Photothrombotic Stroke Model

There are various rodent stroke models used widely in a preclinical study for their different aspects of pathological and remedies mechanisms. A photothrombosis stroke model (PTS) has been established to induce ischemic damage within a cortical region via photochemical activation of a photosensitive dye. A photosensitive dye, Rose Bengal (4,5,6,7-tetrachloro-2′,4′,5′,7′-tetraiodofluorescein) is injected into rodents and enters to the bloodstream. Illumination of the target brain area with a certain wavelength of light induces a clotting cascade and leads to thrombosis, which is termed as photothrombotic lesions. The dye is activated by light exposure and generates singlet oxygen. This singlet oxygen damages the endothelial cell membrane followed by platelet accumulation and thrombi formation, interrupting the cerebral blood flow to the end. After the formation of the infarct, the volume or size can be determined by the histological staining and imaging. The key advantage of PTS model is that it allows for ischemic infarction in region of interest to the cortex, in a reproducible and non-invasive way. The PTS is especially suited for the study of cellular and molecular mechanisms involved in cerebral ischemia and their recovery. This chapter describes the existing procedure of the PTS for the development of ischemic penumbra, its measurement, limitations, and significance.