title: Lanthanide-loaded erythrocytes as highly sensitive chemical exchange saturation transfer MRI contrast agents.
abstract: Chemical exchange saturation transfer (CEST) agents are a new class of frequency-encoding MRI contrast agents with a great potential for molecular and cellular imaging. As for other established MRI contrast agents, the main drawback deals with their low sensitivity. The sensitivity issue may be tackled by increasing the number of exchanging protons involved in the transfer of saturated magnetization to the "bulk" water signal. Herein we show that the water molecules in the cytoplasm of red blood cells can be exploited as source of exchangeable protons provided that their chemical shift is properly shifted by the intracellular entrapment of a paramagnetic shift reagent. The sensitivity of this system is the highest displayed so far among CEST agents (less than 1 pM of cells), and the natural origin of this system makes it suitable for in vivo applications. The proposed Ln-loaded RBCs may be proposed as reporters of the blood volume in the tumor region.
authors.affiliation: Department of Molecular Biotechnology and Health Sciences, Molecular Imaging and Preclinical Centers, University of Torino , Torino, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Ferrauto
authors.forename: Daniela
authors.initials: D
authors.lastname: Delli Castelli
authors.forename: Enza
authors.initials: E
authors.lastname: Di Gregorio
authors.forename: Sander
authors.initials: S
authors.lastname: Langereis
authors.forename: Dirk
authors.initials: D
authors.lastname: Burdinski
authors.forename: Holger
authors.initials: H
authors.lastname: Grüll
authors.forename: Enzo
authors.initials: E
authors.lastname: Terreno
authors.forename: Silvio
authors.initials: S
authors.lastname: Aime
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage / Q000737:chemistry; D004912:Erythrocytes / Q000737:chemistry*; D006801:Humans; D028581:Lanthanoid Series Elements / Q000008:administration & dosage / Q000737:chemistry; D008279:Magnetic Resonance Imaging; D051379:Mice; D009374:Neoplasms, Experimental / Q000175:diagnosis*; D009942:Organometallic Compounds / Q000008:administration & dosage / Q000737:chemistry
chemical_list: D003287:Contrast Media; D028581:Lanthanoid Series Elements; D009942:Organometallic Compounds