mikela

• Martinez, Mikel Amirola; Combriat, Thomas Michel Daniel; Ferencevic, Katharina; Wilhelmsen, Ingrid; Dalmao-Fernandez, Andrea & Olsen, Petter Angell [Vis alle 9 forfattere av denne artikkelen] (2025). Aspects of zone-like identity and holotomographic tracking of human stem cell-derived liver sinusoidal endothelial cells. Frontiers in Cell and Developmental Biology. 13. doi: 10.3389/fcell.2025.1528991. Fulltekst i vitenarkiv Vis sammendrag

  Introduction: Liver sinusoidal endothelial cells (LSEC) are specialized endothelial cells with unique metabolic and barrier functions adapted to the needs of the liver sinusoid. LSECs are highly sensitive to their environment, and this fragile nature causes challenges in analyzing their phenotype under in vitro conditions. Methods: In this work, we first differentiated LSEC-like cells (scLSECs) from two human pluripotent stem cell lines and characterized them by a panel of qPCR markers, immunohistochemistry, substrate oxidation for energy metabolism, scavenger function, and nitric oxide secretion. We then introduced holotomography, a technique that allows to recover quantitative and three-dimensional information about the refractive indexes of cell components, as a tool to image and track scLSEC in vitro in a minimally intrusive, label-free manner. Results and discussion: Holotomography and developed machine learning-based algorithm for image processing allowed us to describe and monitor changes in intracellular pore-like structures over time. Finally, we tested the possibility of inducing aspects of zone-specific LSEC phenotype and metabolism using culture-based treatments, which resulted in modest shifts in marker expression and metabolic activity. The presented strategy provides an advanced tool kit for investigating liver endothelial cells.

• Wilhelmsen, Ingrid; Martinez, Mikel Amirola; Stokowiec, Justyna; Wang, Chencheng; Aizenshtadt, Aleksandra & Krauss, Stefan Johannes Karl (2023). Characterization of human stem cell-derived hepatic stellate cells and liver sinusoidal endothelial cells during extended in vitro culture. Frontiers in Bioengineering and Biotechnology. 11. doi: 10.3389/fbioe.2023.1223737. Fulltekst i vitenarkiv Vis sammendrag

  Background: There is a significant need for predictive and stable in vitro human liver representations for disease modeling and drug testing. Hepatic stellate cells (HSCs) and liver sinusoidal endothelial cells (LSECs) are important non-parenchymal cell components of the liver and are hence of relevance in a variety of disease models, including hepatic fibrosis. Pluripotent stem cell- (PSC-) derived HSCs (scHSCs) and LSECs (scLSECs) offer an attractive alternative to primary human material; yet, the suitability of scHSCs and scLSECs for extended in vitro modeling has not been characterized. Methods: In this study, we describe the phenotypic and functional development of scHSCs and scLSECs during 14 days of 2D in vitro culture. Cell-specific phenotypes were evaluated by cell morphology, immunofluorescence, and gene- and protein expression. Functionality was assessed in scHSCs by their capacity for intracellular storage of vitamin A and response to pro-fibrotic stimuli induced by TGF-β. scLSECs were evaluated by nitric oxide- and factor VIII secretion as well as endocytic uptake of bioparticles and acetylated low-density lipoprotein. Notch pathway inhibition and co-culturing scHSCs and scLSECs were separately tested as options for enhancing long-term stability and maturation of the cells. Results and Conclusion: Both scHSCs and scLSECs exhibited a post-differentiation cell type-specific phenotype and functionality but deteriorated during extended culture with PSC line-dependent variability. Therefore, the choice of PSC line and experimental timeframe is crucial when designing in vitro platforms involving scHSCs and scLSECs. Notch inhibition modestly improved long-term monoculture in a cell line-dependent manner, while co-culturing scHSCs and scLSECs provides a strategy to enhance phenotypic and functional stability.

• Busek, Mathias; Aizenshtadt, Aleksandra; Martinez, Mikel Amirola; Delon, Ludivine Sylvie Claude & Krauss, Stefan Johannes Karl (2022). Academic User View: Organ-on-a-Chip Technology. Biosensors. ISSN 2079-6374. 12(2). doi: 10.3390/bios12020126. Fulltekst i vitenarkiv Vis sammendrag

  The pleasantness of gentle stroking (CT-targeted touch) varies highly between individuals and studies, indicating that relevant factors may not be accounted for. We propose that the affective value of a touch event is determined by how well its perceived purpose matches the goals of the touch receiver. The perceived purpose or meaning of touch is in turn informed by the sensory characteristics together with the setting, person factors, and the touchee’s expectations. Affective touch is often a sign of affection, intended to soothe or show support. In a typical lab study however, the toucher is a stranger and its purpose is research. The purpose of laboratory touch is nevertheless compatible with the goal of participants, namely to contribute to research. To fully understand how the perception of affective touch emerges, more studies should directly manipulate participants’ beliefs about the purpose of touch.

• Skottvoll, Frøydis Sved; Aizenshtadt, Aleksandra; Hansen, Frederik Andre; Martinez, Mikel Amirola; Andersen, Jannike Mørch & Bogen, Inger Lise [Vis alle 11 forfattere av denne artikkelen] (2022). Direct Electromembrane Extraction-Based Mass Spectrometry: A Tool for Studying Drug Metabolism Properties of Liver Organoids. Analysis & Sensing. 2(2). doi: 10.1002/anse.202100051. Fulltekst i vitenarkiv Vis sammendrag

  This work introduces a strategy for organoid analysis - direct Electromembrane Extraction based Mass Spectrometry (dEME-MS) – for coupling liver organoids with mass spectrometry (MS). dEME-MS comprises electrophoresis of selected small molecules from a culture chamber across an oil membrane, and to a MS compatible solution. This enables clean micro-extraction of drugs and their metabolites as produced in the liver organoids to capillary liquid chromatography-mass spectrometry. Applying dEME-MS, proof-of-concept of directly measuring methadone metabolism is demonstrated on adult liver organoids. With 50 liver organoids and 1 μM methadone, methadone metabolism was monitored from 0 to 24 hours (11 time points). All analytes had <0.4 % variance in retention times with >100 measurements. dEME-MS is capable of automated and selective monitoring of drug metabolism in liver organoids, and could serve as a valuable tool for automated drug discovery efforts.

• Busek, Mathias; Aizenshtadt, Aleksandra; Koch, Timo; Frank, Anna; Delon, Ludivine Sylvie Claude & Martinez, Mikel Amirola [Vis alle 12 forfattere av denne artikkelen] (2022). Pump-less, recirculating organ-on-a-chip (rOoC) platform. Lab on a Chip. ISSN 1473-0197. s. 345–361. doi: 10.1039/d2lc00919f. Fulltekst i vitenarkiv Vis sammendrag

  We developed a novel, pump-less directional flow recirculating organ-on-a-chip (rOoC) platform that creates controlled unidirectional gravity-driven flow by a combination of a 3D-tilting system and an optimized microfluidic layout. The rOoC platform was assembled utilizing a layer-to-layer fabrication technology based on thermoplastic materials. It features two organoid compartments supported by two independent perfusion channels and separated by a hydrogel barrier. We developed a computational model to predict wall shear stress values and then measured the flow rate in the microfluidic channels with micro-Particle-Image-Velocimetry (μPIV). The suitability of the rOoC for functional culture of endothelial cells was tested using HUVECs seeded in the perfusion channels. HUVECs aligned in response to the directional flow, formed a barrier and were able to sprout into the organoid compartments. Next, we demonstrated the viability of human stem-cell derived liver organoids in the organoid compartments. Finally, we show the possibility to circulate immune cells in the microfluidic channels that retain viability without being trapped or activated. The rOoC platform allows growing and connecting of two or more tissue or organ representations on-chip with the possibility of applying gradients, endothelial barriers, microvasculature and circulating cells independent of external tubing and support systems.

• Busek, Mathias; Nøvik, Steffen; Aizenshtadt, Aleksandra; Martinez, Mikel Amirola; Combriat, Thomas Michel Daniel & Grünzner, Stefan [Vis alle 7 forfattere av denne artikkelen] (2021). Thermoplastic elastomer (Tpe)–poly(methyl methacrylate) (pmma) hybrid devices for active pumping pdms-free organ-on-a-chip systems. Biosensors. ISSN 2079-6374. 11(5). doi: 10.3390/bios11050162. Fulltekst i vitenarkiv Vis sammendrag

  Polydimethylsiloxane (PDMS) has been used in microfluidic systems for years, as it can be easily structured and its flexibility makes it easy to integrate actuators including pneumatic pumps. In addition, the good optical properties of the material are well suited for analytical systems. In addition to its positive aspects, PDMS is well known to adsorb small molecules, which limits its usability when it comes to drug testing, e.g., in organ-on-a-chip (OoC) systems. Therefore, alternatives to PDMS are in high demand. In this study, we use thermoplastic elastomer (TPE) films thermally bonded to laser-cut poly(methyl methacrylate) (PMMA) sheets to build up multilayered microfluidic devices with integrated pneumatic micro-pumps. We present a low-cost manufacturing technology based on a conventional CO2 laser cutter for structuring, a spin-coating process for TPE film fabrication, and a thermal bonding process using a pneumatic hot-press. UV treatment with an Excimer lamp prior to bonding drastically improves the bonding process. Optimized bonding parameters were characterized by measuring the burst load upon applying pressure and via profilometer-based measurement of channel deformation. Next, flow and long-term stability of the chip layout were measured using microparticle Image Velocimetry (uPIV). Finally, human endothelial cells were seeded in the microchannels to check biocompatibility and flow-directed cell alignment. The presented device is compatible with a real-time live-cell analysis system.

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