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Petkantchin R, Rousseau A, Eker O, Zouaoui Boudjeltia K, Raynaud F, Chopard B. A simplified mesoscale 3D model for characterizing fibrinolysis under flow conditions. Sci Rep 2023; 13:13681. [PMID: 37608073 PMCID: PMC10444897 DOI: 10.1038/s41598-023-40973-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 08/19/2023] [Indexed: 08/24/2023] Open
Abstract
One of the routine clinical treatments to eliminate ischemic stroke thrombi is injecting a biochemical product into the patient's bloodstream, which breaks down the thrombi's fibrin fibers: intravenous or intravascular thrombolysis. However, this procedure is not without risk for the patient; the worst circumstances can cause a brain hemorrhage or embolism that can be fatal. Improvement in patient management drastically reduced these risks, and patients who benefited from thrombolysis soon after the onset of the stroke have a significantly better 3-month prognosis, but treatment success is highly variable. The causes of this variability remain unclear, and it is likely that some fundamental aspects still require thorough investigations. For that reason, we conducted in vitro flow-driven fibrinolysis experiments to study pure fibrin thrombi breakdown in controlled conditions and observed that the lysis front evolved non-linearly in time. To understand these results, we developed an analytical 1D lysis model in which the thrombus is considered a porous medium. The lytic cascade is reduced to a second-order reaction involving fibrin and a surrogate pro-fibrinolytic agent. The model was able to reproduce the observed lysis evolution under the assumptions of constant fluid velocity and lysis occurring only at the front. For adding complexity, such as clot heterogeneity or complex flow conditions, we propose a 3-dimensional mesoscopic numerical model of blood flow and fibrinolysis, which validates the analytical model's results. Such a numerical model could help us better understand the spatial evolution of the thrombi breakdown, extract the most relevant physiological parameters to lysis efficiency, and possibly explain the failure of the clinical treatment. These findings suggest that even though real-world fibrinolysis is a complex biological process, a simplified model can recover the main features of lysis evolution.
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Affiliation(s)
- Remy Petkantchin
- Scientific and Parallel Computing Group, Computer Science Department, University of Geneva, Geneva, Switzerland.
- Complex System Modeling Group, Computer Science Department, University of Geneva, Geneva, Switzerland.
| | - Alexandre Rousseau
- Laboratory of Experimental Medicine (ULB222), Faculty of Medicine, Université libre de Bruxelles, CHU de Charleroi, Charleroi, Belgium
| | - Omer Eker
- Department of Neuroradiology, Hôpital Pierre Wertheimer, Hospices Civils de Lyon, Lyon, France
- CREATIS Laboratory, UMR 5220, U1206, Université Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, Lyon, France
| | - Karim Zouaoui Boudjeltia
- Laboratory of Experimental Medicine (ULB222), Faculty of Medicine, Université libre de Bruxelles, CHU de Charleroi, Charleroi, Belgium
| | - Franck Raynaud
- Scientific and Parallel Computing Group, Computer Science Department, University of Geneva, Geneva, Switzerland
- Complex System Modeling Group, Computer Science Department, University of Geneva, Geneva, Switzerland
| | - Bastien Chopard
- Scientific and Parallel Computing Group, Computer Science Department, University of Geneva, Geneva, Switzerland
- Complex System Modeling Group, Computer Science Department, University of Geneva, Geneva, Switzerland
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Composite Fibrin and Carbon Microfibre Implant to Modulate Postraumatic Inflammation after Spinal Cord Injury. Cells 2023; 12:cells12060839. [PMID: 36980180 PMCID: PMC10047285 DOI: 10.3390/cells12060839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 03/02/2023] [Accepted: 03/05/2023] [Indexed: 03/11/2023] Open
Abstract
Poor functional recovery after spinal cord injury (SCI) drives the development of novel strategies to manage this devastating condition. We recently showed promising immunomodulatory and pro-regenerative actions of bio-functionalized carbon microfibres (MFs) implanted in a rodent model of SCI. In order to maximize tissue repair while easing MF implantation, we produced a composite implant based on the embedding of several MFs within a fibrin hydrogel. We used intravital imaging of fluorescent reporter mice at the early stages and spinal sections of the same animals 3 months later to characterize the neuroinflammatory response to the implant and its impact on axonal regeneration. Whereas fibrin alone was inert in the first week, its enzymatic degradation drove the chronic activation of microglial cells and axonal degeneration within 3 months. However, the presence of MFs inside the fibrin hydrogel slowed down fibrin degradation and boosted the early recruitment of immune cells. Noteworthy, there was an enhanced contribution of monocyte-derived dendritic cells (moDCs), preceding a faster transition toward an anti-inflammatory environment with increased axonal regeneration over 3 months. The inclusion of MF here ensured the long-term biocompatibility of fibrin hydrogels, which would otherwise preclude successful spinal cord regeneration.
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Risman RA, Kirby NC, Bannish BE, Hudson NE, Tutwiler V. Fibrinolysis: an illustrated review. Res Pract Thromb Haemost 2023; 7:100081. [PMID: 36942151 PMCID: PMC10024051 DOI: 10.1016/j.rpth.2023.100081] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 01/16/2023] [Accepted: 01/25/2023] [Indexed: 02/18/2023] Open
Abstract
In response to vessel injury (or other pathological conditions), the hemostatic process is activated, resulting in a fibrous, cellular-rich structure commonly referred to as a blood clot. Succeeding the clot's function in wound healing, it must be resolved. This illustrated review focuses on fibrinolysis-the degradation of blood clots or thrombi. Fibrin is the main mechanical and structural component of a blood clot, which encases the cellular components of the clot, including platelets and red blood cells. Fibrinolysis is the proteolytic degradation of the fibrin network that results in the release of the cellular components into the bloodstream. In the case of thrombosis, fibrinolysis is required for restoration of blood flow, which is accomplished clinically through exogenously delivered lytic factors in a process called external lysis. Fibrinolysis is regulated by plasminogen activators (tissue-type and urokinase-type) that convert plasminogen into plasmin to initiate fiber lysis and lytic inhibitors that impede this lysis (plasminogen activator inhibitors, alpha 2-antiplasmin, and thrombin activatable fibrinolysis inhibitor). Furthermore, the network structure has been shown to regulate lysis: thinner fibers and coarser clots lyse faster than thicker fibers and finer clots. Clot contraction, a result of platelets pulling on fibers, results in densely packed red blood cells (polyhedrocytes), reduced permeability to fibrinolytic factors, and increased fiber tension. Extensive research in the field has allowed for critical advancements leading to improved thrombolytic agents. In this review, we summarize the state of the field, highlight gaps in knowledge, and propose future research questions.
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Affiliation(s)
| | - Nicholas C Kirby
- Department of Chemistry, East Carolina University, Greenville, North Carolina, USA
| | | | - Nathan E Hudson
- Department of Physics, East Carolina University Greenville, North Carolina, USA
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Microscale structural changes of individual fibrin fibers during fibrinolysis. Acta Biomater 2022; 141:114-122. [PMID: 35007782 PMCID: PMC8898298 DOI: 10.1016/j.actbio.2022.01.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 12/31/2021] [Accepted: 01/04/2022] [Indexed: 02/06/2023]
Abstract
Fibrinolysis is the enzymatic digestion of fibrin, the primary structural component in blood clots. Mechanisms of fibrin fiber digestion during lysis have long been debated and obtaining detailed structural knowledge of these processes is important for developing effective clinical approaches to treat ischemic stroke and pulmonary embolism. Using dynamic fluorescence microscopy, we studied the time-resolved digestion of individual fibrin fibers by the fibrinolytic enzyme plasmin. We found that plasmin molecules digest fibers along their entire lengths, but that the rates of digestion are non-uniform, resulting in cleavage at a single location along the fiber. Using mathematical modeling we estimated the rate of plasmin arrival at the fiber surface and the number of digestion sites on a fiber. We also investigated correlations between local fiber digestion rates, cleavage sites, and fiber properties such as initial thickness. Finally, we uncovered a previously unknown tension-dependent mechanism that pulls fibers apart during digestion. Taken together these results promote a paradigm shift in understanding mechanisms of fibrinolysis and underscore the need to consider fibrin tension when assessing fibrinolytic approaches. STATEMENT OF SIGNIFICANCE: We developed a method for interrogating lysis of individual fibrin fibers, enabling the time-resolved observation of individual fiber digestion for the first time. Our results resolve longstanding disagreements about fibrinolytic processes and reveal previously unknown mechanisms that also play a role. Also, we developed the first microscale mathematical model of plasmin-fibrin interaction, which predicts the number of plasmin molecules on each fiber and can serve as a framework for investigating novel therapeutics.
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Bannish BE, Hudson NE. The Utility and Potential of Mathematical Models in Predicting Fibrinolytic Outcomes. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2021; 20:100337. [PMID: 34957356 PMCID: PMC8694003 DOI: 10.1016/j.cobme.2021.100337] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The enzymatic degradation of blood clots, fibrinolysis, is an important part of a healthy hemostatic system. If intrinsic fibrinolysis is ineffective, thrombolysis - the clinically-induced enzymatic degradation of blood clots - may be necessary to treat life-threatening conditions. In this review we discuss recent models of fibrinolysis and thrombolysis, and open questions that could be resolved through modeling and modeling-experimental collaboration. In particular, we focus on 2- and 3-dimensional models that can be used to study effects of fibrin network structure and realistic blood vessel geometries on the phenomena underlying lytic outcomes. Significant open questions such as the role of clot contraction, network and inherent fiber tension, and fibrinolytic inhibitors in lysis could benefit from mathematical models aimed at understanding the underlying biological mechanisms.
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Affiliation(s)
- Brittany E. Bannish
- Department of Mathematics and Statistics, University of Central Oklahoma, Edmond, OK 73034, USA
- Center for Interdisciplinary Biomedical Education and Research, University of Central Oklahoma, Edmond, OK 73034, USA
| | - Nathan E. Hudson
- Nathan E. Hudson, Department of Physics, East Carolina University, Greenville, NC 27858, USA
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Raynaud F, Rousseau A, Monteyne D, Perez-Morga D, Zouaoui Boudjeltia K, Chopard B. Investigating the two regimes of fibrin clot lysis: an experimental and computational approach. Biophys J 2021; 120:4091-4106. [PMID: 34384765 PMCID: PMC8510862 DOI: 10.1016/j.bpj.2021.08.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 07/07/2021] [Accepted: 08/04/2021] [Indexed: 12/03/2022] Open
Abstract
It has been observed in vitro that complete clot lysis is generally preceded by a slow phase of lysis during which the degradation seems to be inefficient. However, this slow regime was merely noticed, but not yet quantitatively discussed. In our experiments, we observed that the lysis ubiquitously occurred in two distinct regimes, a slow and a fast lysis regime. We quantified extensively the duration of these regimes for a wide spectrum of experimental conditions and found that on average, the slow regime lasts longer than the fast one, meaning that during most of the process, the lysis is ineffective. We proposed a computational model in which the properties of the binding of the proteins change during the lysis: first, the biochemical reactions take place at the surface of the fibrin fibers, then in the bulk, resulting in the observed fast lysis regime. This simple hypothesis appeared to be sufficient to reproduce with a great accuracy the lysis profiles obtained experimentally.
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Affiliation(s)
- Franck Raynaud
- Department of Computer Science, University of Geneva, Geneva, Switzerland.
| | - Alexandre Rousseau
- Laboratoire de Médecine Expérimentale, Medicine Faculty, Université libre de Bruxelles (ULB 222 Unit), ISPPC CHU de Charleroi, Hôpital A. Vésale, Montigny-le-Tilleul, Belgium
| | - Daniel Monteyne
- Laboratory of Molecular Parasitology, IBMM, Université libre de Bruxelles, Gosselies, Belgium; Center for Microscopy and Molecular Imaging, Université libre de Bruxelles, Gosselies, Belgium
| | - David Perez-Morga
- Laboratory of Molecular Parasitology, IBMM, Université libre de Bruxelles, Gosselies, Belgium; Center for Microscopy and Molecular Imaging, Université libre de Bruxelles, Gosselies, Belgium
| | - Karim Zouaoui Boudjeltia
- Laboratoire de Médecine Expérimentale, Medicine Faculty, Université libre de Bruxelles (ULB 222 Unit), ISPPC CHU de Charleroi, Hôpital A. Vésale, Montigny-le-Tilleul, Belgium
| | - Bastien Chopard
- Department of Computer Science, University of Geneva, Geneva, Switzerland
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