Mission Magazine - Smart Medicine

Smart Medicine

October 2002

by Amanda Gallagher

If you had your television set on for at least 15 minutes in 1991 you saw it: a U.S. Air Force smart bomb racing down a narrow Iraqi elevator shaft and exploding with the cleanest precision. The target looked impossibly small – the hit was impossibly perfect. The maneuver was a classic example of how smart bomb technology worked.

Now Health Science Center doctors have upped the ante and shrunk the bull’s-eye. A team of radiologists, pharmacologists and scientists is creating nanomolecular "smart bombs" – tiny capsules of medicine designed to seek and destroy diseases in the human body.

"This is a new way of delivering drugs and radiation therapy that is more effective than regular medicine because it goes directly to the disease site," said William T. Phillips, M.D., a professor in the department of radiology.

Dr. Phillips, along with Beth A. Goins, Ph.D., associate professor, radiology, are pioneers on an exploding frontier called bionanoscience. Simply put, they are manipulating the molecules on tiny capsules of medicine. Their work effectively answers the age-old question "how does the medicine know where to go?"

The capsules are made from organic lipids, or fats. "The lipids are derived from soybeans. They mimic what is already in our bodies," Dr. Phillips said. "We dry the fats and when we add water, they spontaneously form little bubbles, or lipid spheres. We encapsulate medicine in these spheres."

Don’t be fooled ndash; these capsules don’t look like the stuff that holds together your Tylenol®. They are 100 to 200 nanometers in size, which is slightly larger than a molecule, but still too small to see under an ordinary microscope.

Liposome therapy is already a big business, bringing in more than $400 million a year. But it is the way Health Science Center scientists have altered the lipid spheres that will make a tremendous impact on the way we track, treat and cure disease.

Health Science Center researchers have created nanomolecular lipid spheres, minuscule capsules of medicine programmed to zero in on the lymph nodes.

Researchers coat the lipid spheres with biotin, a naturally occurring vitamin cofactor. Researchers also inject a molecule called avidin. Avidin is attracted to biotin; the two molecules join together and cluster as they pass through the lymph nodes.

Making Medicine Smart

"The liposome therapies currently on the market are basically carrier systems for drugs that would be toxic if they weren’t encapsulated," Dr. Goins said. "We altered the liposomes to develop the first method of lymph node targeting."

In other words, Health Science Center researchers are able to program the liposomes to go directly to the lymph nodes – a key region in the spread of cancer and infectious diseases such as anthrax, tuberculosis and HIV.

"In typical drug delivery, less than 1 percent of the medicine releases in the area it needs to deliver the therapy. The rest goes through the kidney and the liver and could be potentially toxic," Dr. Phillips said. "This is a way for us to target and control the therapy with less toxicity to the rest of the system."

The Health Science Center team has a patent pending on the method, which is still in the experimental phase. But it is only one way to employ this incredibly "smart" medicine.

Dr. Goins set an industry standard for labeling the liposomes with a substance called technetium-99m. Dr. Goins used it to prove liposomes were congregating in areas of inflammation. The discovery could change the way doctors pinpoint disease.

"Many times a physician knows a patient has an infection but doesn’t know exactly where it is in the body," Dr. Goins said. "The patient could be injected with the radiolabeled liposomes and imaged to see if an infection is present and where it is located."

Dr. Phillips, along with radiological sciences graduate students Luis Medina and Ande Bao, are using imaging to see how liposome delivery systems work. "If we can prove through imaging that the liposomes are going to a certain place, then we can discover new ways of delivering a drug," Dr. Phillips said. Their work is funded in part by a grant from the San Antonio Area Foundation.

Further down the road, scientists could customize the lipid spheres for each patient. "We are interested in designing modular systems in which the drugs are encapsulated and each component is prepared separately and attached when needed," Dr. Goins said. "This potentially could provide patients with individualized treatment, customized to their specific disease."

It doesn’t end there. Dr. Phillips is collaborating with other Health Science Center researchers to develop treatments for head and neck cancers. He says someday doctors will be able to use the "smart technology" to blast out any ailment. "There isn’t a drug you couldn’t use with a liposome," Dr. Phillips said. "We can encapsulate antibiotics, anti-inflammatories, even local anesthetics. Someday you could use it to treat arthritis in your knee, for example."

It is almost a fantasy technology – too small to see and almost too overwhelming to comprehend. But it may eventually turn our bodies into healthy utopias, where "smart bombs" wipe out cruel diseases and take few casualties along the way.