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Medcalf RL, Keragala CB. The Fibrinolytic System: Mysteries and Opportunities. Hemasphere 2021; 5:e570. [PMID: 34095754 PMCID: PMC8171360 DOI: 10.1097/hs9.0000000000000570] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 04/07/2021] [Indexed: 02/07/2023] Open
Abstract
The deposition and removal of fibrin has been the primary role of coagulation and fibrinolysis, respectively. There is also little doubt that these 2 enzyme cascades influence each other given they share the same serine protease family ancestry and changes to 1 arm of the hemostatic pathway would influence the other. The fibrinolytic system in particular has also been known for its capacity to clear various non-fibrin proteins and to activate other enzyme systems, including complement and the contact pathway. Furthermore, it can also convert a number of growth factors into their mature, active forms. More recent findings have extended the reach of this system even further. Here we will review some of these developments and also provide an account of the influence of individual players of the fibrinolytic (plasminogen activating) pathway in relation to physiological and pathophysiological events, including aging and metabolism.
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Affiliation(s)
- Robert L. Medcalf
- Molecular Neurotrauma and Haemostasis, Australian Centre for Blood Diseases, Central Clinical School, Monash University, Victoria, Australia
| | - Charithani B. Keragala
- Molecular Neurotrauma and Haemostasis, Australian Centre for Blood Diseases, Central Clinical School, Monash University, Victoria, Australia
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Miszta A, Ahmadzia HK, Luban NLC, Li S, Guo D, Holle LA, Berger JS, James AH, Gobburu JVS, van den Anker J, de Laat B, Wolberg AS. Application of a plasmin generation assay to define pharmacodynamic effects of tranexamic acid in women undergoing cesarean delivery. J Thromb Haemost 2021; 19:221-232. [PMID: 33001565 PMCID: PMC7875467 DOI: 10.1111/jth.15114] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 09/17/2020] [Accepted: 09/18/2020] [Indexed: 12/27/2022]
Abstract
Essentials Tranexamic acid (TXA) is an antifibrinolytic drug used to reduce bleeding. Assaying plasmin generation (PG) in plasma detects clinically relevant TXA levels in vitro and ex vivo. 3.1-16.2 µg/mL TXA half-maximally inhibits PG in plasma from women undergoing cesarean delivery. PG velocity shows the strongest dose-relationship at low TXA concentrations (≤10 µg/mL). ABSTRACT: Background Tranexamic acid (TXA) is used to reduce bleeding. TXA inhibits plasmin(ogen) binding to fibrin and reduces fibrinolysis. TXA antifibrinolytic activity is typically measured by clot lysis assays; however, effects on plasmin generation (PG) are unclear due to a lack of tools to measure PG in plasma. Aims Develop an assay to measure PG kinetics in human plasma. Determine effects of TXA on PG and compare with fibrinolysis measured by rotational thromboelastometry (ROTEM). Methods We characterized effects of plasminogen, tissue plasminogen activator, fibrinogen, and α2 -antiplasmin on PG in vitro. We also studied effects of TXA on PG in plasma from 30 pregnant women administered intravenous TXA (5, 10, or 15 mg/kg) during cesarean delivery. PG was measured by calibrated fluorescence. PG parameters were compared with TXA measured by mass spectrometry and ROTEM of whole blood. Results The PG assay is specific for plasmin and sensitive to tissue plasminogen activator, fibrin(ogen), and α2 -antiplasmin. Addition of TXA to plasma in vitro dose dependently prolonged the clot lysis time and delayed and reduced PG. For all doses of TXA administered intravenously, the PG assay detected delayed time-to-peak (≤3 hours) and reduced the velocity, peak, and endogenous plasmin potential (≤24 hours) in plasma samples obtained after infusion. The PG time-to-peak, velocity, and peak correlated significantly with TXA concentration and showed less variability than the ROTEM lysis index at 30 minutes or maximum lysis. Conclusions The PG assay detects pharmacologically relevant concentrations of TXA administered in vitro and in vivo, and demonstrates TXA-mediated inhibition of PG in women undergoing cesarean delivery.
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Affiliation(s)
- Adam Miszta
- Department of Pathology and UNC Blood Research Center, University of North Carolina, Chapel Hill, NC, USA
- Synapse Research Institute, Maastricht, The Netherlands
| | - Homa K. Ahmadzia
- Division of Maternal-Fetal Medicine, Department of Obstetrics & Gynecology, The George Washington University, Washington, DC, USA
| | - Naomi L. C. Luban
- Division of Hematology/Oncology, Department of Pediatrics and Pathology, George Washington University School of Medicine and Health Sciences, Washington, DC, USA
| | - Shuhui Li
- Center for Translational Medicine, School of Pharmacy, University of Maryland, Baltimore, MD, USA
| | - Dong Guo
- Center for Translational Medicine, School of Pharmacy, University of Maryland, Baltimore, MD, USA
| | - Lori A. Holle
- Department of Pathology and UNC Blood Research Center, University of North Carolina, Chapel Hill, NC, USA
| | - Jeffrey S. Berger
- Department of Anesthesiology, The George Washington University, Washington, DC, USA
| | - Andra H. James
- Division of Maternal-Fetal Medicine, Department of Obstetrics & Gynecology, Duke University, Durham, NC, USA
| | - Jogarao V. S. Gobburu
- Center for Translational Medicine, School of Pharmacy, University of Maryland, Baltimore, MD, USA
| | - John van den Anker
- Division of Clinical Pharmacology, Department of Pediatrics, Children’s National Hospital, George Washington University of School of Medicine and Health Sciences, Washington, DC, USA
| | - Bas de Laat
- Synapse Research Institute, Maastricht, The Netherlands
| | - Alisa S. Wolberg
- Department of Pathology and UNC Blood Research Center, University of North Carolina, Chapel Hill, NC, USA
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