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Glassman PM, Hood ED, Ferguson LT, Zhao Z, Siegel DL, Mitragotri S, Brenner JS, Muzykantov VR. Red blood cells: The metamorphosis of a neglected carrier into the natural mothership for artificial nanocarriers. Adv Drug Deliv Rev 2021; 178:113992. [PMID: 34597748 PMCID: PMC8556370 DOI: 10.1016/j.addr.2021.113992] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/26/2021] [Accepted: 09/24/2021] [Indexed: 12/18/2022]
Abstract
Drug delivery research pursues many types of carriers including proteins and other macromolecules, natural and synthetic polymeric structures, nanocarriers of diverse compositions and cells. In particular, liposomes and lipid nanoparticles represent arguably the most advanced and popular human-made nanocarriers, already in multiple clinical applications. On the other hand, red blood cells (RBCs) represent attractive natural carriers for the vascular route, featuring at least two distinct compartments for loading pharmacological cargoes, namely inner space enclosed by the plasma membrane and the outer surface of this membrane. Historically, studies of liposomal drug delivery systems (DDS) astronomically outnumbered and surpassed the RBC-based DDS. Nevertheless, these two types of carriers have different profile of advantages and disadvantages. Recent studies showed that RBC-based drug carriers indeed may feature unique pharmacokinetic and biodistribution characteristics favorably changing benefit/risk ratio of some cargo agents. Furthermore, RBC carriage cardinally alters behavior and effect of nanocarriers in the bloodstream, so called RBC hitchhiking (RBC-HH). This article represents an attempt for the comparative analysis of liposomal vs RBC drug delivery, culminating with design of hybrid DDSs enabling mutual collaborative advantages such as RBC-HH and camouflaging nanoparticles by RBC membrane. Finally, we discuss the key current challenges faced by these and other RBC-based DDSs including the issue of potential unintended and adverse effect and contingency measures to ameliorate this and other concerns.
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Affiliation(s)
- Patrick M Glassman
- Department of Systems Pharmacology and Translational Therapeutics, Center for Targeted Therapeutics and Translational Nanomedicine of the Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Elizabeth D Hood
- Department of Systems Pharmacology and Translational Therapeutics, Center for Targeted Therapeutics and Translational Nanomedicine of the Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Laura T Ferguson
- Department of Systems Pharmacology and Translational Therapeutics, Center for Targeted Therapeutics and Translational Nanomedicine of the Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States; Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Zongmin Zhao
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, IL 60612, United States
| | - Don L Siegel
- Department of Pathology & Laboratory Medicine, Division of Transfusion Medicine & Therapeutic Pathology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Samir Mitragotri
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02138, United States
| | - Jacob S Brenner
- Department of Systems Pharmacology and Translational Therapeutics, Center for Targeted Therapeutics and Translational Nanomedicine of the Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States; Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Vladimir R Muzykantov
- Department of Systems Pharmacology and Translational Therapeutics, Center for Targeted Therapeutics and Translational Nanomedicine of the Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States.
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Glassman PM, Villa CH, Ukidve A, Zhao Z, Smith P, Mitragotri S, Russell AJ, Brenner JS, Muzykantov VR. Vascular Drug Delivery Using Carrier Red Blood Cells: Focus on RBC Surface Loading and Pharmacokinetics. Pharmaceutics 2020; 12:E440. [PMID: 32397513 PMCID: PMC7284780 DOI: 10.3390/pharmaceutics12050440] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 04/30/2020] [Accepted: 05/08/2020] [Indexed: 01/26/2023] Open
Abstract
Red blood cells (RBC) have great potential as drug delivery systems, capable of producing unprecedented changes in pharmacokinetics, pharmacodynamics, and immunogenicity. Despite this great potential and nearly 50 years of research, it is only recently that RBC-mediated drug delivery has begun to move out of the academic lab and into industrial drug development. RBC loading with drugs can be performed in several ways-either via encapsulation within the RBC or surface coupling, and either ex vivo or in vivo-depending on the intended application. In this review, we briefly summarize currently used technologies for RBC loading/coupling with an eye on how pharmacokinetics is impacted. Additionally, we provide a detailed description of key ADME (absorption, distribution, metabolism, elimination) changes that would be expected for RBC-associated drugs and address unique features of RBC pharmacokinetics. As thorough understanding of pharmacokinetics is critical in successful translation to the clinic, we expect that this review will provide a jumping off point for further investigations into this area.
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Affiliation(s)
- Patrick M. Glassman
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania; Philadelphia, PA 19104, USA; (C.H.V.); (J.S.B.)
| | - Carlos H. Villa
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania; Philadelphia, PA 19104, USA; (C.H.V.); (J.S.B.)
| | - Anvay Ukidve
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA; (A.U.); (Z.Z.); (S.M.)
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA
| | - Zongmin Zhao
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA; (A.U.); (Z.Z.); (S.M.)
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA
| | - Paige Smith
- Disruptive Health Technology Institute, Carnegie Mellon University, Pittsburgh, PA 15213, USA; (P.S.); (A.J.R.)
- Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Samir Mitragotri
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA; (A.U.); (Z.Z.); (S.M.)
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA
| | - Alan J. Russell
- Disruptive Health Technology Institute, Carnegie Mellon University, Pittsburgh, PA 15213, USA; (P.S.); (A.J.R.)
- Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Jacob S. Brenner
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania; Philadelphia, PA 19104, USA; (C.H.V.); (J.S.B.)
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Vladimir R. Muzykantov
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania; Philadelphia, PA 19104, USA; (C.H.V.); (J.S.B.)
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Zhang Y, Zhong Y, Ye M, Xu J, Liu J, Zhou J, Wang S, Guo D, Wang Z, Ran H. Polydopamine-modified dual-ligand nanoparticles as highly effective and targeted magnetic resonance/photoacoustic dual-modality thrombus imaging agents. Int J Nanomedicine 2019; 14:7155-7171. [PMID: 31564871 PMCID: PMC6731970 DOI: 10.2147/ijn.s216603] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 08/01/2019] [Indexed: 12/29/2022] Open
Abstract
Background Platelet activation and subsequent aggregation are the initial stages of thrombosis. A molecular probe that specifically targets activated platelets and remains retained under high shear stress in vivo can enhance the imaging effect to achieve early and accurate diagnosis. Methods and materials In this study, we constructed nanoparticles (NPs) using polydopamine to carry two peptides that simultaneously bind integrin αIIbβ3 and P-selectin on activated platelets to enhance the targeting of NPs to thrombus. Results The targeting specificity and binding stability of the NPs on red and white thrombi were demonstrated in vitro using a simulated circulatory device and the targeting effect of the NPs on mixed thrombus was studied by magnetic resonance (MR)/photoacoustic (PA) dual-modality imaging in vivo. NPs that were surface modified with both peptides have higher selectivity and retention to red and white thrombi in vitro than NPs with a single or no peptide, and the targeting effect was closely related to the number and distribution of activated platelets as well as the structure and type of thrombus. The NPs also have MR/PA dual-modality imaging functionality, significantly enhancing the imaging of mixed thrombus in vivo. Conclusion These dual-targeted NPs have improved targeting specificity and binding stability to different thrombi under high shear stress and are beneficial for the early diagnosis of thrombosis.
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Affiliation(s)
- Yu Zhang
- Department of Radiology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China.,Chongqing Key Laboratory of Ultrasound Molecular Imaging, Department of Ultrasound, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Yixin Zhong
- Department of Radiology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China.,Chongqing Key Laboratory of Ultrasound Molecular Imaging, Department of Ultrasound, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Man Ye
- Department of Radiology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Jie Xu
- Department of Radiology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Jia Liu
- Department of Radiology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Jun Zhou
- Department of Radiology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Shike Wang
- Department of Radiology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Dajing Guo
- Department of Radiology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Zhigang Wang
- Chongqing Key Laboratory of Ultrasound Molecular Imaging, Department of Ultrasound, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Haitao Ran
- Chongqing Key Laboratory of Ultrasound Molecular Imaging, Department of Ultrasound, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China
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Intravascular forward-looking ultrasound transducers for microbubble-mediated sonothrombolysis. Sci Rep 2017; 7:3454. [PMID: 28615645 PMCID: PMC5471247 DOI: 10.1038/s41598-017-03492-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 04/28/2017] [Indexed: 02/07/2023] Open
Abstract
Effective removal or dissolution of large blood clots remains a challenge in clinical treatment of acute thrombo-occlusive diseases. Here we report the development of an intravascular microbubble-mediated sonothrombolysis device for improving thrombolytic rate and thus minimizing the required dose of thrombolytic drugs. We hypothesize that a sub-megahertz, forward-looking ultrasound transducer with an integrated microbubble injection tube is more advantageous for efficient thrombolysis by enhancing cavitation-induced microstreaming than the conventional high-frequency, side-looking, catheter-mounted transducers. We developed custom miniaturized transducers and demonstrated that these transducers are able to generate sufficient pressure to induce cavitation of lipid-shelled microbubble contrast agents. Our technology demonstrates a thrombolysis rate of 0.7 ± 0.15 percent mass loss/min in vitro without any use of thrombolytic drugs.
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Red blood cells: Supercarriers for drugs, biologicals, and nanoparticles and inspiration for advanced delivery systems. Adv Drug Deliv Rev 2016; 106:88-103. [PMID: 26941164 DOI: 10.1016/j.addr.2016.02.007] [Citation(s) in RCA: 227] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 02/17/2016] [Accepted: 02/19/2016] [Indexed: 12/19/2022]
Abstract
Red blood cells (RBCs) constitute a unique drug delivery system as a biologic or hybrid carrier capable of greatly enhancing pharmacokinetics, altering pharmacodynamics (for example, by changing margination within the intravascular space), and modulating immune responses to appended cargoes. Strategies for RBC drug delivery systems include internal and surface loading, and the latter can be performed both ex vivo and in vivo. A relatively new avenue for RBC drug delivery is their application as a carrier for nanoparticles. Efforts are also being made to incorporate features of RBCs in nanocarriers to mimic their most useful aspects, such as long circulation and stealth features. RBCs have also recently been explored as carriers for the delivery of antigens for modulation of immune response. Therefore, RBC-based drug delivery systems represent supercarriers for a diverse array of biomedical interventions, and this is reflected by several industrial and academic efforts that are poised to enter the clinical realm.
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Villa CH, Cines DB, Siegel DL, Muzykantov V. Erythrocytes as Carriers for Drug Delivery in Blood Transfusion and Beyond. Transfus Med Rev 2016; 31:26-35. [PMID: 27707522 DOI: 10.1016/j.tmrv.2016.08.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 08/01/2016] [Accepted: 08/12/2016] [Indexed: 10/20/2022]
Abstract
Red blood cells (RBCs) are innate carriers that can also be engineered to improve the pharmacokinetics and pharmacodynamics of many drugs, particularly biotherapeutics. Successful loading of drugs, both internally and on the external surface of RBCs, has been demonstrated for many drugs including anti-inflammatory, antimicrobial, and antithrombotic agents. Methods for internal loading of drugs within RBCs are now entering clinical use. Although internal loading can result in membrane disruption that may compromise biocompatibility, surface loading using either affinity or chemical ligands offers a diverse set of approaches for the production of RBC drug carriers. A wide range of surface determinants is potentially available for this approach, although there remains a need to characterize the effects of coupling agents to these surface proteins. Somewhat surprisingly, recent data also suggest that red cell-mediated delivery may confer tolerogenic immune effects. Questions remaining before widespread application of these technologies include determining the optimal loading protocol, source of RBCs, and production logistics, as well as addressing regulatory hurdles. Red blood cell drug carriers, after many decades of progress, are now poised to enter the clinic and broaden the potential application of RBCs in blood transfusion.
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Affiliation(s)
- Carlos H Villa
- Department of Pathology and Laboratory Medicine, Hospital of the University of Pennsylvania, Philadelphia, PA.
| | - Douglas B Cines
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Don L Siegel
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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Myerson JW, Anselmo AC, Liu Y, Mitragotri S, Eckmann DM, Muzykantov VR. Non-affinity factors modulating vascular targeting of nano- and microcarriers. Adv Drug Deliv Rev 2016; 99:97-112. [PMID: 26596696 PMCID: PMC4798918 DOI: 10.1016/j.addr.2015.10.011] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 09/29/2015] [Accepted: 10/09/2015] [Indexed: 12/22/2022]
Abstract
Particles capable of homing and adhering to specific vascular biomarkers have potential as fundamental tools in drug delivery for mediation of a wide variety of pathologies, including inflammation, thrombosis, and pulmonary disorders. The presentation of affinity ligands on the surface of a particle provides a means of targeting the particle to sites of therapeutic interest, but a host of other factors come into play in determining the targeting capacity of the particle. This review presents a summary of several key considerations in nano- and microparticle design that modulate targeted delivery without directly altering epitope-specific affinity. Namely, we describe the effect of factors in definition of the base carrier (including shape, size, and flexibility) on the capacity of carriers to access, adhere to, and integrate in target biological milieus. Furthermore, we present a summary of fundamental dynamics of carrier behavior in circulation, taking into account interactions with cells in circulation and the role of hemodynamics in mediating the direction of carriers to target sites. Finally, we note non-affinity aspects to uptake and intracellular trafficking of carriers in target cells. In total, recent findings presented here may offer an opportunity to capitalize on mitigating factors in the behavior of ligand-targeted carriers in order to optimize targeting.
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Qureshi AI, Qureshi MH, Lobanova I, Bashir A, Khan AA, Bologna SM, Peterson M, Suri MFK. Histopathological Characteristics of IV Recombinant Tissue Plasminogen -Resistant Thrombi in Patients with Acute Ischemic Stroke. JOURNAL OF VASCULAR AND INTERVENTIONAL NEUROLOGY 2016; 8:38-45. [PMID: 26958152 PMCID: PMC4762410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Affiliation(s)
- Adnan I. Qureshi
- Zeenat Qureshi Stroke Institute, St Cloud, MN, and CentraCare Health, St. Cloud, MN, USA
| | - Mushtaq H. Qureshi
- Zeenat Qureshi Stroke Institute, St Cloud, MN, and CentraCare Health, St. Cloud, MN, USA
| | - Iryna Lobanova
- JFK New Jersey Neuroscience Institute at Seton Hall University, Edison, NJ, USA
| | - Asif Bashir
- Zeenat Qureshi Stroke Institute, St Cloud, MN, and CentraCare Health, St. Cloud, MN, USA
| | - Asif A. Khan
- Zeenat Qureshi Stroke Institute, St Cloud, MN, and CentraCare Health, St. Cloud, MN, USA
| | - Stephen M. Bologna
- Zeenat Qureshi Stroke Institute, St Cloud, MN, and CentraCare Health, St. Cloud, MN, USA
| | - Michelle Peterson
- Zeenat Qureshi Stroke Institute, St Cloud, MN, and CentraCare Health, St. Cloud, MN, USA
| | - M. Fareed K. Suri
- Zeenat Qureshi Stroke Institute, St Cloud, MN, and CentraCare Health, St. Cloud, MN, USA
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Villa CH, Pan DC, Zaitsev S, Cines DB, Siegel DL, Muzykantov VR. Delivery of drugs bound to erythrocytes: new avenues for an old intravascular carrier. Ther Deliv 2015; 6:795-826. [PMID: 26228773 PMCID: PMC4712023 DOI: 10.4155/tde.15.34] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
For several decades, researchers have used erythrocytes for drug delivery of a wide variety of therapeutics in order to improve their pharmacokinetics, biodistribution, controlled release and pharmacodynamics. Approaches include encapsulation of drugs within erythrocytes, as well as coupling of drugs onto the red cell surface. This review focuses on the latter approach, and examines the delivery of red blood cell (RBC)-surface-bound anti-inflammatory, anti-thrombotic and anti-microbial agents, as well as RBC carriage of nanoparticles. Herein, we discuss the progress that has been made in surface loading approaches, and address in depth the issues relevant to surface loading of RBC, including intrinsic features of erythrocyte membranes, immune considerations, potential surface targets and techniques for the production of affinity ligands.
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Affiliation(s)
- Carlos H Villa
- Department of Pathology & Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Daniel C Pan
- Department of Systems Pharmacology & Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Sergei Zaitsev
- Department of Systems Pharmacology & Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Douglas B Cines
- Department of Pathology & Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Donald L Siegel
- Department of Pathology & Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Vladimir R Muzykantov
- Department of Systems Pharmacology & Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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Abstract
Despite continued achievements in antithrombotic pharmacotherapy, difficulties remain in managing patients at high risk for both thrombosis and hemorrhage. Utility of antithrombotic agents (ATAs) in these settings is restricted by inadequate pharmacokinetics and narrow therapeutic indices. Use of advanced drug delivery systems (ADDSs) may help to circumvent these problems. Various nanocarriers, affinity ligands, and polymer coatings provide ADDSs that have the potential to help optimize ATA pharmacokinetics, target drug delivery to sites of thrombosis, and sense pathologic changes in the vascular microenvironment, such as altered hemodynamic forces, expression of inflammatory markers, and structural differences between mature hemostatic and growing pathological clots. Delivery of ATAs using biomimetic synthetic carriers, host blood cells, and recombinant fusion proteins that are activated preferentially at sites of thrombus development has shown promising outcomes in preclinical models. Further development and translation of ADDSs that spare hemostatic fibrin clots hold promise for extending the utility of ATAs in the management of acute thrombotic disorders through rapid, transient, and targeted thromboprophylaxis. If the potential benefit of this technology is to be realized, a systematic and concerted effort is required to develop clinical trials and translate the use of ADDSs to the clinical arena.
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Abstract
Studies in animal models have shown that plasminogen activators bound to erythrocytes (RBC-PA) have an extended lifetime in the circulation and are safer than free PAs. RBC-PAs incorporate into nascent thrombi, which are focally lysed from within, an attractive thromboprophylactic option. In static systems, RBC-PAs cleave surrounding fibrin fibers, forming pores larger than the cells themselves, and move around the pore edges, enlarging them until eventual clot dissolution. We hypothesized that under flow in blood vessels, RBC-PAs form functional patent channels before clot dissolution. Here we used perfusion chambers to study clot lysis by RBC-PAs under static versus arterial and venous flow conditions. We found that flow decelerates bulk clot lysis but quickly generates patent channels filled with passing RBCs, via pore enlargement and merging in the direction of flow. Formation of such channels by RBC-PAs may help rescue ischemic tissue before bulk dissolution of potentially occlusive clots.
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Sustained thromboprophylaxis mediated by an RBC-targeted pro-urokinase zymogen activated at the site of clot formation. Blood 2010; 115:5241-8. [PMID: 20410503 DOI: 10.1182/blood-2010-01-261610] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plasminogen activators (PAs) are used to treat life-threatening thrombosis, but not for thromboprophylaxis because of rapid clearance, risk of bleeding, and central nervous system (CNS) toxicity. We describe a novel strategy that may help to overcome these limitations by targeting a thrombin-activated PA pro-drug to circulating red blood cells (RBCs). We fused a single chain antibody (scFv Ter-119) that binds to mouse glycophorin A (GPA) with a variant human single-chain low molecular weight urokinase construct that can be activated selectively by thrombin (scFv/uPA-T). scFv/uPA-T bound specifically to mouse RBCs without altering their biocompatibility and retained its zymogenic properties until converted by thrombin into an active 2-chain molecule. As a result, RBC-bound scFv/uPA-T caused thrombin-induced fibrinolysis. One hour and 48 hours after intravenous (IV) injection in mice, approximately 70% and approximately 35% of scFv/uPA-T was retained in the blood, respectively, and approximately 95% of the circulating scFv/uPA-T remained bound to RBCs. A single IV injection of scFv/uPA-T provided effective prophylaxis against arterial and venous thrombosis for up to 24 hours. Thus, prophylactic delivery of RBC-targeted PA pro-drugs activated selectively at the site of clot formation represents a new approach to prevent thrombosis in clinical settings where the risk of clotting is high.
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