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Background Lumbar facet arthropathy (LFA) is a degenerative, arthritic joint disorder and a common specific cause of axial low back pain and functional impairment. Currently, no disease-modifying therapies are available for symptomatic LFA. Mesenchymal stem/stromal cell (MSC)-based therapy represents an emerging regenerative treatment modality with the promise to target the underlying pathophysiology of LFA. Despite encouraging clinical evidence supporting the safety and efficacy of MSC therapy in other osteoarthritis, its therapeutic utility in LFA remains largely unexplored. We recently completed a prospective, single-arm, open-label phase I clinical trial that demonstrated a favourable safety profile and preliminary clinical benefit following intra-articular administration of bone marrow-derived MSCs (BMSCs) in patients with symptomatic LFA. Building on these findings, we present the protocol for CellKine II , a prospective, randomised, double-blind, placebo-controlled, cross-over phase II clinical trial to evaluate the safety and preliminary efficacy of intra-articular delivery of allogeneic, culture-expanded BMSCs in patients with painful LFA. Methods and analysis This study is a single-centre, randomised, double-blind, placebo-controlled, cross-over phase II trial with a target accrual of 40 patients. Eligible patients will be randomly assigned in a 1:1 ratio to receive a single intra-articular injection of either Arm A: BMSC or Arm B: Placebo (dimethyl sulfoxide). At the 6-month follow-up, all patients will be unblinded. Patients initially randomised to Arm A will continue follow-up for up to 12 months. Patients initially randomised to Arm B may cross over to receive the BMSC treatment, followed by an additional 12 months of post-BMSC treatment follow-up, or they may continue observation for another 6 months without BMSC treatment. Overall, each patient will be followed up to 12 months after BMSC treatment. The primary endpoints are back pain, functional outcomes and adverse events at 6 months post-randomisation. Ethics and dissemination This study will be conducted in compliance with U.S. federal regulations and Mayo Clinic institutional research policies and procedures. The protocol has been approved by the Mayo Clinic Institutional Review Board (IRB) and the Data Safety Monitoring Board (IRB No. 21-013278). The results of this trial will be disseminated through publication in peer-reviewed journals and on ClinicalTrials.gov. Trial registration number NCT06001853 .

As machine learning (ML)-based decision support tools proliferate in clinical practice, understanding how clinicians integrate personalized ML predictions alongside randomized controlled trial (RCT) evidence is critical. We designed a web-based clinical decision support system (CDSS) presenting survival and adverse event data from a simulated RCT and ML model across 12 synthetic multiple myeloma scenarios. In a within-subjects study with 32 physicians, we evaluated how clinicians synthesize competing evidence sources to make treatment decisions. When ML and RCT outputs were concordant, physicians reported greater confidence than with RCT data alone. When results were discordant, most physicians shifted toward the ML-supported treatment, often before reviewing any information about model training or validation, suggesting a tendency toward automation bias rather than algorithm avoidance. Despite reporting higher perceived reliability after viewing model quality disclosures, physicians were largely unable to describe the validation procedures they had reviewed. Taken together, these findings reveal that clinicians may over-rely on ML recommendations even when equipped with tools designed to support critical appraisal. We discuss implications for CDSS design, clinician training, and the institutional safeguards needed before ML-based systems are deployed in high-stakes oncology settings.

Foundation models are reshaping computational pathology by enabling scalable task-agnostic representations of histopathological whole-slide images (WSIs). Unlike earlier task-specific deep learning systems, pathology foundation models (PFMs) leverage massive whole-slide image repositories and self-supervised Vision Transformer architectures to achieve broad generalization and few-shot adaptability. Their evolution reflects a shift from weakly supervised approaches such as Clustering-Constrained Attention Multiple Instance Learning (CLAM) and hierarchical architectures such as Hierarchical Image Pyramid Transformer (HIPT) to large-scale efforts including foundation models, UNI, Virchow, Phikon, CONtrastive learning from Captions for Histopathology (CONCH), GigaPath, H-Optimus, Transformer-Based Pathology Image and Text Alignment Network (TITAN), and the Mayo Clinic Atlas. These models demonstrate impressive performance across diagnostic and prognostic benchmarks while also opening pathways for multimodal integration with genomics and clinical data. Yet significant barriers remain including inconsistent generalization across institutions, interpretability lagging behind clinical needs, and slow integration into routine laboratory workflows. Certain domains of anatomic pathology such as cytopathology, transplant pathology, frozen sections, and rare tumor subtypes remain particularly resistant to current models. Here, we review the development of PFMs, critically evaluate their strengths and limitations, and outline priorities for their safe and effective clinical translation. We argue that the next phase of PFM development will depend on rigorous benchmarking, pathologist-in-the-loop deployment, and multimodal fusion ensuring these models evolve from research tools into clinically robust systems.

Extracellular vesicles derived from mesenchymal stem cells (MSC-EVs) exhibit great therapeutic potential in ischemia-associated conditions and diseases such as myocardial infarction, ischemic stroke, and wound healing. Enhancing the therapeutic efficacy of MSC-EVs could advance their clinical application. Diverse cargos (proteins, mRNA, microRNA, etc.) in MSC-EVs contribute to the therapeutic effects in various diseases. Vascular endothelial growth factor (VEGF) is one of the primary driving molecules in promoting angiogenesis and protecting endothelial cells lining blood vessels from apoptosis. In this study, we explored the feasibility of engineering parent MSCs with VEGF mRNA to potentiate therapeutic effects of their derived EVs. We first detected elevated levels of VEGF mRNA and protein in transfected MSCs and demonstrated the bioactivity of secreted VEGF by an angiogenesis assay. Furthermore, EVs derived from VEGF mRNA-engineered MSCs (VEGF-MSC-EVs) contained high levels of VEGF mRNA and protein and showed superior ability to protect human umbilical vein endothelial cells (HUVECs) from apoptosis compared to EVs derived from control MSCs (control MSC-EVs). To our knowledge, this is the first report demonstrating that VEGF-MSC-EVs boost therapeutic efficacy by promoting endothelial cell survival. Our findings offer a novel approach for cell-free therapy in ischemia-associated conditions and diseases.

Background and Objectives: Cervical artery dissection (CeAD) is a leading cause of ischemic stroke in younger adults, yet sex-specific variations in its clinical presentation, imaging characteristics, and outcomes remain underexplored. We aimed to evaluate these differences using data from a large, multicenter registry. Methods: We analyzed data from the STOP-CAD registry, which includes patients with radiologically confirmed non-traumatic CeAD enrolled between 2015 and 2021 across multiple centers. Clinical and imaging characteristics were compared between men and women using multivariable logistic regression. Outcomes assessed included ischemic stroke recurrence at 180 days, excellent functional outcome (modified Rankin Scale [mRS] 0–1) at 90 days, symptomatic intracerebral hemorrhage (sICH), and mortality. Results: Among 4,023 patients with CeAD, 1,783 (44.6%) were women. Compared to men, women were younger (median age: 42 vs 50 years), more likely to have a history of migraine (26.9% vs 8.3%) and connective tissue disorders (14.3% vs 5.8%), and presented more frequently with non-ischemic symptoms such as headache, neck pain, or tinnitus (adjusted OR [aOR] 2.0; 95% CI, 1.8–2.3; p<0.001). Women had significantly higher odds of vertebral artery dissection (OR, 1.3; 95% CI, 1.2-1.5; p<0.001), multivessel involvement (OR, 2.1; 95% CI, 1.7-2.5; p<0.001), and pseudoaneurysm formation (OR, 1.3; 95% CI, 1.1-1.6; p=0.003). Despite these differences, there was no significant sex-based difference in key clinical outcomes: excellent functional recovery at 90 days (OR 0.94; 95% CI 0.76-1.15 p=0.542), ischemic stroke recurrence at 180 days (OR 0.56 CI 0.23-1.3 p=0.213), or mortality (OR 0.83; 95% CI 0.47-1.48, p=0.529). Conclusion: In this large international cohort, we observed women with CeAD were younger, more likely to present with non-ischemic symptoms with distinct imaging features. These underscore the need for heightened clinical suspicion of CeAD in women presenting with atypical symptoms, even in the absence of ischemic deficits or conventional vascular risk factors, and suggest that sex-specific phenotyping may enhance diagnostic accuracy and early management.

Background: Patients with cervical artery dissection (CAD) have a higher prevalence of cerebral aneurysms, likely due to underlying vasculopathies. Understanding risk factors and outcomes in this population may inform screening and management strategies. Methods: We conducted a post-hoc analysis of the STOP-CAD study, a multicenter international registry of patients with non-major trauma-related CAD across 63 centers. Cerebral aneurysms were identified based on medical history and intracranial vascular imaging obtained for dissection diagnosis. We compared demographic, clinical, laboratory, and imaging characteristics between patients with and without aneurysms. Variables with p<0.05 in univariate analysis were entered into a multivariable binary logistic regression to identify independent predictors. Clinical outcomes including ischemic stroke and symptomatic intracranial hemorrhage at follow-up were compared between both groups. Results: Out of 4023 patients included in the STOP-CAD study, 116 (2.9%) had at least one incidental cerebral aneurysm. In adjusted binary logistic regression, patients with cerebral aneurysm were more likely to have a history of migraine (aOR 1.78 95% CI 1.15-2.75, p=0.009), history of hypertension (aOR 1.65 95% CI 1.12-2.43, p = 0.010), known connective tissue disorder (aOR 3.47 95% CI 1.71-7.03), history of dissection (aOR 2.63 95% CI 1.31-5.28, p = 0.007), and a dissecting aneurysm at the site of the dissection (aOR 1.94 95% CI 1.25-3.01, p = 0.003). At follow-up, the presence of a cerebral aneurysm was not associated with ischemic stroke (7.8% vs. 5.6% p>0.1), but with a trend towards increased odds of symptomatic intracranial hemorrhage (3.4% vs. 1.2%, p = 0.062). Conclusions: Patients with CAD and concurrent incidental cerebral aneurysm were more likely to have a history of migraine headaches and markers of underlying vasculopathy and had a non-significantly increased risk of intracranial hemorrhage at follow-up. Further studies are needed to identify best practices for surveillance and risk stratification in this subgroup.

Background: Cervical artery dissection (CeAD) accounts for nearly 25% of all ischemic strokes in young adults. CeAD can lead to the development of dissecting aneurysms (DA). However, the incidence, risk factors and outcomes of CeAD patients with DA is not well established. This study aims to identify risk factors for developing DA, subsequent growth, and impact on patient outcomes. Methods: This is a secondary analysis of the Antithrombotics for Stroke Prevention in Cervical Artery Dissection (STOP-CAD), a multicenter cross-sectional international retrospective study. CeAD patients were stratified for the presence of DA. We used multivariable regression to identify factors associated with DA. Patients with DA were further analyzed for DA growth. The primary outcome was ischemic stroke after CeAD+DA diagnosis. Secondary outcomes included ischemic stroke after CeAD+DA with DA growth. Multivariable logistic regression analysis was used to assess the association between DA and risk factors. We also performed univariate Cox regression and generated Kaplan-Meier survival curves comparing study outcomes based on presence of DA and subsequent growth. Results: Of the 4023 patients included in the STOP-CAD study, 4008 were included in this analysis and 767 (19%) patients had DA (546 with DA on initial presentation). Patients with DA had a mean age of 46 [IQR 37-55] years and 50% (383) were women. In combined adjusted analyses, DA patients were more often non-Hispanic (aOR 0.63, 95% CI 0.41-0.94, p<0.02), more commonly had a history of migraine (aOR 1.27, 95% CI 1.01-1.59, p=0.037), connective tissue disorder (aOR 2.02, 95% CI 1.22-3.36, p=0.007), minor neck trauma (aOR 1.70, 95% CI 1.29-2.26, p<0.001) and were more likely to present with ischemic stroke (aOR 1.73, 95% CI 1.05-2.87, p=0.031). DA growth was noted in 55 out of 546 (10%) patients with DA on presentation. There was no significant difference in the risk of ischemic stroke by day 180 in patients with DA (hazard ratio [HR] 0.92 [95% CI, 0.65-1.30]; P =0.63) or DA growth (HR 2.40, [95% CI, 0.79-7.24]; P =0.12). Conclusion: In this subanalysis of STOP-CAD, nearly one in five patients with CeAD developed a DA. Factors associated with a higher likelihood of DA included non-Hispanic ethnicity, history of migraine, connective tissue disorder, minor neck trauma, and ischemic stroke at presentation. DA diagnosis and DA growth did not impact the risk of subsequent ischemic stroke at 6 months.

Background: The clinical characteristics and complications associated with de novo pseudoaneurysm formation beyond the acute phase of cervical artery dissection remain poorly defined. In this study, we examined the incidence, risk factors, and related ischemic and hemorrhagic events of post-acute de novo pseudoaneurysm formation. Methods: We analyzed data from the STOP-CAD study (Antithrombotic Treatment for Stroke Prevention in Cervical Artery Dissection). A de novo pseudoaneurysm was defined as a new (not present on initial imaging) focal enlargement in the diameter of the artery, greater than the native lumen. The incidence of de novo pseudoaneurysm was assessed at 90 days, 180 days, and beyond 180 days of follow-up. Univariate and multivariate regression analyses were conducted to identify risk factors for post-acute de novo pseudoaneurysm formation. Kaplan-Meier survival estimates were used to compare ischemic and hemorrhagic events between patients with and without de novo pseudoaneurysms. Results: Among 4008 patients, 546 were excluded as they had dissecting pseudoaneursyms on initial presentation. Therefore, 3,462 patients were included in this analysis of whom 220 patients (6.35%) developed a de novo pseudoaneurysm over a maximum follow-up of 4.4 years. Of these, 127 (57.72%) were detected within the first 90 days, and 172 (78.18%) within the first 180 days. In multivariate regression analyses, in addition to hypertension, active smoking and Hispanic ethnicity, fibromuscular dysplasia (FMD) was an independent risk factor for post-acute de novo pseudoaneurysm formation (adjusted OR: 2.160; 95% CI: 1.408–3.315; p < 0.001). Notably, the presence of a de novo pseudoaneurysm was not associated with a significant increase in ischemic (hazard ratio [HR] 1.43 [95% CI, 0.89–2.30]; P=0.14) or hemorrhagic events (hazard ratio [HR] 1.42 [95% CI, 0.43–4.69]; P=0.57). Conclusion: De novo pseudoaneurysm formation following a diagnosis of a cervical artery dissection is not uncommon and most frequently occurs within the first 180 days. FMD was independently associated with this complication. The development of a de novo pseudoaneurysm did not significantly increase the risk of subsequent ischemic or hemorrhagic events.

Background and Objectives: Pregnancy and the postpartum period increase the risk of cervical artery dissection (CEAD), a notable cause of stroke in young women. We aimed to describe the clinical presentation, imaging findings, and outcomes of CEAD occurring during pregnancy or shortly after delivery. Methods: We analyzed data from the STOP-CAD registry, a large international multicenter study of patients treated with antithrombotic therapy for non-traumatic CEAD between 2015 and 2021. This sub-study focused on women who were pregnant or within 12 weeks postpartum at the time of symptom onset. We assessed baseline clinical features, imaging results, acute stroke treatments, and functional outcomes. Results: Among 1,783 women in the registry, 62 (3.5%) had pregnancy-associated CEAD, with a median age of 34 years (IQR, 30-38). One-third had a history of migraine (33.9%), one-fifth had hypertension (21.0%), while other vascular risk factors were rare. Recent minor neck trauma was reported in 17.7%. Ischemic stroke symptoms occurred in 25 (40.3%) patients, and 23 (37.1%) had acute infarcts on imaging. However, most (59.7%) presented with non-ischemic symptoms. Vertebral artery dissections were more common than carotid dissections (62.9% vs. 48.4%), and 33.9% had multivessel involvement. Among patients presenting with ischemic stroke symptoms, 4 received thrombolysis and 7 underwent thrombectomy. Remarkably, 92% had excellent functional recovery (modified Rankin Score 0–1) at 90 days, and there were no stroke recurrences at 180 days. Conclusion: Pregnancy- and postpartum-associated CEAD is uncommon and associated with ischemic stroke in nearly half of patients. A history of migraine and hypertension may be potential risk factors. Despite the severity of presentation, most patients had favorable outcomes with timely treatment.

Background: Although the embolic stroke of undetermined source (ESUS) construct was proposed as a unifying concept for embolic-appearing strokes without an identified cause, it includes patients with diverse and often unrecognized underlying mechanisms. This study investigates the differential rate of recurrent stroke according to the completeness of neurodiagnostic testing in a diverse multicenter cohort. Methods: This was a retrospective analysis of a multicenter observational cohort study (n=27 sites). Patients with ESUS were categorized into three groups: (1) established mechanism after further work up (ESUS-E), (2) patients who underwent a comprehensive diagnostic workup without an identified etiology (ESUS 2.0), and (3) no advanced workup (ESUS-NAW). The primary outcome of recurrent ischemic stroke was assessed by comparing ESUS 2.0 to both ESUS-E and ESUS-NAW groups using adjusted Cox proportional hazards models. Results: Of the 2,281 patients included, 694 (30%) were classified as ESUS-E, 344 (15%) as ESUS 2.0, and 1,443 (55%) as ESUS-NAW. The ESUS 2.0 group had a significantly lower annualized recurrence rate (1.98 per 100 person-years) compared to both the ESUS-NAW group (7.7 per 100 person-years; aHR 0.27, 95% CI: 0.11–0.62; p=0.002) and the ESUS-E group (6.10 per 100 person-years; aHR = 0.35; 95% CI 0.15–0.85, p=0.020). Within the ESUS-E group, cancer (aHR 5.33; 95% CI: 2.09–13.63; p < 0.001) and non-stenosing atherosclerotic disease or arch atheroma (aHR 3.40; 95% CI: 1.18–9.83; p = 0.023) were associated with significantly increased risk of recurrence when compared to ESUS 2.0. Conclusion: These findings demonstrate a lower risk of recurrent stroke in patients classified as ESUS 2.0, diverging from the 5–6% annual recurrence rates observed in prior ESUS trials. These findings suggest that patients who receive comprehensive diagnostic evaluation without identification of a specific etiology have a lower risk of recurrent stroke, an important consideration for the design of future ESUS studies.