Station crew completes microcapsule experiment
Posted: July 30, 2002

The Expedition Five crew of the International Space Station has successfully completed a manufacturing experiment to create microcapsules that could aid the development of an improved drug delivery method in the body.

A total of eight samples were processed in the Microencapsulation Electrostatic Processing (MEPS) experiment, said MEPS Principal Investigator Dr. Dennis Morrison, with the Medical Sciences Division at NASA's Johnson Space Center in Houston.

"All data and the microcapsules produced during the experiment runs will be returned on the STS-112 Space Shuttle mission," Morrison said. "The experiment appeared to run without any anomalies. We are very anxious to get back our samples and start analyzing them."

The first four experiment runs studied the encapsulation process, using different modes of mixing dissimilar fluids to create microcapsules for two different formulations of a light-activated anticancer drug derived from a porphyrin molecule isolated from blood, Morrison said. To treat cancers, this drug is injected into blood vessels leading to the tumor where it is preferentially absorbed by tumor cells and later activated by applying near-infrared light that penetrates deep into tissues. Superoxides released by the light then kill the tumor cells. The fifth experiment encapsulated DNA from genetically engineered E. coli bacteria.

Two later experiment runs encapsulated a mix of two anti-cancer drugs and tiny ferromagnetic particles that would allow doctors to trigger them with a magnetic field to release their drugs into tumor tissues. A third experiment encapsulated the same drug mixture without trigger particles and then a high voltage electrostatic field was used to deposit a thin polymer coating onto the microcapsule outer membrane.

The automated MEPS experiment cures, filters, washes and harvests the microcapsules for analysis on the ground. Experiments such as this could eventually lead to the development of anti-tumor drugs that allow the delivery of higher doses of chemotherapeutic drugs to specific treatment sites, reducing the unwanted side effects experienced by cancer patients.

"The MEPS experiments in microgravity are conducted to better understand the manufacturing process on Earth, where the gravity-induced sedimentation of the different density components greatly confuses the understanding of what conditions, fluid flow, temperature, etc. produce the most uniform microcapsules with the maximum drug loading," Morrison said. "Thus, we are not just checking out hardware, but making microcapsules for further study and to develop large scale production techniques so that companies can make these for various types of drug deliveries into human and veterinary patients."

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