Rescuing ischemic stroke by biomimetic nanovesicles through accelerated thrombolysis and sequential ischemia-reperfusion protection

Revolutionizing Stroke Care: Nanotechnology-Based Brain Delivery as a Novel Paradigm for Treatment and Diagnosis

Stroke, a severe medical condition arising from abnormalities in the coagulation-fibrinolysis cycle and metabolic processes, results in brain cell impairment and injury due to blood flow obstruction within the brain. Prompt and efficient therapeutic approaches are imperative to control and preserve brain functions. Conventional stroke medications, including fibrinolytic agents, play a crucial role in facilitating reperfusion to the ischemic brain. However, their clinical efficacy is hampered by short plasma half-lives, limited brain tissue distribution attributed to the blood-brain barrier (BBB), and lack of targeted drug delivery to the ischemic region. To address these challenges, diverse nanomedicine strategies, such as vesicular systems, polymeric nanoparticles, dendrimers, exosomes, inorganic nanoparticles, and biomimetic nanoparticles, have emerged. These platforms enhance drug pharmacokinetics by facilitating targeted drug accumulation at the ischemic site. By leveraging nanocarriers, engineered drug delivery systems hold the potential to overcome challenges associated with conventional stroke medications. This comprehensive review explores the pathophysiological mechanism underlying stroke and BBB disruption in stroke. Additionally, this review investigates the utilization of nanocarriers for current therapeutic and diagnostic interventions in stroke management. By addressing these aspects, the review aims to provide insight into potential strategies for improving stroke treatment and diagnosis through a nanomedicine approach.

Advances in Nano-Functional Materials in Targeted Thrombolytic Drug Delivery

Thrombotic disease has been listed as the third most fatal vascular disease in the world. After decades of development, clinical thrombolytic drugs still cannot avoid the occurrence of adverse reactions such as bleeding. A number of studies have shown that the application of various nano-functional materials in thrombus-targeted drug delivery, combined with external stimuli, such as magnetic, near-infrared light, ultrasound, etc., enrich the drugs in the thrombus site and use the properties of nano-functional materials for collaborative thrombolysis, which can effectively reduce adverse reactions such as bleeding and improve thrombolysis efficiency. In this paper, the research progress of organic nanomaterials, inorganic nanomaterials, and biomimetic nanomaterials for drug delivery is briefly reviewed.

Platelet Membrane-Coated r-SAK Improves Thrombolytic Efficacy by Targeting Thrombus

Thrombolytic therapy is one of the most effective treatments for thrombus dissolution and recanalization of blocked vessels in thrombotic diseases. However, the application of the thrombolytic strategy has been limited due to unsatisfactory thrombolytic efficacy, relatively higher bleeding complications, and consequently restricted indications. Recombinant staphylokinase (r-SAK) is a third-generation thrombolytic agent produced by genetic engineering technology, which exhibits a better thrombolytic efficacy than urokinase and recombinant streptokinase. Inspired by the natural affinity of platelets in hemostasis and pathological thrombosis, we developed a platelet membrane (PM)-coated r-SAK (PM-r-SAK). Results from animal experiments and human in vitro studies showed that the PM-r-SAK had a thrombolytic efficacy equal to or better than its 4-fold dose of r-SAK. In a totally occluded rabbit femoral artery thrombosis model, the PM-r-SAK significantly shortened the initial recanalization time compared to the same dose and 4-fold dose of r-SAK. Regarding the recanalized vessels, the PM-r-SAK prolonged the time of reperfusion compared to the same dose and 4-fold dose of r-SAK, though the differences were not significant. An in vitro thrombolytic experiment demonstrated that the thrombolytic efficacy of PM-r-SAK could be inhibited by platelet-poor plasma from patients taking aspirin and ticagrelor. PM coating significantly improves the thrombolytic efficacy of r-SAK, which is related to the thrombus-targeting activity of the PM-r-SAK and can be inhibited by aspirin- and ticagrelor-treated plasma.

Progress of nanomaterials in the treatment of thrombus

Thrombus has long been the major contributor of death and disability because it can cause adverse effects to varying degrees on the body, resulting in vascular blockage, embolism, heart valve deformation, widespread bleeding, etc. However, clinically, conventional thrombolytic drug treatments have hemorrhagic complication risks and easy to miss the best time of treatment window. Thus, it is an urgent need to investigate newly alternative treatment strategies that can reduce adverse effects and improve treatment effectiveness. Drugs based on nanomaterials act as a new biomedical strategy and promising tools, and have already been investigated for both diagnostic and therapeutic purposes in thrombus therapy. Recent studies have some encouraging progress. In the present review, we primarily concern with the latest developments in the areas of nanomedicines targeting thrombosis therapy. We present the thrombus' formation, characteristics, and biomarkers for diagnosis, overview recent emerging nanomedicine strategies for thrombus therapy, and focus on the future design directions, challenges, and prospects in the nanomedicine application in thrombus therapy.

Advances in nanomedicines: a promising therapeutic strategy for ischemic cerebral stroke treatment

Ischemic stroke, prevalent among the elderly, necessitates attention to reperfusion injury post treatment. Limited drug access to the brain, owing to the blood-brain barrier, restricts clinical applications. Identifying efficient drug carriers capable of penetrating this barrier is crucial. Blood-brain barrier transporters play a vital role in nutrient transport to the brain. Recently, nanoparticles emerged as drug carriers, enhancing drug permeability via surface-modified ligands. This article introduces the blood-brain barrier structure, elucidates reperfusion injury pathogenesis, compiles ischemic stroke treatment drugs, explores nanomaterials for drug encapsulation and emphasizes their advantages over conventional drugs. Utilizing nanoparticles as drug-delivery systems offers targeting and efficiency benefits absent in traditional drugs. The prospects for nanomedicine in stroke treatment are promising.

ROS-Suppression Nanoplatform Combined Activation of STAT3/Bcl-2 Pathway for Preventing Myocardial Infarction in Mice

Myocardial infarction (MI) is the leading cause of death worldwide. The most effective way to treat myocardial infarction is to rescue ischemic cardiomyocytes. After an ischemic event, the overproduction of reactive oxygen species (ROS) is a key driver of myocardial injury. The produced ROS affects mitochondrial function and induces apoptosis in cardiomyocytes. This was accomplished by constructing platelet-membrane-encapsulated ROS-responsive drug-releasing nanoparticles (PMN@NIC-MalNPs) to deliver malonate and niclosamide (NIC). The results revealed that PMN@NIC-MalNPs degraded and released malonate and niclosamide in a high-level ROS microenvironment, effectively reducing the oxidative stress and apoptosis rate. By enhancing basal mitochondrial oxygen consumption rate (OCR), adenosine triphosphate (ATP) production, and spare respiratory capacity (SRC) in vitro, reduced the oxidative stress levels and restored mitochondrial function. In vivo studies revealed that the PMN@NIC-MalNPs improved cardiac dysfunction, inhibited succinate dehydrogenase (SDH) activity, increased ATP production, and reduced the myocardial infarct size in myocardial infarction model mice. Further, transcriptome analysis and Western blot revealed that PMN@NIC-MalNPs prevented apoptosis by activating the expressions of the signal transducer and activator of transcription 3 (STAT3) and Bcl-2, and inhibiting the expression of Bax. Thus, this study provides a novel therapeutic solution for treating myocardial infarction and predicting the viability of an antioxidant and antiapoptotic therapeutic solution in the treatment of myocardial injury.

Platelet Membrane-Encapsulated Nanocomplexes Based on Profundity Scavenging ROS Strategy for Myocardial Infarction Therapy

Ischemia-induced myocardial injury has become a serious threat to human health, and its treatment remains a challenge. The occurrence of ischemic events leads to a burst release of reactive oxygen species (ROS), which triggers extensive oxidative damage and leads to dysfunctional autophagy, making it difficult for cells to maintain homeostasis. Antioxidants and modulation of autophagy have thus become promising strategies for the treatment of ischemic myocardial injury. This study proposes an antioxidant-activated autophagy therapeutic regimen based on combining melanin (Mel), an excellent antioxidant with metformin mimetic ploymetformin via electrostatic interactions, to obtain a nanocomplex (Met-Mel). The nanocomplex is finally encapsulated with platelet membranes (PMN) to construct a biomimetic nanoparticle (PMN@Met-Mel) capable of targeting injured myocardium. The prepared PMN@Met-Mel has good Mel loading capacity and optimal biosafety. It exhibits excellent antioxidant activity and autophagy activation, rapidly restoring mitochondrial function. Moreover, RNA sequencing (RNA-seq) analysis reveals that PMN@Met-Mel operates mechanistically by triggering the activation of the autophagy pathway. Subsequent in vivo experiments showcase promising cardioprotective effects of these nanoparticles. These discoveries present a newly devised nanoplatform with promising potential for the effective treatment of myocardial infarction.

An Ultrasmall Cu/Cu2O Nanoparticle-Based Diselenide-Bridged Nanoplatform Mediating Reactive Oxygen Species Scavenging and Neuronal Membrane Enhancement for Targeted Therapy of Ischemic Stroke

Ischemic stroke is one of the major causes of death and disability worldwide, and an effective and timely treatment of ischemic stroke has been a challenge because of the narrow therapeutic window and the poor affinity with thrombus of the thrombolytic agent. In this study, rPZDCu, a multifunctional nanoparticle (NP) with the effects of thrombolysis, reactive oxygen species (ROS) scavenging, and neuroprotection, was synthesized based on an ultrasmall Cu4.6O NP, the thrombolytic agent rt-PA, and docosahexaenoic acid (DHA), which is a major component of the neuronal membrane. rPZDCu showed strong thrombus-targeting ability, which was achieved by the platelet cell membrane coating on the NP surface, and a good thrombolytic effect in both the common carotid artery clot model and embolic middle cerebral artery occlusion (MCAO) model of rats. Furthermore, rPZDCu exhibited a good escape from the phagocytosis of macrophages, effective promotion of the polarization of microglia, and efficient recovery of neurobiological and behavioral functions in the embolic MCAO model of rats. This is a heuristic report of (1) the Cu0/Cu+ NP for the treatments of brain diseases, (2) the integration of DHA and ROS scavengers for central nervous system therapies, and (3) diselenide-based ROS-responsive NPs for ischemic stroke treatments. This study also offers an example of cell membrane-camouflaged stimuli-responsive nanomedicine for brain-targeting drug delivery.

Application of stimuli-responsive nanomedicines for the treatment of ischemic stroke

Ischemic stroke (IS) refers to local brain tissue necrosis which is caused by impaired blood supply to the carotid artery or vertebrobasilar artery system. As the second leading cause of death in the world, IS has a high incidence and brings a heavy economic burden to all countries and regions because of its high disability rate. In order to effectively treat IS, a large number of drugs have been designed and developed. However, most drugs with good therapeutic effects confirmed in preclinical experiments have not been successfully applied to clinical treatment due to the low accumulation efficiency of drugs in IS areas after systematic administration. As an emerging strategy for the treatment of IS, stimuli-responsive nanomedicines have made great progress by precisely delivering drugs to the local site of IS. By response to the specific signals, stimuli-responsive nanomedicines change their particle size, shape, surface charge or structural integrity, which enables the enhanced drug delivery and controlled drug release within the IS tissue. This breakthrough approach not only enhances therapeutic efficiency but also mitigates the side effects commonly associated with thrombolytic and neuroprotective drugs. This review aims to comprehensively summarize the recent progress of stimuli-responsive nanomedicines for the treatment of IS. Furthermore, prospect is provided to look forward for the better development of this field.

Modulation of microglial polarization by sequential targeting surface-engineered exosomes improves therapy for ischemic stroke

Microglia are important cells that act on regulating neuroinflammation and neurofunction after the induction of ischemic stroke (IS). Consequently, the efficient accumulation of drugs within ischemic regions, particularly in microglia, serves as a valuable approach for achieving effective therapy by attenuating microglia-mediated cerebral ischemic injury. In this study, we designed mannose (man)-conjugated luteolin (lut)-loaded platelet-derived exosomes (lut/man-pEXO) as surface engineered multifunctional cascade-delivery drug carriers to target ischemic blood vessels and subsequent microglia to enhance drug accumulation and induce neuroprotection of neurovascular unit (NVU) against IS. The results revealed that as platelets naturally gathered in pathological ischemic cerebral vessels, lut/man-pEXO could bind to platelets and efficiently target ischemic injury sites. Moreover, owing to the selective binding affinity of mannose present in lut/man-pEXO towards the mannose receptor expressed on microglia, lut/man-pEXO exhibited superior microglia-targeting properties, inducing the increased uptake of lut by microglia. As a result, lut/man-pEXO regulated microglia by inhibiting the activation of detrimental M1 and promoting the transition towards the anti-inflammatory type (M2), thus attenuating ischemic damage of NVU by reducing the infarct area, rescuing the damage of blood-brain barrier (BBB) and preventing inflammatory transformation of astrocytes.

Thrombolytic therapy based on lyophilized platelet-derived nanocarriers for ischemic stroke

BACKGROUND

Intravenous administration of fibrinolytic drugs, such as recombinant tissue plasminogen activator (rtPA) is the standard treatment of acute thrombotic diseases. However, current fibrinolytics exhibit limited clinical efficacy because of their short plasma half-lives and risk of hemorrhagic transformations. Platelet membrane-based nanocarriers have received increasing attention for ischemic stroke therapies, as they have natural thrombus-targeting activity, can prolong half-life of the fibrinolytic therapy, and reduce side effects. In this study we have gone further in developing platelet-derived nanocarriers (defined as cellsomes) to encapsulate and protect rtPA from degradation. Following lyophilization and characterization, their formulation properties, biocompatibility, therapeutic effect, and risk of hemorrhages were later investigated in a thromboembolic model of stroke in mice.

RESULTS

Cellsomes of 200 nm size and loaded with rtPA were generated from membrane fragments of human platelets. The lyophilization process did not influence the nanocarrier size distribution, morphology, and colloidal stability conferring particle preservation and long-term storage. Encapsulated rtPA in cellsomes and administered as a single bolus showed to be as effective as a continuous clinical perfusion of free rtPA at equal concentration, without increasing the risk of hemorrhagic transformations or provoking an inflammatory response.

CONCLUSIONS

This study provides evidence for the safe and effective use of lyophilized biomimetic platelet-derived nanomedicine for precise thrombolytic treatment of acute ischemic stroke. In addition, this new nanoformulation could simplify the clinical use of rtPA as a single bolus, being easier and less time-consuming in an emergency setting than a treatment perfusion, particularly in stroke patients. We have successfully addressed one of the main barriers to drug application and commercialization, the long-term storage of nanomedicines, overcoming the potential chemical and physical instabilities of nanomedicines when stored in an aqueous buffer.

Simultaneous ischemic regions targeting and BBB crossing strategy to harness extracellular vesicles for therapeutic delivery in ischemic stroke

Extracellular vesicles (EVs) derived from adipose-derived stem cells (ADSC-EVs) hold great promise for ischemic stroke treatment, but their therapeutic efficacy is greatly limited due to insufficient targeting ability. Previous reports focused on single ischemic targeting or blood-brain barrier (BBB) penetration, precise delivery to the brain parenchyma has not been fully considered. This study leveraged the targeting ability of RGD peptide and the cell penetrating ability of Angiopep-2 peptide to deliver ADSC-EVs precisely to the impaired brain parenchyma. We found that dual-modified EVs (RA-EVs) significantly enhanced the transcellular permeability across BBB in vitro, and not only targeted ischemic blood vessels but also achieved rapid accumulation in the ischemic lesion area after intravenous administration in vivo. RA-EVs further decreased the infarct volume, apoptosis, BBB disruption, and neurobehavioral deficits. RNA sequencing revealed the molecular regulation mechanism after administration. These findings demonstrate that dual-modification optimizes brain parenchymal targeting and highlights the significance of recruitment and penetration as a previously unidentified strategy for harnessing EVs for therapeutic delivery in ischemic stroke.

Cell Membrane-Derived Nanovehicles for Targeted Therapy of Ischemic Stroke: From Construction to Application

Ischemic stroke (IS) is a prevalent form of stroke and a leading cause of mortality and disability. Recently, cell membrane-derived nanovehicles (CMNVs) derived from erythrocytes, thrombocytes, neutrophils, macrophages, neural stem cells, and cancer cells have shown great promise as drug delivery systems for IS treatment. By precisely controlling drug release rates and targeting specific sites in the brain, CMNVs enable the reduction in drug dosage and minimization of side effects, thus significantly enhancing therapeutic strategies and approaches for IS. While there are some reviews regarding the applications of CMNVs in the treatment of IS, there has been limited attention given to important aspects such as carrier construction, structural design, and functional modification. Therefore, this review aims to address these key issues in CMNVs preparation, structural composition, modification, and other relevant aspects, with a specific focus on targeted therapy for IS. Finally, the challenges and prospects in this field are discussed.

REVIEW: "ISCHEMIC STROKE: From Fibrinolysis to Functional Recovery" Nanomedicine: Emerging Approaches to Treat Ischemic Stroke

Stroke is responsible for 11% of all deaths worldwide, the majority of which are caused by ischemic strokes, thus making the need to urgently find safe and effective therapies. Today, these can be cured either by mechanical thrombectomy when the thrombus is accessible, or by intravenous injection of fibrinolytics. However, the latter present several limitations, such as potential severe side effects, few eligible patients and low rate of partial and full recovery. To design safer and more effective treatments, nanomedicine appeared in this medical field a few decades ago. This review will explain why nanoparticle-based therapies and imaging techniques are relevant for ischemic stroke management. Then, it will present the different nanoparticle types that have been recently developed to treat this pathology. It will also study the various targeting strategies used to bring nanoparticles to the stroke site, thereby limiting side effects and improving the therapeutic efficacy. Finally, this review will present the few clinical studies testing nanomedicine on stroke and discuss potential causes for their scarcity.

Biomimetic nanoparticles in ischemic stroke therapy

Abstract

Ischemic stroke is one of the most severe neurological disorders with limited therapeutic strategies. The utilization of nanoparticle drug delivery systems is a burgeoning field and has been widely investigated. Among these, biomimetic drug delivery systems composed of biogenic membrane components and synthetic nanoparticles have been extensively highlighted in recent years. Biomimetic membrane camouflage presents an effective strategy to prolong circulation, reduce immunogenicity and enhance targeting. For one thing, biomimetic nanoparticles reserve the physical and chemical properties of intrinsic nanoparticle. For another, the biological functions of original source cells are completely inherited. Compared to conventional surface modification methods, this approach is more convenient and biocompatible. In this review, membrane-based nanoparticles derived from different donor cells were exemplified. The prospect of future biomimetic nanoparticles in ischemic stroke therapy was discussed.

Graphic abstract

Melanin/melanin-like nanoparticles: As a naturally active platform for imaging-guided disease therapy

The development of biocompatible and efficient nanoplatforms that combine diagnostic and therapeutic functions is of great importance for precise disease treatment. Melanin, an endogenous biopolymer present in living organisms, has attracted increasing attention as a versatile bioinspired functional platform owing to its unique physicochemical properties (e.g., high biocompatibility, strong chelation of metal ions, broadband light absorption, high drug binding properties) and inherent antioxidant, photoprotective, anti-inflammatory, and anti-tumor effects. In this review, the fundamental physicochemical properties and preparation methods of natural melanin and melanin-like nanoparticles were outlined. A systematical description of the recent progress of melanin and melanin-like nanoparticles in single, dual-, and tri-multimodal imaging-guided the visual administration and treatment of osteoarthritis, acute liver injury, acute kidney injury, acute lung injury, brain injury, periodontitis, iron overload, etc. Was then given. Finally, it concluded with a reasoned discussion of current challenges toward clinical translation and future striving directions. Therefore, this comprehensive review provides insight into the current status of melanin and melanin-like nanoparticles research and is expected to optimize the design of novel melanin-based therapeutic platforms and further clinical translation.

Plasma-Derived Nanoclusters for Site-Specific Multimodality Photo/Magnetic Thrombus Theranostics

Traditional thrombolytic therapeutics for vascular blockage are affected by their limited penetration into thrombi, associated off-target side effects, and low bioavailability, leading to insufficient thrombolytic efficacy. It is hypothesized that these limitations can be overcome by the precisely controlled and targeted delivery of thrombolytic therapeutics. A theranostic platform is developed that is biocompatible, fluorescent, magnetic, and well-characterized, with multiple targeting modes. This multimodal theranostic system can be remotely visualized and magnetically guided toward thrombi, noninvasively irradiated by near-infrared (NIR) phototherapies, and remotely activated by actuated magnets for additional mechanical therapy. Magnetic guidance can also improve the penetration of nanomedicines into thrombi. In a mouse model of thrombosis, the thrombosis residues are reduced by ≈80% and with no risk of side effects or of secondary embolization. This strategy not only enables the progression of thrombolysis but also accelerates the lysis rate, thereby facilitating its prospective use in time-critical thrombolytic treatment.

Surface-tethered ROS-responsive micelle backpacks for boosting mesenchymal stem cell vitality and modulating inflammation in ischemic stroke treatment

Mesenchymal stem cells (MSCs) exhibited remarkable therapeutic potential in ischemic stroke due to their exceptional immunomodulatory ability and paracrine effect; they have also been regarded as excellent neuroprotectant delivery vehicles with inflammatory tropism. However, the presence of high levels of reactive oxygen species (ROS) and an oxidative stress environment at the lesion site inhibits cell survival and further therapeutic effects. Using bioorthogonal click chemistry, ROS-responsive luteolin-loaded micelles were tethered to the surface of MSCs. As MSCs migrated to the ischemic brain, the micelles would achieve ROS-responsive release of luteolin to protect MSCs from excessive oxidative damage while inhibiting neuroinflammation and scavenging ROS to ameliorate ischemic stroke. This study provided an effective and prospective therapeutic strategy for ischemic stroke and a framework for a stem cell-based therapeutic system to treat inflammatory cerebral diseases.

Engineered inhaled nanocatalytic therapy for ischemic cerebrovascular disease by inducing autophagy of abnormal mitochondria

Mitochondrial dysfunction and subsequent accumulation of reactive oxygen species (ROS) are key contributors to the pathology of ischemic cerebrovascular disease. Therefore, elimination of ROS and damaged mitochondria is crucial for the effective treatment of this disease. For this purpose, we designed an inhalation nanotherapeutic agent, P/D@Mn/Co3O4, to treat ischemic cerebrovascular disease. Mn/Co3O4 effectively removed excess ROS from cells, reduced acute cellular oxidative stress, and protected neural cells from apoptosis. Furthermore, it depleted the H+ surrounding mitochondria and depolarized the mitochondrial membrane potential, inducing mitophagy and eliminating abnormal mitochondria, thereby avoiding the continuous overproduction of ROS by eliminating the source of ROS regeneration. On intranasal administration, Mn/Co3O4 encapsulated by platelet membranes and 2,3-(dioxy propyl)-trimethylammonium chloride can bypass the blood-brain barrier, enter the brain through the trigeminal and olfactory pathways, and target inflammatory regions to remove ROS and damaged mitochondria from the lesion area. In rat models of stroke and vascular dementia, P/D@Mn/Co3O4 effectively inhibited the symptoms of acute and chronic cerebral ischemia by scavenging ROS and damaged mitochondria in the affected area. Our findings indicate that the nanotherapeutic agent developed in this study can be used for the effective treatment of ischemic cerebrovascular disease.

Tailored Apoptotic Vesicle Delivery Platform for Inflammatory Regulation and Tissue Repair to Ameliorate Ischemic Stroke

Apoptotic vesicles (ApoVs) hold great promise for inflammatory regulation and tissue repair. However, little effort has been dedicated to developing ApoV-based drug delivery platforms, while the insufficient targeting capability of ApoVs also limits their clinical applications. This work presents a platform architecture that integrates apoptosis induction, drug loading, and functionalized proteome regulation, followed by targeting modification, enabling the creation of an apoptotic vesicle delivery system to treat ischemic stroke. Briefly, α-mangostin (α-M) was utilized to induce mesenchymal stem cell (MSC) apoptosis while being loaded onto MSC-derived ApoVs as an anti-oxidant and anti-inflammatory agent for cerebral ischemia/reperfusion injury. Matrix metalloproteinase activatable cell-penetrating peptide (MAP), a microenvironment-responsive targeting peptide, was modified on the surface of ApoVs to obtain the MAP-functionalized α-M-loaded ApoVs. Such engineered ApoVs targeted the injured ischemic brain after systemic injection and achieved an enhanced neuroprotective activity due to the synergistic effect of ApoVs and α-M. The internal protein payloads of ApoVs, upon α-M activation, were found engaged in regulating immunological response, angiogenesis, and cell proliferation, all of which contributed to the therapeutic effects of ApoVs. The findings provide a universal framework for creating ApoV-based therapeutic drug delivery systems for the amelioration of inflammatory diseases and demonstrate the potential of MSC-derived ApoVs to treat neural injury.

Biomimetic oxygen-boosted hybrid membrane nanovesicles as the treatment strategy for ischemic stroke with the concept of the neurovascular unit

The pathogenesis of ischemic cerebrovascular disease has revealed that ischemic stroke often leads to deprivation of oxygen, blood-brain barrier (BBB) damage and enhanced inflammatory activation, eventually causing severe brain tissue damage. Herein, we prepared hybrid membrane nanovesicles (YC-1@[RBC-PL] NVs) composed of red blood cell (RBC) membrane and platelet (PL) membrane encapsulating hypoxia inducible factor-1α (HIF-1α) inhibitor YC-1 for contributing to the protection of the neurovascular unit (NVU) in ischemic stroke. YC-1@[RBC-PL] NVs targeted the ischemic brain by the thrombus targeting properties of PL membrane and relieved the hypoxia inside ischemic brain in the presence of YC-1 and catalase in YC-1@[RBC-PL] NVs. Finally, YC-1@[RBC-PL] NVs attenuated ischemic injury to NVU by reducing infarct volume, preserving BBB integrity, and blocking activation of astrocyte and microglia in a middle cerebral artery occlusion/reperfusion (MCAO/R) model.

iPSC-sEVs alleviate microglia senescence to protect against ischemic stroke in aged mice

The polarization of microglia plays an important role in the outcome of ischemic stroke (IS). In the aged population, senescent microglia show a predominant pro-inflammatory phenotype, which leads to worse outcomes in aged ischemic stroke compared to young ischemic stroke. Recent research demonstrated that inducible pluripotent stem cell-derived small extracellular vesicles (iPSC-sEVs) possess the significant anti-ageing ability. We hypothesized that iPSC-sEVs could alleviate microglia senescence to regulate microglia polarization in aged ischemic stroke. In this study, we showed that treatment with iPSC-sEVs significantly alleviated microglia senescence as indicated by the decreased senescence-associated proteins including P16, P21, P53, and γ-H2AX as well as the activity of SA-β-gal, and inhibited pro-inflammatory activation of microglia both in vivo and in vitro. Furthermore, iPSC-sEVs shifted microglia from pro-inflammatory phenotype to anti-inflammatory phenotype, which reduced the apoptosis of neurons, and improved the outcome of aged stroke mice. Mechanism studies showed that iPSC-sEVs reversed the loss of Rictor and downstream p-AKT (s473) in senescent microglia, which was involved in the senescence and pro-inflammatory phenotype regulation of microglia. Inhibition of Rictor abolished the iPSC-sEVs-afforded phosphorylation of AKT and alleviation of inflammation of senescent microglia. Proteomics results indicated that iPSC-sEVs carried transforming growth factor-β1 (TGF-β1) to upregulate Rictor and p-AKT in senescent microglia, which could be hindered by blocking TGF-β1. Taken together, our work demonstrates iPSC-sEVs reverse the senescent characteristic of microglia in aged brains and therefore improve the outcome after stroke, at least, via delivering TGF-β1 to upregulate Rictor and p-AKT. Our data suggest that iPSC-sEVs might be a novelty therapeutic method for aged ischemic stroke and other diseases involving senescent microglia.

Magnetic Response Combined with Bioactive Ion Therapy: A RONS-Scavenging Theranostic Nanoplatform for Thrombolysis and Renal Ischemia-Reperfusion Injury

Currently, the limited efficacy of antithrombotic treatments is attributed to the inadequacy of pure drugs and the low ability of drugs to target the thrombus site. More importantly, timely thrombolysis is essential to reduce the sequelae of cardiovascular disease, but ischemia-reperfusion injury (IRI) remains a major challenge that must be solved after blood flow recovery. Herein, a multifunctional therapeutic nanoparticle (NP) based on Fe₃O₄ and strontium ions encapsulated in mesoporous polydopamine was successfully constructed and then loaded with TNK-tPA (FeM@Sr-TNK NPs). The NPs (59.9 min) significantly prolonged the half-life of thrombolytic drugs, which was 3.04 times that of TNK (19.7 min), and they had good biological safety. The NPs were shown to pass through vascular models with different inner diameters, curvatures, and stenosis under magnetic targeting and to enable accurate diagnosis of thrombi by photoacoustic imaging. NPs combined with the magnetic hyperthermia technique were used to accelerate thrombolysis and quickly open blocked blood vessels. Then, renal IRI-induced functional metabolic disorder and tissue damage were evidently attenuated by scavenging toxic reactive oxygen and nitrogen species and through the protective effects of bioactive ion therapy, including reduced apoptosis, increased angiogenesis, and inhibited fibrosis. In brief, we constructed a multifunctional nanoplatform for integrating a "diagnosis-therapy-protection" approach to achieve comprehensive management from thrombus to renal IRI, promoting the advancement of related technologies.

Recent Advances in Blood Cell-Inspired and Clot Targeted Thrombolytic Therapies

Myocardial infarction, stroke, and pulmonary embolism are all deadly conditions associated with excessive thrombus formation. Standard treatment for these conditions involves systemic delivery of thrombolytic agents to break up clots and restore blood flow; however, this treatment can impact the hemostatic balance in other parts of the vasculature, which can lead to excessive bleeding. To avoid this potential danger, targeted thrombolytic treatments that can successfully target thrombi and release an effective therapeutic load are necessary. Because activated platelets and fibrin make up a large proportion of clots, these two components provide ample opportunities for targeting. This review will highlight potential thrombus targeting mechanisms as well as recent advances in thrombolytic therapies which utilize blood-cells and clotting proteins to effectively target and lyse clots.

Harnessing nanobiotechnology for cerebral ischemic stroke management

Cerebral ischemic stroke remains one of the most serious neurological disorders that pose threats to human health, causing a large amount of long-term disability or even death throughout the world. Based on its physiologic and pathological features, there are limited available therapeutic options for effective ischemic stroke management. Encouragingly, a rapid advancement of nanobiotechnology is bringing new insights into exploring more alternative strategies against cerebral ischemic stroke, which can cleverly overcome the limitations related to conventional treatment methods. Therefore, this review focuses on the recent achievements of nanobiotechnology for ischemic stroke management, which emphasizes diverse targeted delivery strategies using various nanoplatforms including liposomes, micelles, polymeric nanoparticles, nanogels, inorganic nanomaterials, and cell-derived nano-vectors based on the pathophysiological features of ischemic stroke. Moreover, different therapeutic approaches against ischemic stroke such as neuroprotection, anti-inflammation, thrombolysis, increased blood-brain barrier penetration and reactive oxygen species scavenging are highlighted. Meanwhile, this review discusses how these versatile nanoplatforms were designed to assist in the treatment of ischemic stroke. Based on this, challenges, opportunities, and future perspectives using nanobiotechnology through rational design for effective ischemic stroke management are revealed.

Thrombus-specific/responsive biomimetic nanomedicine for spatiotemporal thrombolysis and alleviation of myocardial ischemia/reperfusion injury

Acute myocardial infarction (AMI) is usually caused by coronary thrombosis. However, the short half-life, lack of targetability and inevitable ischemia/reperfusion injury secondary to revascularization, which characterizes tissue plasminogen activator (tPA) limit its thrombolytic efficacy for AMI. To address the targeted and site-specific delivery of tPA, the current study reports the construction of a thrombus-targeting and responsive biomimetic nanoparticle (PTPN) for spatiotemporal treatment of AMI. PTPN was constituted by the thrombus microenvironment- responsive phenylboronic acid (PBA) nanocarrier, antioxidant molecular protocatechualdehyde (PC) and tPA with thrombolytic effect, which were enclosed by the platelet membrane. The thrombus-targeting capability of the platelet membrane enabled the adhesion of PTPN to damaged endothelial cells. The nanoparticle disintegrated under slightly acid condition and re-opened the infarct-related artery during the period of ischemia. Sequentially, ROS induced by blood reperfusion was eliminated by PC released from particle disintegration, and the cardiomyocyte mitochondrial function was protected from reperfusion injury. Therefore, this thrombus-specific/responsive biomimetic nanomedicine provides a spatiotemporal paradigm for AMI treatment with promising clinical translation prospects.

Biomimetic Nanoplatelets to Target Delivery Hirudin for Site-Specific Photothermal/Photodynamic Thrombolysis and Preventing Venous Thrombus Formation

Due to the high recurrence rate and mortality of venous thrombosis, there is an urgent need for research on antithrombotic strategies. Because of the short half-life, poor targeting capabilities, bleeding complications, and neurotoxic effects of conventional pharmacological thrombolysis methods, it is essential to develop an alternative strategy to noninvasive thrombolysis and decrease the recurrence rate of venous thrombosis. A platelet-mimetic porphyrin-based covalent organic framework-engineered melanin nanoplatform, to target delivery of hirudin to the vein thrombus site for noninvasive thrombolysis and effective anticoagulation, is first proposed. Owing to the thrombus-hosting properties of platelet membranes, the nanoplatform can target the thrombus site and then activate hyperthermia and reactive oxygen species for thrombolysis under near-infrared light irradiation. The photothermal therapy/photodynamic therapy combo can substantially improve the effectiveness (85.7%) of thrombolysis and prevent secondary embolism of larger fragments. Afterward, the highly loaded (97%) and slow-release hirudin (14 days) are effective in preventing the recurrence of blood clots without the danger of thrombocytopenia. The described biomimetic nanostructures offer a promising option for improving the efficacy of thrombolytic therapy and reducing the risk of bleeding complications in thrombus associated diseases.

Thrombus-targeted nano-agents for NIR-II diagnostic fluorescence imaging-guided flap thromboembolism multi-model therapy

In oral and maxillofacial surgery, flap repair is essential to the quality of postoperative life. Still, thrombosis is fatal for the survival of the flaps. Besides, some postoperative thrombotic diseases, such as pulmonary embolism, also intimidate patients’ life. The traditional diagnostic methods are still limited by a large amount of hardware and suffer from inconvenience, delay, and subjectivity. Moreover, the treatments mainly rely upon thrombolytics, such as urokinase (UK) plasminogen activator, which may cause bleeding risk, especially intracerebral hemorrhage. Herein, a kind of poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) containing a first near-infrared window (NIR-I) phototheranostic agent Y8 and urokinase plasminogen activator (UK) as the core, and modified with the fibrin-targeting peptide Gly–Pro–Arg–Pro–Pro (GPRPP) were developed for the flap and postoperative thromboembolism treatment (named GPRPP-Y8U@P). The conjugated molecule Y8 endows GPRPP-Y8U@P with the capacity of NIR-II imaging and excellent photothermal/photodynamic therapeutic effects. In vivo experiments demonstrated that GPRPP-Y8U@P could quickly locate thrombus by NIR-II fluorescence imaging, and semi-quantitative analysis of the embolized blood vessels' paraffin section verified its thrombolytic efficiency. Additionally, the urokinase trapped in the NPs would not result in nonspecific bleeding, tremendously improving physical security and curative effects with minimizing side effects. Overall, the advantages of GPRPP-Y8U@P, such as precise localization of the thrombus, thrombus ablation in the site, and mild side effects, demonstrated the attractiveness of this approach for effective clinical monitoring of thrombus therapy.