Bioreactor expands health research

Good neighborhoods help you grow. It is true of humans, and of the cells of which we and all complex organisms are made. A challenge which has faced cell science throughout its short history is that most cell cultures produce flat, one-cell-thick specimens that offer limited insight into how cells work together. Such knowledge is crucial if we are to understand the chemistry and mechanics of healthy organs and of cancers, infectious diseases, immune system failures, and other public health problems.
The heart of the bioreactor is the rotating wall vessel, shown without its support equipment (links to 1266x877-pixel, 280K JPG). (NASA)
The National Aeronautics and Space Administration, in concert with the biomedical community, has initiated work that offers significant advances in cell culturing technology on Earth that enables further unique research progress aboard Space Shuttle, Mir, and - soon - International Space Station. The NASA Biotechnology Cell Science Program, directed by Dr. Neal Pellis at NASA's Johnson Space Center, involves more than 100 scientists, engineers, and support personnel around the nation.
A new spin on cell growth
They are meeting the challenge with a unique new technology, the rotating wall vessel bioreactor. It spins a fluid medium filled with cells to neutralize most of gravity's effects and encourage cells to grow in a natural manner. The rotating bioreactor was invented by NASA as a model of microgravity effects on cells.
Ground tests of the bioreactor yielded three-dimensional tissue specimens approximating natural growth, a striking change from the pancake shapes of traditional cultures.
As cells replicate, they "self associate" to form a complex matrix of collagens, proteins, fibers, and other chemicals. This highly evolved microenvironment tells the cells who is next door or nearby, how they should grow and into what shapes, and how to respond to stimuli such as bacteria and wounds. Thus, we have the opportunity to study the complex order of tissue in a culture system that can be manipulated by drugs, hormones, and genetic engineering.
Staying in touch
As with a city, the lives of a cell are governed by its neighborhood connections. Those connections that don't work have been implicated in muscular dystrophy, osteoporosis, glaucoma, and the spread (metastasis) of cancer cells throughout the body.
Studying these mechanisms outside the body on Earth is limited by gravity's effects because the cells do not easily self-associate to grow naturally. The bioreactor promotes self-association in a container about the size of a soup can. The clear shell allows scientists to check growth, and the center holds a cylindrical filter that passes oxygen and nutrients in and carbon dioxide and wastes out. This ensures that the fluid rotates without shear forces that would destroy the cells. The rotating vessel does not really cancel gravity, but ideally maintains cells in continual free-fall similar to that experienced by astronauts in the microgravity of space.
Earth-based bioreactor cultures typically maintain cell growth for at least 60 days. On Earth, a sample then becomes so large (about 1 cm) that it is no longer suspended. In long space missions, large-sample growth in bioreactors can be studied in order to understand the extended growth and differentiation of cells, such as engineering complex tissue or modeling slow-growing tumors.
With long-term stays aboard the Mir space station and, soon, the International Space Station, NASA and the biomedical community have this opportunity to explore this new frontier in cell science and contribute to public health.
Targeted health issues
Infectious disease: Human immunodeficiency virus (HIV), Ebola virus, Lyme disease.Cancer models: Prostate, breast, ovary, lung, and colon cancers.Diabetes: Work on a pancreatic tissue for transplant.Therapies: Musculoskeletal tissue disorders (in space and on earth).Drug efficacy: Non-animal/nonclinical testing of drug effects and toxicity.