Current treatments for neuromyelitis optica spectrum disorder (NMOSD) highlight recurrence management, while little attention is paid to the relief of residual neurological dysfunction. Here we aimed to evaluate the safety and efficacy of human umbilical cord-derived mesenchymal stromal cells (hUC-MSCs) in reducing relapses and mitigating neurological impairments. This trial, hUC-MSC-NMOSD (ChiCTR-INR-16008037), a single-arm, dose-escalation, open-label study, included 31 NMOSD patients of three dose groups received four infusions every three months, with 15-month follow-up. Primary outcome was time to first recurrence; secondary outcomes focused on clinical scores, MRI lesions and exploratory findings. HUC-MSC infusion was well tolerated in all groups of patients. Adverse events were mostly mild, with urinary tract infections being the most common. Severe adverse events were rare and unrelated to the treatment. The median relapse-free interval increased significantly post-treatment from 305 (95%CI 226-382·5) to 760 (589-1016·5) (p < 0·001), especially in the medium- and high-dose groups. During the two years before and after therapy, the mean Annualized Relapse Rate (ARR) dropped considerably from 1 (0·75-1) to 0 (0-0·5) (p < 0·001). Clinical scores improved in the low and medium-dose groups. The total volume of high-signal white matter lesions in brain significantly decreased after therapy from 4144·5 (2857·2-5508·6) to 2914·4 (2453-3684·11) (p = 0·016). Exploratory single-cell RNA sequencing and metabolomics detection revealed a potential participation of thioredoxin and oxidative phosphorylation (OXPHOS)-mediated boosting of Treg differentiation and suppressive capacity. This trial indicates that intravenous hUC-MSC administration is safe and shows potential efficacy in treating NMOSD. Medium dose might be the best possible compromise between safety and effectiveness.

INTRODUCTION:Double-Filtration plasmapheresis (DFPP) and efgartigimod (EFG) are both effective acute exacerbation therapies for generalized myasthenia gravis (gMG), yet real-world comparative evidence remains limited. This study aims to systematically compare their clinical efficacy and safety to guide individualized treatment strategies. METHODS:This prospective multicenter study (Aug 2019-Mar 2025) evaluated gMG patients treated with a cycle of DFPP (3-5 sessions) or EFG (4 weekly infusions). Primary endpoints included changes in Quantitative Myasthenia Gravis (QMG) and Myasthenia Gravis Activities of Daily Living (MG-ADL) scores from baseline (T0) to post-treatment (T1) and 1 month after T1 (T2). Secondary endpoints covered clinical meaningful improvement (CMI), deep improvement rates (defined as ≥ 5-point reduction in MG-ADL or ≥ 9-point in QMG), immunological changes, and safety. RESULTS:Among 66 MG patients (EFG = 41, DFPP = 25), both DFPP and EFG significantly reduced QMG and MG-ADL scores at T1 and T2. In moderate-to-severe gMG (MGFA ≥ IIb), 3/5-session DFPP was superior to 4-infusion EFG at T2 (p < 0.05), while efficacy was comparable in mild cases (MGFA ≤ IIa). Sustained CMI rates (through T2) increased with higher treatment intensity; the 5-session DFPP rate was significantly higher than the 3-session DFPP (85% vs. 45%, p = 0.049) and numerically higher than the 4-infusion EFG (85% vs. 70%, p = 0.413). The proportion of patients achieving deep improvement in 5-session DFPP was higher than 4-infusion EFG. DFPP broadly reduced immunoglobulins/complement versus EFG's selective immunoglobulin G (IgG) reduction. Adverse events occurred in 28.0% of the DFPP group (mainly catheter-related thrombosis) and 39.0% of the EFG group (predominantly headache; p = 0.431), with no serious events reported. CONCLUSION:Both DFPP and EFG effectively treat gMG, though DFPP offers greater benefit in moderate-to-severe cases, underscoring the need for individualized therapy.

Background:Efgartigimod (EFG), a neonatal Fc receptor (FcRn) antagonist for generalized myasthenia gravis (gMG), exhibits variable treatment responses. This study aimed to investigate the associations of baseline clinical characteristics and multidimensional immune profiles with the clinical response to EFG in patients with acetylcholine receptor antibody-positive (AChR+) gMG, and develop a predictive model. Methods:This multicenter retrospective observational study enrolled 35 AChR+ gMG patients who received at least one cycle of EFG. Responders were defined as those achieving a Myasthenia Gravis Activities of Daily Living (MG-ADL) score reduction of ≥ 2 points that was sustained for ≥ 1 month. After univariable screening, three models (Clinical, Immune, Integrated) were constructed using a complete-case modeling subset of 26 patients via multivariable logistic regression, least absolute shrinkage and selection operator (LASSO), and random forest algorithms. The optimal model was selected via leave-one-out cross-validation (LOOCV) and translated into a clinical risk score and an online calculator. Results:Among 35 patients, 25 responded (68.6%). Non-responders had significantly higher baseline NK cell counts (p = 0.013) and showed a trend toward lower IL-12p70 levels (p = 0.095). Both NK cell (OR = 0.985) and IL-12p70 (OR = 11.657) were independent predictors of EFG response. The Immune Model (NK cells + IL-12p70) demonstrated robust discrimination (AUC = 0.861), outperforming the Clinical Model (AUC = 0.625, p = 0.021) and the Integrated Model (AUC = 0.847, p = 0.782). It showed good calibration and clinical utility. Bootstrap validation confirmed robustness (corrected AUC = 0.872, optimism=0.017). A derived clinical risk score stratified patients into high (100%), moderate (80.0%), and low (33.3%) response probability groups. An online prediction calculator was developed. Conclusion:Baseline NK cell counts and IL-12p70 levels may predict EFG response in AChR+ gMG. The dual-biomarker Immune Model demonstrates robust performance, and has been translated into an online tool but yet requires validation in prospective, larger cohorts.

N6-methyladenosine (m6A), the most prevalent RNA modification, plays a pivotal role in regulating mRNA metabolism and cellular processes such as immune responses. Although the m6A methyltransferase METTL3 is known to regulate T-cell homeostasis and influence experimental autoimmune encephalomyelitis (EAE, a model for multiple sclerosis (MS)), its function within B cells remains poorly defined. Crucially, we observed that METTL3 expression is significantly downregulated in peripheral blood mononuclear cells (PBMCs) from MS patients and within B cells isolated from EAE mice. To directly investigate the functional consequences of this B-cell-specific METTL3 reduction in neuroinflammation, we generated B cell-specific METTL3 knockout mice (Mettl3flox/floxCD19Cre). Strikingly, this targeted deletion of METTL3 in B cells markedly exacerbated EAE severity, demonstrated by significantly worsened clinical disease scores, increased spinal cord inflammation, and greater demyelination. Further mechanistic dissection revealed how B-cell METTL3 deficiency drives this exacerbated pathology: it promoted B cell apoptosis, inhibited the differentiation of regulatory B cell (Breg) subpopulations, increased the proportion of pro-inflammatory iNOS+ macrophages, and elevated the production of IL-6, BAFF, and BCMA. In the central nervous system, it promotes neurological damage by affecting axonal function and facilitating the loss of neurons. Collectively, these findings demonstrate that METTL3 functions as a critical negative regulator within B cells, restraining their contribution to neuroinflammation in the EAE model. Importantly, therapeutically relevant overexpression of METTL3 specifically in B cells significantly reduced both the clinical severity and incidence of EAE, underscoring its potential as a novel therapeutic target for MS and similar autoimmune disorders involving pathogenic B-cell responses.

While double-filtration plasmapheresis (DFPP) and intravenously administered methylprednisolone (IVMP) are both established treatments for acute attacks of neuromyelitis optica spectrum disorder (NMOSD), their comparative efficacy and safety profiles remain a critical area of investigation. This study aimed to evaluate the clinical outcomes and adverse events of DFPP versus IVMP in patients with NMOSD, with a focus on disability improvement and treatment tolerability. A prospective single-center cohort study was performed with 146 patients with NMOSD, who were treated with DFPP, IVMP, and combination therapy (DFPP + IVMP). Primary efficacy was measured by changes in Expanded Disability Status Scale (EDSS) scores (ΔEDSS). Secondary outcomes included Modified Rankin Scale (mRS) scores. Safety profiles, including liver enzyme elevation and infection rates, were monitored. The DFPP group (n = 81) demonstrated a significant clinical response, with a median EDSS improvement of 0.5 (IQR 0.0–1.0) points. The response rate (defined as ΔEDSS > 0) was 66.7

Multiple sclerosis (MS) is an inflammatory disease that is often characterized by the development of irreversible clinical disability. Age is a strong risk factor that is strongly associated with the clinical course and progression of MS. Several lines of evidence suggest that with aging, microglia have an aging-related gene expression signature and are close to disease-associated microglia (DAM), which exhibit decreased phagocytosis but increased production of inflammatory factors. The gene expression signatures of microglia in MS overlap with those in aging, inflammation and DAM. Moreover, the clearance of damaged myelin by microglia is impaired in the aged brain. Autophagy is a cellular process that decreases in activity with age. In this review, we provide an overview of the role of autophagy and aging in MS. We describe the impact of autophagy and aging on microglial activation in MS and the molecules involved in autophagy and aging, which are related to the phagocytosis and activation of microglia. We propose that a decrease in autophagy in microglia occurs with aging, leading to a decrease in phagocytosis. Decreases in phagocytosis and increases in the production of inflammatory factors by microglia contribute to chronic inflammation in the aged brain and disease progression in MS. Thus, the modulation of autophagy in microglia serves as a potential therapeutic target for MS.

Multiple sclerosis (MS) is a chronic inflammatory disease that leads to myelin loss and neurological dysfunction. Clinical studies show increased anti-Kir4.1 antibody levels in MS patients' serum, indicating its diagnostic potential. However, the specific mechanism has remained elusive. In a mouse model of experimental autoimmune encephalomyelitis (EAE), it is found that impaired Kir4.1 channels in oligodendrocyte precursor cells (OPCs) hindered myelin repair in the spinal cord. Using a thermal shift assay (TSA), the small molecule 2-D08 is identified, which effectively activated Kir4.1 channels and reduced demyelination in both EAE mice and marmosets. The neuroprotective effects are mainly due to enhanced phosphorylation of FYN tyrosine kinase, promoting OPCs differentiation. The findings highlight the critical role of Kir4.1 channels in MS pathogenesis and suggest that pharmacological activation of these channels by 2-D08 can be a promising therapeutic strategy for enhancing brain recovery in demyelinating diseases.

Background and purpose:Double-filtration plasmapheresis (DFPP) has emerged as a plasma-saving alternative to therapeutic plasma exchange for autoimmune encephalitis (AE), but prospective evidence regarding its dual effects on both clinical efficacy and immunomodulation remains limited. This study aimed to evaluate the clinical and immunological effects of DFPP in AE. Methods:In this prospective single-center cohort study, 57 patients diagnosed with AE according to international criteria were enrolled between 2018 and 2023. Participants received DFPP (median 3-5 sessions), either alone or combined with immunotherapies. The primary outcome was neurological improvement, measured by the change in modified Rankin Scale (ΔmRS). Secondary outcomes included symptomatic change (ΔCASE score), immunological parameter shifts, and adverse events. Subgroup analyses were conducted based on antibody type, treatment timing, and combination therapies. Results:The cohort had a median age of 47 years (IQR: 24-65), with 49.1 % being female. DFPP significantly reduced median mRS scores from 3.00 to 1.00 (p < 0.001) and CASE scores from 3.00 to 1.00 (p < 0.001). The overall functional improvement rate was 71.9 %. Initiation of DFPP within 14 days of symptom onset was associated with significantly higher response rates (100 % vs. 63.6 %, p < 0.05) and greater neurological improvement (p < 0.05). Combination with IVMP or IVIG did not enhance efficacy compared to DFPP alone (p = 0.600). Immunological profiling revealed significant reductions in IgG (77.55 %), IgA (76.11 %), and IgM (79.96 %), along with modulation of lymphocyte subsets and cytokine levels. Adverse events occurred in 28.1 % of patients, predominantly mild catheter-related thrombosis. Conclusions:DFPP is an effective and well-tolerated treatment for autoimmune encephalitis, significantly improving neurological function modulates immune responses.

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system and is a leading cause of disability in young adults. Most therapeutic strategies are based on immunosuppressant effects. However, none of the drugs showed complete remission and may result in serious adverse events such as infection. Mesenchymal stem cells (MSCs) have gained much attention and are considered a potential therapeutic strategy owing to their immunomodulatory effects and neuroprotective functions. Experimental autoimmune encephalomyelitis (EAE), a classical animal model for MS, is widely used to explore the efficacy and mechanism of MSC transplantation. This review summarises the therapeutic mechanism of MSCs in the treatment of EAE, including the effects on immune cells (T cells, B cells, dendritic cells, natural killer cells) and central nervous system-resident cells (astroglia, microglia, oligodendrocytes, neurons) as well as various strategies to improve the efficacy of MSCs in the treatment of EAE. Additionally, we discuss the clinical application of MSCs for MS patients as well as the challenges and prospects of MSC transplantation.

Introduction:Myasthenia gravis (MG), an IgG-mediated autoimmune disorder targeting neuromuscular junctions, shows refractory in 12-20% of generalised MG (gMG) patients despite immunotherapies. Plasma exchange (PLEX) transiently depletes pathogenic mediators, while neonatal Fc receptor antagonists (eg, efgartigimod) offer novel therapeutic potential. Both PLEX and efgartigimod require adjunctive non-steroidal immunosuppressive therapy (NSIST) for sustained remission. This study aims to evaluate the effectiveness and safety of efgartigimod working as a bridge treatment after PLEX but before NSIST taking effect, while concurrently conducting a comparative analysis of clinical outcomes between PLEX and efgartigimod in gMG. Methods and analysis:This multicentre, open-label, three-arm trial (n=45 gMG patients) assigns cohorts to PLEX+efgartigimod, PLEX alone or efgartigimod alone. The intervention comprises PLEX and/or efgartigimod. Oral glucocorticoids and cholinesterase inhibitors are allowed during this study. NSIST starts the day after completing PLEX or the second dose of efgartigimod. Outcomes are assessed at weeks 4, 8, 12, 16, 20, 24, 36 and 48. Primary endpoint: proportion achieving minimal symptom expression (MSE) at week 48. Secondary endpoints: median time to first MSE, adverse events (AE) incidence/severity, exacerbation rates, neurological functional assessment scores, cholinesterase inhibitor/corticosteroid usage, serological evolution of immunological markers. All AEs are systematically documented and causality-assessed. Ethics and dissemination:Ethical clearance for this investigation was granted by the Institutional Review Board of Punan Hospital in accordance with Declaration of Helsinki principles. All enrolled participants will provide written informed consent through standardised documentation processes prior to study enrolment. The results will be accessible in peer-reviewed publications. Trial registration number:ChiCTR2500104662.

Serum AQP4 antibody (AQP4-IgG) is the causative antibody of neuromyelitis optica spectrum disorder (NMOSD) but AQP4-IgG in cerebrospinal fluid (CSF) has been seldom studied. We aimed to explore the clinical value and influencing factors of CSF AQP4-IgG in NMOSD. In this study, we screened 137 patients with NMOSD diagnosed according to the 2015 International Consensus Diagnostic Criteria (IPND criteria). From this cohort, paired CSF and serum samples were simultaneously collected from 82 patients (including seropositive and seronegative subgroups) for antibody titer measurement. We explored the relationship between CSF AQP4-IgG and patient’s clinical features. Their demographic, clinical, laboratory data and MRI images were collected and analyzed. 74 patients were seropositive for AQP4-IgG and 8 patients were seronegative. Among the 74 patients seropositive for AQP4-IgG, 46 were CSF-positive and 28 were CSF-negative, while none of the 8 seronegative patients were CSF-positive. CSF AQP4-IgG positive and negative patients showed significant differences in EDSS and relapse status. Out of the 82 patients, 67 patients were during relapse and only patients during relapse were included in the next analysis. Between the CSF-positive and CSF-negative patients, no significant differences were found in EDSS, relapse manifestation, CSF indicators, serum cytokine levels, lymphocyte subsets or MRI lesions. Responses to treatment during relapse and length of hospital stay showed no significant differences either. A positive correlation between the serum and CSF titers (rs: 0.64, p < 0.001) was found. Further binary logistic regression analysis revealed that CSF AQP4-IgG positivity was associated with serum AQP4-IgG titers and EDSS scores. CSF AQP4-IgG positivity primarily results from passive diffusion of serum antibodies across the blood-brain barrier, which is different from the CNS-restricted antibody production in MOG-IgG associated disorders (MOGAD). Limited prognostic value of CSF AQP4-IgG was revealed in this study.

Glycogen storage disease type IIIa (GSD IIIa) is a rare etiology among patients with adult-onset myopathy, which is typically associated with axonopathy rather than demyelination. We report a genetically and pathologically confirmed case that exhibited prominent electrophysiological hallmarks of demyelination, including prolonged distal motor latency, temporal dispersion, prolonged F-waves, and conduction block. The presence of these diverse demyelinating characteristics in this context, excluding other factors, is infrequently reported, suggesting that glycogen accumulation may influence not only muscles but also potentially the myelin, thereby broadening our comprehension of this rare disease spectrum.

Recurrent immune-mediated peripheral neuropathy is a rare immune disorder that presents significant therapeutic challenges. Ofatumumab (OFA) is a fully humanized anti-CD20 monoclonal antibody with low immunogenicity. We report a patient with recurrent immune-mediated peripheral neuropathy who achieved sustained remission following OFA treatment after multiple relapses. Over a two-year period, the patient experienced over 20 episodes of bilateral upper and lower limb weakness. Furthermore, the patient was unresponsive to intravenous immunoglobulin, plasma exchange, corticosteroids, mycophenolate mofetil, and Telitacicept. Subcutaneous OFA administration resulted in marked reductions in CD19+ and CD20+ B-cell counts and a relapse-free period exceeding 20 months, with no adverse events observed. This case provides early evidence supporting OFA as a safe and effective alternative for recurrent immune-mediated peripheral neuropathy.

Stroke remains a leading cause of death and disability worldwide. Recent evidence suggests that stroke pathophysiology extends beyond vascular dysfunction to include complex interactions within the neurovascular unit (NVU), particularly involving fibrinogen. This blood-derived protein accumulates in the brain following blood-brain barrier (BBB) disruption and plays crucial roles in neuroinflammation and tissue repair. Through its unique structural domains, fibrinogen interacts with multiple cellular components, including astrocytes, microglia, and neural stem cells, thereby modulating inflammatory responses and neural repair mechanisms. This review examines fibrinogen's structure and its diverse functions in stroke pathophysiology, focusing on its interactions with vascular cells, glial cells, and peripheral immune cells. We also discuss emerging therapeutic strategies targeting fibrinogen-mediated pathways and the challenge of translating experimental results into effective clinical treatments.

Background:Autoimmune encephalitis (AE) is a severe neurological disorder, but limited evidence comparing the efficacy of double filtration plasmapheresis (DFPP) and intravenous methylprednisolone (IVMP) as first-line treatments in the acute phase. This study aimed to evaluate the clinical outcomes of DFPP versus IVMP in antibody-positive patients with AE. Methods:A prospective observational cohort study was conducted at Renji Hospital from July 2018 to May 2024. Thirty-eight patients with antibody-confirmed AE in the acute phase who received either DFPP (n=22) or IVMP (n=16) as first-line therapy were included. The primary outcome was improvement in the Modified Rankin Scale (mRS), and the secondary outcome was improvement in the Clinical Assessment Scale for Autoimmune Encephalitis (CASE). Adverse events were recorded for safety assessment. Univariate and multivariate logistic regression analyses were performed. Results:The DFPP group demonstrated significantly higher rates of functional improvement, with 68.2% (15/22) achieving mRS reduction compared to 31.3% (5/16) in the IVMP group (p=0.047). Similarly, symptomatic improvement (CASE score reduction) was observed in 72.7% (17/22) of DFPP patients versus 43.8% (7/16) with IVMP (p=0.099). Multivariate analysis identified DFPP as the sole independent predictor of better outcomes (OR: 5.234, 95% CI: 1.179-23.235, p=0.030). Adverse events were limited to the DFPP group (3/22), including manageable deep venous thrombosis and hepatic impairment. Conclusion:DFPP demonstrated superior short-term efficacy compared to IVMP in improving functional and symptomatic outcomes in acute-phase AE, suggesting its potential as a preferred first-line therapy. Further large-scale randomized trials are warranted to validate these findings.

This study investigates distinct neuroinflammatory patterns in neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein antibody disease (MOGAD) using multi-tracer PET and MR imaging. Eight NMOSD (5F/3M; median age 36.5) and six MOGAD patients (2F/4M; median age 34.0) underwent PET scans with [18F]FDG (glucose metabolism), the translocator protein (TSPO) ligand [18F]PBR06 (glial activation), and [11C]acetate (astrocyte metabolism), integrated with synchronous 3T MRI sequences. Standardized uptake value ratios (SUVRs) referenced to contralateral white matter (WM) or whole brain were statistically compared across specific anatomic regions: active lesions, normal-appearing WM (NAWM), and periventricular zones. Both groups exhibited elevated [18F]PBR06 SUVR within lesions compared to contralateral WM, marking microgliosis. Crucially, NMOSD lesions showed significantly lower [18F]FDG SUVR (p ​= ​0.01; metabolic impairment) and [11C]acetate SUVR (astrocyte dysfunction) than MOGAD lesions. Lesional [18F]PBR06 uptake correlated significantly with [18F]FDG uptake. Beyond lesions, NMOSD patients had higher [18F]FDG SUVR in cerebellar WM (p ​< ​0.01) and periventricular regions near the fourth ventricle (p ​= ​0.01), and higher [18F]PBR06 SUVR in cerebral WM (p ​= ​0.03), contrasted with MOGAD. With lesions in both disorders demonstrating microgliosis, NMOSD exhibited more severe lesion-specific metabolic suppression and astrocyte dysfunction, reflected in reduced [11C]acetate uptake, coupled with regional inflammation (microgliosis) and hypermetabolism. These differential multi-tracer PET patterns, especially the combined reduction in lesional astrocytic ([11C]acetate) and metabolic ([18F]FDG) markers in NMOSD versus MOGAD, highlight multimodal PET/MRI as a powerful tool for differentiating NMOSD and MOGAD pathophysiology.

Telitacicept, a novel recombinant fusion protein comprising the ligand-binding domain of the TACI receptor and the Fc component of human IgG, has rarely been studied for the treatment of neuromyelitis optica spectrum disorders (NMOSD). This study aimed to explore the effects of telitacicept in NMOSD mice. An NMOSD mouse model was constructed. Fifty microliters of 0.8 mg/mL telitacicept was injected intravenously on Days 4, 8, 12 and 16 postimmunization (p.i.). Behavioral scoring, magnetic resonance imaging and histopathological evaluation were conducted on Day 19. B lymphocytes and their subgroups were analyzed by flow cytometry. Concentration of serum IgM was measured using an ELISA kit. Concentrations of B lymphocyte stimulator (BLyS) and IL-6 were measured via LEGENDplex. Differentially expressed genes of B lymphocytes were screened via mRNA sequencing and verified by qPCR. Behavioral score of telitacicept-treated NMOSD mice significantly decreased (p < 0.0001). Inflammation, demyelination, loss of AQP4 and GFAP in the spinal cord were markedly alleviated (p < 0.05). B lymphocytes and their subsets were reduced to varying degrees (p < 0.05). Telitacicept treatment significantly reduced serum IgM levels (p < 0.01), as well as BLyS and IL-6 concentrations (p < 0.05). Telitacicept induced differential gene expression in B lymphocytes, inhibiting the expression of transcription factors related to B lymphocyte maturation, such as IRF8, BLIMP1, and Pou2af1, as well as cell surface receptors such as CD19 and CD21. Telitacicept has a therapeutic effect on NMOSD mice by regulating the differentiation of B lymphocyte subsets and inhibiting the production of pathogenic antibodies.

The retinal astrocyte death induced by complement-dependent cytotoxicity (CDC) is the major etiology of retinal injury in patients with neuromyelitis optica spectrum disorders (NMOSD). Human umbilical cord-derived mesenchymal stromal cells (hUCMSCs) and their derived extracellular vesicles (EVs) have emerged as a potential therapeutic option due to their immunomodulatory capabilities. This study is aimed at establishing a serum-free culture system for hUCMSCs (SF-UCMSCs) and investigating the inhibiting effect of EVs derived from SF-UCMSCs on CDC-induced retinal astrocyte death. The results showed that SF-UCMSCs retained canonical mesenchymal stromal cells’ characteristics under serum-free culture conditions. Pharmacokinetic analysis showed that intravenously administered SF-UCMSCs predominantly accumulated in the lungs, liver, spleen, and kidneys, with no detectable localization in the retina. Notably, EVs derived from SF-UCMSCs exerted a protective effect against CDC-mediated damage to murine retinal astrocytes, as evidenced by reduced formation of C5b-9 + membrane attack complexes and diminished astrocyte death. Mechanistically, this protective effect was associated with the transfer of CD59 from EVs to astrocytes. In summary, the establishment of this serum-free culture system facilitates the development of hUCMSC-derived EVs as therapeutic agents, circumventing the risks of immune rejection and potential tumorigenicity associated with cellular transplantation. This study also provides a mechanistic basis and therapeutic strategy for managing autoimmune diseases characterized by CDC-mediated pathogenesis.

Human umbilical cord mesenchymal stem cells (hUC-MSCs) have great potential for treating autoimmune diseases for their immunomodulatory and tissue-regenerative abilities; however, their therapeutic role in neuromyelitis optica spectrum disorder (NMOSD) remains uncertain. 106 hUC-MSCs prepared in 200 μl PBS were intravenously administered to a systemic NMOSD model on day 10 and day 14 after immunization. Then, disease progression, immune responses, and blood–brain barrier integrity were evaluated. Additionally, we tested the effects of hUC-MSCs on astrocyte viability and apoptosis using an aquaporin 4 (AQP4) IgG and complement-induced cytotoxicity model in vitro. hUC-MSCs alleviated NMOSD progression in vivo with improved motor function, reduced inflammatory infiltration, myelin loss, and preservation of astrocytes and neurons. hUC-MSC treatment did not affect autoimmune reactions in the spleen, however, decreased cytokine release in the spinal cord and mitigated blood–brain barrier disruption. Furthermore, in vitro studies revealed that co-culture with hUC-MSCs significantly restored astrocyte viability and reduced apoptosis in AQP4 IgG and complement-mediated damage. Our results revealed that hUC-MSCs displayed therapeutic efficacy in NMOSD and showed potential in attenuating blood–brain barrier disruption, as well as AQP4 IgG and complement-induced astrocyte apoptosis.