Platelets as delivery vehicles for targeted enrichment of NO · to cerebral glioma for magnetic resonance imaging.

Using a magnetic resonance imaging (MRI) contrast agent, MRI has made substantial contributions to glioma diagnosis. Metal-free MRI agents, such as the nano free radical nitric oxide (NO ^· ) micelle, can overcome the inherent toxicity of metal-based agents in certain patient populations. However, the low spatial resolution of nano NO ^· micelle in MRI limits its clinical development. In this study, we pretreated platelets (PLTs) and loaded them with nano NO ^· micelles to synthesize NO ^· @PLT, which can overcome the low contrast and poor in vivo stability of nitroxide-based MRI contrast agents. The PLTs can serve as potential drug carriers for targeting and delivering nano NO ^· micelles to gliomas and thus increase the contrast in T1-weighted imaging (T1WI) of MRI. This drug carrier system uses the unique tumor-targeting ability of PLTs and takes advantage of the high signal presentation of steady nano NO ^· micelles in T1WI, thereby ultimately achieving signal amplification of glioma in T1WI. With the effect of PLTs-tumor cell adhesion, NO ^· @PLT has per-nitroxide transverse relativities of approximately 2-fold greater than those of free NO ^· particles. These features allow a sufficient NO ^· @PLT concentration to accumulate in murine subcutaneous glioma tumors up from 5 min to 2.5 h (optimum at 1.5 h) after systemic administration. This results in MRI contrast comparable to that of metal-based agents. This study established a promising metal-free MRI contrast agent, NO ^· @PLT, for glioma diagnosis, because it has superior spatial resolution owing to its high glioma-targeting ability and has significant translational implications in the clinic.
(© 2023. The Author(s).)