Experimental ICH Model

The mice were anesthetized with a single intraperitoneal injection of ketamine (100 mg/kg) and xylazine (10 mg/kg). The mice were placed in a stereotactic frame (RWD Life Science Co., Shenzhen, China). Intracerebral hemorrhage was induced by intracranial injection of type IV collagenase (Sigma-Aldrich, St. Louis, MI, United States). The right corpus striatum was the target region (Figure 1). In summary, a burr hole of 0.6 mm in diameter, which was 0.2 mm anterior to the bregma and 2.0 mm lateral to the midline, was drilled. A 30-gauge needle was inserted into the right striatum with its tip 3.5 mm below the dural surface. Intracerebral hemorrhage was induced by a slow injection of 0.04 U type IV collagenase in 0.5 μL saline into the right striatum at a rate of 0.15 μL/min.

Experimental intracerebral hemorrhage in mice by injection of bacterial type IV collagenase. (A) A simplified diagram of a coronal brain section that is 0.2 mm anterior to bregma, illustrating the proposed site of collagenase injection. The lateral ventricle is marked as LV. CPu represents caudate–putamen, a part of the striatum. GP means the globus pallidus. IC is the internal capsule. L, left; R, right. (B) Representative photographs showing the location of burr hole on the skull and the injection site on the brain surface (yellow spot). (C) Representative photographs of coronal brain sections, obtained at 24 h after ICH. Please note that brain section number 5 was flipped horizontally for better visualization of the hematoma. The hematoma was within the right hemisphere.