Cellular Biotechnology Operations Support Systems: The Effect of Microgravity on the Immune Function of Human Lymphoid Tissue (CBOSS-02-HLT) - 01.09.14
Science Objectives for Everyone Cells grown in microgravity replicate and grow into complex structures, unlike cells grown on Earth. To better understand the mechanisms that cause the differentiation of cells in microgravity, six cell lines of common human illnesses were grown on ISS. The cells were returned to Earth and were used in the studies of several human diseases. This study is important for understanding the mechanisms needed to fight diseases of the human immune system.
Science Results for Everyone
This investigation of Human Lymphoid Tissue (HLT) cultures sought better understanding of how cells differentiate in microgravity and, ultimately, of how the human immune system fights disease. Early results indicate that cell suspensions showed impaired immune responses in microgravity, with the extent of that impairment depending on the activation state of the cells. Cells activated in microgravity did not demonstrate increases in antibody or cytokine production, while those activated prior to microgravity exposure did. Thus, microgravity may suppress immune responses involving circulating antibodies in ways similar to Human Immunodeficiency Virus (HIV), which could explain immune dysfunction seen in astronauts.
Wyle, Integrated Science and Engineering, Houston, TX, United States
Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)
Human Exploration and Operations Mission Directorate (HEOMD)
ISS Expedition Duration
December 2001 - June 2002
Previous ISS Missions
A previous version of the BSTC flew on STS-86/Mir and STS-90. BTR flew on STS-89 and STS-91. Cell-growth experiments have flown on the Shuttle since STS-70.
- CBOSS-02-HLT is one of seven in the suite of CBOSS experiments. The purpose of CBOSS is to support biotechnological research aboard ISS by providing a stable environment for growing cells.
- This self-contained apparatus is designed to allow multiple experiments studying various types of cells to operate simultaneously. It is a multi-component cell incubator intended to grow three-dimensional clusters of cells in microgravity.
- CBOSS-02-HLT uses human lymphoid tissue to study the effects microgravity has on the human immune response. These studies are important for addressing crew health especially for long duration missions.
The purpose of the Cellular Biotechnology Operations Support System (CBOSS) study was to support biotechnological research on board ISS by providing a stable environment in which to grow cells. The system was a multi-component cell incubator intended to grow three-dimensional clusters of cells in microgravity. A self-contained apparatus, CBOSS was designed to allow multiple experiments to be performed, thereby enabling scientists to study various types of cells operating simultaneously.
In the human body, cells normally grow within a scaffolding of protein and carbohydrate fibers that creates a three dimensional structure. But outside the body, cells tend to grow in flat sheets and are incapable of duplicating the structure they normally hold, which can make them behave differently in the laboratory than they would in the body. Past research has shown that cells grown in a microgravity environment arrange themselves into three-dimensional shapes that more closely duplicate how they would behave in the body. Cell culture in microgravity thus becomes a tool for studying cells in a state that is closer to that which occurs normally in the body.
Impaired immune function has been observed in astronauts during flight, and these observations are bolstered by evidence of lymphocyte dysfunction in the rotating wall vessel (RWV) culture system (the ground-based analog or model for cell culture in microgravity conditions). Using human lymphoid tissue cells that have been isolated from human tonsils and derived from five donors for the experiment, the goal of this study was to determine whether microgravity was detrimental to the immune responses of human lymphoid tissue cell suspensions.
These experiments will shed light on where immune responses break down and we hope to uncover improper regulation of certain factors. This knowledge would allow development of therapies for microgravity induced immune suppression and assay systems can be developed for on-board early detection of immune failures. This culture system is well suited for testing of any potential countermeasures.
In the human body cells normally grow within a scaffolding of protein and carbohydrate fibers that help create a three dimensional structure. This is how organs maintain their shape. Studying cells on Earth is difficult because outside the body cells tend to grow in flat sheets and are not capable of duplicating the structure they normally hold, which often makes them behave differently in the lab than they would in the body. Past research, however, has shown that cells grown in microgravity arrange themselves into three-dimensional shapes, more closely duplicating how they behave in the body. CBOSS, then, becomes very useful as a tool for studying cells in a state as close to that which occurs normally in the body. CBOSS-02-HLT is important for understanding cellular and molecular mechanisms of compromised immunity and may help uncover new pathways in regulation of the human immune system. This may lead to immunotherapy treatments for patients who suffer from sickle cell anemia, human immunodeficiency virus and other immunosuppressant diseases.
BSTC and GSM were housed side by side in lockers 1 and 5, respectively, of EXPRESS Rack 4. At the end of Increment 3, BTR was transferred to EXPRESS Rack 4, as well. GSM does not use power or gas supplied by the EXPRESS Rack, but does interface with the Station computer via the EXPRESS Rack's Ethernet connection. BCSS-1 and -4, housed directly below BSTC and GSM in lockers 2 and 6, do not require EXPRESS Rack support. BTR is located in EXPRESS Rack 1, locker 6. It operates on 160 watts of continuous power and Ethernet connection provided by the rack.
After the CBOSS hardware was installed on ISS, the crew activated the experiments and monitored the status of the experiments and hardware. Crew members used a syringe to inject cells into fresh TCMs, using the TCMs' injection ports. They also added fresh media to growing cell lines and fixatives at the end of the experiment to halt growth. When the cultures were fixed, the TCMs were transferred to the BTR for storage. The crew performed periodic preventive maintenance on the CBOSS components. Video and data was downloaded to the CBOSS flight control team at the Johnson Space Center's Telescience Center. The CBOSS-02-HLT experiment's TCM was returned to the principle investigator for in-depth analysis.
The CBOSS hardware supported six cell culture investigations with different detailed scientific objectives. There were problems in the growth and preservation of all of the cell lines grown on Expeditions 3 and 4. The PC12 and erythroleukemia cells did not survive well in long term culture, so no scientific results are expected from these experiments. It was found that there was more bubble formation than expected that may lead to cell death at the air-liquid interface. Although not well documented in this experiment, it was noted that poor mixing of cells/tissues and medium occurred in the other CBOSS payloads as well. Both the poor mixing and greater than expected bubble formation were important lessons learned that led to the addition of the CBOSS-Fluid Dynamics Investigation (CBOSS-FDI) to study mixing and bubble formation in microgravity on later Expeditions.
The human lymphoid tissue cultures were activated on board station but did not survive in longer-term culture. Early preliminary results, which were in agreement with RWV ground studies (microgravity simulation), indicated that the human tonsil cell suspensions show impaired immune responses in microgravity and that the extent of impairment depended on the activation state of the cells. Cells in all conditions showed metabolic activity, indicating that they were alive. Cells that were activated in microgravity did not demonstrate any increases in antibody or cytokine production; however, if the cells were activated prior to exposure to microgravity, they did demonstrate such responses. These results indicated that microgravity suppresses humoral immune responses in a not dissimilar fashion to that of Human Immunodeficiency Virus on Earth, and that this phenomenon may reflect immune dysfunction observed in astronauts during space flights (Fitzgerald et al. 2006). (Evans et al. 2009)
Fitzgerald W, Chen S, Walz C, Zimmerberg J, Margolis L, Grivel J. Immune suppression of human lymphoid tissues and cells in rotating suspension culture and onboard the International Space Station. Society for In Vitro Biology. 2009 07/16/2009; 45: 622-632.
Ground Based Results Publications
Jessup JM, Pellis NR. NASA biotechnology: cell science in microgravity.. In Vitro Cellular and Developmental Biology - Animal. 2001; 37(2): 2. PMID: 11332737.
NASA Image: ISS004E5210 - Image of a Quad Tissue Culture Module Assembly (QTCMA) 5 on ISS Expedition 4 after activation of the cells. A syringe was used to inject cells into the pink nutrient growth media. The BSTC can hold eight of these QTCMAs, which will be used to grow human cells on ISS. When the samples completed their growth cycle, the crew transfered the QTCMAs from the BSTC to the BTR, where they were stored until they are examined at a ground-based laboratory. Courtesy image from Marshall Space Flight Center.
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Image shows blocks of human lymphoid tissue being cultured in the Rotating Wall Vessel system. Image courtesy of NASA.
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