Long-circulating gadolinium-loaded liposomes: potential use for magnetic resonance imaging of the blood pool.
In our previous paper, we reported a method of liposome loading with Gadolinium (Gd) via so called polychelating amphiphilic polymer (PAP). A novel Gd-containing polymeric probe, suitable for the incorporation into the liposomal membrane, was prepared from a low-molecular-weight DTPA-polylysine by linking its N-terminus to a lipid anchor, NGPE-PE. When compared with known membranotropic MR probes, such as Gd-DTPA-SA and Gd-DTPA-PE, liposomes containing new membrane-bound polychelator possess enhanced relaxivity for water protons resulting in an increase of tissue signal intensity on MR images. In this study, we developed the optimized protocol to prepare a liposomal MR contrast agent with high relaxivity and narrow size distribution. Gd-containing liposomes were additionally modified with PEG to provide longevity in vivo. We also demonstrated that upon intravenous administration in rabbit and dog, the new preparation causes a prolonged decrease in the blood T(1) value (reflecting the proton relaxation rate in the blood) and may be considered as a potential contrast agent for MRI of the blood pool.
Department of Pharmaceutical Sciences, Bouve College of Health Sciences, Northeastern University, Mugar Building, Room 312, 360 Huntington Avenue, 02115, Boston, MA, USA
V
Weissig
J
Babich
V
Torchilin