All-optical thrombotic stroke model for near-surface blood vessels in rat: focal illumination of exogeneous photosensitizers combined with real-time two-photon imaging

摘要

Photothrombotic microstrokes are produced in rat cortex by 532-nm single-photon optical excitation of an intravenously injected photosensitizer, rose bengal. The dynamics of blood flow and clot formation in the cortical vasculature are observed using two-photon laser scanning microscopy of an intravenously injected fluorescent dye. Flowing and clotted vessels are clearly distinguishable in both large and small vessels, down to individual capillaries, using this technique. We find that by tightly focusing the laser light used to excite the photosensitizer, clots can be formed in individual blood vessels without affecting neighboring vessels tens of micrometers away. We observe many changes in blood flow as a result of localized clot formation, including upstream vascular dilation, clot clearing, i.e. recanalization, and complete reversal of blood flow direction downstream.