Nanomedicine Opportunities in Cardiology

A Journey of Challenges and Victories: A Bibliometric Worldview of Nanomedicine since the 21st Century

Nanotechnology profoundly affects the advancement of medicine. Limitations in diagnosing and treating cancer and chronic diseases promote the growth of nanomedicine. However, there are very few analytical and descriptive studies regarding the trajectory of nanomedicine, key research powers, present research landscape, focal investigative points, and future outlooks. Herein, articles and reviews published in the Science Citation Index Expanded of Web of Science Core Collection from first January 2000 to 18th July 2023 are analyzed. Herein, a bibliometric visualization of publication trends, countries/regions, institutions, journals, research categories, themes, references, and keywords is produced and elaborated. Nanomedicine-related academic output is increasing since the COVID-19 pandemic, solidifying the uneven global distribution of research performance. While China leads in terms of publication quantity and has numerous highly productive institutions, the USA has advantages in academic impact, commercialization, and industrial value. Nanomedicine integrates with other disciplines, establishing interdisciplinary platforms, in which drug delivery and nanoparticles remain focal points. Current research focuses on integrating nanomedicine and cell ferroptosis induction in cancer immunotherapy. The keyword "burst testing" identifies promising research directions, including immunogenic cell death, chemodynamic therapy, tumor microenvironment, immunotherapy, and extracellular vesicles. The prospects, major challenges, and barriers to addressing these directions are discussed.

Tailored mechanosensitive nanogels release drugs upon exposure to different levels of stenosis

Owing to the unhealthy lifestyle and genetic susceptibility of today's population, atherosclerosis is one of the global leading causes of life-threatening cardiovascular diseases. Although a rapid intervention is required for severe blood vessel constrictions, a systemic administration of anticoagulant drugs is not the preferred method of choice as the associated risk of bleeding complications is high. In this study, we present mechanosensitive nanogels that exhibit tunable degrees of disintegration upon exposure to different levels of stenosis. Those nanogels can be further functionalized to encapsulate charged drug molecules such as heparin, and they efficiently release their cargo when passing stenotic constrictions; however, passive drug leakage in the absence of mechanical shear stress is very low. Furthermore, heparin molecules liberated from those mechanosensitive nanogels show a similar blood clot lysis efficiency as the free drug molecules, which demonstrates that drug encapsulation into those nanogels does not interfere with the functionality of the cargo. Thus, the hemocompatible and mechanoresponsive nanogels developed here represent a smart and efficient drug delivery platform that can offer safer solutions for vascular therapy.

Mechanisms of thrombosis and research progress on targeted antithrombotic drugs

Globally, the incidence of thromboembolic diseases has increased in recent years, accompanied by an increase in patient mortality. Currently, several targeting delivery strategies have been developed to treat thromboembolic diseases. In this review, we discuss the mechanisms of thrombolysis and current anticoagulant drugs, particularly those with targeting capability, highlighting advances in the accurate treatment of thrombolysis with fewer adverse effects. Such approaches include magnetic drug-loading systems combined with molecular imaging to recanalize blood vessels and systems based on chimeric Arg-Gly-Asp (RGD) sequences that can target platelet glycoprotein receptor. With such progress in targeted antithrombotic drugs, targeted thrombolysis treatment shows significant potential benefit for patients.

Red blood cell hitchhiking enhances the accumulation of nano- and micro-particles in the constriction of a stenosed microvessel

We investigate the circulation of nano- and micro-particles, including spherical particles and filamentous nanoworms, with red blood cells (RBCs) suspension in a constricted channel that mimics a stenosed microvessel. Through three-dimensional simulations using the immersed boundary-based Lattice Boltzmann method, the influence of channel geometries, such as the length and ratio of the constriction, on the accumulation of particles is systematically studied. Firstly, we find that the accumulation of spherical particles with 1 μm diameter in the constriction increases with the increases of both the length and ratio of the constriction. This is attributed to the interaction between spheres and RBCs. The RBCs "carry" the spheres and they accumulate inside the constriction together, due to the altered local hydrodynamics induced by the existence of the constriction. Secondly, nanoworms demonstrate higher accumulation than that of spheres inside the constriction, which is associated with the escape of nanoworms from RBC clusters and their accumulation near the wall of main channel. The accumulated near-wall nanoworms will eventually enter the constriction, thus enhancing their concentration inside the constriction. However, an exceptional case occurs in the case of constrictions with large ratio and long length. In such circumstances, the RBCs aggregate together tightly and concentrate at the center of the channel, which makes the nanoworms hardly able to escape from RBC clusters, leading to a similar accumulation of nanoworms and spheres inside the constriction. This study may provide theoretical guidance for the design of nano- and micro-particles for biomedical engineering applications, such as drug delivery systems for patients with stenosed microvessels.

Nanoparticle-mediated delivery of siRNA into zebrafish heart: a cell-level investigation on the biodistribution and gene silencing effects

Nanomaterials hold promise for the delivery of nucleic acids to facilitate gene therapy in cardiac diseases. However, as much of the in vivo study of nanomaterials was conducted via the "trial and error" method, the understanding of the nanomaterial-mediated delivery in cardiac tissue was limited to the gross efficiency in manipulating the gene expression while little was known about the delivery process and mechanism in particular at the cell level. In this study, small interfering RNA (siRNA) nanoparticles formulated with a polyamidoamine (PAMAM) nanomaterial were applied to the injured heart of zebrafish. The distribution of nanoparticles in cardiomyocytes, endothelial cells, macrophages and leukocytes was quantitatively analyzed with precision at the cell level by using transgenic models. Based on the distribution characteristics, gene silencing effects in a specific group of cells were analyzed to illustrate how siRNA nanoparticles could get potent gene silencing in different cells in vivo. The results elucidated the heterogeneous distribution of siRNA nanoparticles and how nanoparticles could be efficient despite the significant difference in cellular uptake efficiency in different cells. It demonstrated a paradigm and the need to decouple cellular processes to understand nanoparticle-mediated delivery in complex tissue and the investigation/methodology may lead to important information to guide the design of advanced targeted drug-delivery systems in heart.

Spatially resolved small-angle X-ray scattering for characterizing mechanoresponsive liposomes using microfluidics

Atherosclerosis gives rise to blood vessel occlusion associated with blood flow alteration and substantial increase of average wall shear stress. This modification was proved acting as a purely physical trigger for targeted vasodilator release from a particular type of liposomes composed of 1,3-diaminophospholipids (Pad-PC-Pad). The flow-induced structural changes of these faceted liposomes, however, are completely unknown. Therefore, spatially resolved small-angle X-ray scattering was combined with microfluidics to uniquely study the purely physical mechanisms, which give rise to the highly efficient drug release from mechanoresponsive liposomes of nanometer size. The microfluidic device, designed to mimic a stenotic blood vessel, consisted of a 1-mm-wide channel with a constriction, 125 ​μm in diameter. Here, the changes of the average bilayer thickness and the mean size of the mechanoresponsive liposomes have been locally detected under flow conditions. Overall shape and bilayer thickness do change already near the constriction inlet, but the alteration is dominant near the outlet. At a flow rate of 0.2 ​μL/s, the liposome's bilayer thickness increased by 30 % compared to the situation well before the constriction and under static condition. The detected bilayer thickness increase of the faceted liposomes is in line with the mechanically induced loss of interdigitation between the phospholipid amide chains. These results imply that rather the gradient force than the wall shear stress provokes structural changes of Pad-PC-Pad liposomes and the related drug release at stenoses. The approach, i.e. the combination of microfluidics and spatially resolved small-angle X-ray scattering, paves the way to design highly efficient and specific systems for the targeted drug delivery at constrictions with predefined morphology.

Nanomedicine Magic Bullet for Human Cancer

Nanotechnology is the new tool that has changed healthcare, engineering, and space science. The technology involves nanoparticles that are effectively a bridge between bulk materials and atomic or molecular structures. The properties of materials change its surface plasmon resonance in metals, supermagnetism in magnetic materials as their size approaches to nanoscale. Taking in to account of their small sizes (less than 100nm) and their miraculous properties, unlike their precursor bulk material, nanoparticles are exploited to create new diagnostics and therapeutics with respect to several human diseases. Nanomedicine is generating a new generation of innovative revolution in nanoscale drug delivery strategies, site-specific drug delivery, and personalized therapy in cancer by releasing the drug at a specific site. This chapter discusses the evolution of nanomedicine to several advancements in the field of nanoparticle technologies, targeting and controlled release strategies, with the desire of generating robust and efficient nanotherapeutic tools against cancer.

Nanotechnology for the detection and therapy of stroke

Over the years, nanotechnology has greatly developed, moving from careful design strategies and synthesis of novel nanostructures to producing them for specific medical and biological applications. The use of nanotechnology in diagnostics, drug delivery, and tissue engineering holds great promise for the treatment of stroke in the future. Nanoparticles are employed to monitor grafted cells upon implantation, or to enhance the imagery of the tissue, which is coupled with a noninvasive imaging modality such as magnetic resonance imaging, computed axial tomography or positron emission tomography scan. Contrast imaging agents used can range from iron oxide, perfluorocarbon, cerium oxide or platinum nanoparticles to quantum dots. The use of nanomaterial scaffolds for neuroregeneration is another area of nanomedicine, which involves the creation of an extracellular matrix mimic that not only serves as a structural support but promotes neuronal growth, inhibits glial differentiation, and controls hemostasis. Promisingly, carbon nanotubes can act as scaffolds for stem cell therapy and functionalizing these scaffolds may enhance their therapeutic potential for treatment of stroke. This Progress Report highlights the recent developments in nanotechnology for the detection and therapy of stroke. Recent advances in the use of nanomaterials as tissue engineering scaffolds for neuroregeneration will also be discussed.

The use of shear stress for targeted drug delivery

Stenosed segments of arteries significantly alter the blood flow known from healthy vessels. In particular, the wall shear stress at critically stenosed arteries is at least an order of magnitude higher than in healthy situations. This alteration represents a change in physical force and might be used as a trigger signal for drug delivery. Mechano-sensitive drug delivery systems that preferentially release their payload under increased shear stress are discussed. Therefore, besides biological or chemical markers, physical triggers are a further principle approach for targeted drug delivery. We hypothesize that such a physical trigger is much more powerful to release drugs for vasodilation, plaque stabilization, or clot lysis at stenosed arteries than any known biological or chemical ones.

Phase-shift, stimuli-responsive perfluorocarbon nanodroplets for drug delivery to cancer

This review focuses on phase-shift perfluorocarbon nanoemulsions whose action depends on an ultrasound-triggered phase shift from a liquid to gas state. For drug-loaded perfluorocarbon nanoemulsions, microbubbles are formed under the action of tumor-directed ultrasound and drug is released locally into tumor volume in this process. This review covers in detail mechanisms involved in the droplet-to-bubble transition as well as mechanisms of ultrasound-mediated drug delivery.

In vivo prevention of arterial restenosis with paclitaxel-encapsulated targeted lipid-polymeric nanoparticles

Following recent successes with percutaneous coronary intervention (PCI) for treating coronary artery disease (CAD), many challenges remain. In particular, mechanical injury from the procedure results in extensive endothelial denudation, exposing the underlying collagen IV-rich basal lamina, which promotes both intravascular thrombosis and smooth muscle proliferation. Previously, we reported the engineering of collagen IV-targeting nanoparticles (NPs) and demonstrated their preferential localization to sites of arterial injury. Here, we develop a systemically administered, targeted NP system to deliver an antiproliferative agent to injured vasculature. Approximately 60-nm lipid-polymeric NPs were surface functionalized with collagen IV-targeting peptides and loaded with paclitaxel. In safety studies, the targeted NPs showed no signs of toxicity and a ≥3.5-fold improved maximum tolerated dose versus paclitaxel. In efficacy studies using a rat carotid injury model, paclitaxel (0.3 mg/kg or 1 mg/kg) was i.v. administered postprocedure on days 0 and 5. The targeted NP group resulted in lower neointima-to-media (N/M) scores at 2 wk versus control groups of saline, paclitaxel, or nontargeted NPs. Compared with sham-injury groups, an ∼50% reduction in arterial stenosis was observed with targeted NP treatment. The combination of improved tolerability, sustained release, and vascular targeting could potentially provide a safe and efficacious option in the management of CAD.

Anti-angiogenic perfluorocarbon nanoparticles for diagnosis and treatment of atherosclerosis

Complementary developments in nanotechnology, genomics, proteomics, molecular biology and imaging offer the potential for early, accurate diagnosis. Molecularly-targeted diagnostic imaging agents will allow noninvasive phenotypic characterization of pathologies and, therefore, tailored treatment close to the onset. For atherosclerosis, this includes anti-angiogenic therapy with specifically-targeted drug delivery systems to arrest the development of plaques before they impinge upon the lumen. Additionally, monitoring the application and effects of this targeted therapy in a serial fashion will be important. This review covers the specific application of alpha(nu)beta(3)-targeted anti-angiogenic perfluorocarbon nanoparticles in (1) the detection of molecular markers for atherosclerosis, (2) the immediate verification of drug delivery with image-based prediction of therapy outcomes, and (3) the serial, noninvasive observation of therapeutic efficacy.

Nanoparticle technologies for cancer therapy

Nanoparticles as drug delivery systems enable unique approaches for cancer treatment. Over the last two decades, a large number of nanoparticle delivery systems have been developed for cancer therapy, including organic and inorganic materials. Many liposomal, polymer-drug conjugates, and micellar formulations are part of the state of the art in the clinics, and an even greater number of nanoparticle platforms are currently in the preclinical stages of development. More recently developed nanoparticles are demonstrating the potential sophistication of these delivery systems by incorporating multifunctional capabilities and targeting strategies in an effort to increase the efficacy of these systems against the most difficult cancer challenges, including drug resistance and metastatic disease. In this chapter, we will review the available preclinical and clinical nanoparticle technology platforms and their impact for cancer therapy.

Gold nanoparticles: From nanomedicine to nanosensing

Because of their photo-optical distinctiveness and biocompatibility, gold nanoparticles (AuNPs) have proven to be powerful tools in various nanomedicinal and nanomedical applications. In this review article, we discuss recent advances in the application of AuNPs in diagnostic imaging, biosensing and binary cancer therapeutic techniques. We also provide an eclectic collection of AuNPs delivery strategies, including assorted classes of delivery vehicles, which are showing great promise in specific targeting of AuNPs to diseased tissues. However, successful clinical implementations of the promised applications of AuNPs are still hampered by many barriers. In particular, more still needs to be done regarding our understanding of the pharmacokinetics and toxicological profiles of AuNPs and AuNPs-conjugates.

[Clinical application of nanoparticles, and their possible health risk]

Nanomaterials are getting rapidly developing practical applications, beside many others also in the clinical practice. Their beneficial attributes make the use of the nanostructures a large improvement in effective therapy as coating of implants, bone replacement materials, coating of active substances, nano-sized liposomes to achieve better pharmacologic qualities. Beside new beneficial chemical qualities originating from their size, due to the use of nanomaterials also adverse health effects may occur. Only in view of the possible effects on human health is the responsible use acceptable. The difference in qualities from other kinds of material can be explained by the nano-size. Investigations performed in the last decade have shown beside their local effect also systemic effects, like the rise of reactive oxygen species production, increase of platelet aggregation, which raises the cardiovascular risk. Due to the incomplete knowledge available now, it is not possible to assess the exact health risk; accordingly the application of nanomaterials in medical care has to be especially careful because of their possible partly unknown adverse health effects.

In vivo molecular imaging of vascular stress

Noninvasive in vivo imaging is an emerging specialty in experimental radiology aiming at developing hardware and appropriate contrast agents to visualize the molecular basis and pathophysiological processes of many pathological conditions, including atherosclerosis. The list of potentially useful tracers and targets for in vivo molecular imaging in the cascade of early atherosclerotic events has been narrowed down to some very promising endothelial factors, i.e., cell adhesion molecules, macrophages, apoptosis, lipoproteins, heat shock proteins, and others. In this review, we will update on the progress of recent developments in the field of noninvasive molecular imaging in experimental atherosclerosis.

Affinity manipulation of surface-conjugated RGD peptide to modulate binding of liposomes to activated platelets

Platelet adhesion, activation and fibrinogen-mediated aggregation are primary events in vascular thrombosis and occlusion. An injectable delivery system that can carry thrombolytics selectively to the sites of active platelet aggregation has immense potential in minimally invasive targeted therapy of vascular occlusion. To this end we are studying liposomes surface-modified by fibrinogen-mimetic RGD motifs that can selectively target and bind integrin GPIIb-IIIa on activated platelets. Here we report liposome surface-modification with a conformationally constrained high affinity cyclic RGD motif to modulate the GPIIb-IIIa-binding capability of the liposomes. Such affinity enhancement is important for practical in vivo applications to compete with native fibrinogen towards binding GPIIb-IIIa. The platelet-binding of RGD-modified liposomes was studied by fluorescence and scanning electron microscopy, and flow cytometry, in vitro. Binding of RGD-modified liposomes was also tested in vivo in a rat carotid injury model and analyzed ex vivo by fluorescence microscopy. The results from all experiments show that cyclic RGD-liposomes bind activated platelets significantly higher compared to linear RGD-liposomes. Hence, the results establish the feasibility of modulating the platelet-targeting and binding ability of vascularly targeted liposomes by manipulating the affinity of surface-modifying ligands.

Vitamin E TPGS-emulsified poly(lactic-co-glycolic acid) nanoparticles for cardiovascular restenosis treatment

AIMS

Paclitaxel is one of the most effective antiproliferative agents and it has been applied in the development of drug-eluting stents. There are difficulties, however, in using paclitaxel in clinical applications owing to its poor solubility and side effects. We have synthesized nanoparticles of biodegradable polymers for the effective and sustainable delivery of paclitaxel and other antiproliferative agents for restenosis treatment.

METHODS & RESULTS

Paclitaxel-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles were prepared by a modified solvent extraction/evaporation method with D-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS) or polyvinyl alcohol (PVA) as an emulsifier. Drug-loaded nanoparticles were characterized for size and size distribution, surface morphology, surface charge, drug-encapsulation efficiency and in vitro drug-release kinetics. Cellular uptake of fluorescent nanoparticles was investigated in vitro in coronary artery smooth muscle cells and in vivo in the carotid arteries of rabbits. The antiproliferative effects of the nanoparticle formulations were assessed in vitro in close comparison with Taxol((R)). Both the PVA- and TPGS-emulsified nanoparticles have similar size and size distribution, surface morphology and dispersion stability and showed great advantages over paclitaxel in in vitro cellular uptake and cytotoxicity than Taxol. The TPGS-emulsified nanoparticle formulation has higher drug-encapsulation efficiency, cellular uptake and cytotoxicity than the PVA-emulsified nanoparticle formulation. IC(50) in 24-h culture with coronary artery smooth muscle cells is 748 ng/ml for paclitaxel, 708 ng/ml for PVA-emulsified nanoparticles and 474 ng/ml for TPGS-emulsified nanoparticles, respectively.

CONCLUSION

TPGS-emulsified PLGA nanoparticles have great potential for the effective and sustainable delivery of antiproliferative agents and for the development of nanoparticle-coated stents, which may become the third generation of cardiovascular stents.

Targeting of Vulnerable Plaque Macrophages with Polymer-Based Nanostructures

Macrophages are key cellular elements of atherosclerotic plaque pathogenesis and are a significant risk factor for plaque rupture. Current diagnostic techniques for the detection of plaque macrophages are often limited by insufficient sensitivity and selectivity and have not reached broad clinical practice until now. Supramolecular nanometer-sized structures such as conjugates, nanoparticles, micelles, or vesicles built from novel polymers promise to be useful in cell-specific delivery and may be of particular value for the detection and treatment of vulnerable plaque macrophages. Key properties of polymer-based nanostructures are high stability, improved biocompatibility, long circulation half-lives, defined biodegradation, targeting moieties, and triggerable controlled release. This review gives an insight into several promising research projects with polymer-based nanostructures for macrophage detection or treatment that might enter cardiologic practice in the near future.

Nanotechnological applications in medicine

Nanotechnology-based tools and techniques are rapidly emerging in the fields of medical imaging and targeted drug delivery. Employing constructs such as dendrimers, liposomes, nanoshells, nanotubes, emulsions and quantum dots, these advances lead toward the concept of personalized medicine and the potential for very early, even pre-symptomatic, diagnoses coupled with highly-effective targeted therapy. Highlighting clinically available and preclinical applications, this review explores the opportunities and issues surrounding nanomedicine.