Novel synthetic clot analogs for in-vitro stroke modelling

PLOS ONE RESEARCH ARTICLE Novel synthetic clot analogs for in-vitro stroke modelling Helena Guerreiro ID1*, Nadine Wortmann2, Thomas Andersek2, Tuan N. Ngo1, Andreas M. Frölich1, Dieter Krause2, Jens Fiehler1, Anna A. Kyselyova ID1☯, Fabian Flottmann1☯ 1 Department of Diagnostic and Interventional Neuroradiology, University Medical Center HamburgEppendorf, Hamburg, Germany, 2 Institute of Product Development and Mechanical Engineering Design, Hamburg University of Technology, Hamburg, Germany a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 ☯ These authors contributed equally to this work. * Abstract Purpose OPEN ACCESS Citation: Guerreiro H, Wortmann N, Andersek T, Ngo TN, Frölich AM, Krause D, et al. (2022) Novel synthetic clot analogs for in-vitro stroke modelling. PLoS ONE 17(9): e0274211. https://doi.org/ 10.1371/journal.pone.0274211 Editor: Karen M. Doyle, National University of Ireland - Galway, IRELAND Received: January 17, 2022 Accepted: August 19, 2022 Published: September 9, 2022 Copyright: © 2022 Guerreiro et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the manuscript and its Supporting Information files. Funding: This work was supported by the German Federal Ministry of Education and Research – BMBF under the Grant number 161L0154A (HG, NW, JF, AK, DK) https://www.bmbf.de The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The increased demand for training of mechanical thrombectomy in ischemic stroke and development of new recanalization devices urges the creation of new simulation models both for training and device assessment. Clots properties have shown to play a role in procedural planning and thrombectomy device effectiveness. In this study, we analyzed the characteristics and applicability of completely synthetic, animal-free clots in the setting of an invitro model of mechanical thrombectomy for training and device assessment. Methods Synthetic clots based on agarose (n = 12) and silicone (n = 11) were evaluated in an in-vitro neurointervention simulation of mechanical thrombectomy with clot extraction devices. Calcified clots of mixed nature were simulated with addition of 3D printed structures. 9 clots were excluded due to insufficient vessel occlusion and failure to integrate with clot extraction device. Synthetic thrombi were characterized and compared using a categorical score-system on vessel occlusion, elasticity, fragmentation, adherence and device integration. Results Both agarose-based and silicone-based clots demonstrated relevant flow arrest and a good integration with the clot extraction device. Silicone-based clots scored higher on adherence to the vessel wall and elasticity. Conclusion Selected synthetic clots can successfully be implemented in an in-vitro training environment of mechanical thrombectomy. The clots’ different properties might serve to mimic fibrin-rich and red blood cell-rich human thrombi. Competing interests: The authors have declared that no competing interests exist. PLOS ONE | https://doi.org/10.1371/journal.pone.0274211 September 9, 2022 1/9 PLOS ONE Synthetic clot analogs for in-vitro stroke modelling Introduction Clinical evidence has shown in the past years the undeniable value of mechanical thrombectomy (MT) in the treatment of acute large vessel occlusion (LVO) [1]. This led to a global increase in the demand for interventionalists with technical proficiency in endovascular stroke treatment [2]. Training of neurointerventionalists may be challenging due to the delicate nature of neurovascular interventions and the scarce availability of dedicated stoke simulation models representing realistic stroke-specific interventional challenges. Animal models used for medical training or device testing are associated not only with an ethical dilemma but also with high costs and a poor reproducibility of human anatomy [3]. In this study we use a fully animal-free experimental setting, comprised of a previously described neurointervention simulation model—HAmburg Anatomical NEurointerventional Simulator (HANNES) [4] and custom-designed 3D-printed models of intracranial vasculature as a realistic and cost-effective training environment for mechanical thrombectomy (MT). Clot composition has been shown to play a role in the etiology and characterization of ischemic stroke in large vessel occlusions [5]. This may play a role in the development and research of new therapy concepts and thrombectomy devices. One previous study states the importance of artificially made thrombi from human or pig´s blood in the pre-evaluation of thrombus extraction devices and as training material [6]. In this study we analyzed the feasibility of completely animal-free, synthetically made clots in the setting of neurovascular simulation of MT and their interaction with extraction devices. Our hypothesis was that synthetic clots allow for sufficient vessel occlusion and device interaction in an experimental simulation model of mechanical thrombectomy when evaluated by experienced neurointerventionalists, and that different clot compositions may show different mechanical properties which may mimic characteristics found in human clots. Material & methods Synthetic clot development and selection Synthetically produced clots (n = 23) mainly composed of agarose (n = 12, A1-12) or silicone (n = 11, S1-11) were tested in a previously described neurovascular simulation model [4]. Different concentrations of these compounds were mixed with a 3:1 mixture of methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI) (C. Kreul GmbH & Co. KG, Hallerndorf, Germany) or/and micro-glass beads (MGB) (Carl Roth GmbH + Co KG, Karlsruhe, Germany) in different proportions in order to simulate different degrees of stiffness, elasticity, adhesion and fragmentation (Table 1). 3D-printed supporting structures, spiral- or barbed-shaped, were found to be most suitable to be integrated in agarose clots (n = 3) in order to simulate the irregularly shaped calcifications found in-vivo (Flexible Resin, Formlabs 2, MA, USA). Failure to cause a sufficient vessel occlusion (e.g., due to distinctive fragility) or interact with the clot extraction device (and thus, affecting sufficient assessment of stent-retrieval suitability) was considered an exclusion criterion. From the 23 clots that were intended for in-vitro testing, 9 clots were excluded: 4 out of 12 agarose-based clots due to insufficient vessel occlusion and failure to integrate with the stent retriever and 1 out of 12 due to failure to integrate with the stent retriever. 4 out of 11 silicone-based clots were excluded due to failure to interact with the stent retrie (...truncated)