Cellular uptake of ribonucleic acids entrapped into liposomes.

Ribonucleic acids were entrapped into phospholipid vesicles (liposomes). After incubation of the liposomes containing RNA (L- RNA), the RNA was introduced into the cells. The kinetics of L- RNA uptake by the cells in culture were studied. The uptake of L- RNA is linear over a broad vesicle concentration range depending on temperature, and at 37 degrees C uptake levels reach a plateau after 3 hours. Inhibitors of cellular energy metabolism have little effect on the uptake, and thus fusion, as the main mechanism of uptake, is proposed.