Morphological changes of tumor microvasculature following photodynamic therapy

摘要

Abstract: In this study, the effect of PDT on tumor microvasculature was studied by light and electron microscope. Walker-256 tumors, implanted subcutaneously in rats, were exposed to 200J/cm$+2$/ 630nm light, 24h after injection of PsD-007 at dose of 15mg/kg of body weight. Animals were killed and tumors were removed at time 0, 1/2, 1, 2, 6, 12 and 24h after treatment. The tumors with PDT displayed progressive injury to both microvasculature and tumor cells. Pathological changes such as swelling or vacuolization of mitochondria in endothelial cells could be seen immediately following PDT. At 6h post PDT, the injury to endothelial cells became more severe. Microthrombosis, diffuse hemorrhage and perivascular tumor cell mecrosis are also noted. By 12-24h after PDT, complete destruction of microvessels and obvious tumor cell mecrosis were observed. Untreated tumors or light only or drug only didn't show these changes. The results indicated that disruption of tumor microvasculature may be an important mechanism of action of PDT. !9