Recanalization and reperfusion in clinically-relevant porcine model of stroke.

Introduction: Stroke is a leading cause of death and long-term disability. Pigs have been considered an ideal large animal model in biomedicine; however, the complex vascular anatomy has posed challenges for stroke research. Nonetheless, we have previously overcome these limitations and demonstrated the feasibility of endovascularly inducing stroke in pigs. Here, we study to further mimic clinical situation by achieving recanalization, which has not been previously accomplished.

Methods: A stroke was induced in eight juvenile male domestic pigs. In anaestethised animals catheter was placed in the ascending pharyngeal artery near the rete mirabile (RM) under X-ray guidance. The animals were then transferred to an MRI scanner. Gadolinium-based contrast agent (GBCA) was infused at various speeds until transcatheter cerebral perfusion was visible on MRI. Subsequently, a mixture of thrombin and GBCA was infused, and the retention of contrast on MRI scans proved successful induction of thrombosis. Subsequent DWI and PWI MR images confirmed the successful induction of stroke. Two hours after ischemia, we intra-arterially infused rtPA (20 mg) and confirmed recanalization of the thrombosed vessels using MRI. One month later the stroke was confirmed through follow-up MRI scans and post-mortem histological and immunohistochemical analyses.

Results: We successfully induced stroke with an average lesion size based on ADC at 8.18 ± 4.98 cm³, ranging from 3.27 to 17.33 cm³. After recanalization, the severely hypoperfused area (Tmax>6) was only 1.168 ± 0.223 cm³. Subsequent histological analysis revealed neuronal loss within the lesion, the formation of astrocytic scar tissue, and elevated levels of activated microglia.

Discussion: Our study demonstrates the successful recanalization of cerebral vasculature in porcine model of ischemic stroke. It makes the model highly relevant to the current clinical workflow and offers an attractive avenue for studying novel diagnostics, therapeutics and further exploration of the underlying pathomechanisms. The feasibility of continuous MR imaging throughout the entire procedure facilitates the achievement of the aforementioned goals more readily.