Efficient Intracellular Delivery of an MR Imaging Probe by a Novel Cell Penetrating Peptide

A novel cell penetrating peptide (CyLoP-1) was obtained by structure activity relationship studies. It exhibited efficient transport across the cell membrane and distribution in the entire cytosol as well. These distinctive properties were only slightly influenced by the coupling of Gd-DOTA. This conjugate was slightly less internalized into 3T3 fibroblasts, but the cellular distribution was retained. MR studies on labeled cells revealed an exceptional high contrast enhancement in T1-weighted images. These results demonstrate its potential to be used for efficient transmembrane delivery of imaging agents and as vector for probes specifically targeted to cytosolic constituent.