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Updated: Jun 1, 2026
The Stroke Preclinical Assessment Network Multi-Laboratory Model of Thromboembolic Stroke with Thrombolysis: TE-MCAo
Published on: December 19, 2025
Watershed infarcts in a multiple microembolic model of monkey
Takakuni Maki1, Hideaki Wakita, Mitsuhito Mase
1Department of Neurology, Graduate School of Medicine, Kyoto University, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan.
Abstract:
It has long been debated whether watershed infarcts are caused by hemodynamic or embolic mechanisms. In the present study, we investigated microembolic roles in the pathogenesis of watershed infarcts by examining MRI in a macaque monkey model of multiple microinfarcts. 50 μm microbeads were injected into each internal carotid artery twice with a month interval. Monkeys (n=4) injected with 2250-2800 microbeads per unilateral side showed both cortical and internal watershed infarcts in the acute phase and atrophic changes with microbleeds in the chronic phase. These results suggest embolic pathogenesis can contribute to the genesis of both cortical and internal watershed infarcts in primates.
Insights
Embolic mechanisms, not just hemodynamic ones, can cause watershed infarcts. This study in macaque monkeys demonstrated microembolic roles in both cortical and internal watershed infarcts, suggesting a new understanding of stroke pathogenesis.
Area of Science:
- Neurology
- Vascular Biology
- Neuroimaging
Background:
- Watershed infarcts are brain lesions occurring in areas supplied by major cerebral arteries.
- The exact cause of watershed infarcts, whether hemodynamic or embolic, remains a subject of debate.
- Understanding the pathogenesis is crucial for developing effective stroke treatments.
Purpose of the Study:
- To investigate the role of microemboli in the development of watershed infarcts.
- To examine the acute and chronic changes associated with microembolic stroke in a primate model.
- To differentiate between hemodynamic and embolic causes of watershed infarcts.
Main Methods:
- A macaque monkey model was used to study multiple microinfarcts.
- 50 μm microbeads were injected into the internal carotid arteries.
- Magnetic Resonance Imaging (MRI) was employed to examine infarcts and associated changes.
Main Results:
- Monkeys developed both cortical and internal watershed infarcts in the acute phase after microbead injection.
- Chronic phase observations included atrophic changes and microbleeds in the affected brain regions.
- The study successfully modeled microembolic events leading to watershed infarcts.
Conclusions:
- Embolic pathogenesis is a significant contributor to the genesis of both cortical and internal watershed infarcts in primates.
- This finding challenges the traditional view solely focusing on hemodynamic factors.
- The macaque model provides valuable insights into stroke mechanisms and potential therapeutic targets.
