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Updated: May 3, 2026
A Fibrin-Enriched and tPA-Sensitive Photothrombotic Stroke Model
Published on: June 4, 2021
Pro-inflammatory mediators and apoptosis correlate to rt-PA response in a novel mouse model of thromboembolic stroke
Saema Ansar1, Eva Chatzikonstantinou1, Rushani Thiagarajah1
1Department of Neurology, University Medicine Mannheim, Heidelberg University, Heidelberg, Germany.
Background:
A recent study suggests that patients with persistent occlusion of the middle cerebral artery (MCA) following treatment with recombinant tissue plasminogen activator (rt-PA) have better outcomes than patients with MCA occlusion not receiving rt-PA. We performed a study to elucidate possible mechanisms of this finding in a new model of thromboembolic stroke closely mimicking human pathophysiology.
Methods:
Thromboembolic stroke was induced by local injection of thrombin directly into the right MCA of C57 black/6J mice. Rt-PA was administered 20 and 40 min after clot formation. The efficiency of rt-PA to induce thrombolysis was measured by laser Doppler. After 24 h, all animals were euthanized and interleukin (IL)-6, tumor necrosis factor-alpha (TNF-α), matrix metalloproteinase (MMP)-9, Caspase-3, hsp 32 and hsp 70 protein levels were investigated by immunofluorescence. Presence of hemorrhage was verified and infarct volume was measured using histology.
Results:
Thrombin injection resulted in clot formation giving rise to cortical brain infarction. Early rt-PA treatment starting at 20 min after the clot formation resulted in 100% recanalization. However, rt-PA-induced thrombolysis dissolved the clot in only 38% of the animals when administered 40 min after clot formation. Protein levels of IL-6, TNF-α, MMP-9, Caspase-3, hsp 32 and hsp 70 were increased after MCAO, whereas treatment with rt-PA attenuated the expressions of inflammatory markers in those animals where the thrombolysis was successful. In addition, the infarct size was significantly reduced with rt-PA treatment compared to non-treated MCAO, regardless of whether MCA thrombolysis was successful.
Conclusions:
The present study demonstrates a clear correlation of the protein expression of inflammatory mediators, apoptosis and stress genes with the recanalization data after rt-PA treatment. In this model rt-PA treatment decreases the infarct size regardless of whether vessel recanalization is successful.
Insights
Recombinant tissue plasminogen activator (rt-PA) treatment reduces stroke infarct size, even if recanalization is unsuccessful. Early rt-PA administration improves clot dissolution and reduces inflammatory markers in a mouse model of middle cerebral artery occlusion.
Area of Science:
- Neuroscience
- Biomedical Research
- Stroke Medicine
Background:
- Previous studies suggest improved outcomes for stroke patients with persistent middle cerebral artery occlusion (MCAO) treated with recombinant tissue plasminogen activator (rt-PA).
- Mechanisms underlying this observation require further elucidation in a relevant preclinical model.
Purpose of the Study:
- To investigate the mechanisms behind improved outcomes in MCAO patients treated with rt-PA.
- To evaluate the efficacy of rt-PA in a novel thromboembolic stroke model mimicking human pathophysiology.
Main Methods:
- Thromboembolic stroke induced via direct thrombin injection into the mouse MCA.
- rt-PA administered at 20 and 40 minutes post-clot formation.
- Assessed thrombolysis efficiency, protein levels of inflammatory markers (IL-6, TNF-α), apoptosis (Caspase-3), and stress genes (hsp 32, hsp 70), hemorrhage, and infarct volume.
Main Results:
- Early rt-PA (20 min) achieved 100% recanalization; later treatment (40 min) achieved 38% recanalization.
- rt-PA attenuated inflammatory markers in successfully recanalized animals.
- Significant infarct size reduction observed with rt-PA treatment, irrespective of successful recanalization.
Conclusions:
- rt-PA treatment correlates with reduced expression of inflammatory mediators, apoptosis, and stress genes post-stroke.
- rt-PA demonstrates a neuroprotective effect by reducing infarct size, independent of successful vessel recanalization in this model.
