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Updated: Mar 9, 2026
A Fibrin-Enriched and tPA-Sensitive Photothrombotic Stroke Model
Published on: June 4, 2021
Direct comparison of microglial dynamics and inflammatory profile in photothrombotic and arterial occlusion evoked
Maria L Cotrina1, Nanghong Lou1, Jessica Tome-Garcia2
1Division of Glia Disease and Therapeutics, Center for Translational Neuromedicine, University of Rochester Medical School, Rochester, NY 14640, USA.
Abstract:
Many focal cerebral ischemia models utilize the middle cerebral artery occlusion (MCAO) evoked by coagulation to induce ischemic damage in the cortex and mimic the pathology observed in human patients. A second, increasingly popular model, the photothrombotic stroke, uses a laser beam to irradiate the MCA after administration of a photosensitizing dye. This widely used procedure is slowly replacing the MCAO model because of the easiness of the surgical protocol and the reproducibility of the damage. However, the photochemical reaction also results in wider microvascular injury. In this study, we have evaluated the impact of these two types of stroke in the cell survival and evolution of stroke, focusing on microglial cells, the first responders to cell injury. Two groups of heterozygote Cx3CR1-GFP reporter mice (to follow microglia) were subject to stroke injury either with coagulator-mediated occlusion or photothrombotic MCA damage. Microglial cells' dynamics of activation and phagocytosis together with astrocytic response and leukocyte infiltration were characterized at 1, 3 and 7days after damage. Photothrombotic stroke delayed microglial and astrocytic invasion of the ischemic core and accumulation of phagocytic microglia. It also elicited higher levels of inflammatory cytokines/chemokines and increased infiltration from the periphery. In addition, only the neurons in the MCAO stroke showed phenotype plasticity by downregulating the transcription factor NeuN. These data provide a better understanding of the exact temporal and spatial dynamics of the inflammatory response in these two animal models of stroke and identify more relevant targets for human therapy.
Insights
Comparing two stroke models, photothrombotic stroke delayed microglial response and increased inflammation compared to middle cerebral artery occlusion (MCAO). MCAO uniquely altered neuronal gene expression, offering distinct insights into stroke pathology and therapeutic targets.
Area of Science:
- Neuroscience
- Immunology
- Pathology
Background:
- Middle cerebral artery occlusion (MCAO) and photothrombotic stroke are common animal models for focal cerebral ischemia.
- Photothrombotic stroke is increasingly favored due to surgical ease and reproducibility, but causes broader microvascular injury.
- Understanding the distinct inflammatory and cellular responses in these models is crucial for stroke research.
Purpose of the Study:
- To compare the impact of MCAO and photothrombotic stroke on cell survival and inflammatory evolution, with a focus on microglial cells.
- To characterize the dynamics of microglial activation, phagocytosis, astrocytic response, and leukocyte infiltration in both models.
- To identify differences in neuronal plasticity between the two stroke models.
Main Methods:
- Utilized heterozygote Cx3CR1-GFP reporter mice to track microglial cells.
- Induced focal cerebral ischemia using either coagulator-mediated MCAO or photothrombotic MCA damage.
- Analyzed microglial and astrocytic responses, leukocyte infiltration, inflammatory cytokine levels, and neuronal gene expression (NeuN) at 1, 3, and 7 days post-stroke.
Main Results:
- Photothrombotic stroke delayed microglial and astrocytic invasion into the ischemic core and reduced phagocytic microglia accumulation.
- Photothrombotic stroke induced higher levels of inflammatory cytokines/chemokines and increased peripheral leukocyte infiltration.
- Only MCAO-induced stroke resulted in neuronal phenotype plasticity, evidenced by downregulation of the transcription factor NeuN.
Conclusions:
- Photothrombotic stroke elicits a delayed and distinct inflammatory response compared to MCAO, with broader microvascular and peripheral immune cell involvement.
- MCAO model demonstrates unique neuronal plasticity, suggesting differential mechanisms of injury and recovery.
- These findings enhance understanding of temporal and spatial inflammatory dynamics in stroke models, aiding the identification of targeted human therapies.
