Adjuvant Treatment With Neuroserpin Increases the Therapeutic Window for Tissue-Type Plasminogen Activator Administration in a Rat Model of Embolic Stroke

Abstract

Background-After stroke, the thrombolytic effect of tissue-type plasminogen activator (tPA) in the intravascular space is beneficial, whereas its extravascular effect on ischemic neurons is deleterious. We tested the hypothesis that neuroserpin, a natural inhibitor of tPA, reduces tPA-induced neuronal toxicity and increases its therapeutic window for treatment of embolic stroke. Methods and Results-Rats were subjected to embolic middle cerebral artery occlusion (MCAO). Ischemic brains were treated with neuroserpin in combination with recombinant human tPA (nϭ7), tPA alone (nϭ7), or saline (nϭ9). Neuroserpin (20 L of 16 mol/L active neuroserpin) was intracisternally injected 3 hours and tPA (10 mg/kg) was intravenously administered 4 hours after ischemia. MRI measurements were performed to study blood brain barrier (BBB) leakage and ischemic lesion volume. Administration of tPA alone 4 hours after ischemia significantly (PϽ0.05) increased BBB leakage in the ischemic core measured by Gd-DTPA-enhanced MRI compared with rats treated with saline. However, treatment with neuroserpin in combination with tPA significantly (PϽ0.05) reduced BBB leakage, brain edema, and ischemic lesion volume compared with rats treated with tPA alone, although ischemic lesion volumes were the same in both groups before the treatment. Immunostaining revealed that MCAO resulted in reduction of neuroserpin immunoreactivity in the ipsilateral hemisphere after 2 to 6 hours of ischemia. Zymographic assay showed increased plasminogen activity in areas with BBB leakage in rats treated with tPA. Conclusions-Administration of neuroserpin after stroke is neuroprotective, seemingly because it blocks the extravascular effect of tPA, leading to subsequent decrease in stroke volume and widening of the therapeutic window for the thrombolytic effect of tPA. (Circulation. 2002;106:740-745.)

Nitrite Does Not Provide Additional Protection to Thrombolysis in a Rat Model of Stroke with Delayed Reperfusion

“…Studies using permanent ischemia (Bardutzky et al, 2005) and reperfusion injury (Neumann-Haefelin et al, 2002) show that the penumbra, defined by perfusion-diffusion mismatch on MRI, decreases to a minimum 2.5 to 4 h after MCAO. Although this implies that therapy would be minimally effective after that duration, several agents show beneficial effects with reperfusion 4 to 6 h after stroke onset (Pfefferkorn and Rosenberg, 2003;Zhang et al, 2002). In our study, infarct volume in the 6-h ischemia groups was higher than in the 2-h groups.…”

Analysis of Combined Treatment of Embolic Stroke in Rat with r-tPA and a GPIIb/IIIa Inhibitor

“…Importantly, compared with control animals, microvascular cerebral perfusion is significantly increased whether the MCA is patent or not. Treatment of embolic stroke in the rat with rtPA at 4 hours after stroke onset fails to improve and likely worsens histologic and neurologic outcome (Zhang RL et al, 1999;Jiang et al, 2000;Zhang ZG et al, 2002;Zhang L et al, 2003) and yields a persistent and severe hypoperfusion . Our data presented in this study explicitly show by means of MRI and fluorescence perfusion measurements, for the first time, that at 4 hours after embolic stroke we can significantly reduce microvascular perfusion deficits mediated by the GPIIb/IIIa receptor.…”

“…We have previously demonstrated using MRI and non-MRI approaches that treatment of embolic stroke with r-tPA alone at 4 hours after stroke onset fails to improve CBF and reduce infarct volume compared with saline-treated animals Ding et al, 2004;Zhang ZG et al, 2002;Zhang L et al, 2003). In the present study, using magnetic resonance imaging (MRI), we investigated the effects of combination treatment of 7E3 F(ab 0 ) 2 and r-tPA by means of MRI including the measurements of the apparent diffusion coefficient of water (ADC w ) by diffusion-weighted imaging (DWI), cerebral blood flow (CBF) by perfusion weighted imaging (PWI), magnetic resonance angiography (MRA), relaxation time constants of T 1 by T 1 -weighted imaging (T1WI) and T 2 by T 2 -weighted imaging (T2WI), as well as fluorescence microscopy and histology.…”

tPA and Proteolysis in the Neurovascular Unit

“…29 Alternatively, blocking neurotoxic properties of tPA with neuroserpin, neuronal serine protease inhibitor, increased the time-to-treatment window for thrombolysis in rat stroke models. 30 Finally, there may be thrombolytic agents such as microplasmin 31 or vampire bat salivary plasminogen activator 32 that may not trigger MMP dysregulation or enhance excitotoxic neurodegeneration.…”