Lysosome-disrupting peptide increases the efficiency of in-vivo gene transfer by liposome-encapsulated DNA

The main limitation of liposome-mediated gene transfer is its low efficiency, a result of degradation of the transferred DNA in the lysosome compartment. In an effort to overcome this problem, lysosome-disrupting peptide was co-encapsulated with a luciferase expression vector in liposomes. The encapsulation level of the peptide was high (> 80%) and did not affect DNA encapsulation efficiency. Liposomes encapsulating DNA were injected into mice and the efficiency of gene transfer and expression were measured. Polymerase chain reaction (PCR) analysis of DNA purified from mouse livers and spleens indicated that co-encapsulation of lysosome-disrupting peptide with DNA significantly increased the amount of transferred DNA found 5 days post-injection in the organ cells. Luciferase activity at 5 days post-injection in spleens of mice that were injected with liposomes containing luciferase expression vector and lysosome-disrupting peptide was significantly higher than that in mice injected with liposomes containing only luciferase expression vector or liposomes containing luciferase expression vector and control peptide. These results indicate that the efficiency of in-vivo liposome-mediated gene transfer can be significantly increased by co-encapsulation of lysosome-disrupting peptide with the transferred DNA.