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Litvinov RI, Weisel JW. Blood clot contraction: Mechanisms, pathophysiology, and disease. Res Pract Thromb Haemost 2023; 7:100023. [PMID: 36760777 PMCID: PMC9903854 DOI: 10.1016/j.rpth.2022.100023] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 11/09/2022] [Accepted: 11/17/2022] [Indexed: 01/18/2023] Open
Abstract
A State of the Art lecture titled "Blood Clot Contraction: Mechanisms, Pathophysiology, and Disease" was presented at the International Society on Thrombosis and Haemostasis (ISTH) Congress in 2022. This was a systematic description of blood clot contraction or retraction, driven by activated platelets and causing compaction of the fibrin network along with compression of the embedded erythrocytes. The consequences of clot contraction include redistribution of the fibrin-platelet meshwork toward the periphery of the clot and condensation of erythrocytes in the core, followed by their deformation from the biconcave shape into polyhedral cells (polyhedrocytes). These structural signatures of contraction have been found in ex vivo thrombi derived from various locations, which indicated that clots undergo intravital contraction within the blood vessels. In hemostatic clots, tightly packed polyhedrocytes make a nearly impermeable seal that stems bleeding and is impaired in hemorrhagic disorders. In thrombosis, contraction facilitates the local blood flow by decreasing thrombus obstructiveness, reducing permeability, and changing susceptibility to fibrinolytic enzymes. However, in (pro)thrombotic conditions, continuous background platelet activation is followed by platelet exhaustion, refractoriness, and impaired intravital clot contraction, which is associated with weaker thrombi predisposed to embolization. Therefore, assays that detect imperfect in vitro clot contraction have potential diagnostic and prognostic values for imminent or ongoing thrombosis and thrombotic embolism. Collectively, the contraction of blood clots and thrombi is an underappreciated and understudied process that has a pathogenic and clinical significance in bleeding and thrombosis of various etiologies. Finally, we have summarized relevant new data on this topic presented during the 2022 ISTH Congress.
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Affiliation(s)
- Rustem I Litvinov
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - John W Weisel
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
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2
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Spiewak R, Gosselin A, Merinov D, Litvinov RI, Weisel JW, Tutwiler V, Purohit PK. Biomechanical origins of inherent tension in fibrin networks. J Mech Behav Biomed Mater 2022; 133:105328. [PMID: 35803206 PMCID: PMC9434494 DOI: 10.1016/j.jmbbm.2022.105328] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 06/02/2022] [Accepted: 06/18/2022] [Indexed: 10/17/2022]
Abstract
Blood clots form at the site of vascular injury to seal the wound and prevent bleeding. Clots are in tension as they perform their biological functions and withstand hydrodynamic forces of blood flow, vessel wall fluctuations, extravascular muscle contraction and other forces. There are several mechanisms that generate tension in a blood clot, of which the most well-known is the contraction/retraction caused by activated platelets. Here we show through experiments and modeling that clot tension is generated by the polymerization of fibrin. Our mathematical model is built on the hypothesis that the shape of fibrin monomers having two-fold symmetry and off-axis binding sites is ultimately the source of inherent tension in individual fibers and the clot. As the diameter of a fiber grows during polymerization the fibrin monomers must suffer axial twisting deformation so that they remain in register to form the half-staggered arrangement characteristic of fibrin protofibrils. This deformation results in a pre-strain that causes fiber and network tension. Our results for the pre-strain in single fibrin fibers is in agreement with experiments that measured it by cutting fibers and measuring their relaxed length. We connect the mechanics of a fiber to that of the network using the 8-chain model of polymer elasticity. By combining this with a continuum model of swellable elastomers we can compute the evolution of tension in a constrained fibrin gel. The temporal evolution and tensile stresses predicted by this model are in qualitative agreement with experimental measurements of the inherent tension of fibrin clots polymerized between two fixed rheometer plates. These experiments also revealed that increasing thrombin concentration leads to increasing internal tension in the fibrin network. Our model may be extended to account for other mechanisms that generate pre-strains in individual fibers and cause tension in three-dimensional proteinaceous polymeric networks.
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Affiliation(s)
- Russell Spiewak
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Andrew Gosselin
- Department of Biomedical Engineering, Rutgers - The State University of New Jersey, 599 Taylor Road, Room 209, Piscataway, NJ 08854, USA
| | - Danil Merinov
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, 1154 BRB II/III, 421 Curie Boulevard, Philadelphia, PA 19104-6058, USA
| | - Rustem I Litvinov
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, 1154 BRB II/III, 421 Curie Boulevard, Philadelphia, PA 19104-6058, USA
| | - John W Weisel
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, 1154 BRB II/III, 421 Curie Boulevard, Philadelphia, PA 19104-6058, USA.
| | - Valerie Tutwiler
- Department of Biomedical Engineering, Rutgers - The State University of New Jersey, 599 Taylor Road, Room 209, Piscataway, NJ 08854, USA.
| | - Prashant K Purohit
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA 19104, USA.
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3
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Labeling fibrin fibers with beads alter single fibrin fiber lysis, external clot lysis, and produce large fibrin aggregates upon lysis. Blood Coagul Fibrinolysis 2022; 33:364-371. [PMID: 35834714 DOI: 10.1097/mbc.0000000000001150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Fluorescent beads are often used as a tool for visualizing fibrin fibers in single fiber mechanics studies and studies of single fiber lysis. Here we investigate the effect of beads on fibrin fiber lysis and extensibility to enhance understanding of this common research technique. We selected beads of the same diameter as those used in previous studies, as well as, beads of similar size to microparticles in the bloodstream. We used fluorescence microscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM) to quantify changes in fiber lysis, fiber extensibility, and clot structure in the presence and absence of beads. Fibrin clot structure and lysis were altered in the presence of beads. Fibrin clots formed with beads had a higher fiber density, smaller diameter fibers, and smaller pores. The rate of lysis for clots was reduced when beads were present. Lysis studies of bead-labeled individual fibers showed that beads, at concentrations similar to those reported for microparticles in the blood, cause a subset of fibers to resist lysis. In the absence of beads, all fibers lyse. These results demonstrate that beads alter fiber lysis through both a change in fibrin clot structure as well as changes to individual fiber lysis behavior. Additionally, the lysis of clots with beads produced large fibrin aggregates. This data encourages researchers to use careful consideration when labeling fibrin fibers with fluorescent beads and suggests that particles binding fibrin(ogen) in the bloodstream may be an underappreciated mechanism increasing the risk of thrombosis.
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Abstract
SignificanceFibrin plays a vital role in biology as the fibrous network that stabilizes blood clots and also through interaction with numerous blood components. While much is known about fibrin mechanics, comparatively little is known about how fibrin's mechanics influence its biochemistry. We show that structural changes in fibrin under mechanical tension reduces binding of tissue plasminogen activator, an enzyme that initiates lysis. Furthermore, these structural transitions also led to decreased platelet activation through suppressed binding between platelet integrins and fibrin. Our work shows that fibrin possesses an intrinsic mechano-chemical feedback loop that regulates its bioactivity via molecular structural rearrangements.
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Engineered Molecular Therapeutics Targeting Fibrin and the Coagulation System: a Biophysical Perspective. Biophys Rev 2022; 14:427-461. [PMID: 35399372 PMCID: PMC8984085 DOI: 10.1007/s12551-022-00950-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 03/25/2022] [Indexed: 02/07/2023] Open
Abstract
The coagulation cascade represents a sophisticated and highly choreographed series of molecular events taking place in the blood with important clinical implications. One key player in coagulation is fibrinogen, a highly abundant soluble blood protein that is processed by thrombin proteases at wound sites, triggering self-assembly of an insoluble protein hydrogel known as a fibrin clot. By forming the key protein component of blood clots, fibrin acts as a structural biomaterial with biophysical properties well suited to its role inhibiting fluid flow and maintaining hemostasis. Based on its clinical importance, fibrin is being investigated as a potentially valuable molecular target in the development of coagulation therapies. In this topical review, we summarize our current understanding of the coagulation cascade from a molecular, structural and biophysical perspective. We highlight single-molecule studies on proteins involved in blood coagulation and report on the current state of the art in directed evolution and molecular engineering of fibrin-targeted proteins and polymers for modulating coagulation. This biophysical overview will help acclimatize newcomers to the field and catalyze interdisciplinary work in biomolecular engineering toward the development of new therapies targeting fibrin and the coagulation system.
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6
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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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Haller SJ, Dudley AT. Extracellular mechanotransduction. J Gen Physiol 2022; 154:213008. [PMID: 35171207 PMCID: PMC8855477 DOI: 10.1085/jgp.202113026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 01/04/2022] [Accepted: 01/27/2022] [Indexed: 12/17/2022] Open
Abstract
We highlight the force-sensing function of extracellular matrix and present a complementary mechanotransduction paradigm.
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Affiliation(s)
- Stephen J Haller
- Mary and Dick Holland Regenerative Medicine Program, Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE
| | - Andrew T Dudley
- Mary and Dick Holland Regenerative Medicine Program, Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE
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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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Rausch MK, Parekh SH, Dortdivanlioglu B, Rosales AM. Synthetic hydrogels as blood clot mimicking wound healing materials. PROGRESS IN BIOMEDICAL ENGINEERING (BRISTOL, ENGLAND) 2021; 3:042006. [PMID: 35822083 PMCID: PMC9273113 DOI: 10.1088/2516-1091/ac23a4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Excessive bleeding-or hemorrhage-causes millions of civilian and non-civilian casualties every year. Additionally, wound sequelae, such as infections, are a significant source of chronic morbidity, even if the initial bleeding is successfully stopped. To treat acute and chronic wounds, numerous wound healing materials have been identified, tested, and adopted. Among them are topical dressings, such as gauzes, as well as natural and biomimetic materials. However, none of these materials successfully mimic the complex and dynamic properties of the body's own wound healing material: the blood clot. Specifically, blood clots exhibit complex mechanical and biochemical properties that vary across spatial and temporal scales to guide the wound healing response, which make them the ideal wound healing material. In this manuscript, we review blood clots' complex mechanical and biochemical properties, review current wound healing materials, and identify opportunities where new materials can provide additional functionality, with a specific focus on hydrogels. We highlight recent developments in synthetic hydrogels that make them capable of mimicking a larger subset of blood clot features: as plugs and as stimuli for tissue repair. We conclude that future hydrogel materials designed to mimic blood clot biochemistry, mechanics, and architecture can be combined with exciting platelet-like particles to serve as hemostats that also promote the biological wound healing response. Thus, we believe synthetic hydrogels are ideal candidates to address the clear need for better wound healing materials.
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Affiliation(s)
- Manuel K. Rausch
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX 78712, United States of America
- Department of Aerospace Engineering & Engineering Mechanics, University of Texas at Austin, Austin, TX 78712, United States of America
- Oden Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, TX 78712, United States of America
- Authors to whom any correspondence should be addressed. , , and
| | - Sapun H. Parekh
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX 78712, United States of America
- Authors to whom any correspondence should be addressed. , , and
| | - Berkin Dortdivanlioglu
- Oden Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, TX 78712, United States of America
- Department of Civil, Architectural and Environmental Engineering, University of Texas at Austin, Austin, TX 78712, United States of America
- Authors to whom any correspondence should be addressed. , , and
| | - Adrianne M. Rosales
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX 78712, United States of America
- Authors to whom any correspondence should be addressed. , , and
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10
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Yesudasan S, Averett RD. Fracture mechanics analysis of fibrin fibers using mesoscale and continuum level methods. INFORMATICS IN MEDICINE UNLOCKED 2021; 23. [PMID: 33981824 PMCID: PMC8112576 DOI: 10.1016/j.imu.2021.100524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Computational models for simulating and predicting fibrin fiber fracture are important tools for studying bulk mechanical properties and mechanobiological response of fibrin networks in physiological conditions. In this work, we employed a new strategy to model the mechanical response of a single fibrin fiber using a collection of bundled protofibrils and modeled the time-dependent properties using discrete particle simulations. Using a systematic characterization of the parameters, this model can be used to mimic the elastic behavior of fibrin fibers accurately and also to simulate fibrin fiber fracture. In addition, a continuum model was modified and used to obtain the individual fibrin fiber fracture toughness properties. Using this model and the experimentally available fibrin mechanical properties, we predicted the range of fracture toughness (1 to k P a m ) values of a typical fibrin fiber of diameter 100 nm and its critical flaw size to rupture (~4 nm), both of which are not currently available in the literature. The models can be collectively used as a foundation for simulating the mechanical behavior of fibrin clots. Moreover, the tunable discrete mesoscopic model that was employed can be extended to simulate and estimate the mechanical properties of other biological or synthetic fibers.
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Affiliation(s)
- Sumith Yesudasan
- Department of Engineering Technology, Sam Houston State University, Huntsville, TX, 77341, USA
| | - Rodney D Averett
- School of Chemical, Materials, and Biomedical Engineering, College of Engineering, University of Georgia, Athens, GA, 30602, USA
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11
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Cone SJ, Fuquay AT, Litofsky JM, Dement TC, Carolan CA, Hudson NE. Inherent fibrin fiber tension propels mechanisms of network clearance during fibrinolysis. Acta Biomater 2020; 107:164-177. [PMID: 32105833 PMCID: PMC7160043 DOI: 10.1016/j.actbio.2020.02.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 02/13/2020] [Accepted: 02/18/2020] [Indexed: 11/21/2022]
Abstract
Proper wound healing necessitates both coagulation (the formation of a blood clot) and fibrinolysis (the dissolution of a blood clot). A thrombus resistant to clot dissolution can obstruct blood flow, leading to vascular pathologies. This study seeks to understand the mechanisms by which individual fibrin fibers, the main structural component of blood clots, are cleared from a local volume during fibrinolysis. We observed 2-D fibrin networks during lysis by plasmin, recording the clearance of each individual fiber. We found that, in addition to transverse cleavage of fibers, there were multiple other pathways by which clot dissolution occurred, including fiber bundling, buckling, and collapsing. These processes are all influenced by the concentration of plasmin utilized in lysis. The network fiber density influenced the kinetics and distribution of these pathways. Individual cleavage events often resulted in large morphological changes in network structure, suggesting that the inherent tension in fibers played a role in fiber clearance. Using images before and after a cleavage event to measure fiber lengths, we estimated that fibers are strained ~23% beyond their equilibrium length during polymerization. To understand the role of fiber tension in fibrinolysis we modeled network clearance under differing amounts of fiber polymerized strain (prestrain). The comparison of experimental and model data indicated that fibrin tension enables 35% more network clearance due to network rearrangements after individual cleavage events than would occur if fibers polymerized in a non-tensed state. Our results highlight many characteristics and mechanisms of fibrin breakdown, which have implications on future fibrin studies, our understanding of the fibrinolytic process, and the development of thrombolytic therapies. STATEMENT OF SIGNIFICANCE: Fibrin fibers serve as the main structural element of blood clots. They polymerize under tension and have remarkable extensibility and elasticity. After the cessation of wound healing, fibrin must be cleared from the vasculature by the enzyme plasmin in order to resume normal blood flow: a process called fibrinolysis. In this study we investigate the mechanisms that regulate the clearance of individual fibrin fibers during fibrinolysis. We show that the inherent tension in fibers enhances the action of plasmin because every fiber cleavage event results in a redistribution of the network tension. This network re-equilibration causes fibers to buckle, bundle, and even collapse, leading to a more rapid fiber clearance than plasmin alone could provide.
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Affiliation(s)
- Sean J Cone
- Department of Physics, East Carolina University; 1000 E 5(th) St, Greenville, NC 27858, United States
| | - Andrew T Fuquay
- Medical Physics Graduate Program, Duke University; DUMC 2729, 2424 Erwin Rd Suite 101, Durham, NC 27705, USA
| | - Justin M Litofsky
- Department of Physics, East Carolina University; 1000 E 5(th) St, Greenville, NC 27858, United States
| | - Taylor C Dement
- Department of Physics, East Carolina University; 1000 E 5(th) St, Greenville, NC 27858, United States
| | - Christopher A Carolan
- Department of Mathematics, East Carolina University; 1000 E 5(th) St, Greenville, NC 27858, United States
| | - Nathan E Hudson
- Department of Physics, East Carolina University; 1000 E 5(th) St, Greenville, NC 27858, United States.
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12
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Lee SJJ, Nguyen DM, Grewal HS, Puligundla C, Saha AK, Nair PM, Cap AP, Ramasubramanian AK. Image-based analysis and simulation of the effect of platelet storage temperature on clot mechanics under uniaxial strain. Biomech Model Mechanobiol 2019; 19:173-187. [PMID: 31312933 DOI: 10.1007/s10237-019-01203-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 07/08/2019] [Indexed: 12/19/2022]
Abstract
Optimal strength and stability of blood clots are keys to hemostasis and in prevention of hemorrhagic or thrombotic complications. Clots are biocomposite materials composed of fibrin network enmeshing platelets and other blood cells. We have previously shown that the storage temperature of platelets significantly impacts clot structure and stiffness. The objective of this work is to delineate the relationship between morphological characteristics and mechanical response of clot networks. We examined scanning electron microscope images of clots prepared from fresh apheresis platelets, and from apheresis platelets stored for 5 days at room temperature or at 4 °C, suspended in pooled plasma. Principal component analysis of nine different morphometric parameters revealed that a single principal component (PC1) can distinguish the effect of platelet storage on clot ultrastructure. Finite element analysis of clot response to uniaxial strain was used to map the spatially heterogeneous distribution of strain energy density for each clot. At modest deformations (25% strain), a single principal component (PC2) was able to predict these heterogeneities as quantified by variability in strain energy density distribution and in linear elastic stiffness, respectively. We have identified structural parameters that are primary regulators of stress distribution, and the observations provide insights into the importance of spatial heterogeneity on hemostasis and thrombosis.
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Affiliation(s)
- Sang-Joon J Lee
- Department of Mechanical Engineering, San José State University, San Jose, CA, 95192, USA
| | - Dustin M Nguyen
- Department of Chemical and Materials Engineering, San José State University, San Jose, CA, 95192, USA
| | - Harjot S Grewal
- Department of Chemical and Materials Engineering, San José State University, San Jose, CA, 95192, USA
| | - Chaitanya Puligundla
- Department of Chemical and Materials Engineering, San José State University, San Jose, CA, 95192, USA
| | - Amit K Saha
- Department of Biochemistry, Stanford University, Palo Alto, CA, 94304, USA
| | - Prajeeda M Nair
- Blood Research Program, US Army Institute of Surgical Research, Fort Sam Houston, San Antonio, TX, 78234, USA
| | - Andrew P Cap
- Blood Research Program, US Army Institute of Surgical Research, Fort Sam Houston, San Antonio, TX, 78234, USA
| | - Anand K Ramasubramanian
- Department of Chemical and Materials Engineering, San José State University, San Jose, CA, 95192, USA.
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13
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Hoffmann GA, Wong JY, Smith ML. On Force and Form: Mechano-Biochemical Regulation of Extracellular Matrix. Biochemistry 2019; 58:4710-4720. [PMID: 31144496 DOI: 10.1021/acs.biochem.9b00219] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The extracellular matrix is well-known for its structural role in supporting cells and tissues, and its important biochemical role in providing signals to cells has increasingly become apparent. These structural and biochemical roles are closely coupled through mechanical forces: the biochemistry of the extracellular matrix determines its mechanical properties, mechanical forces control release or display of biochemical signals from the extracellular matrix, and the mechanical properties of the matrix in turn influence the mechanical set point at which signals are sent. In this Perspective, we explain how the extracellular matrix is regulated by strain and mechanical forces. We show the impact of biochemistry and mechanical forces on in vivo assembly of extracellular matrix and illustrate how matrix can be generated in vitro using a variety of methods. We cover how the matrix can be characterized in terms of mechanics, composition, and conformation to determine its properties and to predict interactions. Finally, we explore how extracellular matrix remodeling, ligand binding, and hemostasis are regulated by mechanical forces. These recently discovered mechano-biochemical interactions have important functions in wound healing and disease progression. It is likely that mechanically altered extracellular matrix interactions are a commonly recurring theme, but due to limited tools to generate extracellular matrix fibers in vitro and lack of high-throughput methods to detect these interactions, it is hypothesized that many of these interactions have yet to be discovered.
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Affiliation(s)
- Gwendolyn A Hoffmann
- Department of Biomedical Engineering , Boston University , 44 Cummington Mall , Boston , Massachusetts 02215 , United States
| | - Joyce Y Wong
- Department of Biomedical Engineering , Boston University , 44 Cummington Mall , Boston , Massachusetts 02215 , United States
| | - Michael L Smith
- Department of Biomedical Engineering , Boston University , 44 Cummington Mall , Boston , Massachusetts 02215 , United States
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14
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Bradshaw MJ, Hoffmann GA, Wong JY, Smith ML. Fibronectin fiber creep under constant force loading. Acta Biomater 2019; 88:78-85. [PMID: 30780000 DOI: 10.1016/j.actbio.2019.02.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 02/06/2019] [Accepted: 02/15/2019] [Indexed: 12/12/2022]
Abstract
Viscoelasticity is a fundamental property of virtually all biological materials, and proteinaceous, fibrous materials that constitute the extracellular matrix (ECM) are no exception. Viscoelasticity may be particularly important in the ECM since cells can apply mechanical stress resulting from cell contractility over very long periods of time. However, measurements of ECM fiber response to long-term constant force loading are scarce, despite the increasing recognition that mechanical strain regulates the biological function of some ECM fibers. We developed a dual micropipette system that applies constant force to single fibers for up to 8 h. We utilized this system to study the time dependent response of fibronectin (Fn) fibers to constant force, as Fn fibers exhibit tremendous extensibility before mechanical failure as well as strain dependent alterations in biological properties. These data demonstrate the Fn fibers continue to stretch under constant force loading for at least 8 h and that this long-term creep results in plastic deformation of Fn fibers, in contrast to elastic deformation of Fn fibers under short-term, but fast loading rate extension. These data demonstrate that physiologically-relevant loading may impart mechanical features to Fn fibers by switching them into an extended state that may have altered biological functions. STATEMENT OF SIGNIFICANCE: Measurements of extracellular matrix (ECM) fiber response to constant force loading are scarce, so we developed a novel technique for applying constant force to single ECM fibers. We used this technique to measure constant force creep of fibronectin fibers since these fibers have been shown to be mechanotransducers whose functions can be altered by mechanical strain. We found that fibronectin fibers creep under constant force loading for the duration of the experiment and that this creep behavior resembles a power law. Furthermore, we found that constant force creep results in plastic deformation of the fibers, which suggests that the mechanobiological switching of fibronectin can only occur once after long-term loading.
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Affiliation(s)
- Mark J Bradshaw
- Department of Mechanical Engineering, Boston University, Boston, MA 02215, United States
| | - Gwendolyn A Hoffmann
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, United States
| | - Joyce Y Wong
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, United States
| | - Michael L Smith
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, United States.
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15
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Pieters M, Wolberg AS. Fibrinogen and fibrin: An illustrated review. Res Pract Thromb Haemost 2019; 3:161-172. [PMID: 31011700 PMCID: PMC6462751 DOI: 10.1002/rth2.12191] [Citation(s) in RCA: 139] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 01/30/2019] [Indexed: 12/19/2022] Open
Abstract
Since its discovery over 350 years ago, studies of fibrinogen have revealed remarkable characteristics. Its complex structure as a large (340 kDa) hexameric homodimer supports complex roles in hemostasis and homeostasis. Fibrinogen synthesis is regulated at the transcriptional and translational levels, undergoing both constitutive (basal) secretion from liver, and inducible upregulation in response to inflammatory events. In addition, alternative splicing yields fibrinogen variants with unique properties and contributions to coagulation biochemistry. During coagulation, fibrinogen conversion to fibrin occurs via thrombin‐mediated proteolytic cleavage that produces intermediate protofibrils and then mature fibers that provide remarkable biochemical and mechanical stability to clots. Fibrin formation, structure, and stability are regulated by various genetic, biochemical, and environmental factors, allowing for dynamic kinetics of fibrin formation and structure. Interactions between fibrinogen and/or fibrin and plasma proteins and receptors on platelets, leukocytes, endothelial cells, and other cells enable complex functions in hemostasis, thrombosis, pregnancy, inflammation, infection, cancer, and other pathologies. Disorders in fibrinogen concentration and/or function increase risk of bleeding, thrombosis, and infection. This illustrated review covers fundamental aspects of fibrinogen and fibrin biology, biochemistry, biophysics, epidemiology, and clinical applications. Continued efforts to enhance our understanding of fibrinogen and fibrin in these processes are likely to advance treatment and prevention of many human diseases.
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Affiliation(s)
- Marlien Pieters
- Center of Excellence for Nutrition North-West University Potchefstroom South Africa
| | - Alisa S Wolberg
- Department of Pathology and Laboratory Medicine University of North Carolina Chapel Hill North Carolina
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Tutwiler V, Peshkova AD, Le Minh G, Zaitsev S, Litvinov RI, Cines DB, Weisel JW. Blood clot contraction differentially modulates internal and external fibrinolysis. J Thromb Haemost 2019; 17:361-370. [PMID: 30582674 DOI: 10.1111/jth.14370] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Indexed: 01/16/2023]
Abstract
Essentials Clot contraction influences the rate of fibrinolysis in vitro. Internal fibrinolysis is enhanced ∼2-fold in contracted vs. uncontracted blood clots. External fibrinolysis is ∼4-fold slower in contracted vs. uncontracted blood clots. Contraction can modulate lytic resistance and potentially the clinical outcome of thrombosis. SUMMARY: Background Fibrinolysis involves dissolution of polymeric fibrin networks that is required to restore blood flow through vessels obstructed by thrombi. The efficiency of lysis depends in part on the susceptibility of fibrin to enzymatic digestion, which is governed by the structure and spatial organization of fibrin fibers. How platelet-driven clot contraction affects the efficacy of fibrinolysis has received relatively little study. Objective Here, we examined the effects of clot contraction on the rate of internal fibrinolysis emanating from within the clot to simulate (patho)physiological conditions and external fibrinolysis initiated from the clot exterior to simulate therapeutic thrombolysis. Methods Clot contraction was prevented by inhibiting platelet myosin IIa activity, actin polymerization or platelet-fibrin(ogen) binding. Internal fibrinolysis was measured by optical tracking of clot size. External fibrinolysis was determined by the release of radioactive fibrin degradation products. Results and Conclusions Clot contraction enhanced the rate of internal fibrinolysis ∼2-fold. In contrast, external fibrinolysis was ~4-fold slower in contracted clots. This dichotomy in the susceptibility of contracted and uncontracted clots to internal vs. external lysis suggests that the rate of lysis is dependent upon the interplay between accessibility of fibrin fibers to fibrinolytic agents, including clot permeability, and the spatial proximity of the fibrin fibers that modulate the effects of the fibrinolytic enzymes. Understanding how compaction of blood clots influences clot lysis might have important implications for prevention and treatment of thrombotic disorders.
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Affiliation(s)
- Valerie Tutwiler
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Alina D Peshkova
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russian Federation
| | - Giang Le Minh
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russian Federation
| | - Sergei Zaitsev
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Rustem I Litvinov
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russian Federation
| | - Douglas B Cines
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - John W Weisel
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
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Feller T, Hársfalvi J, Csányi C, Kiss B, Kellermayer M. Plasmin-driven fibrinolysis in a quasi-two-dimensional nanoscale fibrin matrix. J Struct Biol 2018; 203:273-280. [DOI: 10.1016/j.jsb.2018.05.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Revised: 05/28/2018] [Accepted: 05/29/2018] [Indexed: 11/28/2022]
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