Heating drug delivery to vascular wall with Rhodamine B and fluorescence labeled Paclitaxel ranging 50 to 70°C: ex vivo study

We studied heating drug delivery to vascular wall with Rhodamine B ranging 50 to 70°C ex vivo study. Porcine carotid artery was dipped in the heated Rhodamine B solution in 15 s and then cooled by 37°C saline. Rhodamine B concentration distribution in the vascular wall cross-section was measured by a fluorescence microscope using 550 nm for excitation and 620 nm emission for fluorescence detection. The total amount of measured fluorescence in the vascular wall was calculated as a indication of delivered Rhodamine B quantity. The delivered Rhodamine B quantity was increased with increasing heating temperature with 50 to 70°C. In the cases of 60 to 70°C heating, the delivered Rhodamine B quantity was 3.1 to 23.3 fold by that of 37°C. Defined penetration depth of the delivered Rhodamine B in the vascular wall was also significantly increased with 65°C and 70°C heating. We also studied heating drug delivery to the vascular wall with fluorescence labeled Paclitaxel with 70°C in 15 s and 60 s heating ex vivo. In both contact duration, the delivered Paclitaxel quantity was increased. To understand these drug delivery enhancement effects, we investigated the vascular cross-sectional structure change by the heating. Some holes over 50 nm in diameter appeared on the internal elastic lamina with 70°C heating. We prospected that vascular surface structure change by the heating might enhance drug delivery to the vascular wall.