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Evaluating Cell Death Signaling by Immunofluorescence in a Rat Model of Ischemic Stroke
Published on: January 3, 2025
Plasma and brain matrix metalloproteinase-9 after acute focal cerebral ischemia in rats
Kyung-Pil Park1, Anna Rosell, Christian Foerch
1Neuroprotection Research Laboratory, MGH East 149-2401 Charlestown, MA 02129, USA.
Background And Purpose:
Plasma levels of matrix metalloproteinase-9 (MMP-9) have been proposed to be a useful biomarker for assessing pathological events in brain. Here, we examined the temporal profiles of MMP-9 in blood and brain using a rat model of acute focal cerebral ischemia.
Methods:
Plasma and brain levels of MMP-2 and MMP-9 were quantified at 3, 6, 12, and 24 hours after permanent middle cerebral artery occlusion in male Sprague-Dawley rats. Infarct volumes at 24 hours were confirmed with 2,3,5-triphenyl-tetrazolium-chloride staining.
Results:
In plasma, zymographic bands were detected between 70 and 95 kDa corresponding to pro-MMP-2, pro-MMP-9, and activated MMP-9. A higher 135-kDa band was also seen that is likely to be NGAL-conjugated MMP-9. After ischemia, there were no significant changes in pro-MMP-2, but plasma levels of pro-MMP-9 steadily increased over the course of 24 hours. Activated MMP-9 levels in plasma were significantly elevated only at 24 hours. Plasma NGAL-MMP-9 complexes showed a transient elevation between 3 to 6 hours, after which levels decreased back down to pre-ischemic baselines. In brain homogenates, pro-MMP-2, pro-MMP-9, and activated MMP-9 were seen but no NGAL-MMP-9 bands were detected. Compared to the contralateral hemisphere, MMP-2 and MMP-9 levels in ischemic brain progressively increased over the course of 24 hours. Overall levels of MMP-9 in plasma and brain were significantly correlated, especially at 24 hours. Plasma levels of pro-MMP-9 at 24 hours were correlated with final infarct volumes.
Conclusions:
Elevated plasma levels of MMP-9 appear to be correlated with brain levels within 24 hours of acute cerebral ischemia in rats. Further investigation into clinical profiles of MMP-9 in acute stroke patients may be useful.
Insights
Plasma matrix metalloproteinase-9 (MMP-9) levels correlate with brain levels after acute cerebral ischemia in rats. Elevated MMP-9 in plasma within 24 hours may serve as a biomarker for stroke assessment.
Area of Science:
- Biochemistry
- Neuroscience
- Biomarker Discovery
Background:
- Matrix metalloproteinase-9 (MMP-9) is implicated in brain pathological events.
- Assessing MMP-9 in blood and brain is crucial for understanding acute cerebral ischemia.
Purpose of the Study:
- To examine the temporal profiles of MMP-9 in blood and brain.
- To evaluate MMP-9 as a potential biomarker in a rat model of acute focal cerebral ischemia.
Main Methods:
- Quantified plasma and brain levels of MMP-2 and MMP-9 at 3, 6, 12, and 24 hours post-occlusion.
- Used permanent middle cerebral artery occlusion in Sprague-Dawley rats.
- Confirmed infarct volumes using 2,3,5-triphenyl-tetrazolium-chloride staining.
Main Results:
- Plasma pro-MMP-9 levels increased steadily over 24 hours post-ischemia.
- Activated MMP-9 in plasma was significantly elevated at 24 hours.
- Plasma and brain MMP-9 levels showed significant correlation, particularly at 24 hours, with plasma pro-MMP-9 correlating with infarct volume.
Conclusions:
- Elevated plasma MMP-9 levels correlate with brain MMP-9 levels within 24 hours of acute cerebral ischemia in rats.
- Plasma MMP-9 shows potential as a biomarker for acute stroke.
- Further clinical studies in stroke patients are warranted.
