@article{PointnerKranzWagneretal., author = {Pointner, Daniel and Kranz, Michael and Wagner, Maria Stella and Haus, Moritz and Lehle, Karla and Krenkel, Lars}, title = {Automated deep learning based detection of cellular deposits on clinically used ECMO membrane lungs}, series = {Frontiers in Bioinformatics}, volume = {6}, journal = {Frontiers in Bioinformatics}, publisher = {Frontiers}, doi = {10.3389/fbinf.2026.1771574}, pages = {18}, abstract = {Introduction: Despite the promising application of extracorporeal membrane oxygenation (ECMO) in the treatment of critically ill patients, coagulation-associated technical complications, primarily clot formation and critical bleeding, remain a major challenge during ECMO therapy. The deposition of nucleated cells on the surface has been shown, yet the role of these cells towards complication development is still matter of ongoing research. In particular, the membrane lung (MemL) is prone to clot formation. Therefore, the investigation of nuclear deposits on its hollow-fibers may provide insights for a better understanding of the cellular mechanisms involved in the development of ECMO complications. Methods: To support current research, this study aimed to develop a deep learning-based tool for the automated detection and quantitative analysis of nuclear depositions on MemL hollow-fiber mats. A customized fluorescence microscopy workflow, combined with a semi-automated iterative labeling strategy, was used to generate a high-quality dataset for model training. Results: Six configurations of instance segmentation models were evaluated, with a Mask R-CNN with ResNet 101 backbone using dilated convolution providing the most balanced performance in both nuclei count and area accuracy. Compared with U-Net-based approaches such as Cellpose or StarDist, the proposed model demonstrated superior segmentation of overlapping and low-intensity nuclei, maintaining accuracy even in densely packed cellular regions. Discussion: We present an automated image analysis tool for clinically used MemLs, which exhibit complex three-dimensional hollow-fiber architectures and irregular cellular deposits that challenge conventional tools. A dedicated graphical user interface enables streamlined detection, morphometric analysis, and spatial clustering of nuclei, establishing a reproducible workflow for high-throughput analysis of fluorescence microscopy images. This approach eliminates labor-intensive manual counting and facilitates large-scale studies on cell-fiber interactions and disease-related correlations.}, language = {en} } @misc{KranzPointnerLehleetal., author = {Kranz, Michael and Pointner, Daniel and Lehle, Karla and Lubnow, Matthias and Krenkel, Lars}, title = {High-resolution flow field investigations in membrane lungs, considering the complex blood rheology}, series = {1st European Fluid Dynamics Conference (EFDC1), 16-20.September 2024, Aachen}, journal = {1st European Fluid Dynamics Conference (EFDC1), 16-20.September 2024, Aachen}, doi = {10.35096/othr/pub-8921}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-89214}, pages = {2}, abstract = {Despite major improvements over the last years, coagulative disorders and clotting phenomena in membrane lungs (MLs) are still considerable complications in extracorporeal membrane oxygenation (ECMO). ECMO is an increasingly used treatment for patients with severe respiratory failure or cardiac arrest [1]. For both, evaluation of therapeutic decisions and fundamental research on patient specific intra-device clotting phenomena, the direct visualization and analysis of clot formation in combination with a detailed flow field correlation is highly desirable and therefore an intensively followed research topic. Modelling blood flow and shear induced coagulation in MLs is challenging. The relevant geometry of oxygenator fibers and chaining threads is complex and spans several length scales. In relevant scales and regimes, blood shows several significant non-Newtonian effects. Viscosity impacts shear rate, which is important in several coagulation mechanisms. Additionally, coagulation processes are influencing fluid properties and geometry significantly. Existing approaches of previous research work are only able to consider some, but not all relevant effects and geometrical details. Due to the enormous size of the discretized geometries, highly detailed viscosity and coagulations models are not applicable. Our goal is to develop a model for combined viscosity and coagulation properties of blood flow in MLs. In our work, we compare the influence of different levels of detail of the ML geometry as well as the influence of considering realistic blood flow behavior (viscosity change by considering the local hematocrit distribution within the F{\aa}hraeus-Lindqvist-Effect) on the resulting flow field in relevant subsections of a ML. High-resolution micro-CT geometry reconstructions [1] are compared to idealized generic fiber representations. For realistic blood flow modelling, Newtonian representation is compared to the established Carreau-Yasuda and a multiphase Euler-Euler approach. Results are presented for relevant subsections as well as for the complete ML.}, language = {en} } @misc{KranzWagnerPointneretal., author = {Kranz, Michael and Wagner, Maria Stella and Pointner, Daniel and Waldbauer, Selina and M{\"u}ller, Thomas and Lubnow, Matthias and Foltan, Maik and Krenkel, Lars and Lehle, Karla}, title = {Polymeric Embedding of Membrane Lungs: A Novel Method for Histological Investigations of Intra-Device Clot Formation}, series = {12th EuroELSO Congress, 24-27. April 2024, Krakow}, journal = {12th EuroELSO Congress, 24-27. April 2024, Krakow}, language = {en} } @inproceedings{KranzPointnerWagneretal., author = {Kranz, Michael and Pointner, Daniel and Wagner, Maria Stella and Lubnow, Matthias and Lehle, Karla and Krenkel, Lars}, title = {High-Resolution Flow Investigations in Membrane-Lungs for Understanding Shear-Induced Blood Clot Formation}, series = {New Results in Numerical and Experimental Fluid Mechanics XV : Contributions to the 24th STAB/DGLR Symposium, Regensburg, Germany, 2024}, booktitle = {New Results in Numerical and Experimental Fluid Mechanics XV : Contributions to the 24th STAB/DGLR Symposium, Regensburg, Germany, 2024}, editor = {Dillmann, Andreas and Heller, Gerd and Kr{\"a}mer, Ewald and Breitsamter, Christian and Wagner, Claus and Krenkel, Lars}, publisher = {Springer}, address = {Cham}, doi = {10.1007/978-3-032-11115-9_12}, pages = {125 -- 134}, abstract = {Complex blood flow phenomena in membrane lungs (MLs) play a crucial role in intra-device clot formation and the occurrence of thromboembolic events. At present, however, the local flow conditions within an ML are not yet sufficiently known. The aim was to gain a deeper understanding of local flow regimes inside MLs by performing highly resolved computational fluid dynamics (CFD) of generic and native fiber mat bundles. Straight cylinders with a diameter of 380 μm in parallel arrangement were the foundation of the generic model. For validation, a method for reconstructing a native geometry from a microcomputed tomography (μCT) scan was established, with both models used for CFD. While the generic model showed a symmetrical flow regime without indicating any pathological flow, the native model did show an irregular fiber arrangement and no symmetrical flow regime. In conclusion, the fiber arrangement significantly affects the local flow regimes inside MLs.}, language = {en} } @article{KranzWagnerPointneretal., author = {Kranz, Michael and Wagner, Maria Stella and Pointner, Daniel and Haus, Moritz and Lubnow, Matthias and Lehle, Karla and Krenkel, Lars}, title = {Polymer embedding of membrane lungs for histological investigations of intra-device clot formation}, series = {Cardiovascular Medicine}, volume = {13}, journal = {Cardiovascular Medicine}, publisher = {Frontiers}, address = {Lausanne}, doi = {10.3389/fcvm.2026.1650978}, pages = {21}, abstract = {Extracorporeal membrane oxygenation (ECMO) is an invasive but potentially lifesaving treatment option for severe cardiac or respiratory failure. Despite its beneficial effect, coagulation-related complications, mainly due to clot formation, excessive bleeding and the accumulation of deposits in the membrane lung (ML) remain common, causing higher mortality. In this context, the formation of clots and other deposits in the ML is of particular interest. Previous histological examinations of the polymethylpentene fiber mats inside the ML could only be performed in a top view, prohibiting valid quantification and examination of the multi-layered deposits or fiber mat spanning structures. Our objective was the establishment of a polymer embedding to increase the mechanical stability of the deposits and thus enable cross-sectional microtome cutting through the ML hollow-fibers. Clinically used MLs (PLS, Getinge, Rastatt, Germany) were stabilized with a polymer resin (HistoCURE 8100). Specimens were cut out of the embedded MLs and microtome sections with a thickness of 10 µm were performed. In addition to standard histological staining with hematoxylin-eosin (HE) and Pappenheim (May-Grunwald-Giemsa), fluorescence DNA staining for nucleated cells with 4′,6-diamidino-2-phenylindole (DAPI) and SYTOX™ Green as well as immunohistochemical and immunofluorescence staining for the lysosomal enzyme myeloperoxidase (MPO) and von Willebrand factor (vWF) were established. The protocol provides a method for large volume embedding (400 mL). The cellular and extracellular deposits were securely fixed by the polymer scaffold allowing the examination of clots in MLs in native position which was not possible with conventional paraffin embedding. Multi-layered deposits and fiber mat spanning structures are no longer disrupted during specimen extraction and can now be quantified. Staining with HE, Pappenheim, DAPI, SYTOX™ Green, MPO, and vWF was successfully tested with this protocol. This method may be the foundation for new insights into the complex clotting phenomena observed in MLs}, language = {en} } @article{WagnerKranzKrenkeletal., author = {Wagner, Maria Stella and Kranz, Michael and Krenkel, Lars and Pointner, Daniel and Foltan, Maik and Lubnow, Matthias and Lehle, Karla}, title = {Computer based visualization of clot structures in extracorporeal membrane oxygenation and histological clot investigations for understanding thrombosis in membrane lungs}, series = {Frontiers in Medicine}, journal = {Frontiers in Medicine}, number = {11}, editor = {Becatti, Matteo}, publisher = {Frontiers}, doi = {10.3389/fmed.2024.1416319}, abstract = {Extracorporeal membrane oxygenation (ECMO) was established as a treatment for severe cardiac or respiratory disease. Intra-device clot formation is a common risk. This is based on complex coagulation phenomena which are not yet sufficiently understood. The objective was the development and validation of a methodology to capture the key properties of clots deposed in membrane lungs (MLs), such as clot size, distribution, burden, and composition. One end-oftherapy PLS ML was examined. Clot detection was performed using multidetector computed tomography (MDCT), microcomputed tomography (μCT), and photography of fiber mats (fiber mat imaging, FMI). Histological staining was conducted for von Willebrand factor (vWF), platelets (CD42b, CD62P), fibrin, and nucleated cells (4′, 6-diamidino-2-phenylindole, DAPI). The three imaging methods showed similar clot distribution inside the ML. Independent of the imaging method, clot loading was detected predominantly in the inlet chamber of the ML. The μCT had the highest accuracy. However, it was more expensive and time consuming than MDCT or FMI. The MDCT detected the clots with low scanning time. Due to its lower resolution, it only showed clotted areas but not the exact shape of clot structures. FMI represented the simplest variant, requiring little effort and resources. FMI allowed clot localization and calculation of clot volume. Histological evaluation indicated omnipresent immunological deposits throughout the ML. Visually clot-free areas were covered with leukocytes and platelets forming platelet-leukocyte aggregates (PLAs). Cells were embedded in vWF cobwebs, while vWF fibers were negligible. In conclusion, the presented methodology allowed adequate clot identification and histological classification of possible thrombosis markers such as PLAs.}, language = {en} }