A Mouse Model for Vascular Cognitive Impairment and Dementia Based on Needle-guided Asymmetric Bilateral Common Carotid Artery Stenosis

Our lab used to identify the novel treatments for ischemic stroke and vascular cognitive impairment and dementia. In this study, we have created a new mice model to study vascular cognitive impairment and dementia.

The main challenge is that vascular cognitive impairment and dementia is a complex term which unites many clinical representations and causes. And so the researchers should always keep that in mind when selecting an animal model for their experiments.

We established a novel VCID model which enables dynamic monitoring of brain wave with MRI at the farther inflammation and the mechanism plays a critical role in VCID.

Our model is highly reliable, allows for fine-tuning its parameters depending on the researcher's needs, has ultra low cost, and also allows for MRI scanning in live animals. Inflammation plays a critical role in VCID, and we will further dissect the mechanism of how inflammation leads to dementia and how to ameliorate the disease by modulating inflammation.

[Narrator] To begin, place the four-millimeter-long needle fragments in a sterile Petri dish. Gently tap the sharp end of the needles against a hard surface to blunt them. Using a needle holder, carefully separate the needles from their plastic pieces, and precut 7-0 silk sutures into one- to two-centimeter-long pieces. After anesthetizing the mouse, position it on a heating pad with the ventral side up. Sterilize the surgical site with Betadine solution containing 10% iodine, and deiodize the skin with 70% ethanol. Ensure the anesthesia level is adequate with a toe pinch test. Now, make a vertical midline incision along the trachea. Using micro forceps, gently separate the bilateral thyroid glands, then pull back the skin and underlying tissue using sterile small skin retractors. Under the microscope, use angled tweezers to carefully expose and bluntly dissect one of the CCAs from the vagus nerve and the surrounding sheath. If the CCA tends to adhere to the forceps, moisten the incision site with sterile water or PBS. If necessary, place a small plastic syringe under the neck for posture support. Then, using angled tweezers, thread three precut 7-0 silk suture fragments under the CCA, spacing them approximately one millimeter apart. Create a very loose double knot around the CCA on one of the suture fragments. Position the prepared needle fragment parallel to the CCA, placing it inside the loose knot. Carefully tighten the primary knot around both the needle and the CCA until blood flow is halted. Then secure it with a secondary knot. Gently pull out the needle to allow partial blood flow to resume, and trim the ends of the suture. Confirm that all three suture bands on the CCA are securely tied without being so tight as to fully obstruct blood flow. Ensure the CCA is not pale downstream of the knots and that the sutures are evenly spaced. Repeat isolation and ligation of the CCA on the other side, and confirm the correct distance and restoration of blood flow. Two-dimensional laser speckle imaging revealed that cerebral hypoperfusion was more pronounced in the left hemisphere and persisted for at least 24 weeks post-surgery. The survival rate of male mice post-surgery over six weeks was recorded at 81.6% with higher mortality during the first week. T2-weighted MRI images detected hypo- or hyper-intense regions across multiple brain regions in ABCS-operated mice, indicating brain injury. Directionally encoded color maps from diffusion tensor imaging showed structural damage in ABCS mice, compared to the Sham group. Morris water maze testing showed prolonged latency to escape in ABCS-operated mice, indicating significant learning disabilities. Reduced time spent in the target quadrant during the probe trial further confirmed memory impairment. These deficits persisted for at least 24 weeks after surgery.