proposed nomenclature encompasses forty-three distinct proteoglycan-encoding genes and many alternatively-spliced variants and is based on three criteria: Cellular and subcellular location, overall gene/protein homology, and the utilization of specific protein modules within their respective protein cores.

856 citations

Journal ArticleDOI
TL;DR: A comparison of molecular pathways activated after injury with those involved in the normal neural stem cell niches highlights strategies that could overcome the inhibition of neurogenesis outside the stem cell niche and instruct parenchymal glia towards a neurogenic fate.
Abstract: Astrocyte-like cells, which act as stem cells in the adult brain, reside in a few restricted stem cell niches. However, following brain injury, glia outside these niches acquire or reactivate stem cell potential as part of reactive gliosis. Recent studies have begun to uncover the molecular pathways involved in this process. A comparison of molecular pathways activated after injury with those involved in the normal neural stem cell niches highlights strategies that could overcome the inhibition of neurogenesis outside the stem cell niche and instruct parenchymal glia towards a neurogenic fate. This new view on reactive glia therefore suggests a widespread endogenous source of cells with stem cell potential, which might potentially be harnessed for local repair strategies.

506 citations

Journal ArticleDOI
TL;DR: A review of hydrogel-based biomaterial inks and bioinks for 3D printing can be found in this paper, where the authors provide a comprehensive overview and discussion of the tailorability of material, mechanical, physical, chemical and biological properties.
Abstract: 3D printing alias additive manufacturing can transform 3D virtual models created by computer-aided design (CAD) into physical 3D objects in a layer-by-layer manner dispensing with conventional molding or machining. Since the incipiency, significant advancements have been achieved in understanding the process of 3D printing and the relationship of component, structure, property and application of the created objects. Because hydrogels are one of the most feasible classes of ink materials for 3D printing and this field has been rapidly advancing, this Review focuses on hydrogel designs and development of advanced hydrogel-based biomaterial inks and bioinks for 3D printing. It covers 3D printing techniques including laser printing (stereolithography, two-photon polymerization), extrusion printing (3D plotting, direct ink writing), inkjet printing, 3D bioprinting, 4D printing and 4D bioprinting. It provides a comprehensive overview and discussion of the tailorability of material, mechanical, physical, chemical and biological properties of hydrogels to enable advanced hydrogel designs for 3D printing. The range of hydrogel-forming polymers covered encompasses biopolymers, synthetic polymers, polymer blends, nanocomposites, functional polymers, and cell-laden systems. The representative biomedical applications selected demonstrate how hydrogel-based 3D printing is being exploited in tissue engineering, regenerative medicine, cancer research, in vitro disease modeling, high-throughput drug screening, surgical preparation, soft robotics and flexible wearable electronics. Incomparable by thermoplastics, thermosets, ceramics and metals, hydrogel-based 3D printing is playing a pivotal role in the design and creation of advanced functional (bio)systems in a customizable way. An outlook on future directions of hydrogel-based 3D printing is presented.

427 citations