@article{MayerArrizabalagaLiebetal.2018, author = {Mayer, Margot and Arrizabalaga, Onetsine and Lieb, Florian and Ciba, Manuel and Ritter, Sylvia and Thielemann, Christiane}, title = {Electrophysiological investigation of human embryonic stem cell derived neurospheres using a novel spike detection algorithm}, series = {Biosensors and Bioelectronics}, volume = {2018}, journal = {Biosensors and Bioelectronics}, number = {100}, doi = {10.1016/j.bios.2017.09.034}, pages = {462 -- 468}, year = {2018}, abstract = {Microelectrode array (MEA) technology in combination with three-dimensional (3D) neuronal cell models derived from human embryonic stem cells (hESC) provide an excellent tool for neurotoxicity screening. Yet, there are significant challenges in terms of data processing and analysis, since neuronal signals have very small amplitudes and the 3D structure enhances the level of background noise. Thus, neuronal signal analysis requires the application of highly sophisticated algorithms. In this study, we present a new approach optimized for the detection of spikes recorded from 3D neurospheres (NS) with a very low signal-to-noise ratio. This was achieved by extending simple threshold-based spike detection utilizing a highly sensitive algorithm named SWTTEO. This analysis procedure was applied to data obtained from hESC-derived NS grown on MEA chips. Specifically, we examined changes in the activity pattern occurring within the first ten days of electrical activity. We further analyzed the response of NS to the GABA receptor antagonist bicuculline. With this new algorithm method we obtained more reliable results compared to the simple threshold-based spike detection.}, subject = {Embryonale Stammzelle}, language = {en} } @article{AlligMayerThielemann2018, author = {Allig, Sebastian and Mayer, Margot and Thielemann, Christiane}, title = {Workflow for bioprinting of cell-laden bioink}, series = {Lekar a technika - Clinician and Technology}, volume = {48}, journal = {Lekar a technika - Clinician and Technology}, number = {2}, pages = {46 -- 51}, year = {2018}, abstract = {Applying technologies of additive manufacturing to the field of tissue engineering created a pioneering new approach to model complex cell systems artificially. Regarding its huge potential, bioprinting is still in its infancies and many questions are still unanswered. To address this issue, an extrusion-based bioprinting (EBB) process was used to deposit human embryonic kidney (HEK) cells in a defined pattern. It was shown that the bioprinted construct featured a high degree in viability reaching up to 77\% 10 days after printing (DAP). This work displays a proof of principle for a controlled cell formation which shall later be applied to in vitro drug screening tests using various types of cells.}, subject = {Biomaterial}, language = {en} } @inproceedings{MayerArrizabalagaSchroederetal.2018, author = {Mayer, Margot and Arrizabalaga, Onetsine and Schr{\"o}der, Insa and Ritter, Sylvia and Thielemann, Christiane}, title = {Human Embryonic Stem Cell Derived Neurospheres - 2D and 3D Cell Culture in one sample}, year = {2018}, abstract = {Various studies have shown that two dimensional (2D) neuronal cell cultures does not recapitulate structure and physiology of three-dimensional (3D) in vivo tissues. These findings are of paramount importance for drug screening, since the response to neurotoxicological substances may differ for 2D und 3D cell culture models. To address this topic, we present human embryonic stem cell (hESC) derived neurospheres (NS) coupled onto microelectrode array (MEA) chips as a model system that includes a 3D NS as well as an outgrowing 2D monolayer allowing direct comparison of functionality within one culture. Preliminary results revealed an enhanced functional reactions of 3D NS to GABA receptor antagonist bicuculline compared to the 2D domain. Thus we have the first evidence that hESC derived NS are a promising model system for neurotoxicity testing enabling a direct comparison between functionality of neurons grown in 2D or 3D.}, subject = {Embryonale Stammzelle}, language = {en} } @misc{CibaMayerThielemann2019, author = {Ciba, Manuel and Mayer, Margot and Thielemann, Christiane}, title = {Experimental setup to investigate the effect of psychedelics on in vitro neuronal networks}, doi = {10.6084/m9.figshare.11980434.v1}, year = {2019}, abstract = {Experimental setup to investigate the effect of psychedelics on in vitro neuronal networks: A demonstration of the application of in vitro neuronal networks on high-density-microelectrode arrays (HDMEA) to study electrophysiological properties of neuronal networks in response to psychedelics.}, subject = {Neuronales Netz}, language = {en} } @inproceedings{MayerArrizabalagaRitteretal.2016, author = {Mayer, Margot and Arrizabalaga, Onetsine and Ritter, Sylvia and Thielemann, Christiane}, title = {Human Embryonic Stem Cell Derived Neurospheres - A Novel Three Dimensional Model For Neurotoxicological Studies}, series = {Frontiers}, volume = {2016}, booktitle = {Frontiers}, number = {MEA Meeting 2016}, doi = {10.3389/conf.fnins.2016.93.00081}, year = {2016}, abstract = {At present, most neurotoxicological studies in the field of microelectrode array (MEA) technology are based on in vivo or in vitro animal models, particularly in mice or rats. These models contributed much to our knowledge about molecular and cellular mechanisms of neurotoxins affecting the central nervous system. Yet, animal models are not necessarily capable to forecasting the effectiveness of treatment in clinical trials. Therefore the development and characterization of suitable neuronal cell models derived from human cells is emerging in the field of toxicity testing. In this study, we present neurospheres (NS) as a new three dimensional (3D) neuronal cell model based on human embryonic stem cells (hESC), coupled onto microelectrode arrays (MEA). This cell-based assay serves as platform to investigate effects of neuroactive substances on network communication. In order to characterize the neurospheres' reaction, the well-known GABA receptor antagonist bicuculline and the sodium channel blocker carbamazepine are applied. Preliminary results reveal anticipated and physiologically reasonable alterations in network activity. Thus, we have the first evidence that hESC derived NS are a promising 3D cell model for neurotoxicity testing. In further studies, this model will be used to investigate effects of ionizing radiation on network signaling.}, subject = {Mikroelektrode}, language = {en} } @phdthesis{Mayer2017, author = {Mayer, Margot}, title = {Einfluss ionisierender Strahlung auf die elektrophysiologischen Eigenschaften sich entwickelnder neuronaler Netzwerke}, school = {Technische Hochschule Aschaffenburg}, year = {2017}, subject = {Ionisierende Strahlung}, language = {de} } @article{KrstićJuettnerGiegerichetal.2023, author = {Krstić, Nenad and J{\"u}ttner, Jens and Giegerich, Lars and Mayer, Margot and Knuth, Monika and M{\"u}ller, Achim and Thielemann, Christiane}, title = {3D printed biosensor for continuous glucose measurement in cell cultures}, series = {Annals of 3D Printed Medicine}, volume = {10}, journal = {Annals of 3D Printed Medicine}, publisher = {Elsevier BV}, issn = {2666-9641}, doi = {doi.org/10.1016/j.stlm.2023.100111}, year = {2023}, subject = {Biosensor}, language = {en} } @techreport{MayerMuellerKadereitetal.2014, author = {Mayer, Margot and M{\"u}ller, Benedikt and Kadereit, Suzanne and Ritter, Sylvia and Thielemann, Christiane}, title = {Human neurospheres on microelectrode arrays: a model to investigate ionizing radiation effects on neuronal network communication}, series = {GSI SCIENTIFIC REPORT 2014}, journal = {GSI SCIENTIFIC REPORT 2014}, doi = {10.15120/GR-2015-1-APPA-HEALTH-15}, year = {2014}, subject = {Neuronales Netz}, language = {en} } @techreport{MayerRitterThielemann2013, author = {Mayer, Margot and Ritter, Sylvia and Thielemann, Christiane}, title = {Electrophysiological Effects of Ionising Radiation on Cortical Rat Neurons in vitro}, organization = {GSI Helmholtzzentrum f{\"u}r Schwerionenforschung}, year = {2013}, subject = {Nervenzelle}, language = {en} } @article{ThielemannKrstićJuettneretal.2023, author = {Thielemann, Christiane and Krstić, Nenad and J{\"u}ttner, Jens and Giegerich, Lars and Mayer, Margot and Knuth, Monika and M{\"u}ller, Achim}, title = {3D printed biosensor for continuous glucose measurement in cell cultures}, series = {Annals of 3D Printed Medicine}, volume = {2023}, journal = {Annals of 3D Printed Medicine}, number = {-}, doi = {https://doi.org/10.1016/j.stlm.2023.100111}, pages = {- -- -}, year = {2023}, abstract = {A novel 3D-printed glucose sensor is presented for cell culture application. Glucose sensing was performed using a fluorescence resonance energy transfer (FRET)-based assay principle based on ConA and dextran. Both molecules are encapsulated in alginate microspheres and embedded in the UV-curable, stable hydrogel polyvinyl alcohol (PVA). The rheology of the formulation was adapted to obtain good properties for an extrusion-based printing process. The printed sensor structures were tested for their ability to detect glucose in vitro. A proportional increase in fluorescence intensity was observed in a concentration range of 0 - 2 g/L glucose. Tests with HEK cell cultures also showed good cell compatibility and excellent adhesion properties on plasma-treated Petri dishes. The printed sensors were able to detect the glucose decay associated with the metabolic activities of the fast-growing HEK cells in the cell culture medium over ten days. The proof-of-principle study shows that metabolic processes in cell cultures can be monitored with the new printed sensor using a standard fluorescence wide-field microscope.}, subject = {Biosensor}, language = {en} } @unpublished{Mayer2023, author = {Mayer, Margot}, title = {Aberrant choroid plexus formation in human cerebral organoids exposed to radiation}, doi = {https://doi.org/10.21203/rs.3.rs-3445801/v1}, pages = {22}, year = {2023}, abstract = {Brain tumor patients are commonly treated with radiotherapy, but the efficacy of the treatment is limited by its toxicity, particularly the risk of radionecrosis. We used human cerebral organoids to investigate the mechanisms and nature of postirradiation brain image changes commonly linked to necrosis. Irradiation of cerebral organoids lead to increased formation of ZO1+/AQP1+/CLN3+-choroid plexus (CP) structures. Increased CP formation was triggered by radiation via the NOTCH/WNT signaling pathways and associated with delayed growth and neural stem cell differentiation, but not necrosis. The effect was more pronounced in immature than in mature organoids, reflecting the clinically-observed increased radiosensitivity of the pediatric brain. Protons were more effective than X-rays at the same dose, as also observed in clinical treatments. We conclude that radiation-induced brain image-changes can be attributed to aberrant CP formation, providing a new cellular mechanism and strategy for possible countermeasures.}, subject = {Hirntumor}, language = {en} } @techreport{MayerArrizabalagaRitteretal.2015, author = {Mayer, Margot and Arrizabalaga, Onetsine and Ritter, Sylvia and Thielemann, Christiane}, title = {Human embryonic stem cell derived neurospheres form functional networks on microelectrode arrays}, series = {GSI Scientific Report 2015}, volume = {2015}, journal = {GSI Scientific Report 2015}, number = {GSI Report 2016-1}, doi = {10.15120/GR-2016-1}, pages = {205 -- 205}, year = {2015}, subject = {Embryonale Stammzelle}, language = {en} } @unpublished{SchickelBenderKaysanetal.2025, author = {Schickel, Esther and Bender, Tamara and Kaysan, Leon and Hufgard, Simone and Mayer, Margot and Grosshans, David R. and Thielemann, Christiane and Schroeder, Insa S.}, title = {Human cerebral organoids model tumor infiltration and migration supported by astrocytes in an autologous setting}, series = {bioRxiv}, volume = {2025}, journal = {bioRxiv}, publisher = {Cold Spring Harbor Laboratory}, doi = {https://doi.org/10.1101/2025.01.29.635456}, pages = {43}, year = {2025}, abstract = {SummaryEfforts to achieve precise and efficient tumor targeting of highly malignant brain tumors are constrained by the dearth of appropriate models to study the effects and potential side effects of radiation, chemotherapy, and immunotherapy on the most complex human organ, the brain. We established a cerebral organoid model of brain tumorigenesis in an autologous setting by overexpressing c-MYC as one of the most common oncogenes in brain tumors. GFP+/c-MYChighcells were isolated from tumor organoids and used in two different culture approaches: assembloids comprising of a normal cerebral organoid with a GFP+/c-MYChightumor sphere and co-culture of cerebral organoid slices at air-liquid interface with GFP+/c-MYChighcells. GFP+/c-MYChighcells used in both approaches exhibited tumor-like properties, including overexpression of the c-MYC oncogene, high proliferative and invasive potential, and an immature phenotype as evidenced by increased expression of Ki-67, VIM, and CD133. Organoids and organoid slices served as suitable scaffolds for infiltrating tumor-like cells. Using our highly reproducible and powerful model system that allows long-term culture, we demonstrated that the migratory and infiltrative potential of tumor-like cells is shaped by the environment in which glia cells provide support to tumor-like cells.}, subject = {Hirntumor}, language = {en} } @article{SchickelBenderKaysanetal.2025, author = {Schickel, Esther and Bender, Tamara and Kaysan, Leon and Hufgard, Simone and Mayer, Margot and Grosshans, David R. and Thielemann, Christiane and Schroeder, Insa S.}, title = {Human cerebral organoids model tumor initiation and infiltration in an autologous astrocyte-supported setting}, series = {iScience}, journal = {iScience}, publisher = {Elsevier BV}, issn = {2589-0042}, doi = {https://doi.org/10.1016/j.isci.2025.113334}, year = {2025}, abstract = {Efforts to efficiently target brain tumors are constrained by the dearth of appropriate models to study tumor behavior towards treatment approaches as well as potential side effects to the surrounding normal tissue. We established a reproducible cerebral organoid model of brain tumorigenesis in an autologous setting by overexpressing c-MYC, a common oncogene in brain tumors. GFP+/c-MYChigh cells were isolated from tumor organoids and used in two different approaches: GFP+/c-MYChigh cells co-cultured with cerebral organoid slices or fused as spheres to whole organoids. GFP+/c-MYChigh cells used in both approaches exhibited tumor-like properties, including an immature phenotype and a highly proliferative and invasive potential. We demonstrate that the latter is influenced by astrocytes supporting the GFP+/c-MYChigh cells while X-ray irradiation significantly kills and impairs tissue infiltration of GFP+/c-MYChigh cells. In summary, the model represents major features of tumorous and adjacent normal tissue and may be used to evaluate appropriate cancer treatments.}, subject = {Hirntumor}, language = {en} } @inproceedings{HufgardMayerSchroederetal.2025, author = {Hufgard, Simone and Mayer, Margot and Schroeder, Insa S. and Thielemann, Christiane}, title = {3D compartmentilisation for analyzing functional long-range connectivity between brain regions}, series = {4th Microphysiological Systems World Summit, Brussels, Belgium}, booktitle = {4th Microphysiological Systems World Summit, Brussels, Belgium}, number = {June 2025}, year = {2025}, subject = {Hirnareal}, language = {en} } @article{FlachsEtzelMayeretal.2022, author = {Flachs, Dennis and Etzel, Johannes and Mayer, Margot and Harbecke, Frederic and Belle, Stefan and Rickmeyer, Tim and Thielemann, Christiane}, title = {Characterization of electrically conductive, printable ink based on alginate hydrogel and graphene nanoplatelets}, series = {Biomedical Engineering Advances}, volume = {2022}, journal = {Biomedical Engineering Advances}, number = {4}, doi = {https://doi.org/10.1016/j.bea.2022.100045}, pages = {1 -- 2}, year = {2022}, abstract = {In recent years, there has been an increasing interest in electrically conductive hydrogels for a wide range of biomedical applications, like tissue engineering or biosensors. In this study, we present a cost-effective conductive hydrogel based on alginate and graphene nanoplatelets for extrusion-based bioprinters. The hydrogel is prepared under ambient conditions avoiding high temperatures detrimental for cell culture environments. Investigation of the hydrogel revealed a conductivity of up to 7.5 S/cm, depending on the ratio of platelets. Furthermore, in vitro tests with human embyronic kidney cells - as an example cell type - showed good adhesion of the cells to the surface of the conductive hydrogel. Electrochemical measurements revealed a low electrode impedance which is desirable for the extracellular recording, but also low electrode capacitance, which is unfavorable for electrical stimulation purposes. Therefore, future experiments with the graphene nanoplatelets-based hydrogels will focus on electrodes for biosensors and extracellular recordings of neurons or cardiac myocytes.}, subject = {Hydrogel}, language = {en} }