Zheng Gang Zhang

Alzheimer’s disease (AD) is increasingly recognized as a systemic disorder involving both central and peripheral immune dysfunction, yet the mechanisms by which peripheral immune cells influence neurodegeneration remain poorly understood. Here we identify a physiological extracellular vesicle (EV)-mediated route through which peripheral monocytes communicate with neurons and show that AD-associated monocyte remodeling converts this pathway into a mechanism that mediates neuronal injury. Reanalysis of single-cell transcriptomic data revealed pronounced inflammatory and EV-related transcriptional remodeling in circulating monocytes from patients with AD. Using a genetic CD63-based EV tracking mouse, we found that EVs released from peripheral Lyz2-expressing myeloid cells, including monocytes, accessed the healthy brain parenchyma and preferentially associated with neurons. EVs isolated from primary peripheral monocytes of 5xFAD mice were enriched in inflammatory cargo, including IL-1β, and markedly suppressed distal axonal growth. Neutralization of EV-associated IL-1β partially restored axonal growth, identifying IL-1β as an important mediator of EV-induced neuronal injury. Aβ stimulation reproduced key features of this pathogenic EV phenotype in RAW 264.7 macrophage-like cells and induced coordinated metabolic dysfunction and pro-inflammatory activation in primary peripheral monocytes. Moreover, repeated systemic administration of EVs from Aβ-stimulated RAW 264.7 cells accelerated behavioral and cognitive decline and reduced hippocampal synaptic integrity in 5xFAD mice without increasing cerebral amyloid plaque burden. Together, these findings reveal a peripheral monocyte-EV-neuron communication axis that operates under homeostatic conditions and can be redirected toward pathogenic signaling in AD. Targeting this EV-mediated pathway may provide a therapeutic strategy complementary to current Aβ-directed approaches.

Traumatic brain injury (TBI) is a leading cause of death and long-term neurological disability worldwide. Beyond the initial sudden mechanical insult, TBI is increasingly recognized as a chronic, multisystem disorder involving complex interactions among neurovascular, immune, and metabolic responses. This perspective helps explain the limited success of single-target neuroprotective therapies and underscores the need for multimodal regenerative strategies. Mesenchymal stromal/stem cells (MSCs) have emerged as promising therapeutic candidates for TBI due to their immunomodulatory and reparative properties, which are largely mediated by their secretome, particularly MSC-derived extracellular vesicles (MSC-EVs). These nanoscale vesicles carry selectively packaged nucleic acids, proteins, metabolites, and lipids from their parent cells, which mediate intercellular communication and induce repair pathways in recipient cells. Accumulating evidence indicates that MSC-EVs can reduce apoptosis and inflammation, promote angiogenesis, neurogenesis, and synaptic plasticity, and improve functional recovery following TBI. This review examines the current understanding of the multiscale pathophysiology of TBI and the role of brain-derived EVs in mediating crosstalk between the injured brain and peripheral systems in post-TBI multiorgan dysfunction, the translational potential of MSC-EVs in TBI, with a focus on EV cargo engineering, targeted delivery mechanisms, emerging therapeutic strategies, combinatorial regenerative strategies, as well as the growing role of artificial intelligence (AI)-assisted bioengineering in optimizing EV-based therapeutics, and considers future research directions that may facilitate clinical translation.

Cerebrolysin has a salutary effect on impaired cerebral endothelial cell (CEC) permeability. Using an in vitro endothelial permeability assay, the present study tested the hypothesis that exosomes released by Cerebrolysin-treated CECs (Cerebro-Exos) have a robust therapeutic effect on dysfunctional CECs. Stoichiometric analysis showed marked differences in cargo profiles between Cerebro-Exos and exosomes derived from CECs without Cerebrolysin treatment (Naïve-Exos), in which Cerebro-Exos were highly enriched with metabolic and tight junction related proteins compared to Naïve-Exos. Cerebro-Exos had a superior effect compared to Naïve-Exos on restoring CEC integrity impaired by fibrin and tissue plasminogen activator (tPA). Treatment of fibrin- and tPA-challenged CECs with Cerebro-Exos robustly reduced fibrin- and tPA-augmented proteins involved in inflammation and coagulation and substantially increased fibrin- and tPA-decreased proteins that are related to tight junctions and metabolism. Collectively, these data indicate that Cerebro-Exos have a broad effect on improvement of dysfunctional CECs, which is likely achieved by the alteration of CEC proteins.

Ischemic stroke is a leading cause of disability worldwide, marked by profound disruption of the neurovascular unit (NVU), a dynamic grouping of neurons, astrocytes, cerebral endothelial cells (CECs), microglia, pericytes, and oligodendrocytes. While acute stroke interventions such as tissue plasminogen activator and endovascular thrombectomy address reperfusion, they fail to engage the prolonged and cell-specific processes critical for recovery. Extracellular vesicles (EVs), membrane-bound carriers of proteins, lipids, and nucleic acids, have emerged as key modulators of intercellular communication within the NVU. This review synthesizes current evidence on NVU-derived EVs as both regulators and effectors of post-stroke pathology and repair. We highlight the phase-specific roles of EVs in modulating blood–brain barrier (BBB) integrity, thrombosis, angiogenesis, neurogenesis, oligodendrogenesis, synaptic plasticity, and neuroinflammation. This review places special emphasis on how EV cargo reflects the state of their parent cells and how EV-mediated crosstalk orchestrates coordinated neurorestorative responses. We further discuss the dual nature of EVs, their therapeutic potential for stroke, and the methodological challenges impeding clinical translation, including isolation standardization, cell-specific targeting, and regulatory barriers. Thus, adherence to minimal information for studies of extracellular vesicles (MISEV) guidelines is essential to ensure rigor, reproducibility, and transparency. When combined with temporal and cellular specificity, NVU-derived EVs may represent a biomimetic platform for promoting durable recovery in stroke patients.

Recurrent ovarian cancer (OC) remains a major cause of mortality due to chemoresistance and metastasis. Epigenetic aberrations, particularly dysregulated microRNA (miRNA) expression, contribute to disease progression and represent a promising therapeutic target. Here, we identify the miR‐214‐3p/miR‐199a‐5p cluster as a stage‐associated, tumor‐suppressive network that is lost in recurrent and chemoresistant OC but can be elevated using engineered small extracellular vesicles enriched with this miRNA cluster (m214‐sEVs). Using a clinically relevant mouse model that recapitulates spontaneous OC relapse following platinum‐based chemotherapy, we show that m214‐sEVs are internalized by OC cells and niche fibroblasts, leading to increased intracellular levels of this cluster and suppression of key chemoresistance‐associated pathways, including through downregulation of Toll‐like receptor 4 (TLR4), β‐catenin, and the soluble N‐ethylmaleimide‐sensitive factor attachment protein receptor (SNARE) protein YKT6. m214‐sEV treatment reprograms secondary tumor‐derived sEVs toward a less prometastatic cargo profile and decreases carboplatin resistance and cell migration. Enforced YKT6 overexpression abrogates these effects, establishing YKT6 as a key downstream effector. Collectively, these findings support engineered sEVs as a translatable strategy to overcome chemoresistance and disrupt pro‐tumorigenic EV signaling in recurrent OC.

Recurrent ovarian cancer (OC) remains a major cause of mortality due to chemoresistance and metastasis. Epigenetic dysfunction, particularly through altered microRNA (miRNA) expression, contributes to disease progression. Targeting these molecular aberrations is critical to prevent recurrence, limit metastasis and improve patient outcomes. Here, we identify the miR-214-3p/miR-199a-5p cluster as a stage-associated, tumor-suppressive network that is lost in recurrent and chemoresistant OC, but can be restored using engineered small extracellular vesicles enriched with this cluster (m214-sEVs). Using a clinically relevant mouse model that mimics spontaneous OC relapse following first-line platinum-based chemotherapy, we showed that m214-sEVs were internalized by OC cells and the OC niche fibroblasts via clathrin-mediated endocytosis, resulting in the elevation of miR-214-3p/miR-199a-5p and the downregulation of chemoresistance-associated genes, including toll-like receptor 4 (TLR4), β-catenin, and the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein YKT6. Moreover, secondary tumor-derived sEVs (t-sEVs) released by OC and niche cells that internalized m214-sEVs reduced pro-metastatic proteins, such as integrin β1 and matrix metalloproteinase 9 (MMP9), in their cargo and limited their capacity to promote invasion and resistance. In vitro, YKT6 overexpression in ovarian cancer stem cells (OCSCs) attenuated the effect of m214-sEVs on sensitizing carboplatin to block OCSC migration. These findings demonstrate that engineered m214-sEVs designed to restore clinically lost tumor-suppressive miRNAs can concurrently reverse chemoresistance and reprogram tumor-derived EV communication by targeting oncogenic networks. Statement of Significance: Engineered small extracellular vesicles delivering miR-214-3p/miR-199a-5p overcome chemoresistance and inhibit recurrence in ovarian cancer by targeting oncogenic networks and reprogramming tumor-derived extracellular vesicle communication within the tumor microenvironment.

Neuronal circuitry remodelling, which comprises excitatory and inhibitory neurons, is critical for improving neurological outcomes after a stroke. Preclinical studies have shown that small extracellular vesicles (sEVs) have a therapeutic effect on stroke recovery. However, it is highly challenging to use sEVs to specifically target individual neuronal populations to enhance neuronal circuitry remodelling after stroke. In the present study, using a chemogenetic approach to specifically activate peri‐infarct cortical interneurons in combination with the administration of sEVs derived from cerebral endothelial cells (CEC‐sEVs), we showed that the CEC‐sEVs were preferentially taken up by the activated neurons, leading to significant improvement of functional outcome after stroke, which was associated with augmentation of peri‐infarct cortical axonal/dendritic outgrowth and of axonal remodelling of the corticospinal tract. The ultrastructural and Western blot analyses revealed that neurons with internalization of CEC‐sEVs exhibited significantly reduced numbers of damaged mitochondria and proteins that mediate dysfunctional mitochondria, respectively. Together, these data indicate that the augmented uptake of CEC‐sEVs by activated peri‐infarct cortical interneurons facilitates neuronal circuitry remodelling and functional recovery after stroke, which has the potential to be a novel therapy for improving stroke recovery.

Plexiform neurofibromas (PNs) occur in about a half of neurofibromatosis type 1 (NF1) patients and have garnered significant research attention due to their capacity for growth and potential for malignant transformation. NF1 plexiform neurofibroma (pNF1) is a complex tumor composed of Schwann cell-derived tumor cells (Nf1^−/−) and the tumor microenvironment (TME). Although it has been widely demonstrated that the TME is involved in the formation of neurofibromas, little is known about the effects of the TME on the subsequent progression of human pNF1. Elucidating the molecular interactions between tumor cells and the TME may provide new therapeutic targets to reduce the progression of pNF1. In the present study, we focused on the contributions of fibroblasts, the most abundant cell types in the TME, to the growth of pNF1. To simulate the TME, we used a three-dimensional (3D) coculture model of immortalized pNF1 tumor cells (Nf1^−/−) and primary fibroblasts (Nf1^+/−) derived from pNF1 patients. We performed live-cell imaging of 3D/4D (3D in real-time) cultures through confocal microscopy followed by 3D quantitative analyses using advanced imaging software. The growth of pNF1 spheroids in 3D cocultures with fibroblasts was significantly greater than that of pNF1 spheroids in 3D monocultures. An increase in the growth of pNF1 spheroids also occurred when they were cultured with conditioned media (CM) from fibroblasts. Moreover, fibroblast-derived CM increased the invasive outgrowth and further local invasion of pNF1 spheroids. Interestingly, when small extracellular vesicles (sEVs) were depleted from the fibroblast-derived CM, the stimulation of the growth of pNF1 spheroids was lost. Our results suggest that fibroblast-derived sEVs are a therapeutic target for reducing the growth of pNF1.

The glymphatic system suggests the convective bulk flow of cerebrospinal fluid (CSF) through perivascular spaces and the interstitial spaces of the brain parenchyma for the rapid removal of toxic waste solutes from the brain. However, the presence of convective bulk flow within the brain interstitial spaces is still under debate. We first addressed this argument to determine the involvement of the glymphatic system in brain waste clearance utilizing contrast-enhanced 3D T1-weighted imaging (T1WI), diffusion tensor imaging (DTI), and confocal microscopy imaging. Furthermore, perivascular macrophages (PVMs), which are immune cells located within perivascular spaces, have not been thoroughly explored for their association with the glymphatic system. Therefore, we investigated tracer uptake by PVMs in the perivascular spaces of both the arteries/arterioles and veins/venules and the potential association of PVMs in assisting the glymphatic system for interstitial waste clearance. Our findings demonstrated that both convective bulk flow and diffusion are responsible for the clearance of interstitial waste solutes from the brain parenchyma. Furthermore, our results suggested that PVMs may play an important function in glymphatic system-mediated interstitial waste clearance. The glymphatic system and PVMs could be targeted to enhance interstitial waste clearance in patients with waste-associated neurological conditions and aging.

JOURNAL/nrgr/04.03/01300535-202501000-00030/figure1/v/2026-05-04T135417Z/r/image-tiff Axonal remodeling is a critical aspect of ischemic brain repair processes and contributes to spontaneous functional recovery. Our previous in vitro study demonstrated that exosomes/small extracellular vesicles (sEVs) isolated from cerebral endothelial cells (CEC-sEVs) of ischemic brain promote axonal growth of embryonic cortical neurons and that microRNA 27a (miR-27a) is an elevated miRNA in ischemic CEC-sEVs. In the present study, we investigated whether normal CEC-sEVs engineered to enrich their levels of miR-27a (27a-sEVs) further enhance axonal growth and improve neurological outcomes after ischemic stroke when compared with treatment with non-engineered CEC-sEVs. 27a-sEVs were isolated from the conditioned medium of healthy mouse CECs transfected with a lentiviral miR-27a expression vector. Small EVs isolated from CECs transfected with a scramble vector (Scra-sEVs) were used as a control. Adult male mice were subjected to permanent middle cerebral artery occlusion and then were randomly treated with 27a-sEVs or Scra-sEVs. An array of behavior assays was used to measure neurological function. Compared with treatment of ischemic stroke with Scra-sEVs, treatment with 27a-sEVs significantly augmented axons and spines in the peri-infarct zone and in the corticospinal tract of the spinal grey matter of the denervated side, and significantly improved neurological outcomes. In vitro studies demonstrated that CEC-sEVs carrying reduced miR-27a abolished 27a-sEV-augmented axonal growth. Ultrastructural analysis revealed that 27a-sEVs systemically administered preferentially localized to the pre-synaptic active zone, while quantitative reverse transcription-polymerase chain reaction and Western Blot analysis showed elevated miR-27a, and reduced axonal inhibitory proteins Semaphorin 6A and Ras Homolog Family Member A in the peri-infarct zone. Blockage of the Clathrin-dependent endocytosis pathway substantially reduced neuronal internalization of 27a-sEVs. Our data provide evidence that 27a-sEVs have a therapeutic effect on stroke recovery by promoting axonal remodeling and improving neurological outcomes. Our findings also suggest that suppression of axonal inhibitory proteins such as Semaphorin 6A may contribute to the beneficial effect of 27a-sEVs on axonal remodeling.