A liposome for use in delivering a pharmaceutical agent into a target organ protected by a blood barrier comprises a pharmaceutical agent targeted at an organ protected by said blood brain barrier, wherein said liposome is accumulated in a cell of an immune system of said subject to thereby generate a liposome loaded immune cell, said liposome loaded immune cell is capable of crossing the blood barrier, where an amount of the pharmaceutical agent is released from said liposome in the target organ of the subject.