Oct. 15, 1998 COLLEGE STATION -- All eyes will be on space veteran Sen. John Glenn when the space shuttle Discovery launches on Oct. 29. As part of his mission Glenn will perform unique cancer chemotherapy experiments in collaboration with Texas A&M University's College of Veterinary Medicine.
Glenn will be using Discovery's zero gravity conditions to create "microcapsules," tiny hollow bubbles made of oil and water-like substances that can hold drugs and be placed by injection into the body directly at tumor sites. Microcapsules would bombard tumors with a higher drug dose than previously possible with fewer side effects than standard chemotherapy methods, said Dawn Boothe, an associate professor at Texas A&M's College of Veterinary Medicine who is working with NASA on the project.
Boothe said chemotherapy drugs rarely stay at tumor sites long enough for maximum effectiveness and travel to other parts of the body, killing normal cells and causing weakened immunity, nausea, hair loss and other severe conditions.
"That's one reason why cancer drugs are so dangerous," she said. "Right now we're limited in how much drug we can give because of side effects. If we could put the drug in a vehicle and cause the vehicle to stay at the tumor, the drug wouldn't reach other tissues and the tumor would get be exposed to a much higher drug concentration."
Aboard Discovery, Glenn will create and perfect new microcapsules that he will fill with dye that shows up in CAT scanning and two different drugs currently used in chemotherapy. Once these microcapsules are returned to Earth, Boothe and her co-investigators, Mike Walker, Lisa Howe and Albert Boeckh, will test the microcapsules' performance in radiology laboratories. Because microcapsules block blood flow, researchers must be certain they won't harm normal tissues, Boothe said.
NASA, with the help of the Institute of Research Inc., came up with the idea of microcapsules, which will form only in zero gravity conditions, and created them on earlier shuttle missions. Once removed from weightlessness, however, microcapsules, which are almost invisible to the naked eye, stay formed and can be filled with the drug of choice. They are designed to be passed via a catheter directly into an artery that feeds blood to a tumor.
Once in place, microcapsules release their drugs directly to the tumor. After a certain period of time, they simply dissolve into the body's tissues. And because microcapsules lodge in the arteries, they block the tumor's blood supply and help stop cancer cell growth.
Boothe and her team will use catheters to pass the microcapsules into rabbit kidneys, then use CAT scanning to see if the drugs stay near the site without spreading to other tissues. She said previous testing at Texas A&M without the actual drugs, using only radio contrast material and CAT scanning, was a success.
"The spheres seemed to work," Boothe said. "They seemed to go where we wanted them to go and stay where we wanted them to stay." She said it's too soon to know how long microcapsules would need to release drugs in the body to be effective.
Boothe said she believes the public doesn't have a clear concept of how the space program can help further research into a widespread disease such as cancer.
"I think it's a good example of how veterinary medicine can contribute to human medical needs," Boothe said. "It's very possible that this will help animals as well. It's for the common good."
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