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Thrombosis is characterized by the formation of in vivo blood clots that are localized within arterial or venous blood vessels. These thrombi form beyond the need for physiologically healthy hemostatic responses and can lead to significant medical issues for affected individuals. Unfortunately, the existing standard-of-care therapies for treating thrombosis are systemic in their therapeutic design; therefore, they interfere with the patient's physiological hemostasis. Examples of the severe clinical side effects commonly associated with currently available therapies include, but are not limited to, bleeding complications. Therefore, there is a profound demand for novel therapeutic interventions that can circumvent these debilitating complications, while offering improved therapeutic efficacy. Recent advancements in nanotechnology present an opportunity to develop novel and improved drug delivery systems to meet this clinical demand. Preclinical investigations have begun to uncover the potential of nanotechnology, particularly in the treatment of thrombosis and also in nonhemostatic cardiovascular diseases. This article reviews recent preclinical studies aimed at developing a diverse array of different nanotechnologies for treating thrombosis as well as heart diseases. This review will also outline the limitations with current nanotechnologies and what challenges need to be overcome to translate these novel therapies to the clinic., Competing Interests: None., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Competing Interests: None.

Stroke is a leading cause of death and disability worldwide. The classification of stroke subtypes is difficult but critical for the prediction of clinical course and patient management, and limited treatment options are available. There is an urgent need for improvements in both diagnosis and therapy. Strokes have rapidly evolving phases of damage involving unique compartments of the brain, which imposes severe limitations for current diagnostic and treatment procedures. The rapid development of nanotechnology in other areas of modern medicine has ignited a widespread interest in its potential for the field of stroke. An important feature of nanoparticles is the relative ease in which their structures and surface chemistries can be modified for specific and potentially multiple, simultaneous purposes. Nanoparticles can be synthesized to carry and deliver therapeutics to specific cellular or subcellular compartments; they can be engineered to provide enhanced contrast for imaging based on the detection of changes in the blood flow; or possess ligand-specific chemistries which can facilitate diagnosis and monitor the treatment response. More specifically for a stroke, nanoparticles can be engineered to release their payload in response to the distinct extracellular processes occurring around the clot and in the ischemic penumbra, as well as aid in the detection of pathological hallmarks present at various stages of stroke progression. These capacities allow targeted release of disease-modifying agents in the affected brain tissue, increasing treatment efficacy, and limiting unwanted side effects. While nanospheres, liposomes, and mesoporous nanostructures all emerge as future prospects for stroke treatment and diagnosis, much of this potential is yet to be clinically realized. This review outlines aspects of nanotechnology identified as having potential to revolutionize the field of stroke., Competing Interests: L.M.L. reports receiving a grant from the Royal Hobart Hospital Research Foundation during the time of preparing this manuscript., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

High mobility group box 1 (HMGB1) acts as both a nuclear protein that regulates gene expression, as well as a pro-inflammatory alarmin that is released from necrotic or activated cells. Recently, HMGB1-expression in human atherosclerotic plaques was identified. Therapeutic blockade of HMGB1 reduced the development of diet-induced atherosclerosis in ApoE knockout mice. Thus, we hypothesised an interaction between HMGB1 and activated platelets. Binding of recombinant HMGB1 to platelets was assessed by flow cytometry. HMGB1 bound to thrombin-activated human platelets (MFI 2.49 vs 25.01, p=0.0079). Blood from wild-type, TLR4 and RAGE knockout mice was used to determine potential HMGB1 receptors on platelets. HMGB1 bound to platelets from wild type C57Bl6 (MFI 2.64 vs 20.3, p< 0.05), and TLR4-/- mice (MFI 2.11 vs 25.65, p< 0.05) but failed to show binding to platelets from RAGE-/- mice (p > 0.05). RAGE expression on human platelets was detected by RT-PCR with mRNA extracted from highly purified platelets and confirmed by Western blot and immunofluorescence microscopy. Platelet activation increased RAGE surface expression (MFI 4.85 vs 6.74, p< 0.05). Expression of HMGB1 in human coronary artery thrombi was demonstrated by immunohistochemistry and revealed high expression levels. Platelets bind HMGB1 upon thrombin-induced activation. Platelet specific expression of RAGE could be detected at the mRNA and protein level and is involved in the binding of HMGB1. Furthermore, platelet activation up-regulates platelet surface expression of RAGE. HMGB1 is highly expressed in platelet-rich human coronary artery thrombi pointing towards a central role for HMGB1 in atherothrombosis, thereby suggesting the possibility of platelet targeted anti-inflammatory therapies for atherothrombosis.

Over three decades after the generation of the first mouse monoclonal antibodies by Kohler and Milstein, recombinant antibodies are the fastest growing class of therapeutic proteins. Furthermore, antibodies are key detection reagents in research and diagnostics. Technology improvements have provided several approaches to manufacturing human antibodies with high affinity for biologically relevant targets. Approximately 300 development programs for therapeutic antibodies have been reported in industrial and academic laboratories, and this clearly demonstrates the expectations towards antibody technology. Antibody fragments are a subclass with growing clinical importance. This review focuses on single-chain antibodies as one of the smallest possible format for recombinant antibodies and their use as diagnostic tools and therapeutic agents. We describe the structure, selection and production of single-chain antibodies. Furthermore, we review current applications of antibody fragments focusing on thrombus targeting using fibrin- and platelet-specific single-chain antibodies as well as describing novel noninvasive imaging approaches for the diagnosis of thrombosis and inflammation.

The development of monoclonal antibodies facilitated an enormous progress in modern medicine in the last years. The targeted inhibition of defined molecular structures allows therapeutic concepts, which before were inconceivable. There are numerous antibodies in clinical use within the area of tumour therapy, chronically inflammatory diseases, transplantation, infections and also in cardiovascular medicine. Different antibody formats are used such as IgG molecules, Fab fragments and single chain antibodies. Single chain antibodies represent the smallest functional form of the antibody and are used preferentially as recombinant antibodies. The therapeutic possibilities of antibody technology are extended by fusion to radioactive or therapeutically active substances. This review focuses on the application of antibodies and fusion proteins as antithrombotic and fibrinolytic drugs. The use of antibodies allows the development of inhibitory agents with clearly defined functional properties, as for example for activation-specific GPIIb/IIIa-blockade. In addition antibodies can be used for targeting antithrombotic and fibrinolytic agents to the thrombus, allowing an effective local action with less bleeding complications.

Antibodies are the most rapidly growing class of human therapeutics and the second largest class of drugs after vaccines. At present, several antibodies are approved for therapeutic use in diverse clinical settings, including oncology, chronic inflammatory diseases, transplantation, infectious diseases, and cardiovascular medicine. These approved antibody therapeutics include unmodified immunoglobulin G molecules, radioimmunoconjugates, antibody-drug conjugates, and fragment antigen-binding molecules. At least 150 additional antibodies are in clinical development. A major strength of therapeutic antibodies is their established properties as a drug class with high success rates from clinical trials to regulatory approvals. Much of the experience gained from the generation and optimization of one antibody is applicable to other antibodies. Antibody fragments are a subclass with growing clinical importance. This review focuses on single-chain antibodies as the smallest possible format for recombinant antibodies, and their use as antithrombotic drugs. We describe different antibody formats, the current applications of antibody fragments, and their generation by cloning from hybridoma cell lines as well as their selection from antibody libraries. We review the use of antibody fragments for thrombus targeting using fibrin and platelet-specific single-chain antibodies in combination with anticoagulants and thrombolytic agents as antithrombotic drugs.

We investigated whether the direct fXa inhibitor tick anticoagulant peptide (TAP) can be N-terminally coupled to a clot-targeting, single-chain antibody specific for fibrin (scFv(59D8)). Due to its unique position at the convergence point of the intrinsic and extrinsic pathways early in the coagulation cascade, factor Xa (fXa) represents an attractive therapeutic target. In contrast to indirect inhibitors, direct fXa inhibitors effectively inhibit clot-bound and prothrombinase-associated fXa. Targeting of direct fXa inhibitors to clots promises to enhance local anticoagulative potency and to reduce systemic anticoagulation which potentially results in less bleeding complications.TAP is a highly potent fXa inhibitor. Since its N-terminus is essential for anti-fXa activity, it was a challenging question, whether TAP will be active as a N-terminally coupled fusion molecule. Two step affinity chromatography with Ni(2+) and beta(15-22)-peptide of human fibrin results in a pure 36 kDa protein, which was tested for its targeting function and anti-fXa activity. The recombinant fusion did not destroy the function of the fusion partners. Antibody binding function was on a par with the parent molecule. TAP activity was partially reduced, arguing that a free N-terminus is not required for anti-fXa activity, but is important for maximal potency. In human whole blood clots, scFv(59D8)-TAP revealed anticoagulative properties at concentrations (200 to 500 nM) where non-targeted TAP did not reveal anticoagulative activity at all. In summary, scFv(59D8)-TAP constitutes a promising new anticoagulant with fibrin-targeted factor Xa inhibition. The production in E. coli and the established purification methods are a solid basis for a modern, large scale production at low cost and reproducible activity.