IOWA CITY, Iowa - When the Space Shuttle Columbia begins its scheduled five-day mission on July 19, it will carry a University of Iowa oxygen sensing system that may enable researchers to accurately monitor and study human cell growth and metabolism in space.
Funded by a three-and-one-half-year, $965,000 NASA grant, the UI project will help simulate conditions under which cell growth occurs in the human body by monitoring oxygen levels within the cell growth units carried aboard the shuttle. Mark A. Arnold, UI professor of chemistry and project leader, says that the operation of his oxygen-sensing module will be evaluated during the space shuttle flight. He adds that the success of future space shuttle cell growth experiments depends upon accurate oxygen sensors.
"Oxygen is critical, as too much can be toxic, resulting in cell death, and too little starves the cells, thereby retarding growth. The information provided by our sensor will permit feedback control, thereby maintaining optimal growth conditions. In addition, our oxygen sensing unit is designed to measure the consumption of oxygen by cells, and this information can be used to monitor cell growth," he says.
The oxygen sensor works by providing a radioluminescent light source that supplies radiation for the measurement of an oxygen-dependent luminescence given off by an indicator dye. Eight sensors are incorporated into each sensor module, which, in turn, is integrated into NASA's cell culture module (CCM), which is used to grow various types of cells during space shuttle experiments. Some of the experiments are designed to learn about the phenomenon of muscle, bone and cell deterioration caused by microgravity stress. Arnold notes that the space shuttle oxygen sensor test results will be used to improve the next generation of oxygen sensors for future CCM missions as well as for other NASA bioreactor units. The technology is also being developed for similar Earth-based bioreactor applications.
The UI oxygen sensor is highly sensitive and stable, allowing it to differentiate small changes in dissolved oxygen levels and undergo extended operation without need for re-calibration. Stability is important because heavy demands on astronaut time during a Space Shuttle flight would make periodic sensor re-calibration impossible. (The sensing unit is pre-calibrated in the UI laboratory before arriving at the John F. Kennedy Space Center, and the calibration is maintained throughout the mission.)
These features are made possible by a patented technology developed in Arnold's laboratory within the Department of Chemistry and the Optical Science and Technology Center (OSTC). A former graduate student, Han Chuang, a current graduate student, Julie Seeba, and a systems engineer, Michael Miller, developed the technology.
The UI project is being conducted in collaboration with David Murhammer, UI associate professor of chemical and biochemical engineering, and Michael Cohen, UI professor of pathology. Arnold is developing the sensing technology, while Murhammer is working to optimize the cell growth environment and Cohen is interested in applying the technology to the study of prostate cancer.
Arnold and his colleagues are a part of the Cell Culture Model experiment, one of 13 scientific payloads being carried aboard the space shuttle. The flight is perhaps better known for carrying the heaviest payload to date, the Chandra X-ray Observatory, and for being the first shuttle mission to be led by a female commander, Eileen M. Collins.