Enhanced resection of orthotopic red-fluorescent-protein-expressing human glioma by fluorescence-guided surgery in nude mice.

Malignant glioma is the most common type of primary central nervous system cancer. Gliomas are very difficult to completely resect due to their invasiveness. In the present study, we compared fluorescence-guided and standard bright-light resection of a human glioma orthotopically implanted in nude mice. U87 human glioma cells, expressing red fluorescent protein (RFP), were injected stereotactically into the nude mouse brain through a craniotomy open window. Two weeks after cancer-cell implantation, gliomas were resected under fluorescence guidance or under bright light. U87-RFP tumors were clearly visualized with a long-working distance fluorescence microscope. Almost all cancer cells were removed using fluorescence-guided navigation without damage to the brain tissue. In contrast, brain tumors were difficult to visualize under bright light and many residual cancer cells remained in the brain after bright-light surgery. Fluorescence-guided surgery significantly extended the survival of the mice compared to those who underwent bright-light surgery. These results suggest that fluorescence-guided surgery has significant potential for brain cancer treatment.