CT Perfusion Does Not Modify the Effect of Reperfusion in Patients with Acute Ischemic Stroke Undergoing Endovascular Treatment in the ESCAPE-NA1 Trial

Oxygen-glucose-deprived peripheral blood mononuclear cells act on hypoxic lesions after ischemia-reperfusion injury

BACKGROUND

Despite advances in reperfusion therapies, ischemic stroke remains a major cause of long-term disability due to residual hypoxic lesions persisting after macrovascular reperfusion. These residual hypoxic lesions, caused by microvascular dysfunction, represent an important therapeutic target. We previously demonstrated that oxygen-glucose-deprived peripheral blood mononuclear cells (OGD-PBMCs) migrate to ischemic brain regions and promote functional recovery after stroke. This recovery occurs through mechanisms involving hypoxia-inducible factor-1α, exosomal miR-155-5p, and vascular endothelial growth factor (VEGF). However, it remains unclear whether OGD-PBMCs target hypoxic regions.

METHODS

We evaluated cerebral blood flow using a laser speckle flow imaging system. Next, we utilized pimonidazole to investigate the presence of hypoxic lesions after ischemia-reperfusion injury in a rat suture occlusion model in immunohistochemical analyses. We also compared levels of a cell surface receptor in human PBMCs by flow cytometric analysis under normoxic and OGD conditions.

RESULTS

We found persistent pimonidazole-positive hypoxic lesions at 10- and 28-days post-reperfusion despite restored gross cerebral perfusion. Treatment with the C-X-C motif chemokine receptor 4 (CXCR4) inhibitor AMD3100 before and after OGD-PBMCs administration reduced the number of OGD-PBMCs in the brain parenchyma compared to the control group (P = 0.018). Administered OGD-PBMCs localized within these hypoxic regions via the stromal cell-derived factor-1/CXCR4 chemotactic axis. OGD-PBMCs enhanced VEGF expression, specifically within hypoxic lesions, compared to the phosphate-buffered saline group (P < 0.01). Furthermore, OGD-PBMCs reduced the number of pimonidazole-positive hypoxic cells in the ischemic core on 28 days. These findings demonstrate that OGD-PBMCs selectively migrate to and modulate the microenvironment of hypoxic lesions following cerebral ischemia-reperfusion injury.

CONCLUSION

Targeting these residual hypoxic regions may underline the therapeutic effects of OGD-PBMC treatment and represent a promising strategy for improving stroke recovery despite successful recanalization.

The relative cerebral blood volume (rCBV) < 42% is independently associated with hemorrhagic transformation in anterior circulation large vessel occlusion

BACKGROUND

Pretreatment CT perfusion (CTP) marker relative cerebral blood volume (rCBV) < 42% lesion volume has recently shown to predict poor collateral status and poor 90-day functional outcome. However, there is a paucity of studies assessing its association with hemorrhagic transformation (HT). Here, we aim to assess the relationship between rCBV < 42% lesion volume with HT.

METHODS

In this retrospective study, we included patients with acute ischemic stroke secondary to large vessel occlusion (AIS-LVO) of anterior circulation who had successful recanalization from two comprehensive stroke centers between 9/1/2017 and 10/01/2023. Successful recanalization was defined as modified treatment in cerebral infarction (mTICI) 2b or greater. Logistic regression analysis and ROC analysis were used to assess the relationship between rCBV <42% and HT.

RESULTS

In total, 150 patients (median age: 69 years, 58.7% female) met our inclusion criteria. On multivariable logistic regression analysis, taking into account age, sex, hypertension, hyperlipidemia, diabetes, prior stroke or transient ischemic attack, admission National Institute of Health stroke scale (NIHSS), Alberta Stroke Program Early CT Score (ASPECTS), and intravenous thrombolysis, rCBV <34% (aOR:1.01, P < .05), rCBV <38% (aOR:1.01, P < .05) and rCBV <42% (aOR:1.01, P < .05) lesion volumes were independently associated with HT. On ROC analysis rCBV < 42% (AUC = 0.61, P < .05) performed slightly better than rCBV < 38% (AUC = 0.59, P < .05) and rCBV < 34% (AUC = 0.59, P < .05) in predicting HT.

CONCLUSION

The rCBV <42% lesion volume is independently associated with HT in AIS-LVO patients who underwent successful recanalization.

The Imaging-Neuropathological Gap in Acute Large Vessel Occlusive Stroke

While imaging has traditionally played a fundamental role in the selection of patients undergoing endovascular thrombectomy, recent thrombectomy trials involving patients with large ischemic strokes demonstrated a consistent benefit of endovascular thrombectomy across all imaging strata, suggesting that reperfusion benefit may exist independent of current imaging constructs. Although these findings attest to the uniformly beneficial effects of reperfusion, they also shed doubt on the accuracy and utility of our imaging modalities in defining reversible versus irreversible ischemia and challenge the premise of imaging-based selection. We aimed to review the histopathologic studies and clinical trials that have shaped our understanding of current imaging constructs aiming to outline the existing imaging-neuropathological gap that may be far wider than previously perceived.

CT perfusion derived relative cerebral blood volume < 42 % is negatively associated with poor functional outcomes at discharge in anterior circulation large vessel occlusion stroke

BACKGROUND AND AIM

Recent studies have shown that the CT Perfusion (CTP) parameter of rCBV < 42 % lesion volume can predict 90-day functional outcomes in stroke patients. However, its correlation with discharge outcomes, including functional dependence, has not been investigated. Our study aims to evaluate the relationship between rCBV < 42 % and poor functional outcomes at discharge, defined as a modified Rankin score (mRS) of 3 or higher.

MATERIALS AND METHODS

This retrospective study analyzed patients with confirmed occlusion on CT angiography, who also received CT perfusion between 9/1/2017 and 10/01/2023. Statistical tests (Student's T, Mann-Whitney U, and Chi-Square) were used to assess differences. Univariable and multivariable logistic regression analyses were performed to evaluate the associations of rCBV < 42 % with discharge mRS. A p-value ≤ 0.05 was considered significant.

RESULTS

A total of 268 patients [median age: 68 years (IQR: 59-77), 56.3 % female] met the inclusion criteria. Among them, 85 patients (31.7 %) received intravenous thrombolysis (IVT), and 221 patients (82.5 %) underwent mechanical thrombectomy (MT). After adjusting for various variables, logistic regression analysis indicated that rCBV < 42 % lesion volume was associated with poor functional outcomes at discharge (aOR = 0.97, p < 0.05). T.

CONCLUSION

The rCBV < 42 % could be a valuable tool in prognosticating AIS-LVO patients.

The humanized platelet glycoprotein VI Fab inhibitor EMA601 protects from arterial thrombosis and ischaemic stroke in mice

BACKGROUND AND AIMS

Glycoprotein VI (GPVI) is a platelet collagen/fibrin(ogen) receptor and an emerging pharmacological target for the treatment of thrombotic and thrombo-inflammatory diseases, notably ischaemic stroke. A first anti-human GPVI (hGPVI) antibody Fab-fragment (ACT017/glenzocimab, KD: 4.1 nM) recently passed a clinical phase 1b/2a study in patients with acute ischaemic stroke and was found to be well tolerated, safe, and potentially beneficial. In this study, a novel humanized anti-GPVI antibody Fab-fragment (EMA601; KD: 0.195 nM) was developed that inhibits hGPVI function with very high potency in vitro and in vivo.

METHODS

Fab-fragments of the mouse anti-hGPVI IgG Emf6.1 were tested for functional GPVI inhibition in human platelets and in hGPVI expressing (hGP6tg/tg) mouse platelets. The in vivo effect of Emf6.1Fab was assessed in a tail bleeding assay, an arterial thrombosis model and the transient middle cerebral artery occlusion (tMCAO) model of ischaemic stroke. Using complementary-determining region grafting, a humanized version of Emf6.1Fab (EMA601) was generated. Emf6.1Fab/EMA601 interaction with hGPVI was mapped in array format and kinetics and quantified by bio-layer interferometry.

RESULTS

Emf6.1Fab (KD: 0.427 nM) blocked GPVI function in human and hGP6tg/tg mouse platelets in multiple assays in vitro at concentrations ≥5 µg/mL. Emf6.1Fab (4 mg/kg)-treated hGP6tg/tg mice showed potent hGPVI inhibition ex vivo and were profoundly protected from arterial thrombosis as well as from cerebral infarct growth after tMCAO, whereas tail-bleeding times remained unaffected. Emf6.1Fab binds to a so far undescribed membrane proximal epitope in GPVI. The humanized variant EMA601 displayed further increased affinity for hGPVI (KD: 0.195 nM) and fully inhibited the receptor at 0.5 µg/mL, corresponding to a >50-fold potency compared with ACT017.

CONCLUSIONS

EMA601 is a conceptually novel and promising anti-platelet agent to efficiently prevent or treat arterial thrombosis and thrombo-inflammatory pathologies in humans at risk.

Does Ischemic Core Volume Modify the Treatment Effect of Endovascular Thrombectomy?

Imaging-based selection has become integral in guiding endovascular thrombectomy for large vessel occlusive stroke, driven by positive trial outcomes incorporating parenchymal and perfusion imaging criteria. While small-moderate core trials transformed acute reperfusion therapy, uncertainties persisted for large ischemic strokes. This was recently addressed in several treatment trials which demonstrated a benefit of endovascular thrombectomy in patients with large ischemic strokes, defined by parenchymal and/or perfusion imaging. Although individual trials suggest treatment benefits regardless of core size, patient-level meta-analyses are essential to clarify this relationship. Our aim was to summarize the imaging ramifications of the major endovascular thrombectomy trials of the past decade focusing on the interaction between the core and the treatment effect, to assist in the design of future meta-analyses. The core-treatment relationship that will be investigated in these meta-anlalyses will likely have major implications in our systems of care designs and in determining the utility of imaging-based selection.

CT Perfusion Derived rCBV < 42% Lesion Volume Is Independently Associated with Followup FLAIR Infarct Volume in Anterior Circulation Large Vessel Occlusion

Pretreatment CT Perfusion (CTP) parameter rCBV < 42% lesion volume has recently been shown to predict 90-day mRS. In this study, we aim to assess the relationship between rCBV < 42% and a radiographic follow-up infarct volume delineated on FLAIR images. In this retrospective evaluation of our prospectively collected database, we included acute stroke patients triaged by multimodal CT imaging, including CT angiography and perfusion imaging, with confirmed anterior circulation large vessel occlusion between 9 January 2017 and 10 January 2023. Follow-up FLAIR imaging was used to determine the final infarct volume. Student t, Mann-Whitney-U, and Chi-Square tests were used to assess differences. Spearman's rank correlation and linear regression analysis were used to assess associations between rCBV < 42% and follow-up infarct volume on FLAIR. In total, 158 patients (median age: 68 years, 52.5% female) met our inclusion criteria. rCBV < 42% (ρ = 0.56, p < 0.001) significantly correlated with follow-up-FLAIR infarct volume. On multivariable linear regression analysis, rCBV < 42% lesion volume (beta = 0.60, p < 0.001), ASPECTS (beta = -0.214, p < 0.01), mTICI (beta = -0.277, p < 0.001), and diabetes (beta = 0.16, p < 0.05) were independently associated with follow-up infarct volume. The rCBV < 42% lesion volume is independently associated with FLAIR follow-up infarct volume.