Liposomes— Drug Delivery 
Vehicles of the Future 
Can microscopic artificial membranes help 
doctors treat cancer, angina, and viral 
infections more effectively, and lead to better 
vaccines, bronchodilators, eye drops, and 
sunscreens? The researchers who are devel- 
oping liposome technology hope so. A 
liposome is a tiny sphere of fatty molecules 
surrounding a watery interior. Because they 
are made of the same material as cell 
surface membranes, liposomes stick to cells 
and are not toxic. These characteristics 
make them attractive candidates for drug de- 
livery vehicles. 
In 1 980, two groups of researchers used 
liposomes filled with a common antibiotic to 
cure mice having a severe, but localized, 
infection. The infected cells were of a kind 
that is specialized to take up foreign bodies, 
and so they readily engulfed the liposomes. 
However, getting other kinds of cells to take 
up drug-filled liposomes has proven to be 
more difficult. A number of groups of 
researchers are experimenting with antibody- 
tagged liposomes filled with an anticancer 
drug. The liposomes are guided to the 
diseased tissue by the antibodies, which 
seek out cancerous cells but spare healthy 
ones. This selectivity allows smaller amounts 
of a drug to be used with greater effect, an 
important advantage considering the serious 
toxicity of many anticancer drugs. 
Other research teams are developing 
liposome-drug compounds that would be 
injected into muscle to release growth ,, 
hormone or anticancer agents over a period 
of weeks. Scientists also hope to use 
liposomes to improve the safety and effec- 
tiveness of vaccines, including an influenza 
vaccine. As the cost of both natural lipids 
(extracted from egg yolk and soybeans) and 
artificial lipids declines, the future may bring 
many other liposome-containing medical 
products as well as nonmedical items, such 
as cosmetics. 
