Cationic liposomes in gene delivery

Cationic liposomes have been extensively explored as gene delivery vector for several reasons. It is because disadvantages of viral vectors include risk of replication, possible immunogenicity, and the difficulty of obtaining a large quantity of viral vectors. Currently, a variety of cationic components for liposome formulations have been developed. The components are broadly divided into two classes based on the chemical structure of hydrophobic moieties: long aliphatic (saturated or unsaturated) hydrocarbons and cholesterol ring. A variety of hydrophilic moieties also include tertiary amines, ammonium salt and spermine. The role of liposomes is to condense DNA to form complexes with high affinity to cell surfaces where possible fusion or destabilization of the membrane and/or endocytosis are involved. However, at present, little structure-activity relationships are known. Some vectors are on clinical trials approved by NIH.