@misc{ScharfenbergMottokArtmannetal., author = {Scharfenberg, Georg and Mottok, J{\"u}rgen and Artmann, Christina and Hobelsberger, Martin and Paric, Ivan and Großmann, Benjamin and Pohlt, Clemens and Wackerbarth, Alena and Pausch, Uli and Heidrich, Christiane and Fadanelli, Martin and Elsner, Michael and P{\"o}cher, Daniel and Pittroff, Lenz and Beer, Stefan and Br{\"u}ckl, Oliver and Haslbeck, Matthias and Sterner, Michael and Thema, Martin and Muggenthaler, Nicole and Lenck, Thorsten and G{\"o}tz, Philipp and Eckert, Fabian and Deubzer, Michael and Stingl, Armin and Simsek, Erol and Kr{\"a}mer, Stefan and Großmann, Benjamin and Schlegl, Thomas and Niedersteiner, Sascha and Berlehner, Thomas and Joblin, Mitchell and Mauerer, Wolfgang and Apel, Sven and Siegmund, Janet and Riehle, Dirk and Weber, Joachim and Palm, Christoph and Zobel, Martin and Al-Falouji, Ghassan and Prestel, Dietmar and Scharfenberg, Georg and Mandl, Roland and Deinzer, Arnulf and Halang, W. and Margraf-Stiksrud, Jutta and Sick, Bernhard and Deinzer, Renate and Scherzinger, Stefanie and Klettke, Meike and St{\"o}rl, Uta and Wiech, Katharina and Kubata, Christoph and Sindersberger, Dirk and Monkman, Gareth J. and Dollinger, Markus and Dembianny, Sven and K{\"o}lbl, Andreas and Welker, Franz and Meier, Matthias and Thumann, Philipp and Swidergal, Krzysztof and Wagner, Marcus and Haug, Sonja and Vernim, Matthias and Seidenst{\"u}cker, Barbara and Weber, Karsten and Arsan, Christian and Schone, Reinhold and M{\"u}nder, Johannes and Schroll-Decker, Irmgard and Dillinger, Andrea Elisabeth and Fuchshofer, Rudolf and Monkman, Gareth J. and Shamonin (Chamonine), Mikhail and Geith, Markus A. and Koch, Fabian and {\"U}hlin, Christian and Schratzenstaller, Thomas and Saßmannshausen, Sean Patrick and Auchter, Eberhard and Kriz, Willy and Springer, Othmar and Thumann, Maria and Kusterle, Wolfgang and Obermeier, Andreas and Udalzow, Anton and Schmailzl, Anton and Hierl, Stefan and Langer, Christoph and Schreiner, Rupert}, title = {Forschungsbericht / Ostbayerische Technische Hochschule Regensburg}, editor = {Baier, Wolfgang}, address = {Regensburg}, organization = {Ostbayerische Technische Hochschule Regensburg}, isbn = {978-3-00-048589-3}, doi = {10.35096/othr/pub-1386}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-13867}, language = {de} } @article{KheiroddinSchoeberlAlthammeretal., author = {Kheiroddin, Parastoo and Sch{\"o}berl, Patricia and Althammer, Michael and Cibali, Ezgi and W{\"u}rfel, Thea and Wein, Hannah and Kulawik, Birgit and Buntrock-D{\"o}pke, Heike and Weigl, Eva and Gran, Silvia and Gr{\"u}ndl, Magdalena and Langguth, Jana and Lampl, Benedikt and Judex, Guido and Niggel, Jakob and Pagel, Philipp and Schratzenstaller, Thomas and Schneider-Brachert, Wulf and Gastiger, Susanne and Bodenschatz, Mona and Konrad, Maike and Levchuk, Artem and Roth, Cornelius and Sch{\"o}ner, David and Schneebauer, Florian and Rohrmanstorfer, Ren{\´e} and Burkovski, Andreas and Ambrosch, Andreas and Wagner, Thomas and Kabesch, Michael}, title = {Results of WICOVIR Gargle Pool PCR Testing in German Schools Based on the First 100,000 Tests}, series = {Frontiers in Pediatrics}, volume = {9}, journal = {Frontiers in Pediatrics}, editor = {Buonsenso, Danilo}, publisher = {frontiers}, issn = {2296-2360}, doi = {10.3389/fped.2021.721518}, abstract = {Background: Opening schools and keeping children safe from SARS-CoV-2 infections at the same time is urgently needed to protect children from direct and indirect consequences of the COVID-19 pandemic. To achieve this goal, a safe, efficient, and cost-effective SARS-CoV-2 testing system for schools in addition to standard hygiene measures is necessary. Methods: We implemented the screening WICOVIR concept for schools in the southeast of Germany, which is based on gargling at home, pooling of samples in schools, and assessment of SARS-CoV-2 by pool rRT-PCR, performed decentralized in numerous participating laboratories. Depooling was performed if pools were positive, and results were transmitted with software specifically developed for the project within a day. Here, we report the results after the first 13 weeks in the project. Findings: We developed and implemented the proof-of-concept test system within a pilot phase of 7 weeks based on almost 17,000 participants. After 6 weeks in the main phase of the project, we performed >100,000 tests in total, analyzed in 7,896 pools, identifying 19 cases in >100 participating schools. On average, positive children showed an individual CT value of 31 when identified in the pools. Up to 30 samples were pooled (mean 13) in general, based on school classes and attached school staff. All three participating laboratories detected positive samples reliably with their previously established rRT-PCR standard protocols. When self-administered antigen tests were performed concomitantly in positive cases, only one of these eight tests was positive, and when antigen tests performed after positive pool rRT-PCR results were already known were included, 3 out of 11 truly positive tests were also identified by antigen testing. After 3 weeks of repetitive WICOVIR testing twice weekly, the detection rate of positive children in that cohort decreased significantly from 0.042 to 0.012 (p = 0.008). Interpretation: Repeated gargle pool rRT-PCR testing can be implemented quickly in schools. It is an effective, valid, and well-received test system for schools, superior to antigen tests in sensitivity, acceptance, and costs.}, subject = {Covid-19}, language = {en} } @misc{WeberDendorferSuessetal., author = {Weber, Karsten and Dendorfer, Sebastian and S{\"u}ß, Franz and Kubowitsch, Simone and Schratzenstaller, Thomas and Haug, Sonja and Mohr, Christa and Kiesl, Hans and Drechsler, J{\"o}rg and Westner, Markus and Kobus, J{\"o}rn and Schubert, Martin J. W. and Zenger, Stefan and Pietsch, Alexander and Weiß, Josef and Hinterseer, Sebastian and Schieck, Roland and Scherzinger, Stefanie and Klettke, Meike and Ringlstetter, Andreas and St{\"o}rl, Uta and Bissyand{\´e}, Tegawend{\´e} F. and Seeburger, Achim and Schindler, Timo and Ramsauer, Ralf and Kiszka, Jan and K{\"o}lbl, Andreas and Lohmann, Daniel and Mauerer, Wolfgang and Maier, Johannes and Scorna, Ulrike and Palm, Christoph and Soska, Alexander and Mottok, J{\"u}rgen and Ellermeier, Andreas and V{\"o}gele, Daniel and Hierl, Stefan and Briem, Ulrich and Buschmann, Knut and Ehrlich, Ingo and Pongratz, Christian and Pielmeier, Benjamin and Tyroller, Quirin and Monkman, Gareth J. and Gut, Franz and Roth, Carina and Hausler, Peter and Bierl, Rudolf and Prommesberger, Christian and Ławrowski, Robert Damian and Langer, Christoph and Schreiner, Rupert and Huang, Yifeng and She, Juncong and Ottl, Andreas and Rieger, Walter and Kraml, Agnes and Poxleitner, Thomas and Hofer, Simon and Heisterkamp, Benjamin and Lerch, Maximilian and Sammer, Nike and Golde, Olivia and Wellnitz, Felix and Schmid, Sandra and Muntschick, Claudia and Kusterle, Wolfgang and Paric, Ivan and Br{\"u}ckl, Oliver and Haslbeck, Matthias and Schmidt, Ottfried and Schwanzer, Peter and Rabl, Hans-Peter and Sterner, Michael and Bauer, Franz and Steinmann, Sven and Eckert, Fabian and Hofrichter, Andreas}, title = {Forschungsbericht 2017}, editor = {Baier, Wolfgang}, address = {Regensburg}, organization = {Ostbayerische Technische Hochschule Regensburg}, isbn = {978-3-9818209-3-5}, doi = {10.35096/othr/pub-1383}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-13835}, subject = {Forschung}, language = {de} } @inproceedings{GeithSommerSchratzenstalleretal., author = {Geith, Markus A. and Sommer, Gerhard and Schratzenstaller, Thomas and Holzapfel, Gerhard A.}, title = {First Approaches in Quantifying Acute Vascular Damage due to Stenting}, series = {23rd Congress of the European Society of Biomechanics, July 2-5,2017, Seville, Spain}, booktitle = {23rd Congress of the European Society of Biomechanics, July 2-5,2017, Seville, Spain}, subject = {Stent}, language = {en} } @article{GeithEckmannHaspingeretal., author = {Geith, Markus A. and Eckmann, Jakob D. and Haspinger, Daniel Ch. and Agrafiotis, Emmanouil and Maier, Dominik and Szabo, Patrick and Sommer, Gerhard and Schratzenstaller, Thomas and Holzapfel, Gerhard A.}, title = {Experimental and mathematical characterization of coronary polyamide-12 balloon catheter membranes}, series = {PLoS One}, volume = {15}, journal = {PLoS One}, number = {6}, publisher = {PLOS}, doi = {10.1371/journal.pone.0234340}, pages = {1 -- 22}, abstract = {The experimental quantification and modeling of the multiaxial mechanical response of polymer membranes of coronary balloon catheters have not yet been carried out. Due to the lack of insights, it is not shown whether isotropic material models can describe the material response of balloon catheter membranes expanded with nominal or higher, supra-nominal pressures. Therefore, for the first time, specimens of commercial polyamide-12 balloon catheters membranes were investigated during uniaxial and biaxial loading scenarios. Furthermore, the influence of kinematic effects on the material response was observed by comparing results from quasi-static and dynamic biaxial extension tests. Novel clamping techniques are described, which allow to test even tiny specimens taken from the balloon membranes. The results of this study reveal the semi-compliant, nonlinear, and viscoelastic character of polyamide-12 balloon catheter membranes. Above nominal pressure, the membranes show a pronounced anisotropic mechanical behavior with a stiffer response in the circumferential direction. The anisotropic feature intensifies with an increasing strain-rate. A modified polynomial model was applied to represent the realistic mechanical response of the balloon catheter membranes during dynamic biaxial extension tests. This study also includes a compact set of constitutive model parameters for the use of the proposed model in future finite element analyses to perform more accurate simulations of expanding balloon catheters.}, language = {en} } @article{GeithSwidergalHochholdingeretal., author = {Geith, Markus A. and Swidergal, Krzysztof and Hochholdinger, Bernd and Schratzenstaller, Thomas and Wagner, Marcus and Holzapfel, Gerhard A.}, title = {On the importance of modeling balloon folding, pleating, and stent crimping: An FE study comparing experimental inflation tests}, series = {International Journal for Numerical Methods in Biomedical Engineering}, volume = {35}, journal = {International Journal for Numerical Methods in Biomedical Engineering}, number = {11}, publisher = {Wiley}, doi = {10.1002/cnm.3249}, abstract = {Finite element (FE)-based studies of preoperative processes such as folding,pleating, and stent crimping with a comparison with experimental inflation tests are not yet available. Therefore, a novel workflow is presented in which residual stresses of balloon folding and pleating, as well as stent crimping, and the geometries of all contact partners were ultimately implemented in an FE code to simulate stent expansion by using an implicit solver. The numerical results demonstrate that the incorporation of residual stresses and strains experienced during the production step significantly increased the accuracy of the subsequent simulations, especially of the stent expansion model. During the preoperative processes, stresses inside the membrane and the stent material also reached a rather high level. Hence, there can be no presumption that balloon catheters or stents are undamaged before the actual surgery. The implementation of the realistic geometry, in particular the balloon tapers, and the blades of the process devices improved the simulation of the expansion mech-anisms, such as dogboning, concave bending, or overexpansion of stent cells. This study shows that implicit solvers are able to precisely simulate the mentioned preoperative processes and the stent expansion procedure without a preceding manipulation of the simulation time or physical mass.}, subject = {Stent}, language = {en} } @article{HausleiterKastratiWesselyetal., author = {Hausleiter, J{\"o}rg and Kastrati, Adnan and Wessely, Rainer and Dibra, Alban and Mehilli, Julinda and Schratzenstaller, Thomas and Graf, Isolde and Renke-Gluszko, Magdalena and Behnisch, Boris and Dirschinger, Josef and Wintermantel, Erich and Sch{\"o}mig, Albert}, title = {Prevention of restenosis by a novel drug-eluting stent system with a dose-adjustable, polymer-free, on-site stent coating}, series = {European Heart Journal - Clinical research}, volume = {26}, journal = {European Heart Journal - Clinical research}, number = {15}, doi = {10.1093/eurheartj/ehi405}, pages = {1475 -- 1481}, abstract = {Aims Drug-eluting stents (DES) represent a major advance in interventional cardiology. Along with the success shown, current DES also present limitations related to the presence of polymer-coating, fixed drug, and dose used. With the ISAR (Individualized Drug-Eluting Stent System to Abrogate Restenosis) project, a DES system has been developed that permits individualized choice of the drug and dose to use for the given patient. The objective of this prospective dose finding study was to assess the feasibility, safety, and efficacy of a polymer-free on-site stent coating with increasing rapamycin doses. Methods and results In this dose finding study, 602 patients were sequentially enrolled in four groups: microporous bare metal stent (BMS), DES stents coated with a 0.5, 1.0, and 2.0\% rapamycin solution. The angiographic in-segment restenosis rate at follow-up angiography was the primary study endpoint. In-segment restenosis was significantly reduced from 25.9\% with BMS to 18.9, 17.2, and 14.7\% with 0.5, 1.0, and 2.0\% rapamycin-eluting stents, respectively (P=0.024). Similarly, the need for target lesion revascularization at 1 year follow-up was reduced from 21.5\% with BMS to 16.4, 12.6, and 8.8\% with 0.5, 1.0, and 2.0\% rapamycin-eluting stents, respectively (P=0.006). Conclusion The placement of polymer-free stents coated on-site with rapamycin is feasible and safe. Furthermore, a dose-dependent efficacy in restenosis prevention is achievable with this new DES concept.}, language = {en} } @article{WiesentSchultheissLullaetal., author = {Wiesent, Lisa and Schultheiß, Ulrich and Lulla, Philipp and Noster, Ulf and Schratzenstaller, Thomas and Schmid, Christof and Nonn, Aida and Spear, Ashley}, title = {Computational analysis of the effects of geometric irregularities and post-processing steps on the mechanical behavior of additively manufactured 316L stainless steel stents}, series = {PLoS ONE}, volume = {15}, journal = {PLoS ONE}, number = {12}, publisher = {PLOS}, doi = {10.1371/journal.pone.0244463}, pages = {1 -- 30}, abstract = {Advances in additive manufacturing enable the production of tailored lattice structures and thus, in principle, coronary stents. This study investigates the effects of process-related irregularities, heat and surface treatment on the morphology, mechanical response, and expansion behavior of 316L stainless steel stents produced by laser powder bed fusion and provides a methodological approach for their numerical evaluation. A combined experimental and computational framework is used, based on both actual and computationally reconstructed laser powder bed fused stents. Process-related morphological deviations between the as-designed and actual laser powder bed fused stents were observed, resulting in a diameter increase by a factor of 2-2.6 for the stents without surface treatment and 1.3-2 for the electropolished stent compared to the as-designed stent. Thus, due to the increased geometrically induced stiffness, the laser powder bed fused stents in the as-built (7.11 ± 0.63 N) or the heat treated condition (5.87 ± 0.49 N) showed increased radial forces when compressed between two plates. After electropolishing, the heat treated stents exhibited radial forces (2.38 ± 0.23 N) comparable to conventional metallic stents. The laser powder bed fused stents were further affected by the size effect, resulting in a reduced yield strength by 41\% in the as-built and by 59\% in the heat treated condition compared to the bulk material obtained from tensile tests. The presented numerical approach was successful in predicting the macroscopic mechanical response of the stents under compression. During deformation, increased stiffness and local stress concentration were observed within the laser powder bed fused stents. Subsequent numerical expansion analysis of the derived stent models within a previously verified numerical model of stent expansion showed that electropolished and heat treated laser powder bed fused stents can exhibit comparable expansion behavior to conventional stents. The findings from this work motivate future experimental/numerical studies to quantify threshold values of critical geometric irregularities, which could be used to establish design guidelines for laser powder bed fused stents/lattice structures.}, subject = {Koronarendoprothese}, language = {en} } @article{WesselyHausleiterMichaelisetal., author = {Wessely, Rainer and Hausleiter, J{\"o}rg and Michaelis, Cornelia and Jaschke, Birgit and Vogeser, Michael and Milz, Stefan and Behnisch, Boris and Schratzenstaller, Thomas and Renke-Gluszko, Magdalena and St{\"o}ver, Michael and Wintermantel, Erich and Kastrati, Adnan and Sch{\"o}mig, Albert}, title = {Inhibition of neointima formation by a novel drug-eluting stent system that allows for dose-adjustable, multiple, and on-site stent coating}, series = {Arteriosclerosis, Thrombosis, and Vascular Biology}, volume = {25}, journal = {Arteriosclerosis, Thrombosis, and Vascular Biology}, number = {4}, issn = {1524-4636}, doi = {10.1161/01.ATV.0000157579.52566.ee}, pages = {748 -- 753}, abstract = {Objective The risk of in-stent restenosis can be considerably reduced by stents eluting cytostatic compounds. We created a novel drug-eluting stent system that includes several new features in the rapidly evolving field of stent-based drug delivery. Methods and Results The aim of the present study was the preclinical evaluation of a stent-coating system permitting individual, on-site coating of stents with a unique microporous surface allowing for individualizable, dose-adjustable, and multiple coatings with identical or various compounds, designated ISAR (individualizable drug-eluting stent system to abrogate restenosis). Stents were coated with 0.75\% rapamycin solution, and high-performance liquid chromatography (HPLC)-based determination of drug release profile indicated drug release for >21 days. Rapamycin-eluting microporous (REMP) stents implanted in porcine coronary arteries were safe. To determine the efficacy of REMP stents, this novel drug-eluting stent platform was compared with the standard sirolimus-eluting stent. At 30 days, in-stent neointima formation in porcine coronary arteries was similar in both groups, yielding a significant decrease of neointimal area and injury-dependent neointimal thickness compared with bare-metal stents. Conclusion The ISAR drug-eluting stent platform as a novel concept for stent coating allows for a safe, effective, on-site stent coating process, thus justifying further clinical evaluation to decrease in-stent restenosis in humans. In-stent neointima formation can be successfully attenuated by drug-eluting stents. We introduce a novel conceptual approach for stent-coating that allows for dose-adjustable, on-site stent coating process if desired with multiple compounds. Microporous stents coated with rapamycin proved safe and effective for the limitation of neointima formation in a porcine coronary stent model.}, language = {en} } @article{WiesentSchultheissSchmidetal., author = {Wiesent, Lisa and Schultheiss, Ulrich and Schmid, Christof and Schratzenstaller, Thomas and Nonn, Aida}, title = {Experimentally validated simulation of coronary stents considering different dogboning ratios and asymmetric stent positioning}, series = {PlOS One}, volume = {14}, journal = {PlOS One}, number = {10}, publisher = {PLOS}, doi = {10.1371/journal.pone.0224026}, pages = {1 -- 25}, abstract = {In-stent restenosis remains a major problem of arteriosclerosis treatment by stenting. Expansion-optimized stents could reduce this problem. With numerical simulations, stent designs/ expansion behaviours can be effectively analyzed. For reasons of efficiency, simplified models of balloon-expandable stents are often used, but their accuracy must be challenged due to insufficient experimental validation. In this work, a realistic stent life-cycle simulation has been performed including balloon folding, stent crimping and free expansion of the balloon-stent-system. The successful simulation and validation of two stent designs with homogenous and heterogeneous stent stiffness and an asymmetrically positioned stent on the balloon catheter confirm the universal applicability of the simulation approach. Dogboning ratio, as well as the final dimensions of the folded balloon, the crimped and expanded stent, correspond well to the experimental dimensions with only slight deviations. In contrast to the detailed stent life-cycle simulation, a displacement-controlled simulation can not predict the transient stent expansion, but is suitable to reproduce the final expanded stent shape and the associated stress states. The detailed stent life-cycle simulation is thus essential for stent expansion analysis/optimization, whereas for reasons of computational efficiency, the displacement-controlled approach can be considered in the context of pure stress analysis.}, subject = {Stent}, language = {en} } @article{GeithNothdurfterHeimletal., author = {Geith, Markus A. and Nothdurfter, Laurenz and Heiml, Manuel and Agrafiotis, Emmanouil and Gruber, Markus and Sommer, Gerhard and Schratzenstaller, Thomas and Holzapfel, Gerhard A.}, title = {Quantifying stent-induced damage in coronary arteries by investigating mechanical and structural alterations}, series = {Acta Biomaterialia}, volume = {116}, journal = {Acta Biomaterialia}, number = {October}, publisher = {Elsevier}, doi = {10.1016/j.actbio.2020.08.016}, pages = {285 -- 301}, abstract = {Vascular damage develops with diverging severity during and after percutaneous coronary intervention with stent placement and is the prevailing stimulus for in-stent restenosis. Previous work has failed to link mechanical data obtained in a realistic in vivo or in vitro environment with data collected during imaging processes. We investigated whether specimens of porcine right coronary arteries soften when indented with a stent strut shaped structure, and if the softening results from damage mechanisms inside the fibrillar collagen structure. To simulate the multiaxial loading scenario of a stented coronary artery, we developed the testing device 'LAESIO' that can measure differences in the stress-stretch behavior of the arterial wall before and after the indentation of a strut-like stamp. The testing protocol was optimized according to preliminary experiments, more specifically equilibrium and relaxation tests. After chemical fixation of the specimens and subsequent tissue clearing, we performed three-dimensional surface and second-harmonic generation scans on the deformed specimens. We analyzed and correlated the mechanical response with structural parameters of high-affected tissue located next to the stamp indentation and low-affected tissue beyond the injured area. The results reveal that damage mechanisms, like tissue compression as well as softening, fiber dispersion, and the lesion extent, are direction-dependent, and the severity of them is linked to the strut orientation, indentation pressure, and position. The findings highlight the need for further investigations by applying the proposed methods to human coronary arteries. Additional data and insights might help to incorporate the observed damage mechanisms into material models for finite element analyses to perform more accurate simulations of stent-implantations.}, language = {en} } @misc{WiesentHupkeBalketal., author = {Wiesent, Lisa and Hupke, Constantin and Balk, Christian and Schultheiss, Ulrich and Schratzenstaller, Thomas}, title = {Optimization of the cardiovascular stent design towards improved expansion behaviour and radial stiffness properties}, series = {Biomedizinische Technik}, volume = {63}, journal = {Biomedizinische Technik}, number = {s1}, doi = {10.1515/bmt-2018-6031}, abstract = {- Development of a FEA Tool for a realistic stent simulation - investigation on minor modification on the stent design on the expansion behaviour - analysis of three stent designs: classical stent design with pronounced dogbone effect, two modified stent design (non-dogbone-design)}, subject = {Kardiovaskul{\"a}res System}, language = {en} } @misc{GeithSwidergalSchratzenstalleretal., author = {Geith, Markus A. and Swidergal, Krzysztof and Schratzenstaller, Thomas and Holzapfel, Gerhard A. and Wagner, Marcus}, title = {Numerical analysis of stent delivery systems during pre- and intraoperative processes}, series = {15. Deutsches LS-DYNA Forum, 15.-17.10.2018, Bamberg}, journal = {15. Deutsches LS-DYNA Forum, 15.-17.10.2018, Bamberg}, language = {en} } @article{GeithSommerSchratzenstalleretal., author = {Geith, Markus A. and Sommer, Gerhard and Schratzenstaller, Thomas and Holzapfel, Gerhard A.}, title = {Biomechanical and structural quantification of vascular damage: A unique investigation of stent implantation}, series = {Artery Research}, volume = {20}, journal = {Artery Research}, number = {Issue C}, doi = {10.1016/j.artres.2017.10.025}, pages = {50}, language = {en} } @article{PrantlEigenbergerKleinetal., author = {Prantl, Lukas and Eigenberger, Andreas and Klein, Silvan and Limm, Katharina and Oefner, Peter J. and Schratzenstaller, Thomas and Felthaus, Oliver}, title = {Shear Force Processing of Lipoaspirates for Stem Cell Enrichment Does Not Affect Secretome of Human Cells Detected by Mass Spectrometry In Vitro}, series = {Plastic and Reconstructive Surgery}, volume = {146}, journal = {Plastic and Reconstructive Surgery}, number = {6}, publisher = {American Society of Plastic Surgeons}, doi = {10.1097/PRS.0000000000007343}, pages = {749e -- 758e}, abstract = {Background: Lipofilling is one of the most often performed surgical procedures in plastic and reconstructive surgery. Lipoaspirates provide a ready source of stem cells and secreted factors that contribute to neoangiogenesis and fat graft survival. However, the regulations about the enrichment of these beneficial cells and factors are ambiguous. In this study, the authors tested whether a combination of centrifugation and homogenization allowed the enrichment of viable stem cells in lipoaspirates through the selective removal of tumescent solution, blood, and released lipids without significantly affecting the cell secretome. Methods: Human lipoaspirate was harvested from six different patients using water jet-assisted liposuction. Lipoaspirate was homogenized by first centrifugation (3584 rpm for 2 minutes), shear strain (10 times intersyringe processing), and second centrifugation (3584 rpm for 2 minutes). Stem cell enrichment was shown by cell counting after stem cell isolation. Lipoaspirate from different processing steps (unprocessed, after first centrifugation, after homogenization, after second centrifugation) was incubated in serum-free cell culture medium for mass spectrometric analysis of secreted proteins. Results: Lipoaspirate homogenization leads to a significant 2.6 ± 1.75-fold enrichment attributable to volume reduction without reducing the viability of the stem cells. Protein composition of the secretome did not change significantly after tissue homogenization. Considering the enrichment effects, there were no significant differences in the protein concentration of the 83 proteins found in all processing steps. Conclusions: Stem cells can be enriched mechanically without significantly affecting the composition of secreted proteins. Shear-assisted enrichment of lipoaspirate constitutes no substantial manipulation of the cells' secretome.}, language = {en} } @article{EigenbergerFelthausSchratzenstalleretal., author = {Eigenberger, Andreas and Felthaus, Oliver and Schratzenstaller, Thomas and Haerteis, Silke and Utpatel, Kirsten and Prantl, Lukas}, title = {The Effects of Shear Force-Based Processing of Lipoaspirates on White Adipose Tissue and the Differentiation Potential of Adipose Derived Stem Cells}, series = {cells}, volume = {11}, journal = {cells}, number = {16}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/cells11162543}, pages = {13}, abstract = {Autologous lipotransfer is a promising method for tissue regeneration, because white adipose tissue contains a heterogeneous cell population, including mesenchymal stem cells, endothelial cells, immune cells, and adipocytes. In order to improve the outcome, adipose tissue can be processed before application. In this study, we investigated changes caused by mechanical processing. Lipoaspirates were processed using sedimentation, first-time centrifugation, shear-force homogenization, and second-time centrifugation. The average adipocyte size, stromal vascular cell count, and adipocyte depot size were examined histologically at every processing step. In addition, the adipose derived stem cells (ADSCs) were isolated and differentiated osteogenically and adipogenically. While homogenization causes a disruption of adipocyte depots, the shape of the remaining adipocytes is not changed. On average, these adipocytes are smaller than the depot adipocytes, they are surrounded by the ECM, and therefore mechanically more stable. The volume loss of adipocyte depots leads to a significant enrichment of stromal vascular cells such as ADSCs. However, the mechanical processing does not change the potential of the ADSCs to differentiate adipogenically or steogenically. It thus appears that mechanically processed lipoaspirates are promising for the reparation of even mechanically stressed tissue as that found in nasolabial folds. The changes resulting from the processing correspond more to a filtration of mechanically less stable components than to a manipulation of the tissue.}, language = {en} } @unpublished{BurgerBartschGradetal., author = {Burger, Moritz and Bartsch, Alexander and Grad, Marius and Esper, Lukas and Schultheiß, Ulrich and Noster, Ulf and Schratzenstaller, Thomas}, title = {Enhancement of laser cut edge quality of ultra-thin titanium grade 2 sheets by applying in-process approach using modulated Yb:YAG continuous wave fibre laser}, doi = {10.21203/rs.3.rs-2520041/v1}, abstract = {Titanium is used in many areas due to its excellent mechanical, biological and corrosion-resistant properties. Implants often have thin and filigree structures, providing an ideal application for laser fine cutting. In literature, the main focus is primarily on investigating and optimizing the parameters for titanium sheet thicknesses greater than 1 mm. Hence, in this study, the basic manufacturing parameters of laser power, cutting speed and laser pulsing of a 200 W modulated fibre laser are investigated for 0.15 mm thick titanium grade 2 sheets. A reproducible, continuous cut could be achieved using 90 W laserpower and 2 cutting-speed. Pulse pause variations between 85-335 μs in 50 μs steps and fixed pulse duration of 50 μs show that a minimum kerf width of 23.4 μm, as well as a minimum cut edge roughness Rz of 3.59 μm, is achieved at the lowest pulse pause. An increase in roughness towards the laser exit side, independent of the laser pulse pause, was found and discussed. The results provide initial process parameters for cutting thin titanium sheets and thus provide the basis for further investigations, such as the influence of cutting gas pressure and composition on the cut edge.}, language = {en} } @article{BartschBurgerGradetal., author = {Bartsch, Alexander and Burger, Moritz and Grad, Marius and Esper, Lukas and Schultheiß, Ulrich and Noster, Ulf and Schratzenstaller, Thomas}, title = {Enhancement of laser cut edge quality of ultra-thin titanium grade 2 sheets by applying an in-process approach using modulated Yb:YAG continuous wave fiber laser}, series = {Discover Mechanical Engineering}, volume = {2}, journal = {Discover Mechanical Engineering}, number = {10}, publisher = {Springer}, doi = {10.1007/s44245-023-00018-3}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-65647}, pages = {9}, abstract = {Titanium is used in many areas due to its excellent mechanical, biological and corrosion-resistant properties. Implants often have thin and filigree structures, providing an ideal application for fine cutting with laser. In the literature, the main focus is primarily on investigating and optimizing the parameters for titanium sheets with thicknesses greater than 1 mm. Hence, in this study, the basic manufacturing parameters of laser power, cutting speed and laser pulse of a 200 W modulated fiber laser are investigated for 0.15 mm thick grade 2 titanium sheets. A reproducible, continuous cut could be achieved using 90 W laser-power and 2 mm/s cutting-speed. Pulse pause variations between 85 and 335 μs in 50 μs steps and a fixed pulse width of 50 μs show that a minimum kerf width of 23.4 μm, as well as a minimum cut edge roughness Rz of 3.59 μm, is achieved at the lowest pulse pause duration. An increase in roughness towards the laser exit side, independent of the laser pulse pause duration, was found and discussed. The results provide initial process parameters for cutting thin titanium sheets and thus provide the basis for further investigations, such as the influence of cutting gas pressure and composition on the cut edge.}, language = {en} } @article{ObermaierLehleSchmidetal., author = {Obermaier, Lisa and Lehle, Karla and Schmid, Stefanie and Schmid, Christof and Schratzenstaller, Thomas}, title = {Introduction of a new ex vivo porcine coronary artery model: Evaluation of the direct vascular injury after stent implantation with and without dogbone effect}, series = {European Surgical Research}, volume = {63}, journal = {European Surgical Research}, number = {4}, publisher = {Karger}, address = {Basel}, issn = {1421-9921}, doi = {10.1159/000527883}, pages = {285 -- 293}, abstract = {Introduction: Neointimal hyperplasia after percutaneous coronary intervention remains a major determinant of in-stent restenosis (ISR). The extent of mechanical vessel injury correlates with ISR. A new ex vivo porcine stent model was introduced and evaluated comparing different stent designs. Methods: Coronary arteries were prepared from pig hearts from the slaughterhouse and used for ex vivo implantations of coronary stents. One basic stent design in two configurations (dogbone, DB; non-dogbone, NDB) was used. Vascular injury was determined according to a modified injury score (IS). Results: Standardized experimental conditions ensured comparable vessel dimensions and overstretch data. DB stents caused more severe IS compared to NDB stents. The mean IS and the IS at the distal end of all stents were significantly reduced for NDB stents (ISMean, DB, 1.16 ±0.12; NDB, 1.02 ±0.12; p=0.018; ISDist, DB, 1.39 ±0.28; NDB, 1.13 ±0.24; p=0.03). Discussion/Conclusion: The introduced ex-vivo model allowed the evaluation of different stent designs exclude unfavorable stent designs.}, language = {en} } @article{SchaefferHerrmannSchratzenstalleretal., author = {Schaeffer, Leon and Herrmann, David and Schratzenstaller, Thomas and Dendorfer, Sebastian and B{\"o}hm, Valter}, title = {Preliminary theoretical considerations on the stiffness characteristics of a tensegrity joint for the use in dynamic orthoses}, series = {Journal of Medical Robotics Research}, journal = {Journal of Medical Robotics Research}, publisher = {World Scientific}, doi = {10.1142/S2424905X23400081}, abstract = {Early motion therapy plays an important role for effective long-term healing of joint injuries. In many cases, conventional dynamic orthoses fail to address the intricate movement possibilities of the underlying joints, limited by their simplistic joint representations, often represented by revolute joints, enabling rotations by only one axis. In this paper, a two-dimensional compliant tensegrity joint for use in biomedical applications is investigated. It consists of two compressed members and five compliant tensioned members. Relative movement possibilities are realized by the intrinsic compliance of the structure. In the development of these systems, the first step is the determination of the static stable equilibrium. This analysis is conducted in this paper by considering the potential energy approach or by using the geometric nonlinear finite element method. The mechanical behavior of the structure is assessed with a specific emphasis on its mechanical compliance. The primary objective of this study is the investigation of the influence of structural parameters on the overall stiffness and movability of the structure. The results underscore the significant effect of member parameters on the stiffness and movability of the compliant tensegrity joint, particularly under varying load magnitudes. These findings provide insights for optimizing the joint's performance, contributing to its potential application in advanced orthotic and exoskeleton devices.}, language = {en} } @article{BartschBehamGebhardtetal., author = {Bartsch, Alexander and Beham, Daniela and Gebhardt, Jakob and Ehrlich, Ingo and Schratzenstaller, Thomas and Monkman, Gareth J.}, title = {Mechanical Properties of NdPrFeB Based Magnetoactive Bisphenol-Free Boron-Silicate Polymers}, series = {Journal of Nanomedicine and Nanotechnology}, volume = {14}, journal = {Journal of Nanomedicine and Nanotechnology}, number = {6}, publisher = {Walsh Medical Media}, issn = {2157-7439}, doi = {10.35248/2157-7439.23.14.705}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-67425}, abstract = {Following a ban on many materials containing bisphenol-A, new bisphenol-free Boron silicates have been found as substitutes. The purpose of this study is to describe the mechanical properties of these bisphenol-free magnetoactive borosilicate polymers containing hard magnetic particles. Samples of 0\%, 33\% and 66\% by wt. were loaded for compression using a universal testing machine. The maximum forces occurring for different travel speeds were compared before and after post-magnetization treatments. The post-magnetization included 2 stages. In addition, the change in mechanical properties within 24 hours after the post-magnetization process was investigated. Furthermore, the influence of speed and particle content were investigated. In general, there is a correlation between the required compressive force and, the level of post-magnetization stress, the increase in travel speed and particle content in the boron silicate. Comparison of the non-post-magnetized and post-magnetized samples using two-tailed t-tests shows that the p-values for all weight fraction changes in NdPrFeB particles and travel speeds are less than 0.001. Also, a comparison between tests in which the traverse speed was varied also showed significant changes in the resulting compression forces. The same is valid for changes in the weight ratio of the NdPrFeB particles in the samples. For post-magnetized samples, no significant difference can be observed in the first 24 hours following magnetization. In summary, the material presents viscoelastic, plastic force-displacement behavior, which can be well recognized by its bi-linear curve shape. The investigation shows that borosilicate polymers based on NdPrFeB can have their mechanical behavior modified and controlled by post-magnetization processes. This opens new possibilities for many future applications.}, language = {en} } @article{LooNagarajuPathivadaetal., author = {Loo, Xuyan and Nagaraju, Bhavana and Pathivada, Sai and Bartsch, Alexander and Schratzenstaller, Thomas and Sattler, Robert and Monkman, Gareth J.}, title = {Electrical properties of bisphenol-A-free magnetoactive borosilicate polymers}, series = {AIP Advances}, volume = {14}, journal = {AIP Advances}, number = {5}, publisher = {AIP Publishing}, issn = {2158-3226}, doi = {10.1063/5.0203017}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-72936}, abstract = {The recent REACH regulations require the elimination of bisphenol-A and titanium dioxide from commercially available boron-based polymers. This has led to changes in some of the mechanical characteristics, which strongly influence the properties of magnetoactive borosilicate polymers. This work delivers results on the electrical properties and discusses some implications for future research using bisphenol-A and titanium-dioxide-free substitutes.}, language = {en} }