A comparative study of transfection efficiency between liposomes, immunoliposomes and brain-specific immunoliposomes

This study investigated the transfection ability and efficiency of liposomes and immunoliposomes for exogenous gene delivery into the brain via the venous system. Four groups of rats underwent tail vein injection with one of the following: liposomes encapsulating pCMV (human cytomegalovirus promoter)-LacZ plasmid 80 microg (low dose) or 300 microg (high dose); general immunoliposomes encapsulating 80 microg transferrin receptor antibodies (OX26)-pCMV-LacZ plasmid; or brain-specific immunoliposomes encapsulating 80 microg OX26-pGFAP (glial fibrillary acidic protein promoter)-LacZ plasmid. A control group received no injected agent. The LacZ mRNA levels (1 h post-injection) and beta-galactosidase activity (48 h post-injection) in the brain and peripheral organs were assayed using real-time reverse transcription-polymerase chain reaction and histochemical staining, respectively. Both immunoliposomes delivered exogenous DNA containing the LacZ gene into the brain after venous injection, resulting in extensive LacZ expression in the brain. Furthermore, the brain-specific OX26-pGFAP-LacZ immunoliposome decreased the non-specific expression of LacZ in peripheral organs without affecting transfection efficiency in the brain. Thus, brain-specific immunoliposomes are an efficient and brain-specific targeting vector.