An advanced micelle-based biodegradable HPMA polymer-gadolinium contrast agent for MR imaging of murine vasculatures and tumors†
Abstract
Magnetic resonance (MR) contrast agents have been explored to improve the diagnosis of vascular diseases or tumors, yet clinically used small molecular agents have not been very successful owing to their poor contrast efficiency and short circulation time. Herein we reported a biodegradable HPMA polymeric micelle-based MR contrast agent containing gadolinium (Gd3+) for imaging murine vascular structures and tumors. This nano-sized polymeric agent has a high relaxivity, good biosafety and great biodegradability for MR applications. In vivo MR angiography (MRA) clearly reveals the abdominal, intracranial and tumor-surrounding blood vessels for a longer time after injection of the polymeric agent compared to DTPA-Gd. Furthermore, orthotopic and subcutaneous imaging of a murine breast cancer tumor model demonstrates that this polymeric agent has excellent contrast enhancement in tumors. The enhancement may be due to great accumulation of the polymeric agent in tumors and tumor associated macrophages (TAM) might help improve the accumulation of the polymeric agent in tumors. Thus, in comparison with DTPA-Gd, this polymeric micelle-based biodegradable and biocompatible contrast agent has been demonstrated to have a high MRI contrast efficacy for murine vasculatures and tumors.