The PROMISE study analyzed the safety and effectiveness of the Penumbra System with the ACE68 and ACE64 reperfusion catheters in aspiration thrombectomy of stroke, using A Direct Aspiration First Pass Technique (ADAPT).
Direct implantation of the hydrogel delivery vehicle containing stabilized PEG-N1000G-ChABC-SH3 onto the rat brain cortex in a sub-acute model of stroke resulted in significantly reduced CSPG levels in the penumbra of 49% at 14 and 40% at 28 days post-injury compared to animals treated with the vehicle alone.
The same validation based on penumbra as defined by quantitative <sup>15</sup> O-PET CBF was performed for comparative reasons in 23 patients measured within 48 hours of stroke onset (group B).
Moreover, they provide trophic support to tissue at risk in the penumbra surrounding the infarct area, enhance vasculogenesis, and help promote survival, migration, and differentiation of the endogenous precursor cells after stroke.
Based on preclinical evidence, we propose to test the penumbra freezing concept in a clinical phase IIa trial assessing whether cathodal tDCS-shown in rodents to reduce infarction volume-prevents early infarct growth in human acute Middle Cerebral Artery (MCA) stroke, in adjunction to conventional revascularization methods.
The presence of apoptotic neurons in the ischemic penumbra and perihematoma area may account for poor prognosis, but whether the highly variable stroke outcome reflects differences in genetic susceptibility to apoptosis is elusive.
To study epigenetic processes in ischemic penumbra, we used photothrombotic stroke (PTS), a stroke model in which laser irradiation of the rat brain cortex photosensitized by Rose Bengal induces local vessel occlusion.
We analyzed baseline computed tomography angiogram and computed tomography perfusion within 24 hours of stroke onset along with follow-up imaging and assessed time from stroke onset to baseline imaging, ASPECTS (Alberta Stroke Program Early CT Score), vessel occlusion, collaterals, ischemic core, and penumbra.
Variation in collateral extent significantly alters infarct volume expansion, transiently affects perfusion and diffusion magnetic resonance imaging signatures, and impacts salvage of ischemic penumbra after stroke onset.
Patients with migraine might be more susceptible of spreading depolarizations, which are known to affect vascular and neuronal function and penumbra recovery after stroke.
In AIS patients (n = 55), baseline computerized tomography (CT) was performed ≤ 8 h from symptom onset, whereas CT determination of reperfusion/recanalization was assessed at 24 h. Multiple linear and logistic regression models were used to correlate reperfusion/recanalization with radiological (i.e., hemorrhagic transformation, ischemic core, and penumbra volumes) and clinical outcomes (assessed as National Institutes of Health Stroke Scale [NIHSS] reduction ≥ 8 points or a NIHSS ≤ 1 at 24 h and as modified Rankin Scale [mRS] < 2 at 90 days).
The inflammatory response following CI offers a unique opportunity for drug delivery to the ischemic brain and targeted cells because of the recruitment of leukocytes to the stroke core and penumbra.
Our experience indicates that CEA performed early after IVT for acute ischemic stroke, aiming not only to reduce the risk of stroke recurrence but also to achieve neurological improvement by reperfusion of the ischemic penumbra, may be safe and can lead to favorable outcomes.
The translation of this experimental concept as the basis for the efficient treatment of stroke requires methods by which regional flow and energy metabolism can be repeatedly investigated to demonstrate penumbra tissue, which can benefit from therapeutic interventions.
A previous animal study demonstrated an increased expression of the endocannabinoid receptor 1 (CB1R) in the penumbra area surrounding the ischemic core, suggesting a crucial role in inflammation/reperfusion after stroke.
Further research to refine and validate these techniques may enable their use as MRI-based surrogate markers of the ischemic penumbra for selecting stroke patients for interventional treatment strategies.
The results revealed that SIRT2 was mainly expressed in the cytoplasm and neurites of neurons in the brains of normal subjects, while an elevated expression and nuclear translocation of SIRT2 were detected in the ischemic penumbra of cerebral stroke.
Reperfusion by thrombolysis and/or thrombectomy can rescue penumbra and improve stroke outcomes, but these treatments are currently available to a minority of patients.
Improvement in acute 24-hour National Institutes of Health Stroke Scale was also significantly related to the degree of reperfused penumbra (<i>R</i><sup>2</sup>, 0.31; P<0.0001).