Liposome accumulation in regions of experimental myocardial infarction.

The uptake of liposomes bearing positive, negative, or no net charge on their membrane and containing a radioactive tracer, [99mTc]diethylenetriamine pentaacetic acid, was studied in 12 intact dogs 24 hours after the induction of myocardial infarction, and compared to the relative regional myocardial blood flow determined from radioactive microspheres. Positively charged and neutral liposomes concentrate in infarcted regions against a flow gradient, while negative liposomes are passively distributed according to regional blood flow. Because positively charged and neutral lipisomes concentrate in infarct areas and have the ability to incorporate pharmacologic agents in their aqueous or lipid phase, they may serve as vehicles for drug delivery to infarct zones of low flow.