Mfsd2a‐Targeted Therapy for Ischemic Stroke: Mechanisms, Evidence, and Future Prospects

Intracranial bleeding is the most feared complication of thrombolytic therapy in acute stroke. The risk of brain hemorrhage is the main argument of the European authorities not to approve recombinant tissue plasminogen activator (rtPA), and the fear of hurting patients with rtPA explains its limited use in North America. The common argument is, “Treatment with rt-PA may have some beneficial effect, but that is traded off by a considerable risk of symptomatic hemorrhage.” This argument is false and based on misunderstanding and misconception. The misunderstanding: There is no such trade-off. The National Institute of Neurological Disorders and Stroke (NINDS) rtPA Stroke Study Group observed 2 patients (0.6%) with symptomatic and 1 patient (0.3%) with fatal hemorrhages in the placebo group (n=312) and 20 patients (6.4%) with symptomatic and 9 patients (2.9%) with fatal hemorrhages in the rtPA group (n=312).1 Despite this supposed excess in risks caused by rtPA treatment (odds ratios [OR], 10.6 and 9.2), rtPA treatment significantly reduced the risk for disability and death (modified Rankin Scale >1 at 12 months after stroke) from 73% to 59% (reduction for death alone: 28% to 24%).2 In both European Cooperative Acute Stroke Studies (ECASS) 1 and 2, rtPA increased the risk for parenchymal hematomas (OR, 3.0 and 4.2), but reduced the overall risk for disability and death by 6% and 8% (NS).3,4⇓ A similar observation—an overall risk reduction for disability and death despite an increased risk for intracranial hemorrhages—was made in the Multicenter Acute Stroke Trials (MAST) -Europe and -Italy. Why …

Background Increasing evidence suggests that herbal-derived exosome-like nanoparticles (ELNs) can easily cross biological barriers such as the blood-brain barrier (BBB). However, current understanding of ELNs application in ischemic stroke therapy is still in its infancy. Method We extracted nanoparticles (TGD-NPs) from Tianma Gouteng decoction (TGD) and characterized their morphology and main active compounds. Subsequently, the potential and functional mechanism of TGD-NPs in maintaining the integrity of the BBB were evaluated in middle cerebral artery occlusion (MCAO)-induced ischemic stroke model and oxygen-glucose deprivation/reperfusion (OGD/R)-stimulated cell model. Result We successfully extracted NPs, which retains the main bioactive compounds of TGD: baicalin, emodin, gastrodin, and stachydrine. Functional studies indicated that in mouse MCAO model, TGD-NPs intervention was more effective than TGD preparations in maintaining the integrity of the BBB, reducing the infarct area, and improving the neurological function. Meanwhile, TGD-NPs treatment attenuated the decrease in cell viability caused by OGD/R, and it significantly enhanced expression of tight junction proteins (Occludin and ZO-1). Mechanistic exploration revealed that TGD-NPs markedly upregulated lncRNA OIP5-AS1 expression, and its beneficial effect was attributed to the activation of the S1PR1-ERK1/2-MEK1/2 signaling axis. Conclusion TGD-NPs are positive in maintaining BBB integrity and neurological function after ischemic stroke.

Blood-brain barrier (BBB) dysfunction is a well-established pathological phenotype of ischemic stroke, and targeting BBB integrity has emerged as a promising therapeutic strategy. Danshen-Chuanxiong formula (DS-CX), an effective herbal combination against ischemic stroke, has demonstrated regulatory effects on the BBB at various stages of ischemic stroke. However, its specific BBB-protective components and underlying molecular mechanisms remain unclear. Recent advances in multicellular self-assembled BBB spheroids have shown distinct advantages in disease modeling and drug discovery, offering a novel approach to address these questions. To simulate ischemic stroke-induced BBB dysfunction, we developed an oxygen-glucose deprivation/reoxygenation (OGD/R)-induced BBB disruption model using multicellular spheroids. To identify the effective substances of DS-CX responsible for BBB protection, we conducted a multi-parametric evaluation to assess BBB permeability, tight junctions, cell viability, reactive oxygen species (ROS) levels, inflammatory markers, and apoptotic phenotypes using high-content imaging. Further immunofluorescence and transcription analyses were performed to elucidate the BBB-protective mechanisms of DS-CX and its active components. Similar to the overall effects of DS-CX on BBB protection, preliminary screening fortunately found that both protocatechuic acid, ferulic acid, and senkyunolide I significantly reduced OGD/R-induced leakage, and upregulated the protein and mRNA levels of ZO-1 and Claudin-5 in BBB spheroids. Further multi-phenotypic assessments manifested that DS-CX and its active compounds effectively improved cell survival, reduced ROS production, inhibited inflammation, and decreased apoptosis, compared to the damaged BBB spheroids without drug intervention. Molecular experiments showed that DS-CX and its active constituents not only rescued the abnormal protein levels of pivotal targets related to oxidative stress (HO-1), inflammation (MMP-9, TLR-4), and apoptosis (Caspase-3, Bax, Bcl-2) in OGD/R-treated BBB spheroids, but also normalized the dysregulated mRNA levels of vWF, HO-1, MMP-9, TLR-4, TNF-α, IL-6, IL-1β, and IL-18 caused by OGD/R stimulation. Collectively, the present work successfully identified protocatechuic acid, ferulic acid, and senkyunolide I as key BBB-protective components of DS-CX against ischemic stroke. These compounds likely exert their therapeutic effects through multi-target regulation of oxidative stress, inflammation, and apoptosis. Our findings provide a novel spheroid-based multi-parametric screening approach for discovering BBB-targeted therapies in ischemic stroke.

Section Editors: Marc Fisher MD Antoni Davalos MD The Food and Drug Administration (FDA) evaluates applications for new human drugs, biologics, and complex medical devices. Companies must obtain FDA approval to legally market these products. In August, the FDA gave Concentric Medical clearance to market its Merci Retriever system to “remove blood clots from the brain in patients experiencing an ischemic stroke.” Given that the FDA is charged with “protecting the public health by assuring the safety, efficacy, and security of… biological products and medical devices…, ” “advancing public health by helping to speed innovations that make medicines … more effective, safer, and more affordable,” and “helping the public get the accurate, science-based information they need to use medicines … to improve their health,”1 the FDA’s decision to approve the Merci Retriever system is of concern. The pathways to approval are reviewed by Felten et al in the accompanying article and are outlined in Figure 1. Figure 1. Potential pathways for device approval. The decision to approve the Merci Retriever was based on data from the MERCI (Mechanical Embolus Removal in Cerebral Ischemia) Trial; the approval was granted through the 510(k) process. The Merci Retriever system includes a flexible nickel titanium (nitinol) wire that obtains a helical shape once it is passed through the tip of the guidance catheter. In practice, the catheter/wire is passed distal to the thrombus, the catheter is removed, and the helical configuration assumed by the wire; the clot is then trapped in the helix and withdrawn from the vasculature (Figure 2). The 510(k) clearance means that the Merci Retriever was felt to be substantially equivalent to a predicate device. In this case, the predicate device was the Concentric Retriever, which itself received 510(k) clearance by the FDA in May 2001 for “use in …

Mesenchymal stem cell-derived extracellular vesicles attenuate tPA-induced blood–brain barrier disruption in murine ischemic stroke models

Loss of integrity of the blood-brain barrier (BBB) in ischemic stroke victims initiates a devastating cascade of events causing brain damage. Maintaining the BBB is important to preserve brain function in ischemic stroke. Unfortunately, recombinant tissue plasminogen activator (tPA), the only effective fibrinolytic treatment at the acute stage of ischemic stroke, also injures the BBB and increases the risk of brain edema and secondary hemorrhagic transformation. Thus, it is important to identify compounds that maintain BBB integrity in the face of ischemic injury in patients with stroke. We previously demonstrated that intravenously injected phosphorylated recombinant heat shock protein 27 (prHSP27) protects the brains of mice with transient middle cerebral artery occlusion (tMCAO), an animal stroke-model. Here, we determined whether prHSP27, in addition to attenuating brain injury, also decreases BBB damage in hyperglycemic tMCAO mice that had received tPA. After induction of hyperglycemia and tMCAO, we examined 4 treatment groups: 1) bovine serum albumin (BSA), 2) prHSP27, 3) tPA, 4) tPA plus prHSP27. We examined the effects of prHSP27 by comparing the BSA and prHSP27 groups and the tPA and tPA plus prHSP27 groups. Twenty-four hours after injection, prHSP27 reduced infarct volume, brain swelling, neurological deficits, the loss of microvessel proteins and endothelial cell walls, and mortality. It also reduced the rates of hemorrhagic transformation, extravasation of endogenous IgG, and MMP-9 activity, signs of BBB damage. Therefore, prHSP27 injection attenuated brain damage and preserved the BBB in tPA-injected, hyperglycemic tMCAO experimental stroke-model mice, in which the BBB is even more severely damaged than in simple tMCAO mice. The attenuation of brain damage and BBB disruption in the presence of tPA suggests the effectiveness of prHSP27 and tPA as a combination therapy. prHSP27 may be a novel therapeutic agent for ischemic stroke patients whose BBBs are injured following tPA injections.

Section Editor: Marc Fisher MD Eleven years ago, on June 1, 1991, Dr J.P. Mohr addressed delegates of the International Conference on Stroke, Geneva, about anticoagulants as a therapeutic strategy in stroke. He bemoaned the fact that heparin and warfarin had the “bad luck” to be manufactured initially in the post-World War II period, before drugs were evaluated by controlled clinical trials. As a consequence, clinicians judged their effectiveness on the basis of theory and compared their personal experience with historical controls and with those found in the literature. With the passage of time, the drug patents expired, the views and practices of clinicians became polarized, and any commercial and scientific motive to conduct controlled clinical trials of anticoagulation in secondary stroke prevention, once called for, disappeared. Dr Mohr sadly concluded that “there are no [reliable] data really” for anticoagulation after ischemic stroke. This was probably the platform from which he planned, with colleagues, the Warfarin-Aspirin Recurrent Stroke Study (WARSS).1 Noncardioembolic ischemic stroke underpins ≈60% of all first-ever and recurrent strokes. The major causes are (1) thrombotic occlusion of large and medium-sized arteries that is due to in situ atherothrombosis or atherothromboembolism and (2) thrombotic occlusion of small perforating intracerebral arteries affected by microatheroma/lipohyalinosis. The formation of thrombus on the subendothelial tissue of arteries depends on the initial formation of a platelet plug (by means of platelet adhesion, activation, and aggregation) and the generation of a meshwork of fibrin (by means of the coagulation cascade). Antiplatelet drugs are designed to prevent the formation of the “white” platelet plug, and anticoagulants are designed to prevent the formation of the “red” fibrin clot. Theoretically, antiplatelet and anticoagulant therapy should be effective in preventing recurrent noncardioembolic stroke, provided that they can both be administered safely over a long period of time. ### Indirect Comparisons of Effectiveness Compared With Control A …

Blood–brain barrier (BBB) disruption contributes to brain injury and neurological impairment. Tight junctions (TJs) and cell–cell adhesion complexes develop between endothelial cells in the brain to establish and maintain the BBB. Occludin, the first transmembrane protein identified in TJs, has received intense research interest because numerous in vitro studies have suggested its importance in maintaining BBB integrity. However, its role in maintaining BBB integrity after ischemic stroke is less clear owing to the lack of in vivo evidence. This study aimed to investigate the dynamics and function of occludin across the acute and chronic phases after stroke using occludin-deficient mice. By photochemically induced thrombosis model, the expression of occludin was decreased in brain endothelial cells from ischemic lesions. The neurological function of occludin-deficient mice was continuously impaired compared to that of wild-type mice. BBB integrity evaluated by Evans blue and 0.5-kDa fluorescein in the acute phase and by 10-kDa fluorescein isothiocyanate-labeled dextran in the chronic phase was decreased to a greater extent after stroke in occludin-deficient mice. Furthermore, occludin-deficient mice showed decreased claudin-5 and neovascularization after stroke. Our study reveals that occludin plays an important role from the acute to the chronic phase after ischemic stroke in vivo.

The blood-brain barrier (BBB) serves as a dynamic, selective shield, safeguarding the central nervous system (CNS) by separating the brain from circulating blood, preserving its microenvironment, and ensuring stability. However, in the presence of brain pathology, drug delivery across the BBB and blood-tumor barrier (BTB) becomes challenging, hindering effective treatments. Borneol exhibits promise in bidirectionally modulating the BBB under pathological conditions, suggesting at potential clinical applications for related diseases. Our primary goal in this review is to investigate borneol's potential clinical utility in bidirectionally regulating the BBB under pathological conditions. The PubMed database, CNKI (China National Knowledge Infrastructure), Wanfang Data were searched to retrieve articles on animal experiments and cell-based research published from January 1, 2003, to May 1, 2023, using the following medical subject headings (MeSH) terms: borneol, blood-brain barrier, ischemic stroke, cerebral gliomas, anti-inflammatory. The search was limited to articles published in English and Chinese. In total, 86 articles were deemed eligible for inclusion in this study. The breakdown of the BBB is a key pathological process in ischemic stroke and cerebral glioma. When used alone, the lipophilic properties of borneol can reduce the permeability of the BBB and restore its normal function, thereby repairing brain damage and protecting brain tissue. Its specific protective effects may be related to inflammatory regulation mechanisms. The anti-inflammatory and protective effects of borneol can be used to improve and treat lesions caused by ischemic stroke and cerebral glioma. Furthermore, when combined with other drugs, borneol can accelerate the opening of the BBB, improve permeability through physiological processes, and enhance drug penetration and distribution in the brain without causing pathological damage to the brain. This review summarizes the mechanisms by which borneol regulates the BBB and BTB in ischemic stroke and cerebral glioma, and discusses the potential clinical applications of borneol in the treatment of these diseases. It is believed that in the future, as research methods are refined, more effective and targeted therapies for cerebral glioma and ischemic stroke will be explored related to the protective mechanism of the BBB under pathological conditions with borneol alone or in combination with other drugs.

Neutrophil membrane fusogenic nanoliposomal leonurine for targeted ischemic stroke therapy via remodeling cerebral niche and restoring blood-brain barrier integrity

Blood–brain barrier (BBB) dysfunction, characterized by degradation of BBB junctional proteins and increased permeability, is a crucial pathophysiological feature of acute ischemic stroke. Dysregulation of multiple neurovascular unit (NVU) cell types is involved in BBB breakdown in ischemic stroke that may be further aggravated by reperfusion therapy. Therefore, therapeutic co-targeting of dysregulated NVU cell types in acute ischemic stroke constitutes a promising strategy to preserve BBB function and improve clinical outcome. However, methods for simultaneous isolation of multiple NVU cell types from the same diseased central nervous system (CNS) tissue, crucial for the identification of therapeutic targets in dysregulated NVU cells, are lacking. Here, we present the EPAM-ia method, that facilitates simultaneous isolation and analysis of the major NVU cell types (endothelial cells, pericytes, astrocytes and microglia) for the identification of therapeutic targets in dysregulated NVU cells to improve the BBB function. Applying this method, we obtained a high yield of pure NVU cells from murine ischemic brain tissue, and generated a valuable NVU transcriptome database (https://bioinformatics.mpi-bn.mpg.de/SGD_Stroke). Dissection of the NVU transcriptome revealed Spp1, encoding for osteopontin, to be highly upregulated in all NVU cells 24 h after ischemic stroke. Upregulation of osteopontin was confirmed in stroke patients by immunostaining, which was comparable with that in mice. Therapeutic targeting by subcutaneous injection of an anti-osteopontin antibody post-ischemic stroke in mice resulted in neutralization of osteopontin expression in the NVU cell types investigated. Apart from attenuated glial activation, osteopontin neutralization was associated with BBB preservation along with decreased brain edema and reduced risk for hemorrhagic transformation, resulting in improved neurological outcome and survival. This was supported by BBB-impairing effects of osteopontin in vitro. The clinical significance of these findings is that anti-osteopontin antibody therapy might augment current approved reperfusion therapies in acute ischemic stroke by minimizing deleterious effects of ischemia-induced BBB disruption.

The blood–brain barrier (BBB) is a critical structure that maintains the brain’s homeostasis by regulating the transport of molecules and protecting it from harmful substances. However, in neurological diseases such as ischemic stroke, Alzheimer’s disease, Parkinson’s disease, and multiple sclerosis, the integrity and function of the BBB can be significantly compromised. In these conditions, BBB disruption leads to increased permeability, which facilitates neuroinflammation, exacerbates neuronal damage, and accelerates disease progression. Recent research has highlighted the potential of lipid-based carriers, including liposomes and lipid droplets (LDs), in modulating the BBB’s integrity and function in various neurological diseases. Liposomes, with their ability to cross the BBB via mechanisms such as receptor-mediated transcytosis and carrier-mediated transport, are emerging as promising vehicles for the targeted delivery of therapeutic agents to the brain. These properties allow liposomes to effectively reduce infarct size and promote neuroprotection in ischemic stroke, as well as deliver drugs in the treatment of neurodegenerative diseases. Furthermore, LDs—dynamic regulators of lipid metabolism and cellular energy—play an essential role in maintaining cellular homeostasis, particularly during periods of stress when BBB function is compromised. These LDs help sustain cellular energy needs and modulate inflammatory responses, which are key factors in maintaining BBB integrity. Surface modifications of liposomes can further enhance their targeting efficiency, enabling them to selectively bind to specific brain cell types, including neurons, astrocytes, and microglia. This customization improves the precision of therapeutic delivery and supports the development of more tailored treatments. However, challenges such as immune responses, rapid clearance, and complement activation-related toxicity continue to hinder the broader application of liposomes and LDs in clinical settings. This review will focus on the roles of liposomes and LDs in regulating BBB integrity across a range of neurological diseases, discussing their potential for targeted drug delivery, neuroprotection, and the modulation of neuroinflammation. Additionally, we will explore the strategies being developed to address the limitations that currently restrict their clinical use.

Marc Fisher MD Kennedy Lees MD Section Editors: On September 26, 2008, the New England Journal of Medicine published the results of the European Cooperative Stroke Study (ECASS) III,1 the first randomized, placebo-controlled trial to demonstrate safe and effective use of intravenous recombinant tissue plasminogen activator (rtPA) to treat patients with acute ischemic stroke (AIS) beyond 3 hours from stroke onset. The ECASS investigators studied the safety and efficacy of administering intravenous rtPA to patients with AIS 3 to 4.5 hours after AIS onset. Using the modified Rankin Scale score at 90 days after stroke occurrence as the primary end point of the study, the investigators demonstrated a modest, statistically significant increase in the likelihood of having normal or near normal recovery (modified Rankin Scale=0 or 1) in favor of rtPA treatment compared with placebo (unadjusted OR, 1.34; 95% CI, 1.02 to 1.76; P =0.04). So, what impact will the results of the study have on acute stroke management and stroke research in the United States and elsewhere? With regard to the first part of the question, the answer is complex. First, the ECASS III results will hopefully help to increase the number of thrombolysis eligible patients with AIS who receive rtPA. Twelve years after the US Food and Drug Administration approved the management of AIS within 3 hours of symptom onset as an indication for the use of intravenous rtPA, less than 5% of patients with AIS are being treated worldwide with rtPA within 3 hours of stroke onset. One of the major factors contributing to this parlous state of affairs has been disagreement among healthcare professionals about the validity of the results of the National Institutes of Neurological Disorders and Stroke (NINDS) trial of rtPA for acute stroke.2 In the late 1990s, the stroke community unexpectedly …

Tissue plasminogen activator (tPA) is the only FDA-approved drug for the treatment of ischemic stroke. Delayed tPA administration is associated with increased risks of blood-brain barrier (BBB) disruption and hemorrhagic transformation. Studies have shown that interferon beta (IFNβ) or type I IFN receptor (IFNAR1) signaling confers protection against ischemic stroke in preclinical models. In addition, we have previously demonstrated that IFNβ can be co-administered with tPA to alleviate delayed tPA-induced adverse effects in ischemic stroke. In this study, we investigated the time limit of IFNβ treatment on the extension of tPA therapeutic window and assessed the effect of IFNβ on modulating microglia (MG) phenotypes in ischemic stroke with delayed tPA treatment. Mice were subjected to 40 minutes transient middle cerebral artery occlusion (MCAO) followed by delayed tPA treatment in the presence or absence of IFNβ at 3h, 4.5h or 6h post-reperfusion. In addition, mice with MG-specific IFNAR1 knockdown were generated to validate the effects of IFNβ on modulating MG phenotypes, ameliorating brain injury, and lessening BBB disruption in delayed tPA-treated MCAO mice. Our results showed that IFNβ extended tPA therapeutic window to 4.5h post-reperfusion in MCAO mice, and that was accompanied with attenuated brain injury and lessened BBB disruption. Mechanistically, our findings revealed that IFNβ modulated MG polarization, leading to the suppression of inflammatory MG and the promotion of anti-inflammatory MG, in delayed tPA-treated MCAO mice. Notably, these effects were abolished in MG-specific IFNAR1 knockdown MCAO mice. Furthermore, the protective effect of IFNβ on the amelioration of delayed tPA-exacerbated ischemic brain injury was also abolished in these mice. Finally, we identified that IFNβ-mediated modulation of MG phenotypes played a role in maintaining BBB integrity, because the knockdown of IFNAR1 in MG partly reversed the protective effect of IFNβ on lessening BBB disruption in delayed tPA-treated MCAO mice. In summary, our study reveals a novel function of IFNβ in modulating MG phenotypes, and that may subsequently confer protection against delayed tPA-exacerbated brain injury in ischemic stroke.

Recent studies have suggested a pathogenetic link between ischemic stroke and Takotsubo cardiomyopathy (TCM) with poor outcome, when occurring simultaneously. Increased catecholamine (CAT) levels as well as elevated inflammatory mediators (INF) are found in the blood of patients with ischemic stroke concomitant with Takotsubo syndrome (TTS). On molecular level, the impact of these stressors combined with hypoxemia could compromise the integrity of the blood brain barrier (BBB) resulting in poor outcomes. As a first step in the direction of investigating possible molecular mechanisms, an in vitro model of the described pathological constellation was designed. An immortalized murine microvascular endothelial cell line from the cerebral cortex (cEND) was used as an established in vitro model of the BBB. cEND cells were treated with supraphysiological concentrations of CAT (dopamine, norepinephrine, epinephrine) and INF (TNF-α and Interleukin-6). Simultaneously, cells were exposed to oxygen glucose deprivation (OGD) as an established in vitro model of ischemic stroke with/without subsequent reoxygenation. We investigated the impact on cell morphology and cell number by immunofluorescence staining. Furthermore, alterations of selected tight and adherens junction proteins forming paracellular barrier as well as integrins mediating cell-matrix adhesion were determined by RT-PCR and/or Western Blot technique. Especially by choosing this wide range of targets, we give a detailed overview of molecular changes leading to compromised barrier properties. Our data show that the proteins forming the BBB and the cell count are clearly influenced by CAT and INF applied under OGD conditions. Most of the investigated proteins are downregulated, so a negative impact on barrier integrity can be assumed. The structures affected by treatment with CAT and INF are potential targets for future therapies in ischemic stroke and TTS.