Bone Proteomics (BOP) - 09.17.14
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Reduced activity of bone making cells, called osteoblasts, causes bone loss in space. Scientists don’t yet know how this works, and this experiment looked at how osteoblasts are regulated in space. Stimulating osteoblasts in microgravity with a substance known as Adenosine triphosphate (ATP) seem to increase a protein- and enzyme-signaling pathway involved in cell survival and also seem to affect regulation of several proteins. As the first protein-based study on mammalian cells in space, this effort provides better understanding of osteoblasts to help address microgravity-induced bone loss in space and bone disease on Earth.
Sponsoring Space Agency
European Space Agency (ESA)
ISS Expedition Duration
October 2004 - October 2005
Previous ISS Missions
Long periods of weightlessness induce bone mass loss in astronauts. Previous experiments indicate that this negative effect is mainly due to a reduced activity of osteoblasts; the cells that physiologically produce the bone material throughout our life. Weightlessness alters both the maturation and the bone-production activity of osteoblast cell cultures, but the mechanisms involved are not yet fully understood. The Bone Proteomics experiment will study the molecular mechanisms that regulate the physiology of human osteoblasts in weightlessness. The experiment consists of stimulating osteoblast cells in microgravity with a molecule known as ATP. The specific objectives of the experiment are: To study whether or not ATP can stimulate osteoblast cells in weightless conditions; possibly balancing or overcoming the negative effects of weightlessness. To study, for the first time, the whole protein content of these cells in search of possible explanations concerning the altered physiology of osteoblasts in weightlessness; called a proteomics approach. This experiment will be the first proteomic study on mammalian cells in space, possibly revealing new aspects of osteoblast biology; nevertheless, it is expected to provide new data for a better understanding of osteoblast physiology at the molecular level. The results of this experiment are beneficial to both space and ground research. The former, in the field of bone physiology in microgravity and microgravity-induced bone loss particularly for long-duration space missions; and the latter, for bone disease research on Earth (e.g. osteoporosis).
Samples of osteoblast cells that have been stimulated with ATP in weightlessness will be compared to a ground-based reference experiment. The samples will be analysed by means of an approach that allows for the identification of proteins under different conditions. The experiment hardware consists of a stack of electrical heated culture chambers, a liquid handling system and a glove bag. The osteoblast cells grow in separate culture chambers that are equipped with thin membranes to allow liquid exchange. Liquid exchange is necessary to provide the cells with nutrient, to stimulate the cells and to wash the cells. All fluids are injected and extracted with syringes (the liquid handling system). The operations to be performed by the crew on the payload are basically to exchange liquids in the culture chambers through the use of the syringes at different times during the mission. Liquid exchange is conducted in a glove bag. The culture chambers with the samples of the cells inside will be returned to Earth for analysis.
New hardware was developed in less than nine months for the experiment that provided 70 cm2 per chamber and a total of more than 200 cm2. Preliminary analysis indicated that administration of ATP to MG-63 cells cultured in weightlessness conditions was able to increase extracellular-signal-regulated kinase (ERK) phosphorylation. Analysis of 2D gels revealed several differentially regulated proteins in response to ATP treatment. To the best of our knowledge, BOP is the first proteomic study on mammalian cells cultured in space. The conclusion of the analysis will reveal new aspects of osteoblast biology and provide new insights into the molecular responses of human cells to weightlessness.
Costessi A, Costessi A, Vascotto C, Pines A, Schonenborg R, Romanello M, Schiller P, Moro L, Tell G. Bone Proteomics experiment (BOP): the first proteomic analysis of mammalian cells cultured in weightlessness conditions. 57th International Astronautical Congress, Valencia, Spain; 2006 October 7 pp.
Ground Based Results Publications
ESA Erasmus Experiment Archive
Bone proteomics flight hardware. Image courtesy of ESA.
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Bone proteomics experiment culture chamber. Image courtesy of ESA.
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