CANCER GENE-THERAPY USING PLASMID DNA - PHARMACOKINETIC STUDY OF DNA FOLLOWING INJECTION IN MICE

The fate of plasmid DNA complexed with cationic lipids delivered intra venously in mice was evaluated at selected timepoints up to 6 months p ostinjection. Blood half-life and tissue distribution of plasmid DNA a nd potential expression in tissues were examined, Southern blot analys es of blood indicated that intact plasmid DNA was rapidly degraded, wi th a half-life of less than 5 min for intact plasmid, and was no longe r detectable at 1 hr postinjection. Southern analyses of tissue demons trated that intact DNA was differentially retained in the lung, spleen , liver, heart, kidney, marrow, and muscle up to 24 hr postinjection. After 7 days, no intact plasmid DNA was detectable by Southern blot an alysis; however, the plasmid was detectable by the polymerase chain re action (PCR) in all tissues examined at 7 and 28 days postinjection, A t 6 months postinjection, femtogram levels of plasmid were detected on ly in muscle, Immunohistochemical analyses did not detect encoded prot ein in the tissues harboring residual plasmid at 1 or 7 days postinjec tion.