Compositions and methods using same for delivering agents into a target organ protected by a blood barrier

A method of delivering a pharmaceutical agent into a target organ protected by a blood barrier is provided. The method comprising administering to a subject in need thereof an amount of liposomes which comprise the pharmaceutical agent, the amount and the liposomes are selected such that the liposomes accumulate in cells of an immune system of the subject to thereby generate liposome loaded immune cells, the liposome loaded immune cells become activated and cross the blood barrier, and an effective amount of the pharmaceutical agent is released from the liposomes in the target organ of the subject.