Microlocalization of lipophilic porphyrins: Non-toxic enhancers of boron neutron-capture therapy
International Journal of Radiation Biology
Purpose : To compare the macroscopic and microscopic distributions of the novel non-toxic lipophilic porphyrins copper (II) 5,10,15,20-tetrakis-(3-[1,2 dicarba-closo -dodecaboranyl]methoxyphenyl)-porphyrin (CuTCPH), potentially useful for boron neutron-capture therapy (BNCT), with those of its zinc fl uorescent congener zinc (II) 5,10,15,20-tetrakis-(3-[1,2 dicarba-closododecaboranyl]methoxyphenyl)-porphyrin (ZnTCPH) in tissues of tumor-bearing mice. Materials and methods : ZnTCPH and CuTCPH
... e synthesized, then injected intraperitoneally (ip) into tumor-bearing mice. Macroscopic biodistribution was assessed by determining average boron concentrations in tumor, blood, brain, skin, and liver using atomic-emission spectrometry. The euthanized mice and their vital organs were photographed fi rst under an ultraviolet lamp and then under a bright fl uorescent lamp. Thin sections of liver and tumor were analyzed by confocal fl uorescence microscopy (CFM). Results : ZnTCPH-injected, but not CuTCPH-injected mice bearing subcutaneous tumors showed fl uorescence from liver, spleen and tumors. Macrodistributions of boron in various tissues were similar in mice whether injected with ZnTCPH or CuTCPH. CFM of unfi xed liver sections showed cytoplasmic fl uorescence from Kupff er cells in a periportal lobular distribution evenly throughout the liver. In the tumors studied, such fl uorescence was also cytoplasmic but unlike liver fl uorescence, was macroscopically heterogeneous. Conclusion : ZnTCPH serves as a useful fl uorescent experimental surrogate for CuTCPH to delineate its macroscopic and microscopic distributions in organs and tumors.