PHOTODYNAMIC THERAPY OF HUMAN GLIOMA (U87) IN THE NUDE RAT

We measured the response of normal brain and the human U87 glioma impl anted in the brain of rats (n = 65) to photodynamic therapy (PDT) usin g Photofrin as the sensitizer. Normal brain and U87 tumor implanted wi thin brain of athymic (nude) rats were subjected to PDT (12.5 mg/kg of Photofrin) at increasing optical energy doses (35 J/cm(2), 140 J/cm(2 ), 280 J/cm(2)) of 632 nm light, Photofrin concentration in tumor, bra in adjacent to tumor and normal brain were measured in a separate popu lation of rats. Twenty-four hours after PDT, the brains were removed, sectioned, stained with hematoxylin and eosin (H&E), and the volumes o f the PDT-induced lesion measured, Photofrin concentration in tumor gr eatly exceeded that of normal brain and brain adjacent to tumor (>20 x ), Both normal brain and U87 tumor exhibited superficial tissue damage with PDT at 35 J/cm(2). However, both normal and tumor-implanted brai n exhibited tissue damage with increasing optical dose, A heterogeneou s pattern of pannecrosis along with a uniform volume of pannecrosis wa s detected in the tumor, In contrast, normal brain exhibited a uniform sharply demarcated volume of necrosis, Our data indicate that the U87 human brain tumor model and the normal brain in the athymic rat are s ensitive to PDT and Photofrin with an optical dose-dependent response to treatment.