Spontaneous Reperfusion after In Situ Thromboembolic Stroke in Mice

Durand, Anne; Chauveau, Fabien; Cho, Tae-Hee; Bolbos, Radu; Langlois, Jean‐Baptiste; Hermitte, Laure; Wiart, Marlène; Berthezène, Yves; Nighoghossian, Norbert

doi:10.1371/journal.pone.0050083

Cited by 16 publications

(11 citation statements)

References 13 publications

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“…Performing MRI during occlusion allowed the rigorous selection of animals showing penumbra, thus ensuring that ischemic lesion regression at H24 was due to treatment and not to failure of the animal model. The rate of spontaneous reperfusion at H3 was elevated (one third of animals), in agreement with previous findings [13]. To our knowledge, the present study is the first to report early reperfusion following thrombolytic therapy in this mouse model.…”

Section: Discussionsupporting

confidence: 93%

“…The natural evolution of this model (without intervention) was characterized on MRI, the main finding being a significant rate of spontaneous reperfusion in the first hours after the formation of a stable clot [13]. In this model, intravenous injection of rtPA at a dose of 10 mg/kg 20-30 min after surgery mimics thrombolysis treatment in the clinical setting, with cerebral blood flow (as measured by laser Doppler flowmetry) returning to baseline 30-60 min after the beginning of treatment [12,14,15,16].…”

Section: Introductionmentioning

confidence: 99%

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Effects of a TAFI-Inhibitor Combined with a Suboptimal Dose of rtPA in a Murine Thromboembolic Model of Stroke

et al. 2014

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Background: Since thrombolysis is the only approved intervention for ischemic stroke, improving its efficacy and safety is a therapeutic aim of considerable interest. The activated form of thrombin activatable fibrinolysis inhibitor (TAFI) has antifibrinolytic effects, and inhibition of TAFI might thus favor recanalization. The present study compared efficacy between TAFI inhibition alone and TAFI inhibition in combination with rtPA at a suboptimal dose, in a murine model of thromboembolic stroke. Methods: Focal ischemia was induced in mice by thrombin injection in the middle cerebral artery. Animals were placed within the magnet immediately after surgery for baseline MRI (H0). MRI examination comprised diffusion-weighted imaging (DWI), perfusion-weighted imaging (PWI), and T2-weighted imaging (T2-WI). Animals were randomly assigned to 1 of 5 treatment groups: saline, rtPA 5 mg/kg (tPA⁵: suboptimal or low dose), rtPA 10 mg/kg (tPA¹⁰: standard dose), TAFI-I 100 mg/kg (TAFI-I), and rtPA 5 mg/kg + TAFI-I 100 mg/kg (tPA⁵ + TAFI-I). Treatments were administered inside the magnet, via a catheter placed in the tail vein, using a power injector, as 10% bolus and 90% infusion over a period of 20 min. MRI examination was repeated at 3 h (H3) and 24 h (H24) after surgery. Therapeutic benefit was evaluated by: (1) improvement of reperfusion and (2) reduction in final lesion size. Microhemorrhages were assessed as black spots on T2-WI at H24. Animals were sacrificed after the last MR examination. The surgeon and all investigators were blinded to treatment allocation. Results: A total of 104 mice were operated on. Forty four of these were excluded from the study and 27 from the analysis, according to a priori defined criteria (no lesion or no mismatch), leading to the following distribution: saline (n = 6), tPA⁵ (n = 8), tPA¹⁰ (n = 7), TAFI-I (n = 7), and TAFI-I + tPA⁵ (n = 5). Standard-dose rtPA treatment (tPA¹⁰) significantly improved lesion regression between H0 and H24 compared to saline (-57 ± 18% vs. -36 ± 21%, p = 0.03), which treatment with rtPA⁵ or TAFI-I alone did not. On the other hand, combined treatment with tPA⁵ + TAFI-I showed only a trend toward lesion regression (-49 ± 26%), similarly to treatment with tPA¹⁰, but not significantly different from saline (p = 0.46). Nine animals showed microhemorrhage on T2-WI at H24. These animals were evenly distributed between groups. Conclusions: The present study showed that the combination of TAFI-I with a suboptimal dose of rtPA is not as effective as the standard dose of rtPA, while TAFI inhibition alone is not effective at all. The thromboembolic model is of particular interest in assessing rtPA association to improve thrombolysis, especially when coupled with longitudinal MRI assessment.

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Section: Discussionsupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Effects of a TAFI-Inhibitor Combined with a Suboptimal Dose of rtPA in a Murine Thromboembolic Model of Stroke

et al. 2014

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“…Diabody treatment at this time point did not have any effect, which is in line with the spontaneous resolution of the thrombin-induced clot in this model. 55 In correspondence to the in vitro neurotoxicity data (supplemental Figure 4), the diabody also had no deleterious effect in vivo.…”

Section: Blood 19 February 2015 X Volume 125 Number 8 Dual Tafi/paimentioning

confidence: 55%

Innovative thrombolytic strategy using a heterodimer diabody against TAFI and PAI-1 in mouse models of thrombosis and stroke

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Denorme

et al. 2015

Blood

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• Early thrombolytic treatment with a bispecific inhibitor against TAFI and PAI-1 is effective without exogenous tPA.• Even at the highest dose tested, the bispecific inhibitor against TAFI and PAI-1 does not prolong bleeding time.Circulating thrombin-activatable fibrinolysis inhibitor (TAFI) and plasminogen activator inhibitor-1 (PAI-1) are causal factors for thrombolytic failure. Therefore, we evaluated an antibody-engineered bispecific inhibitor against TAFI and PAI-1 (heterodimer diabody, Db-TCK26D6x33H1F7) in several mouse models of thrombosis and stroke. Prophylactic administration of the diabody (0.8 mg/kg) in a thromboplastin-induced model of thromboembolism led to decreased lung fibrin deposition. In a model of cerebral ischemia and reperfusion, diabody administration (0.8 mg/kg, 1 hour postocclusion) led to a mitigated cerebral injury with a 2.3-fold reduced lesion and improved functional outcomes. In a mouse model of thrombin-induced middle cerebral artery occlusion, the efficacy of the diabody was compared to the standard thrombolytic treatment with recombinant tissuetype plasminogen activator (tPA). Early administration of diabody (0.8 mg/kg) caused a twofold decrease in brain lesion size, whereas that of tPA (10 mg/kg) had a much smaller effect. Delayed administration of diabody or tPA had no effect on lesion size, whereas the combined administration of diabody with tPA caused a 1.7-fold decrease in lesion size. In contrast to tPA, the diabody did not increase accumulative bleeding. In conclusion, administration of a bispecific inhibitor against TAFI and PAI-1 results in a prominent profibrinolytic effect in mice without increased bleeding. (Blood. 2015;125(8):1325-1332 IntroductionPlasminogen activators are the only thrombolytic agents approved to rapidly revascularize a thrombosed vessel. Reperfusion of the ischemiaaffected organ leads to an improved outcome in patients when applied within the first hours after ischemic onset.1 Despite this evidence-based beneficial effect, current thrombolytic agents remain widely underutilized due to life-threatening side effects such as cerebral hemorrhages and possible neurotoxicity.2,3 For acute ischemic stroke, in particular, the only licensed treatment option consists of a high systemic dose of recombinant tissue-type plasminogen activator (tPA), which is actually given to ,10% of the patients. Therefore, there is an unmet clinical need to explore novel therapeutic avenues to enhance fibrinolysis without plasminogen activator-associated adverse effects. Endogenous intravascular fibrinolysis is driven on the release of tPA from the endothelium, which in turn enzymatically activates plasminogen into the fibrin-degrading enzyme, plasmin.4 This activation step is attenuated by circulating thrombin-activatable fibrinolysis inhibitor (TAFI) and plasminogen activator inhibitor-1 (PAI-1). Activated TAFI (TAFIa; encoded by the CPB2 gene) eliminates C-terminal Lys exposed on partially degraded fibrin, which ultimately leads to a diminished efficiency and localizati...

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“…The threshold approach of perfusion metrics is a standard lesion detection technique in dynamic susceptibility-contrast MR imaging (5,12) that utilizes the correlation with metabolic derangement (5,6), and the adaptive approach allows avoidance of the use of global thresholds that remain debated and may not be generalizable across centers (13)(14)(15). At the high signalto-noise ratio (standard deviation, 0.2), the algorithm estimated a volume of 279 au, and the Dice coefficient was 0.9.…”

Section: Simulationsmentioning

confidence: 99%