@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} } @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} } @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} } @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} } @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} }