Would antioxidant-loaded nanoparticles present an effective treatment for ischemic stroke?

Antioxidant nanozymes as next-generation therapeutics to free radical-mediated inflammatory diseases: A comprehensive review

Recent developments in exploring the biological enzyme mimicking properties in nanozymes have opened a separate avenue, which provides a suitable alternative to the natural antioxidants and enzymes. Due to high and tunable catalytic activity, low cost of synthesis, easy surface modification, and good biocompatibility, nanozymes have garnered significant research interest globally. Several inorganic nanomaterials have been investigated to exhibit catalytic activities of some of the key natural enzymes, including superoxide dismutase (SOD), catalase, glutathione peroxidase, peroxidase, and oxidase, etc. These nanozymes are used for diverse biomedical applications including therapeutics, imaging, and biosensing in various cells/tissues and animal models. In particular, inflammation-related diseases are closely associated with reactive oxygen and reactive nitrogen species, and therefore effective antioxidants could be excellent therapeutics due to their free radical scavenging ability. Although biological enzymes and other artificial antioxidants could perform well in scavenging the reactive oxygen and nitrogen species, however, suffer from several drawbacks such as the requirement of strict physiological conditions for enzymatic activity, limited stability in the environment beyond their optimum pH and temperature, and high cost of synthesis, purification, and storage make then unattractive for broad-spectrum applications. Therefore, this review systematically and comprehensively presents the free radical-mediated evolution of various inflammatory diseases (inflammatory bowel disease, mammary gland fibrosis, and inflammation, acute injury of the liver and kidney, mammary fibrosis, and cerebral ischemic stroke reperfusion) and their mitigation by various antioxidant nanozymes in the biological system. The mechanism of free radical scavenging by antioxidant nanozymes under in vitro and in vivo experimental models and catalytic efficiency comparison with corresponding natural enzymes has also been presented.

Perspective insights into hydrogels and nanomaterials for ischemic stroke

Ischemic stroke (IS) is a neurological disorder prevalent worldwide with a high disability and mortality rate. In the clinic setting, tissue plasminogen activator (tPA) and thrombectomy could restore blood flow of the occlusion region and improve the outcomes of IS patients; however, these therapies are restricted by a narrow time window. Although several preclinical trials have revealed the molecular and cellular mechanisms underlying infarct lesions, the translatability of most findings is unsatisfactory, which contributes to the emergence of new biomaterials, such as hydrogels and nanomaterials, for the treatment of IS. Biomaterials function as structural scaffolds or are combined with other compounds to release therapeutic drugs. Biomaterial-mediated drug delivery approaches could optimize the therapeutic effects based on their brain-targeting property, biocompatibility, and functionality. This review summarizes the advances in biomaterials in the last several years, aiming to discuss the therapeutic potential of new biomaterials from the bench to bedside. The promising prospects of new biomaterials indicate the possibility of an organic combination between materialogy and medicine, which is a novel field under exploration.

Structure design mechanisms and inflammatory disease applications of nanozymes

Nanozymes are artificial enzymes with high catalytic activity, low cost, and good biocompatibility, and have received ever-increasing attention in recent years. Various inorganic and organic nanoparticles have been found to exhibit enzyme-like activities and are used as nanozymes for diverse biomedical applications ranging from tumor imaging and therapeutics to detection. However, their further clinical applications are hindered by the potential toxicity and long-term retention of nanomaterials in vivo. Clarifying the catalytic mechanism of nanozymes and identifying the key factors responsible for their behavior can guide the design of nanozyme structure, enlighten the ways to improve their enzyme-like activities, and minimize the dosage of nanozymes, leading to reduced toxicity to the human body for a real biomedical application prospect. In particular, inflammation occurring in numerous diseases is closely related to reactive oxygen species, and the active oxygen scavenging ability of nanozymes potentially exerts excellent therapeutic effects on inflammatory diseases. In this review, we systematically summarize the structure-activity relationship of nanozymes, including regulation strategies for size and morphology, surface structure, and composition. Based on the structure-activity mechanisms, a series of chemically designed nanozymes developed to target various inflammatory diseases are briefly summarized.

Dendrimers for cancer immunotherapy: Avidity-based drug delivery vehicles for effective anti-tumor immune response

Cancer immunotherapy, or the utilization of a patient's own immune system to treat cancer, has shifted the paradigm of cancer treatment. Despite meaningful responses being observed in multiple studies, currently available immunotherapy platforms have only proven effective to a small subset of patients. To address this, nanoparticles have been utilized as a novel carrier for immunotherapeutic drugs, achieving robust anti-tumor effects with increased adaptive and durable responses. Specifically, dendrimer nanoparticles have attracted a great deal of scientific interest due to their versatility in various therapeutic applications, resulting from their unique physicochemical properties and chemically well-defined architecture. This review offers a comprehensive overview of dendrimer-based immunotherapy technologies, including their formulations, biological functionalities, and therapeutic applications. Common formulations include: (1) modulators of cytokine secretion of immune cells (adjuvants); (2) facilitators of the recognition of tumorous antigens (vaccines); (3) stimulators of immune effectors to selectively attack cells expressing specific antigens (antibodies); and (4) inhibitors of immune-suppressive responses (immune checkpoint inhibitors). On-going works and prospects of dendrimer-based immunotherapies are also discussed. Overall, this review provides a critical overview on rapidly growing dendrimer-based immunotherapy technologies and serves as a guideline for researchers and clinicians who are interested in this field. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Dodging blood brain barrier with "nano" warriors: Novel strategy against ischemic stroke

Ischemic stroke (IS) is one of the leading causes of death and disability resulting in inevitable burden globally. Ischemic injury initiates cascade of pathological events comprising energy dwindling, failure of ionic gradients, failure of blood brain barrier (BBB), vasogenic edema, calcium over accumulation, excitotoxicity, increased oxidative stress, mitochondrial dysfunction, inflammation and eventually cell death. In spite of such complexity of the disease, the only treatment approved by US Food and Drug Administration (FDA) is tissue plasminogen activator (t-PA). This therapy overcome blood deficiency in the brain along with side effects of reperfusion which are responsible for considerable tissue injury. Therefore, there is urgent need of novel therapeutic perspectives that can protect the integrity of BBB and salvageable brain tissue. Advancement in nanomedicine is empowering new approaches that are potent to improve the understanding and treatment of the IS. Herein, we focus nanomaterial mediated drug delivery systems (DDSs) and their role to bypass and cross BBB especially via intranasal drug delivery. The various nanocarriers used in DDSs are also discussed. In a nut shell, the objective is to provide an overview of use of nanomedicine in the diagnosis and treatment of IS to facilitate the research from benchtop to bedside.

Nanoparticles-mediated emerging approaches for effective treatment of ischemic stroke

Ischemic stroke leads to high disability and mortality. The limited delivery efficiency of most therapeutic substances is a major challenge for effective treatment of ischemic stroke. Inspired by the prominent merit of nanoscale particles in brain targeting and blood-brain barrier (BBB) penetration, various functional nanoparticles have been designed as promising drug delivery platforms that are expected to improve the therapeutic effect of ischemic stroke. Based on the complex pathological mechanisms of ischemic stroke, this review outline and summarize the rationally designed nanoparticles-mediated emerging approaches for effective treatment of ischemic stroke, including recanalization therapy, neuroprotection therapy, and combination therapy. On this bases, the potentials and challenges of nanoparticles in the treatment of ischemic stroke are revealed, and new thoughts and perspectives are proposed for the design of feasible nanoparticles for effective treatment of ischemic stroke.

Size-Dependent Drug Loading, Gene Complexation, Cell Uptake, and Transfection of a Novel Dendron-Lipid Nanoparticle for Drug/Gene Co-delivery

Dendron micelles have shown promising results as a multifunctional delivery system, owing to their unique molecular architecture. Herein, we have prepared a novel poly(amidoamine) (PAMAM) dendron-lipid hybrid nanoparticle (DLNP) as a nanocarrier for drug/gene co-delivery and examined how the dendron generation of DLNPs impacts their cargo-carrying capabilities. DLNPs, formed by a thin-layer hydration method, were internally loaded with chemo-drugs and externally complexed with plasmids. Compared to generation 2 dendron DLNP (D2LNPs), D3LNPs demonstrated a higher drug encapsulation efficiency (31% vs 87%) and better gene complexation (minimal N/P ratio of 20:1 vs 5:1 for complexation) due to their smaller micellar aggregation number and higher charge density, respectively. Furthermore, D3LNPs were able to avoid endocytosis and subsequent lysosomal degradation and demonstrated a higher cellular uptake than D2LNPs. As a result, D3LNPs exhibited significantly enhanced antitumor and gene transfection efficacy in comparison to D2LNPs. These findings provide design cues for engineering multifunctional dendron-based nanotherapeutic systems for effective combination cancer treatment.

Nanotechnology in the diagnosis and treatment of stroke

Increasing developments in the field of nanotechnology have ignited its use in stroke diagnosis and treatment. The benefits of structural modification, ease of synthesis, and biocompatibility support the use of nanomaterials in the clinic. The pathophysiology of stroke is complex, involving different brain regions; hence, therapeutic agents are required to be delivered to specific regions. Nanoparticles (NPs) can be engineered to help improve the delivery and release of therapeutic agents in a localized manner, especially in the penumbra. This contributes not only to therapy, but also to neurosurgery and neuroimaging. Nanomaterials also offer high efficacy with few adverse effects. In this review, we provide a concise summary of the caveats associated with nanotechnology with respect to stroke therapy and diagnosis.

Effects of Liposomal Simvastatin Nanoparticles on Vascular Endothelial Function and Arterial Smooth Muscle Cell Apoptosis in Rats with Arteriosclerotic Occlusive Disease of Lower Limb via P38 Mitogen-Activated Protein Kinase Nuclear Factor Kappa-B Pathway

This article prepared a simvastatin-NLCs for the treatment of arteriosclerotic occlusive disease of lower limbs. Taking the size distribution, polydispersity coefficient, encapsulation efficiency and drug loading of simvastatin-NLCs as evaluation indicators, various prescription factors of simvastatin- NLCs were investigated. The in vitro release behavior and stability of simvastatin-NLCs were also investigated. A hyperlipidemia rat model was established using high-fat diets. SD rats fed ordinary diet were set as normal control groups. 20 rats, 20 in the simvastatin group and 20 in the simvastatin nanocarrier group. After 5 weeks of drug intervention, the rats were sacrificed and the aorta was taken to determine the smooth muscle cell apoptosis rate. Studies have shown that simvastatin nanocarriers can more effectively reduce blood lipids in hyperlipidemia rats, increase the rate of smooth muscle cell apoptosis in hyperlipidemia rats, and delay the onset of atherosclerosis.

Towards precision nanomedicine for cerebrovascular diseases with emphasis on Cerebral Cavernous Malformation (CCM)

Introduction: Cerebrovascular diseases encompass various disorders of the brain vasculature, such as ischemic/hemorrhagic strokes, aneurysms, and vascular malformations, also affecting the central nervous system leading to a large variety of transient or permanent neurological disorders. They represent major causes of mortality and long-term disability worldwide, and some of them can be inherited, including Cerebral Cavernous Malformation (CCM), an autosomal dominant cerebrovascular disease linked to mutations in CCM1/KRIT1, CCM2, or CCM3/PDCD10 genes.Areas covered: Besides marked clinical and etiological heterogeneity, some commonalities are emerging among distinct cerebrovascular diseases, including key pathogenetic roles of oxidative stress and inflammation, which are increasingly recognized as major disease hallmarks and therapeutic targets. This review provides a comprehensive overview of the different clinical features and common pathogenetic determinants of cerebrovascular diseases, highlighting major challenges, including the pressing need for new diagnostic and therapeutic strategies, and focusing on emerging innovative features and promising benefits of nanomedicine strategies for early detection and targeted treatment of such diseases.Expert opinion: Specifically, we describe and discuss the multiple physico-chemical features and unique biological advantages of nanosystems, including nanodiagnostics, nanotherapeutics, and nanotheranostics, that may help improving diagnosis and treatment of cerebrovascular diseases and neurological comorbidities, with an emphasis on CCM disease.

Surface engineering for efficient capture of circulating tumor cells in renal cell carcinoma: From nanoscale analysis to clinical application

Sensitive detection of circulating tumor cells (CTCs) from patients' peripheral blood facilitates on-demand monitoring of tumor progression. However, clinically significant capture of renal cell carcinoma CTCs (RCC-CTCs) remains elusive due to their heterogenous surface receptor expression. Herein, a novel capture platform is developed to detect RCC-CTCs through integration of dendrimer-mediated multivalent binding, a mixture of antibodies, and biomimetic cell rolling. The nanoscale binding kinetics measured using atomic force microscopy reveal that dendrimer-coated surfaces exhibit an order of magnitude enhancement in off-rate kinetics compared to surface without dendrimers, which translated into cell capture improvements by ~60%. Selectin-induced cell rolling facilitates surface recruitment of cancer cells, further improving cancer cell capture by up to 1.7-fold. Lastly, an antibody cocktail targeting four RCC-CTC surface receptors, which included epithelial cell adhesion molecule (EpCAM), carbonic anhydrase IX (CA9), epidermal growth factor receptor (EGFR), and hepatocyte growth factor receptor (c-Met), improves the capture of RCC cells by up to 80%. The optimal surface configuration outperforms the conventional assay solely relying on EpCAM, as demonstrated by detecting significantly more CTCs in patients' samples (9.8 ± 5.1 vs. 1.8 ± 2.0 CTCs mL-1). These results demonstrate that the newly engineered capture platform effectively detects RCC-CTCs for their potential use as tumor biomarkers.

An Avidity-Based PD-L1 Antagonist Using Nanoparticle-Antibody Conjugates for Enhanced Immunotherapy

Upregulation of programmed death ligand 1 (PD-L1) allows cancer cells to evade antitumor immunity. Despite tremendous efforts in developing PD-1/PD-L1 immune checkpoint inhibitors (ICIs), clinical trials using such ICIs have shown inconsistent benefits. Here, we hypothesized that the ICI efficacy would be dictated by the binding strength of the inhibitor to the target proteins. To assess this, hyperbranched, multivalent poly(amidoamine) dendrimers were employed to prepare dendrimer-ICI conjugates (G7-aPD-L1). Binding kinetics measurements using SPR, BLI, and AFM revealed that G7-aPD-L1 exhibits significantly enhanced binding strength to PD-L1 proteins, compared to free aPD-L1. The binding avidity of G7-aPD-L1 was translated into in vitro efficiency and in vivo selectivity, as the conjugates improved the PD-L1 blockade effect and enhanced accumulation in tumor sites. Our results demonstrate that the dendrimer-mediated multivalent interaction substantially increases the binding avidity of the ICIs and thereby improves the antagonist effect, providing a novel platform for cancer immunotherapy.

Biomaterials to Neuroprotect the Stroke Brain: A Large Opportunity for Narrow Time Windows

Ischemic stroke represents one of the most prevalent pathologies in humans and is a leading cause of death and disability. Anti-thrombolytic therapy with tissue plasminogen activator (t-PA) and surgical thrombectomy are the primary treatments to recanalize occluded vessels and normalize the blood flow in ischemic and peri-ischemic regions. A large majority of stroke patients are refractory to treatment or are not eligible due to the narrow time window of therapeutic efficacy. In recent decades, we have significantly increased our knowledge of the molecular and cellular mechanisms that inexorably lead to progressive damage in infarcted and peri-lesional brain areas. As a result, promising neuroprotective targets have been identified and exploited in several stroke models. However, these considerable advances have been unsuccessful in clinical contexts. This lack of clinical translatability and the emerging use of biomaterials in different biomedical disciplines have contributed to developing a new class of biomaterial-based systems for the better control of drug delivery in cerebral disorders. These systems are based on specific polymer formulations structured in nanoparticles and hydrogels that can be administered through different routes and, in general, bring the concentrations of drugs to therapeutic levels for prolonged times. In this review, we first provide the general context of the molecular and cellular mechanisms impaired by cerebral ischemia, highlighting the role of excitotoxicity, inflammation, oxidative stress, and depolarization waves as the main pathways and targets to promote neuroprotection avoiding neuronal dysfunction. In the second part, we discuss the versatile role played by distinct biomaterials and formats to support the sustained administration of particular compounds to neuroprotect the cerebral tissue at risk of damage.

Bioinspired Nanosponge for Salvaging Ischemic Stroke via Free Radical Scavenging and Self-Adapted Oxygen Regulating

Either hypoxia in an acute ischemic stroke before thrombolysis or the oxygen-boost after thrombolysis cause a high level of free radicals, resulting in successive injuries to neurocytes. To treat an ischemic stroke, it is needed to scavenge free radicals, combining sequentially regulating hypoxia and oxygen-boost microenvironment. Here, we report an engineered nanosponge (Mn₃O₄@nanoerythrocyte-T7, MNET) that could remodel the microenvironment of a stroke by self-adapted oxygen regulating and free radical scavenging. With a long circulation time in blood due to the stealth effect of the erythrocyte and preferential accumulation in the infarct site by the assisting of T7 peptide, MNET exerts a distinct therapeutic effect in two stages of an ischemic stroke: (i) before thrombolysis, rescue neurocyte via rapid free radical scavenging and timely oxygen supply; (ii) after thrombolysis, suppress oxygen-boost via oxygen storage, as well as scavenge free radical to avoid reperfusion injury. MNET holds an attractive potential for ischemic stroke treatment via phased regulation of pathological microenvironment.

Dancing with reactive oxygen species generation and elimination in nanotheranostics for disease treatment

Reactive oxygen species (ROS) play important roles in cell signaling and tissue homeostasis, in which the level of ROS is critical through the equilibrium between ROS generating and eliminating events. A disruption of the balance leads to disease development either by a surplus or a dearth of ROS, which requires ROS-modulating strategies to overturn the defect for disease treatment. Over the past decade, there have been tremendous advances in nanomedicine centering ROS generation and/or elimination as major mechanisms to treat a variety of diseases. In this review, we will discuss the research achievements on two opposite approaches of ROS-generating and ROS-eliminating strategies for treating cancer and other related diseases. Importantly, we will highlight the conceptual and strategic advances of ROS-mediated immunomodulation, including macrophage polarization, immunogenic cell death and T cell activation, which are currently rising as one of the mainstreams of cancer therapy. At the end, the future challenges and opportunities of mediating ROS-based mechanisms are envisioned. In light of the pleiotropic roles of ROS in different diseases, we hope this review is timely to deliver a clear logic of designing principles on ROS generation and elimination for different disease treatments.

Approaches for encephalic drug delivery using nanomaterials: The current status

Nanotechnology, the investigation of little structures, ranging from the size of 1 nm-100 nm presents a breakthrough in the field of targeted drug delivery. The microvasculature in the human brain along with the blood brain barrier (BBB) offers high resistance to the entry of therapeutics agents and other substances in to the brain. Nanoparticles have certain advantages as high permeability, reactivity, surface area and quantum properties and it also meets various medical challenges which may include poor bioavailability, difficulty in targeting, organ toxicity etc. The use of nanoparticles in pharmaceuticals has been inspired by various natural nanomaterials found in the body, which includes proteins, lipids etc. A brief explanation of different types of pharmaceutical approaches used in brain drug delivery is discussed here. Nanotechnology is used treatment of many illnesses which also include diseases related to the brain such as gliomas, epilepsy, migraine, cerebrovascular disease, Parkinson's disease etc., Different type of nanoparticles are prepared, such as polymer-based nanoparticles, metallic nanoparticles, carbon-based nanoparticles, lipid-based nanoparticles, ceramic nanoparticles semiconductor nanoparticles and are studied for their usefulness in drug delivery. The primary function of nanoparticles is to deliver drug moiety to the desired targeted site by overcoming permeability issues. The shape, size and surface area nanoparticles help in increasing the bioavailability, drug retention and multiple drug delivery. Mechanisms of nanoparticles crossing BBB can be divided into passive and active transport, are briefly explained.

Peptide-nanoparticle conjugates: a next generation of diagnostic and therapeutic platforms?

Peptide-nanoparticle conjugates (PNCs) have recently emerged as a versatile tool for biomedical applications. Synergism between the two promising classes of materials allows enhanced control over their biological behaviors, overcoming intrinsic limitations of the individual materials. Over the past decades, a myriad of PNCs has been developed for various applications, such as drug delivery, inhibition of pathogenic biomolecular interactions, molecular imaging, and liquid biopsy. This paper provides a comprehensive overview of existing technologies that have been recently developed in the broad field of PNCs, offering a guideline especially for investigators who are new to this field.