Displaying One Session

Scientific Communications
Session Type
Scientific Communications
Room
Hall M
Date
07.11.2020, Saturday
Session Time
02:30 PM - 04:00 PM

Platelets and immune cells drive stroke progression into the penumbra in mice

Session Type
Scientific Communications
Date
07.11.2020, Saturday
Session Time
02:30 PM - 04:00 PM
Room
Hall M
Lecture Time
02:30 PM - 02:40 PM

Abstract

Background And Aims

In acute ischemic stroke upon a major cerebral artery occlusion, infarcts rapidly grow from the core into the penumbra before recanalization which encompasses brain tissue that receives residual blood flow from collaterals which eventually fails. The underlying mechanisms are unknown.

Methods

To address mechanisms mice underwent filament occlusion of the middle cerebral artery (MCAO) for up to 4 hours. Infarct development was compared between sham-treated mice, and mice in which the platelet glycoprotein (GP) receptor Ib was blocked. Moreover, Rag1-/- mice lacking immune cells underwent the same procedures. Infarct volumes were measured by TTC-staining.

Results

Blocking of platelet GPIb ameliorated ischemic brain damage under MCA occlusion compared to sham-treated mice at all occlusion times tested (mean infarct volume 45.4 mm3 versus 82.5 mm3 at 3h). Inhibition of GPIb reduced T-cell infiltration into ischemic brains pointing to thrombo-inflammation as an underlying mechanism. Accordingly, Rag1-/- mice lacking immune cells were similarly protected from infarct progression under occlusion during MCAO (35.3 mm3 versus 73.2 mm3).

Conclusions

As principal finding we show that it is possible to retard infarct progression into the penumbra under MCA occlusion in mice by either blocking platelet GPIb or by immune cell deficiency. Thus similar thrombo-inflammatory processes underlying ischemia/reperfusion injury (Stoll & Nieswandt, Nat Rev Neurol 2019; 15:473-481) are operative already at the hyperacute stroke stage under vessel occlusion. These findings pave the way for novel treatment strategies targeting thrombo-inflammation to salvage the penumbra before recanalization.

Funded by the German Research Foundation project number 374031971 CRC/TR240

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DIRECT MYOSIN-2 INHIBITION RESTORES CEREBRAL PERFUSION RESULTING IN FUNCTIONAL IMPROVEMENT AFTER ISCHEMIC STROKE

Session Type
Scientific Communications
Date
07.11.2020, Saturday
Session Time
02:30 PM - 04:00 PM
Room
Hall M
Lecture Time
02:40 PM - 02:50 PM

Abstract

Background And Aims

Ischemic stroke treatment faces a major unresolved issue as capillary perfusion remains blocked due to hypoxia-induced stress even after recanalyzation by thrombolysis or thrombectomy. Capillary constriction is mediated by actomyosin contraction in precapillary smooth muscle cells (SMCs). Our aim is to test the validity and potential of smooth muscle myosin-2 (SMM) as a drug target for restoring capillary perfusion and facilitating recovery after stroke.

Methods

The effect of SMM inhibition was investigated in a standard ischemic stroke model by transient middle cerebral artery occlusion (tMCAO) in rats. SMM in the ischemic region of the brain was targeted by the direct administration of the myosin-2 inhibitor para-aminoblebbistatin (AmBleb). Regional cerebral blood flow (rCBF) was followed by SPECT and changes of rCBF in each functional region were analyzed. In addition, neurological deficits of the animals were monitored for 3 weeks.

Results

In line with our in vitro findings that AmBleb could fully relax isolated human and rat cerebral arterioles, rCBF also recovered in vivo in the ischemic brain area within 7 days after treatment. Furthermore, the restored cerebral perfusion also resulted in functional recovery characterized by significantly improved neurological deficits as well as locomotor symmetry.

Conclusions

Direct inhibiton of SMM by AmBleb in SMCs significantly contributed to the improvement of cerebral perfusion and brain functions after stroke indicating that SMM may be a potential drug target in stroke therapy after the chemical or physical removal of the thrombus.

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N,N-DIMETHYLTRYPTAMINE REDUCES INFARCT SIZE AND IMPROVES FUNCTIONAL RECOVERY FOLLOWING TRANSIENT FOCAL BRAIN ISCHEMIA IN RATS

Session Type
Scientific Communications
Date
07.11.2020, Saturday
Session Time
02:30 PM - 04:00 PM
Room
Hall M
Lecture Time
02:50 PM - 03:00 PM

Abstract

Background And Aims

N,N-dimethyltryptamine (DMT) is an endogenous ligand of the Sigma 1 receptor (Sig-1R) with documented in vitro cytoprotective properties against hypoxia in vitro. Our aim was to demonstrate for the first time the neuroprotective effect of DMT following experimental stroke in vivo.

Methods

Transient middle cerebral occlusion (MCAO) was induced for 60 minutes in male Wistar rats under general anaesthesia. Before the removal of the filament the treatment group (n=10) received DMT (1mg/kg-bw bolus intra-peritoneal bolus + 2mg/kg-bw/hour maintenance over 24 hours). Controls (n=10) received vehicle only. A third group (n=10) received a Sig-1R antagonist (BD1063, 1mg/kg-bw bolus + 2mg/kg-bw/hour maintenance) in parallel with the DMT. Lesion volume was measured by MRI 24 hours following the MCAO. Animals were terminated, and the native brains and sera were removed for real-time qPCR and ELISA analysis. Functional recovery was studied in two separate group of pre-trained animals (n=8-8) using the staircase method.

Results

DMT treated rats were characterized by lower ischemic lesion volume (p=0.0373), and better functional recovery (p= 0.0084) compared to the controls. Sig-1R was expressed both in neurons and in microglia in the peri-infarct cortex, and the DMT induced change in the lesion volume was hindered by BD1063. Lower APAF1 expression (mRNA and protein) and higher BNDF levels were documented on DTM, while decreased TNF-α, IL1-β, IL-6 and increased IL-10 expressions indicated the compound’s anti-inflammatory potential.

Conclusions

Our results indicate a Sig-1R dependent reduction of the ischemic brain injury following exogenous DMT administration in rats, presumably through a combined anti-apoptotic, pro-neurotrophic and anti-inflammatory treatment effect.

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SAFINAMIDE AMELIORATES CEREBRAL ISCHEMIA REPERFUSION MEDIATED INJURY IN RATS BY ATTENUATING OXIDATIVE STRESS AND INFLAMMATION

Session Type
Scientific Communications
Date
07.11.2020, Saturday
Session Time
02:30 PM - 04:00 PM
Room
Hall M
Lecture Time
03:00 PM - 03:10 PM

Abstract

Background And Aims

Reperfusion after stroke causes burst of free radicals leading to oxidative stress, inflammation and apoptosis. Safinamide by inhibiting voltage gated sodium, calcium channels and glutamate release may play critical role in stroke injury. Hence, this study was planned to evaluate neuroprotective effects of safinamide in ischemic stroke in rats.

Methods

In male Sprague-Dawley rats (260-290g), middle cerebral artery (MCA) was occluded for 90 minutes. Safinamide (80 mg/kg) was administered at two time points, immediately and 2 hours after reperfusion followed by twice daily dosing for next 2 days. After 72h, neurological deficit score (NDS), rota-rod and grip strength were assessed. Infarct size was evaluated using T2 MR imaging using 7T animal MRI. Further, changes in the levels of oxidative stress markers (MDA, GSH and SOD) and inflammatory cytokines (TNF-α & IL-1β) were assessed.

Results

Sub-acute administration of safinamide significantly (p<0.05) reduced NDS compared to MCAo rats along with improvement in motor in-coordination as assessed by rota-rod and grip-strength (p<0.05). Results of T2 MR imaging revealed significant (p<0.05) reduction in infarct size in comparison with MCAo group. Levels of oxidative stress markers (MDA, GSH & SOD) were normalized significantly (p<0.05) in cortex whereas in striatum, safinamide did not produce significant improvement. Ischemia reperfusion induced altered levels of pro-inflammatory cytokines (TNFα and IL-1β) were also significantly (p<0.05) attenuated in cortex by safinamide treatment.

Conclusions

The results suggest the neuroprotective potential of safinamide in ischemic stroke by attenuating oxidative stress and inflammation. Further, its mechanism of neuroprotection will be explored at molecular level.

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SERUM MMP-9 RELATIONSHIP WITH INFARCT SIZE AND HEMORRHAGIC TRANSFORMATION IN STROKE PATIENTS TREATED WITH THROMBECTOMY

Session Type
Scientific Communications
Date
07.11.2020, Saturday
Session Time
02:30 PM - 04:00 PM
Room
Hall M
Lecture Time
03:10 PM - 03:20 PM

Abstract

Background And Aims

A key feature of ischemia-reperfusion injury in stroke is the breakdown of the blood-brain barrier, especially mediated by activation of matrix metalloproteinase 9 (MMP-9). To date, the impact of MMP-9 has mainly been assessed in the setting of intravenous thrombolysis. We aimed to assess the role of MMP-9 in ischemic stroke in the era of mechanical thrombectomy (MT) based on a combined approach using the kinetics of MMP-9 and sequential MRI.

Methods

HIBISCUS-STROKE is a cohort study including patients admitted for an ischemic stroke due to large vessel occlusion treated with MT following admission MRI. Patients underwent sequential assessment of MMP-9 and follow-up CT at day 1 and MRI at day 6. Infarct growth was defined as the difference between final Fluid-Attenuated Inversion Recovery volume and baseline diffusion-weighted imaging volume. Models were adjusted for main confounding variables including reperfusion status.

Results

Between 10/21/2016 and 04/12/2019, 148 patients were included. A high MMP-9 level at 6 hours from admission (H6) (p=0.02), a high glucose level (p=0.01), a high temperature (p=0.04) and lack of reperfusion (p=0.02) were associated with infarct growth. A high MMP-9 level at H6 (p=0.03), a high glucose level (p=0.03) and a long delay from symptom onset to groin puncture (p=0.01) were associated with the risk of hemorrhagic transformation.

Conclusions

In this MT cohort study, MMP-9 level at H6 predicts infarct growth and hemorrhagic transformation.

This work was supported by the RHU MARVELOUS (ANR-16-RHUS-0009) of Université Claude Bernard Lyon-1 (UCBL), within the program "Investissements d'Avenir“ operated by the French National Research Agency.

Trial Registration Number

Not applicable

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INTERLEUKIN-6, A RELIABLE MARKER OF FUTILE REPERFUSION AFTER MECHANICAL THROMBECTOMY IN ACUTE ISCHEMIC STROKE

Session Type
Scientific Communications
Date
07.11.2020, Saturday
Session Time
02:30 PM - 04:00 PM
Room
Hall M
Lecture Time
03:20 PM - 03:30 PM

Abstract

Background And Aims

Futile reperfusion may be associated with a more severe inflammatory response which is partly mediated by cytokines release. We assessed whether interleukin-6 (IL-6) levels might better characterize this condition in stroke patients with large vessel occlusion (LVO) treated with mechanical thrombectomy (MT).

Methods

HIBISCUS-STROKE is a cohort study including patients admitted for an ischemic stroke due to LVO treated with MT following admission MRI. Patients with thrombolysis in cerebral infarction scale <2b were excluded. Patients underwent sequential assessment of IL-6. Reperfusion was defined as futile if 3-month modified Rankin scorewas 0-2. Our model was adjusted for the main confounding variables.

Results

Between 21/10/2016 and 12/04/2019, 133 patients met the inclusion criteria. Among them 46 (34%) showed a futile reperfusion. Mean age was 69 +/- 15 years. Sixty percent of patients were men. In univariate analysis, high IL-6 levels at 6 (p=0.02), 24 (p<0.01) and 48 hours (p<0.01) were associated with futile reperfusion. Following multivariate analysis, high IL-6 levels at 6 (p=0.04), 24 (p<0.01) and 48 hours (p<0.01), remained associated with futile reperfusion.

figure.jpg

Figure legend: Kinetics of interleukine-6 (IL-6) (H0: admission, H6: hour 6, H24: hour 24, H48: hour 48, M3: month 3) (* indicates p< 0.05)

Conclusions

IL-6 levels may likely predict futile reperfusion in patients with LVO treated with MT. This specific therapeutic target may deserve a particular attention in order to prevent reperfusion injury.

This work was supported by the RHU MARVELOUS (ANR-16-RHUS-0009) of Université Claude Bernard Lyon-1 (UCBL), within the program "Investissements d'Avenir“ operated by the French National Research Agency.

Trial Registration Number

Not applicable

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MICRO-EMBOLI FROM MECHANICAL THROMBECTOMY LEAD TO LARGE DROPS IN PERFUSION IN A 2D REPRESENTATION OF THE MICROVASCULATURE

Session Type
Scientific Communications
Date
07.11.2020, Saturday
Session Time
02:30 PM - 04:00 PM
Room
Hall M
Lecture Time
03:30 PM - 03:40 PM

Abstract

Background And Aims

Clot fragmentation during mechanical thrombectomy is a possible contributor to a lack of tissue reperfusion post-recanalization. Here, we quantify computationally the magnitude of the effect of clot fragmentation on perfusion.

Methods

Mechanical thrombectomy was simulated in a vascular phantom with hard and soft clots. Four different retrieval techniques were used (Table 1) and the size distribution of emboli were quantified. Sampling from these distributions, we simulated micro-emboli in a 2D vascular network of the microvasculature (Fig.1). The embolus travels through the network until it encounters a vessel smaller in diameter, occluding that vessel. This routine is repeated until the perfusion drops to 0 for the network. This simulation is repeated 1000 times for hard clots and soft clots using each retrieval technique.

van.png

Results

Soft clots consistently lead to larger drops in perfusion per percent-of-vessel-volume-blocked. Hard clots lead to larger drops in perfusion per percent-of-vessels-blocked (due to their larger fragments blocking larger vessels). Whichever technique or clot used, perfusion drops faster than a 1:1 ratio.

Table 1 Comparison of perfusion drops per percent-of-vessels-blocked and percent-of-vessel-volume-blocked

Technique

Clot Type

Perfusion drop/Vessels-blocked (%/%)

Perfusion Drop/Stagnated-volume (%/%)

ADAPT

Hard

-6.6

-1.6

Soft

-3.2

-6.7

GC at Cervical ICA

Hard

-3.8

-2.5

Soft

-3.6

-2.8

Solumbra

Hard

-27

-1.3

Soft

-3.2

-4.7

BGC

Hard

-9.3

-1.7

Soft

-5.4

-1.9

Conclusions

Clot fragments from thrombectomy lead to much larger than expected drops in perfusion (~5%/%). Hard clot fragmentation leads to focalised regions of large drops due to their larger fragments, whilst soft clots lead to diffuse regions of perfusion drop.

Trial Registration Number

Not applicable

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EXTRACTED CLOT MATERIAL DEMONSTRATES THAT LARGE ARTERY ATHEROSCLEROTIC CLOTS HAVE A SIGNIFICANTLY LARGER CLOT BURDEN THAN BOTH CARDIOEMBOLIC AND EMBOLIC STROKE OF UNDETERMINED SOURCE

Session Type
Scientific Communications
Date
07.11.2020, Saturday
Session Time
02:30 PM - 04:00 PM
Room
Hall M
Lecture Time
03:40 PM - 03:50 PM

Abstract

Background And Aims

Previous studies have aimed to measure the clot burden using diagnostic imaging, however, this approach suffers from many variables including differing imaging modalities and machines. In this study, we measured the area and number of fragments of the extracted clot material removed during mechanical thrombectomy procedures from 550 acute ischemic stroke patients treated at 4 stroke centres across Europe.

Methods

Gross photos were taken of the Extracted Clot material of each case and the area (cm2) was measured using ImageJ softeware. The area was then compared with the clinical and procedural information. The non-parametric Mann-Whitney test was used for statistical analysis (p<0.05).

Results

The Mean Extracted Clot Area was 0.64cm2, the mean number of fragments was 4.05 and the mean number of passes was 2.44. Large Artery Clots are twice as big as Cardiac Clots (1.09cm2 vs 0.52cm2, p<0.0001*) and are associated with a greater number of fragments (0.63 vs 0.35, p<0.0001*). Large Artery Clots are also twice as big as embolic stroke of undetermined etiology (ESUS) (1.09cm2 vs 0.47cm2, p<0.0001*) and are associated with a significantly large number of fragments (0.63 vs 0.31, p<0.0001*). Cardioembolic clots are similar in size to ESUS clots (0.52cm2 vs 0.47cm2, p<0.355) and are associated with a similar number of fragments (0.35 vs 0.31, p<0.0661).

Conclusions

This study suggests that the etiology of the occlusive clot has a significant impact on the size of the clot, which in turn can significantly impact the success of the procedure.

Funding: Science Foundation Ireland (Grant Number 13/RC/2073) and Cerenovus.

Trial Registration Number

Not applicable

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COMPUTATIONAL MODELLING OF BRAIN PERFUSION IN STROKE PATIENTS

Session Type
Scientific Communications
Date
07.11.2020, Saturday
Session Time
02:30 PM - 04:00 PM
Room
Hall M
Lecture Time
03:50 PM - 04:00 PM

Abstract

Background And Aims

Predicting the clinical outcome of stroke patients requires estimating infarction and penumbra in the brain after a stroke. These estimates can be simulated with the use of computational models of brain perfusion. This requires the integration of different computational models. We present here, computational models of arterial blood flow and tissue perfusion, and their coupling.

Methods

Arterial blood flow is modelled by utilising a steady state one-dimensional network model of the vasculature, stretching from vessels originating from the heart to the pial surface, as depicted in Figure 1(a). A stroke can be modelled by occluding an artery of this network. The network linked to the three-dimensional perfusion model via surface mapping as shown in Figure 1(b). Tissue perfusion is modelled by a porous continuum approach comprising arteriole, capillary and venule compartments.

Results

The model predicts physiologically accurate tissue perfusion both in grey and white matter. Perfusion change resulting from the occlusion of an artery appears to be a good indicator of infarct location and extension. According to Figure 1(c) and (d), the results are in good qualitative agreement with clinical data.

figure1.png

Figure 1: a) One-dimensional network. b) Surface mapping. c) R.MCA occlusion simulation result. d) R.MCA occlusion clinical data.

Conclusions

According to Figure 1(c) and (d), the simulation results are in good qualitative agreement with clinical data. After validation, the presented coupled brain perfusion model will be used to (i) test various hypotheses regarding ischaemic stroke and (ii) optimise treatment devices.

Trial Registration Number

Not applicable

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