Targeting of post-ischemic cerebral endothelium in rat by liposomes bearing polyethylene glycol-coupled transferrin

To achieve an efficient delivery targeting to post-ischemic cerebral vascular endothelium, PEG-liposome conjugated with transferrin (Tf) (Tf-PEG-liposome) was intravenously administered to the rats after 90 min of transient middle cerebral occlusion. The expression of Tf receptor (TfR) in the cerebral endothelium increased with a peak at 1 day after the reperfusion and returned to the control level by 6 days. The Tf-PEG fluorescence was marginally detectable in sham control brain, but remarkably increased with a peak at 2 days, showing about 70% of TfR positive vascular endothelium double-labeled with Tf-PEG. These results indicate that the Tf-PEG-liposome could be utilized as an efficient drug delivery tool to the brain after stroke.