Melbourne Medical School Collected Works - Research Publications
Permanent URI for this collection
Search Results
1 - 10 of 25
-
ItemNo Preview AvailableUltrasonic particles: An approach for targeted gene delivery(ELSEVIER, 2021-10-21)Gene therapy has been widely investigated for the treatment of genetic, acquired, and infectious diseases. Pioneering work utilized viral vectors; however, these are suspected of causing serious adverse events, resulting in the termination of several clinical trials. Non-viral vectors, such as lipid nanoparticles, have attracted significant interest, mainly due to their successful use in vaccines in the current COVID-19 pandemic. Although they allow safe delivery, they come with the disadvantage of off-target delivery. The application of ultrasound to ultrasound-sensitive particles allows for a direct, site-specific transfer of genetic materials into the organ/site of interest. This process, termed ultrasound-targeted gene delivery (UTGD), also increases cell membrane permeability and enhances gene uptake. This review focuses on the advances in ultrasound and the development of ultrasonic particles for UTGD across a range of diseases. Furthermore, we discuss the limitations and future perspectives of UTGD.
-
ItemP2Y12 Antagonists in Cardiovascular Disease-Finding the Best Balance Between Preventing Ischemic Events and Causing Bleeding.(Frontiers Media SA, 2022)Dual antiplatelet therapy comprising of aspirin and oral P2Y12 receptor antagonists are an established cornerstone of therapy in acute coronary syndromes and percutaneous coronary intervention. As a result, the platelet P2Y12 receptor remains a key therapeutic target in cardiovascular medicine since pharmacological antagonists were first developed in the 1990's. With a greater understanding of platelet biology and the role played by the P2Y12 receptor in the amplification of platelet activation and thrombus formation, there has been progressive refinement in the development of P2Y12 receptor antagonists with greater potency and consistency of antiplatelet effect. However, challenges remain in the utilization of these agents particularly in balancing the need for greater protection from ischemic events whilst minimizing the bleeding risk and present a real opportunity for the institution of individualized medicine. Future drug developments will provide clinicians with greater avenues to achieve this.
-
ItemNanobiotechnology approaches for cardiovascular diseases: site-specific targeting of drugs and nanoparticles for atherothrombosis(BMC, 2022-02-08)Atherosclerosis and atherothrombosis, the major contributors to cardiovascular diseases (CVDs), represent the leading cause of death worldwide. Current pharmacological therapies have been associated with side effects or are insufficient at halting atherosclerotic progression effectively. Pioneering work harnessing the passive diffusion or endocytosis properties of nanoparticles and advanced biotechnologies in creating recombinant proteins for site-specific delivery have been utilized to overcome these limitations. Since CVDs are complex diseases, the most challenging aspect of developing site-specific therapies is the identification of an individual and unique antigenic epitope that is only expressed in lesions or diseased areas. This review focuses on the pathological mechanism of atherothrombosis and discusses the unique targets that are important during disease progression. We review recent advances in site-specific therapy using novel targeted drug-delivery and nanoparticle-carrier systems. Furthermore, we explore the limitations and future perspectives of site-specific therapy for CVDs.
-
ItemPharmacological Inhibition of Factor XIIa Attenuates Abdominal Aortic Aneurysm, Reduces Atherosclerosis, and Stabilizes Atherosclerotic Plaques(GEORG THIEME VERLAG KG, 2022-02-01)BACKGROUND: 3F7 is a monoclonal antibody targeting the enzymatic pocket of activated factor XII (FXIIa), thereby inhibiting its catalytic activity. Given the emerging role of FXIIa in promoting thromboinflammation, along with its apparent redundancy for hemostasis, the selective inhibition of FXIIa represents a novel and highly attractive approach targeting pathogenic processes that cause thromboinflammation-driven cardiovascular diseases. METHODS: The effects of FXIIa inhibition were investigated using three distinct mouse models of cardiovascular disease-angiotensin II-induced abdominal aortic aneurysm (AAA), an ApoE-/- model of atherosclerosis, and a tandem stenosis model of atherosclerotic plaque instability. 3F7 or its isotype control, BM4, was administered to mice (10 mg/kg) on alternate days for 4 to 8 weeks, depending on the experimental model. Mice were examined for the development and size of AAAs, or the burden and instability of atherosclerosis and associated markers of inflammation. RESULTS: Inhibition of FXIIa resulted in a reduced incidence of larger AAAs, with less acute aortic ruptures and an associated fibro-protective phenotype. FXIIa inhibition also decreased stable atherosclerotic plaque burden and achieved plaque stabilization associated with increased deposition of fibrous structures, a >2-fold thicker fibrous cap, increased cap-to-core ratio, and reduction in localized and systemic inflammatory markers. CONCLUSION: Inhibition of FXIIa attenuates disease severity across three mouse models of thromboinflammation-driven cardiovascular diseases. Specifically, the FXIIa-inhibiting monoclonal antibody 3F7 reduces AAA severity, inhibits the development of atherosclerosis, and stabilizes vulnerable plaques. Ultimately, clinical trials in patients with cardiovascular diseases such as AAA and atherosclerosis are warranted to demonstrate the therapeutic potential of FXIIa inhibition.
-
ItemMulti-targeted H-1/F-19 MRI unmasks specific danger patterns for emerging cardiovascular disorders(NATURE PORTFOLIO, 2021-10-06)Prediction of the transition from stable to acute coronary syndromes driven by vascular inflammation, thrombosis with subsequent microembolization, and vessel occlusion leading to irreversible myocardial damage is still an unsolved problem. Here, we introduce a multi-targeted and multi-color nanotracer platform technology that simultaneously visualizes evolving danger patterns in the development of progressive coronary inflammation and atherothrombosis prior to spontaneous myocardial infarction in mice. Individual ligand-equipped perfluorocarbon nanoemulsions are used as targeting agents and are differentiated by their specific spectral signatures via implementation of multi chemical shift selective 19F MRI. Thereby, we are able to identify areas at high risk of and predictive for consecutive development of myocardial infarction, at a time when no conventional parameter indicates any imminent danger. The principle of this multi-targeted approach can easily be adapted to monitor also a variety of other disease entities and constitutes a technology with disease-predictive potential.
-
ItemA Recombinant Fusion Construct between Human Serum Albumin and NTPDase CD39 Allows Anti-Inflammatory and Anti-Thrombotic Coating of Medical Devices(MDPI, 2021-09-01)Medical devices directly exposed to blood are commonly used to treat cardiovascular diseases. However, these devices are associated with inflammatory reactions leading to delayed healing, rejection of foreign material or device-associated thrombus formation. We developed a novel recombinant fusion protein as a new biocompatible coating strategy for medical devices with direct blood contact. We genetically fused human serum albumin (HSA) with ectonucleoside triphosphate diphosphohydrolase-1 (CD39), a promising anti-thrombotic and anti-inflammatory drug candidate. The HSA-CD39 fusion protein is highly functional in degrading ATP and ADP, major pro-inflammatory reagents and platelet agonists. Their enzymatic properties result in the generation of AMP, which is further degraded by CD73 to adenosine, an anti-inflammatory and anti-platelet reagent. HSA-CD39 is functional after lyophilisation, coating and storage of coated materials for up to 8 weeks. HSA-CD39 coating shows promising and stable functionality even after sterilisation and does not hinder endothelialisation of primary human endothelial cells. It shows a high level of haemocompatibility and diminished blood cell adhesion when coated on nitinol stents or polyvinylchloride tubes. In conclusion, we developed a new recombinant fusion protein combining HSA and CD39, and demonstrated that it has potential to reduce thrombotic and inflammatory complications often associated with medical devices directly exposed to blood.
-
ItemP2Y12 receptor blockers are anti-inflammatory drugs inhibiting both circulating monocytes and macrophages including THP-1 cells(NATURE PORTFOLIO, 2021-08-31)P2Y12 blockade improves patient outcomes after myocardial infarction. As well as antithrombotic effects, anti-inflammatory effects may contribute to this beneficial clinical outcome. Here we aimed to identify potential anti-inflammatory effects of P2Y12 receptor blockers on monocytes and macrophages. Using flow cytometry, migration assays, flow chambers and RNA microarrays, we investigated the effects of adenosine diphosphate (ADP) and P2Y12 receptor blockers on blood monocytes, THP-1 monocytes and THP-1 monocytes after differentiation to macrophages. P2Y12 -expressing platelets can form aggregates with monocytes in circulating blood. Mediated by platelets, ADP results in activation of the integrin receptor Mac-1 on blood monocytes, as detected by the conformation-specific single-chain antibody MAN-1. Via the same association with platelets, THP-1 monocyte adhesion to the endothelial intercellular adhesion molecule 1 (ICAM-1) is induced by ADP. P2Y12 receptor blockers prevent these ADP effects on monocytes. Interestingly, in contrast to THP-1 monocytes, THP-1 monocytes, after differentiation to macrophages, directly expressed the P2Y12 receptor and consequently ADP was found to be a potent chemoattractant. Again, P2Y12 receptor blockers antagonised this effect. Accordingly, stimulation of THP-1 macrophages with ADP caused a substantial change in gene expression pattern and upregulation of several genes associated with inflammation and atherogenesis. These data establish novel anti-inflammatory effects of P2Y12 receptor blockers on monocytes and macrophages, which are expected to contribute to cardiovascular risk reduction.
-
ItemEarly Endothelial Activation in a Mouse Model of Graft vs Host Disease Following Chemotherapy(FRONTIERS MEDIA SA, 2021-08-05)Allogenic hematopoietic stem cell transplant (allo-HSCT) can lead to sinusoidal obstruction syndrome (SOS) and graft-versus-host disease (GvHD) in some individuals. GvHD is characterised by an immune triggered response that arises due to donor T cells recognizing the recipient tissue as "foreign". SOS results in impaired liver function due to microvascular thrombosis and consequent obstruction of liver sinusoids. Endothelial damage occurs following chemotherapy and allo-HSCT and is strongly associated with GvHD onset as well as hepatic SOS. Animal models of GvHD are rarely clinically relevant, and endothelial dysfunction remains uncharacterised. Here we established and characterised a clinically relevant model of GvHD wherein Balb/C mice were subjected to myeloablative chemotherapy followed by transplantation of bone marrow (BM) cells± splenic T-cells from C57Bl6 mice, resulting in a mismatch of major histocompatibility complexes (MHC). Onset of disease indicated by weight loss and apoptosis in the liver and intestine was discovered at day 6 post-transplant in mice receiving BM+T-cells, with established GvHD detectable by histology of the liver within 3 weeks. Together with significant increases in pro-inflammatory cytokine gene expression in the liver and intestine, histopathological signs of GvHD and a significant increase in CD4+ and CD8+ effector and memory T-cells were seen. Endothelial activation including upregulation of vascular cell adhesion molecule (VCAM)- 1 and downregulation of endothelial nitric oxide synthase (eNOS) as well as thrombosis in the liver indicated concomitant hepatic SOS. Our findings confirm that endothelial activation is an early sign of acute GvHD and SOS in a clinically relevant mouse model of GvHD based on myeloablative chemotherapy. Preventing endothelial activation may be a viable therapeutic strategy to prevent GvHD.
-
ItemThe pulmonary microvasculature entraps induced vascular progenitor cells (iVPCs) systemically delivered after cardiac ischemia-reperfusion injury: Indication for preservation of heart function via paracrine effects beyond engraftment(WILEY, 2019-02-01)OBJECTIVE: Stem cell-based regenerative therapies have been intensively studied with the aim to define an ideal cell type for the treatment of myocardial infarction. We tested systemically delivered, platelet-targeted induced vascular progenitor cells (iVPCs) to study their potential to salvage damaged myocardium after ischemia-reperfusion injury. METHODS: Using a mouse model of ischemia-reperfusion injury, we tested the potential of platelet-targeted iVPCs (1 × 106 targ-iVPCs) compared to non-targ-iVPCs and a saline control. Bioluminescence imaging, echocardiography, and histological analyses were performed. RESULTS: Four weeks after ischemia-reperfusion injury, systemic delivery of targ-iVPCs led to reduced fibrosis and infarct size (PBS: 25.7 ± 3.9 vs targ-iVPC: 18.4 ± 6.6 vs non-targ-iVPC: 25.1 ± 3.7%I/LV, P < 0.05), increased neovascularization, and restored cardiac function (PBS: 44.0 ± 4.2 vs targ-iVPC: 54.3 ± 4.5 vs non-targ-iVPC: 46.4 ± 3.8%EF, P < 0.01). Cell tracking experiments revealed entrapment of intravenously injected iVPCs in the pulmonary microvasculature in both cell-treated groups. CONCLUSIONS: Systemic delivery of iVPCs after cardiac ischemia-reperfusion injury is limited by pulmonary entrapment of the cells. Nevertheless, targ-iVPCs reduced infarct size, fibrosis, increased neovascularization, and most importantly retained cardiac function. These findings contribute to the mechanistic discussion of cell-based therapy and ultimately identify activated platelet-targeted iVPCs as candidates for cell therapy and also describe cell therapy benefits without the necessity of engrafting.
-
ItemPlatelets in Multiple Sclerosis: Early and Central Mediators of Inflammation and Neurodegeneration and Attractive Targets for Molecular Imaging and Site-Directed Therapy(FRONTIERS MEDIA SA, 2021-02-19)Platelets are clearly central to thrombosis and hemostasis. In addition, more recently, evidence has emerged for non-hemostatic roles of platelets including inflammatory and immune reactions/responses. Platelets express immunologically relevant ligands and receptors, demonstrate adhesive interactions with endothelial cells, monocytes and neutrophils, and toll-like receptor (TLR) mediated responses. These properties make platelets central to innate and adaptive immunity and potential candidate key mediators of autoimmune disorders. Multiple sclerosis (MS) is the most common chronic autoimmune central nervous system (CNS) disease. An association between platelets and MS was first indicated by the increased adhesion of platelets to endothelial cells. This was followed by reports identifying structural and functional changes of platelets, their chronic activation in the peripheral blood of MS patients, platelet presence in MS lesions and the more recent revelation that these structural and functional abnormalities are associated with all MS forms and stages. Investigations based on the murine experimental autoimmune encephalomyelitis (EAE) MS model first revealed a contribution to EAE pathogenesis by exacerbation of CNS inflammation and an early role for platelets in EAE development via platelet-neuron and platelet-astrocyte associations, through sialated gangliosides in lipid rafts. Our own studies refined and extended these findings by identifying the critical timing of platelet accumulation in pre-clinical EAE and establishing an initiating and central rather than merely exacerbating role for platelets in disease development. Furthermore, we demonstrated platelet-neuron associations in EAE, coincident with behavioral changes, but preceding the earliest detectable autoreactive T cell accumulation. In combination, these findings establish a new paradigm by asserting that platelets play a neurodegenerative as well as a neuroinflammatory role in MS and therefore, that these two pathological processes are causally linked. This review will discuss the implications of these findings for our understanding of MS, for future applications for imaging toward early detection of MS, and for novel strategies for platelet-targeted treatment of MS.