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A new method for preparing a rat intracerebral hemorrhage model by combining focused ultrasound and microbubbles.

Authors: He Y, Yang J, Hu F, Liao M, Nie Y, Zhu X, Zhang T, Song K, Li Q, Li X, Mei C, Wu Z, Lu Q, Zhong Z

We aimed to prepare a non-invasive, reproducible, and controllable rat model of intracerebral hemorrhage with focused ultrasound (FUS). A rat intracerebral hemorrhage (ICH) model was established by combining FUS and microbubbles (μBs), and edaravone was used to verify whether the free radical scavenger had a protective effect on the model. The brain tissue of each group was sectioned to observe the gross histology, blood-brain barrier (BBB) permeability, cerebral infarction volume, and histopathological changes. Compared with the FUS group, the BBB permeability was significantly increased in the FUS + μBs (F&B) group (p = 0.0021). The second coronal slice in the F&B group had an obvious hemorrhage lesion, and the FUS + μBs + edaravone (F&B&E) group had smaller hemorrhage areas; however, ICH did not occur in the FUS group. The cerebral infarction volume in the F&B group was significantly larger than that in the FUS group (p = 0.0030) and F&B&E group (p = 0.0208). HE staining results showed that nerve fibrinolysis, neuronal necrosis, microglia production, and erythrocytes were found in both the F&B group and the F&B&E group, but the areas of the nerve fibrinolysis and neuronal necrosis in the F&B group were larger than the F&B&E group. A rat ICH model was successfully prepared using the μBs assisted FUS treatment, and edaravone had a therapeutic effect on this model. This model can be used to study the pathophysiological mechanism of ICH-related diseases and in preclinical research on related new drugs.

Introduction

Purpose Other
Study Objective To develop a non-invasive, reproducible, and controllable rat model of intracerebral hemorrhage using focused ultrasound combined with microbubbles.
Animal model / Human subject Rat (Sprague Dawley, SD), 6–7 weeks old, male
Disease model Intracerebral hemorrhage (ICH)
MRI or image guidance method Stereotactic positioning
Targeted brain region(s) Striatum
Target coordinates AP +1.0 mm (anterior to bregma), ML +3.0 mm (right of bregma), DV 5.0 mm (ventral from bregma at skull surface)
Cargo name and characteristics Edaravone
Route of administration Intravenous

Outcomes and Safety

Summary of Outcomes Focused ultrasound combined with microbubbles (FUS + μBs) noninvasively and reproducibly induced intracerebral hemorrhage with increased BBB permeability, larger cerebral infarction and histological neuronal damage in rats (FUS alone only mildly increased BBB but did not cause ICH), and these injuries were reduced by the free radical scavenger edaravone; the successful ultrasonic condition was FUS with microbubbles (FUS + μBs).
Duration of biological effect not specified
Safety-related matter No animals died during the experiments, but µB‑assisted focused ultrasound intentionally produced intracerebral hemorrhage with increased BBB permeability, cerebral infarction, neuronal necrosis and microvascular damage (cavitation/hematoma); a residual thermal effect that may cause additional irreversible tissue injury was also documented, and edaravone partially reduced the infarction and tissue damage.

Brain Region

Ultrasound Parameters

Ultrasound instrument Sonic Concepts Inc., Bothell, USA
FUS Frequency 1.1 MHz
FUS Pressure 9 MPa
FUS Mode pulsed
Pulse duration 1 ms
Duration of a single FUS session 30 s
Focal Characteristics Focal depth: 5 mm
Treatment frequency Single session

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