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Impaired platelet function reduces myocardial infarct size in Galphaq knock-out mice in vivo
Hans-Joerg Weig1, Lorenz Bott-Flügel, Christian Städele
1Medizinische Klinik, Molekulare Kardiologie, Klinikum rechts der Isar und Deutsches Herzzentrum, Technische Universität, Munich, Germany. Hans-JoergWeig@med.uni-tuebingen.de <Hans-JoergWeig@med.uni-tuebingen.de>
Insights
Inhibition of platelet aggregation and secretion significantly reduces heart attack size in mice. This suggests blocking both platelet functions may be a novel therapeutic strategy for acute myocardial infarction.
Area of Science:
- Cardiovascular Biology
- Hematology
- Ischemia-Reperfusion Injury
Background:
- Platelet aggregation and secretion are critical in acute coronary syndromes.
- Galpha(q) knock-out mice (Galpha(q)(-/-)) exhibit eliminated platelet aggregation and secretion.
- The role of restricted platelet function in myocardial infarct size reduction requires investigation.
Purpose of the Study:
- To determine if restricted platelet aggregation and secretion reduce myocardial infarct size in vivo.
- To assess the impact of Galpha(q) deficiency on left ventricular function post-ischemia/reperfusion.
- To evaluate the therapeutic potential of combined platelet aggregation and secretion inhibition.
Main Methods:
- Utilized a mouse model of 30-minute regional myocardial ischemia followed by 24-hour reperfusion (I/R).
- Assessed infarct size using counterstaining and left ventricular function via ultrasound.
- Employed bone marrow transplantation from Galpha(q)(-/-) to wild-type (WT) mice to isolate platelet effects.
Main Results:
- Galpha(q)(-/-) mice showed significantly smaller infarct size to area at risk ratio (5.6% vs. 27.2% in WT, p<0.01).
- Left ventricular fractional shortening was improved in Galpha(q)(-/-) mice compared to WT (42.2% vs. 30.5%, p<0.01).
- WT mice receiving Galpha(q)(-/-) bone marrow had reduced infarct size compared to controls (7.8% vs. 18.4%, p<0.01), confirming platelet-specific effects.
Conclusions:
- Impaired platelet aggregation and secretion in Galpha(q)(-/-) mice protect against myocardial infarct extension.
- Platelet secretion, in addition to aggregation, contributes to infarct size during ischemia-reperfusion.
- Combined blockade of platelet aggregation and secretion presents a promising therapeutic strategy for acute myocardial infarction.
Abstract:
Platelet aggregation and secretion play a crucial role in acute coronary syndromes. In Galpha(q) knock-out mice (Galpha(q)(-/-)) platelet function is eliminated in terms of aggregation and secretion of cytokines. We investigated whether restricted platelet aggregation and secretion reduces myocardial infarct size in vivo. Thirty minute regional myocardial ischemia was followed by 24 h reperfusion (I/R) in vivo. Infarct size was determined by counterstaining. Left ventricular function was measured by ultrasound. Infarct size to area at risk ratio was significantly smaller in Galpha(q)(-/-) mice (5.6+/-1.6%) compared to wild-type (WT) mice (27.2+/-3.0%, p<0.01). Fractional shortening was improved in Galpha(q)(-/-) mice compared to WT (42.2+/-1.4% versus 30.5+/-1.4%, respectively, p<0.01). WT mice, transplanted with Galpha(q)(-/-) bone marrow showed a significant reduction in infarct size compared to control (7.8+/-2.2% versus 18.4+/-2.7%, respectively, p<0.01). Platelets of Galpha(q)(-/-) mice had an impaired aggregation and secretion phenotype. In the in vivo model of ischemia and reperfusion, beyond impaired platelet aggregation, platelet secretion plays an additional role in myocardial infarct extension. Blocking platelet aggregation in combination with secretion might be a promising supplementary therapeutic strategy in acute myocardial infarction.
