Hemorrhagic Conversion of Acute Ischemic Stroke

Optical coherence tomography enables longitudinal evaluation of cell graft-directed remodeling in stroke lesions

Stem cell grafting can promote glial repair of adult stroke injuries during the subacute wound healing phase, but graft survival and glial repair outcomes are perturbed by lesion severity and mode of injury. To better understand how stroke lesion environments alter the functions of cell grafts, we employed optical coherence tomography (OCT) to longitudinally image mouse cortical photothrombotic ischemic strokes treated with allogeneic neural progenitor cell (NPC) grafts. OCT angiography, signal intensity, and signal decay resulting from optical scattering were assessed at multiple timepoints across two weeks in mice receiving an NPC graft or an injection of saline at two days after stroke. OCT scattering information revealed pronounced axial lesion contraction that naturally occurred throughout the subacute wound healing phase that was not modified by either NPC or saline treatment. By analyzing OCT signal intensity along the coronal plane, we observed dramatic contraction of the cortex away from the imaging window in the first week after stroke which impaired conventional OCT angiography but which enabled the detection of NPC graft-induced glial repair. There was moderate, but variable, NPC graft survival at photothrombotic strokes at two weeks which was inversely correlated with acute stroke lesion sizes as measured by OCT prior to treatment, suggesting a prognostic role for OCT imaging and reinforcing the dominant effect of lesion size and severity on graft outcome. Overall, our findings demonstrate the utility of OCT imaging for both tracking and predicting natural and treatment-directed changes in ischemic stroke lesion cores.

Activating PKA signaling increases exosome production and attenuates cerebral ischemia-reperfusion injury by regulating Cx43 expression

BACKGROUND

Connexin 43 (Cx43) plays a crucial role in mediating intracellular communication and facitating the interaction between exosomes and recipient cells. This study investigates whether the activation of cAMP/protein kinase A (PKA) can regulate exosomal Cx43 expression and contribute to the functional recovery following ischemia-reperfusion (I/R) injury.

METHODS

An intraluminal vascular occlusion was performed on Lewis rats to simulate I/R injury. Concurrently, a PKA activator (8-Bromo-cAMP, 5 mg kg-1) or PKA inhibitor (H 89 2HCl, 20 mg kg-1) was administered intravenously via the tail vein (n = 10). Exosomes were isolated from cerebrospinal fluid, and the expression of exosomal markers (CD63 and CD81) and Cx43 was analyzed using Western blot. The expression of CD63 and CD81 in astrocytes was measured to assess exosome uptake. Spatial learning and memory capability were evaluated using the Morris water maze test.

RESULTS

8-Bromo-cAMP significantly increased exosome release in cerebrospinal fluid, accompanied by elevated Cx43 expression. Additionally, 8-Bromo-cAMP enhanced exosome uptake by astrocytes, alleviated blood-brain barrier damage and edema, and improved cognitive function.

CONCLSIONS

PKA activation enhances exosome production, promotes cognitive function recovery, and attenuates cerebral I/R injury by up-regulating exosomal Cx43 expression.

Effect of tirofiban combined with endovascular treatment on hemorrhagic transformation and neurological function in patients with ischemic stroke

OBJECTIVE

To evaluate the effect of Tirofiban combined with endovascular treatment on hemorrhagic transformation (HT) and neurological function in patients with ischemic stroke.

METHODS

A retrospective analysis was performed on 94 patients with ischemic stroke treated at Xi'an International Medical Center Hospital from January 2020 to January 2023. Among them, 45 patients underwent endovascular treatment only and served as the control group. Another 49 patients received Tirofiban in addition to endovascular treatment and they formed the study group. The pre-treatment and 14-day post-treatment NIHSS scores were compared between the two groups. The 24-hour HT rate and the incidence of post-treatment adverse events were also compared between the two groups. Multivariate Cox regression analysis was used to identify factors influencing patient prognosis.

RESULTS

The NIHSS scores in the study group were significantly lower than those in the control group 14 days after treatment (P<0.05). There was no statistically significant difference in the 24-hour HT rate between the two groups (P>0.05). In addition, there were no significant differences in the incidence of adverse events between the two groups (P>0.05). Multivariate Cox regression analysis showed that treatment regimen, age, and time from onset to admission were independent factors affecting 90-day prognosis (P<0.01). A prognostic model based on β-coefficients was constructed: Cox risk = 2.729 * treatment regimen + 2.881 * age + 2.795 * time from onset to admission. The Cox risk was significantly lower in the good prognosis group compared to the poor prognosis group (P<0.0001), with an area under the curve of 0.925 in predicting patient prognosis.

CONCLUSIONS

Tirofiban combined with endovascular treatment can improve quality of life, neurological function, and short-term prognosis in patients with ischemic stroke without increasing the incidence of adverse effects and HT.

Delayed Posterior Fossa Hemorrhage Following a Tangential Gunshot Wound to the Occiput in a Patient With Chronic Liver Disease: A Case Report

Gunshot wounds (GSWs) to the head and neck are a common etiology of traumatic brain injury. Tangential GSWs (TGSWs) are a subset of GSWs wherein the missile penetrates tissue adjacent to the cranium, causing varying degrees of intracranial injury. Most patients sustaining TGSWs present with relatively benign neurological findings, and while a significant proportion have varying degrees of intracranial hemorrhage (ICH) on computed tomography, these tend to respond well to nonoperative management. We present a case report of a 28-year-old male who sustained a TGSW to the occiput, with a nonfocal neurological examination, small-volume posterior fossa ICH, a blunt vertebral artery injury (BVAI), and hepatic coagulopathy, who rapidly decompensated six hours after presenting due to massive posterior fossa hemorrhage with brainstem compression, requiring emergent cardiopulmonary resuscitation followed by suboccipital decompression and cerebrospinal fluid diversion. We propose that the patient's BVAI led to an unexpected thromboembolic event, precipitating an ischemic stroke that underwent hemorrhagic conversion in the setting of coagulopathy. This case report emphasizes the insidious danger that TGSWs to the head and neck present to patients, and risk factors for poor outcomes, such as BVAI and coagulopathy. This report also highlights potential intraoperative challenges during surgery for acute mass lesions in the posterior fossa, such as neurogenic shock and pulmonary edema, that warrant careful consideration and preparation in neurosurgical cases.

Constructing machine learning models based on non-contrast CT radiomics to predict hemorrhagic transformation after stoke: a two-center study

Purpose

Machine learning (ML) models were constructed according to non-contrast computed tomography (NCCT) images as well as clinical and laboratory information to assess risk stratification for the occurrence of hemorrhagic transformation (HT) in acute ischemic stroke (AIS) patients.

Methods

A retrospective cohort was constructed with 180 AIS patients who were diagnosed at two centers between January 2019 and October 2023 and were followed for HT outcomes. Patients were analyzed for clinical risk factors for developing HT, infarct texture features were extracted from NCCT images, and the radiomics score (Rad-score) was calculated. Then, five ML models were established and evaluated, and the optimal ML algorithm was used to construct the clinical, radiomics, and clinical-radiomics models. Receiver operating characteristic (ROC) curves were used to compare the performance of the three models in predicting HT.

Results

Based on the outcomes of the AIS patients, 104 developed HT, and the remaining 76 had no HT. The HT group consisted of 27 hemorrhagic infarction (HI) and 77 parenchymal-hemorrhage (PH). Patients with HT had a greater neutrophil-to-lymphocyte ratio (NLR), baseline National Institutes of Health Stroke Scale (NIHSS) score, infarct volume, and Rad-score and lower Alberta stroke program early CT score (ASPECTS) (all p < 0.01) than patients without HT. The best ML algorithm for building the model was logistic regression. In the training and validation cohorts, the AUC values for the clinical, radiomics, and clinical-radiomics models for predicting HT were 0.829 and 0.876, 0.813 and 0.898, and 0.876 and 0.957, respectively. In subgroup analyses with different treatment modalities, different infarct sizes, and different stroke time windows, the assessment accuracy of the clinical-radiomics model was not statistically meaningful (all p > 0.05), with an overall accuracy of 79.5%. Moreover, this model performed reliably in predicting the PH and HI subcategories, with accuracies of 82.9 and 92.9%, respectively.

Conclusion

ML models based on clinical and NCCT radiomics characteristics can be used for early risk evaluation of HT development in AIS patients and show great potential for clinical precision in treatment and prognostic assessment.

Histidine-rich glycoprotein modulates neutrophils and thrombolysis-associated hemorrhagic transformation

Intravenous thrombolysis using recombinant tissue plasminogen activator (tPA) remains the primary treatment for patients with acute ischemic stroke (AIS). However, the mechanism of tPA-related hemorrhagic transformation (HT) remains poorly understood. Elevation of histidine-rich glycoprotein (HRG) expression was detected by nano-liquid chromatography tandem mass spectrometry at 1 h following tPA infusion as compared to baseline prior to tPA infusion (discovery cohort, n = 10), which was subsequently confirmed in a validation cohort (n = 157) by ELISA. Surprisingly, no elevation of HRG was detected in individuals who subsequently developed HT. During in vitro experiments, HRG reduced neutrophil NETosis, inflammatory cytokine production, and migration across the blood-brain barrier induced by tPA. In a photothrombotic murine AIS model, HRG administration ameliorated HT with delayed thrombolysis, by inhibiting neutrophil immune infiltration and downregulating pro-inflammatory signaling pathways. Neutrophil depletion or NETosis inhibition also alleviated HT, whereas HRG siRNA treatment exacerbated HT. In conclusion, fluctuations in HRG levels may reflect tPA therapy and its associated HT. The inhibitory effect of HRG on neutrophils may counteract tPA-induced immune abnormalities and HT in patients with AIS.

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

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

Perspective from single-cell sequencing: Is inflammation in acute ischemic stroke beneficial or detrimental?

BACKGROUND

Acute ischemic stroke (AIS) is a common cerebrovascular event associated with high incidence, disability, and poor prognosis. Studies have shown that various cell types, including microglia, astrocytes, oligodendrocytes, neurons, and neutrophils, play complex roles in the early stages of AIS and significantly affect its prognosis. Thus, a comprehensive understanding of the mechanisms of action of these cells will be beneficial for improving stroke prognosis. With the rapid development of single-cell sequencing technology, researchers have explored the pathophysiological mechanisms underlying AIS at the single-cell level.

METHOD

We systematically summarize the latest research on single-cell sequencing in AIS.

RESULT

In this review, we summarize the phenotypes and functions of microglia, astrocytes, oligodendrocytes, neurons, neutrophils, monocytes, and lymphocytes, as well as their respective subtypes, at different time points following AIS. In particular, we focused on the crosstalk between microglia and astrocytes, oligodendrocytes, and neurons. Our findings reveal diverse and sometimes opposing roles within the same cell type, with the possibility of interconversion between different subclusters.

CONCLUSION

This review offers a pioneering exploration of the functions of various glial cells and cell subclusters after AIS, shedding light on their regulatory mechanisms that facilitate the transformation of detrimental cell subclusters towards those that are beneficial for improving the prognosis of AIS. This approach has the potential to advance the discovery of new specific targets and the development of drugs, thus representing a significant breakthrough in addressing the challenges in AIS treatment.