The Expedition Five crew has successfully completed a manufacturing experiment that could lead to an improved method of drug delivery in the body.
A total of eight samples were processed last Thursday and Friday 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 last Thursday 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 Thursday encapsulated DNA from genetically engineered E. coli bacteria.
Two experiment runs on Friday 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. The third experiment Friday 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."
The Protein Crystal Growth Single Thermal Enclosure System (PCG-STES) experiment completed processing one sample on Friday. Four other sample processing cylinders remain active in this experiment to grow biological materials for study on the ground and possible applications in medicine and agriculture.
On Tuesday, the Station science team initiated the second of 10 planned tests with the Solidification Using a Baffle in Sealed Ampoules (SUBSA) experiment. The furnace failed to heat properly during the run, possibly due to a software error that can be resolved by ground commanding. The science team and controllers are troubleshooting today. Additional troubleshooting may replace another experiment run planned for Thursday. SUBSA is the first of two Expedition Five materials science experiments that will study basic physical processes similar to those used to make semiconductors for electronic devices and components used in jet engines. A total of 10 samples will be processed during the Expedition.
The experiment also was monitored by a portable vibration sensor located in the Microgravity Science Glovebox and connected to the Space Acceleration Measurement System (SAMS), located in EXPRESS Rack 1. Flight Engineer Peggy Whitson changed out the SAMS hard drive and battery last week to ensure that the portable sensor operated correctly during the run. SAMS supports many of the experiments onboard by characterizing the microgravity environment.
Also on Tuesday, Commander Valery Korzun and Whitson set up and conducted the Pulmonary Function in Flight (PUFF) lung function test. Each PuFF session includes five lung function tests. The focus is on measuring changes in the evenness of gas exchange in the lungs, and on detecting changes in respiratory muscle strength. A decrease in the evenness of gas exchange is a hallmark of virtually every acute condition and disease of the pulmonary system. Changes in respiratory muscle strength may result from long periods in the absence of gravity. The results will help in maintaining crew health during long space missions.
The crew today (Wednesday) was scheduled to conduct their weekly Crew Interactions survey on the Human Research Facility laptop computer. The Interactions experiment will identify and characterize important interpersonal and cultural factors that may impact the performance of the crew and ground support personnel during International Space Station missions.
On Thursday, the crew is scheduled to collect background radiation readings for the EVA Radiation Monitoring (EVARM) experiment and then transfer the measurements to a laptop computer to be downlinked later that day.
On Friday, the crew is scheduled to participate in and videotape a session with the Education Payload Operations experiment. For this activity, they will use a variety of simple toys to illustrate basic principles of physics. Crew Earth Observations photography subjects this week included: fires in Zimbabwe, air quality in industrialized southeastern Africa, and vegetation in the Parana River basin. The number of photo targets is expected to be reduced for several weeks as the Station's orbital path carries it over the shadow-darkened winter of the Southern Hemisphere.
Other experiments under way in the Destiny laboratory module continue to function normally.