Nanoparticles and radiation therapies: Main issues
Abstract
After a brief summary of the nanoparticles developed in the field of photodynamic therapy (PDT), the presentation will focus on the interest of using of multifunctional nanoparticles for the treatment of malignant gliomas. PDT for brain tumors appears to be complementary to conventional treatments. Number studies show the major role of the vascular effect in the tumor eradication by PDT. For interstitial PDT of brain tumors guided by real-time imaging, multifunctional nanoparticles consisting of a surface-localized tumor vasculature targeting neuropilin-1 (NRP-1) peptide and encapsulated photosensitizer and MRI contrast agents, have been designed by our group. Nanoplatforms confer photosensitivity to cells and demonstrate a molecular affinity to NRP-1. Intravenous injection into rats bearing intracranial glioma exhibited a dynamic contrast-enhanced MRI for angiogenic endothelial cells lining the neovessels mainly located in the peripheral tumor. By using MRI completed by NRP-1 protein expression of the tumor and brain adjacent to tumor tissues, we checked the selectivity of the nanoparticles. This is the first in vivo proof of concept of closed-head iPDT guided by real-time MRI using targeted ultrasmall nanoplatforms. Another approach will be also discussed: the combination of radiotherapy and PDT for the treatment of malignant cerebral gliomas, employing scintillating nanoparticles. With this novel therapeutic approach limited light penetration problem could be overcome and activation of the photosensitizer within tumors is performed using ionizing radiation.