MicroRNA Expression Profiles in Cultured Human Fibroblasts in Space (Micro-7) - 07.14.16
The majority of cells in the human body are non-dividing cells that provide critical functions, from blood cells, to cells in different organs. Micro-7 studies how microgravity affects the genetic expression and physical shape of these types of cells for the first time. Understanding how these cells function in microgravity is a step toward understanding how organs, tissues, and the entire body change during spaceflight. Science Results for Everyone
Now that is high culture. This experiment looks at when, in their life cycle, cultured cells undergo genetic changes caused by microgravity. Genetic changes in cells were seen early in flight, but this was due to cell growth, not microgravity. By day 14 in space, gene expression profiles and cell structure were the same in flight and ground samples. Cultured cells seem to multiply faster in space, suggesting microgravity does not inhibit free growth. This may partly explain how cells in the body and in culture respond differently to microgravity; cells in the body are subjected to mechanical forces while cultured cells do not. Experiment Details
Honglu Wu, Ph.D., Johnson Space Center, Houston, TX, United States
Ye Zhang, Ph.D., Johnson Space Center, Houston, TX, United States
NASA Ames Research Center, Moffett Field, CA, United States
BioServe Space Technologies, University of Colorado, Boulder, CO, United States
Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)
Human Exploration and Operations Mission Directorate (HEOMD)
ISS Expedition Duration
March 2014 - September 2014
It is not known how the space flight environment affects non-dividing cells, which are the majority of cells that make up the human body. Changes are observed to organs, tissues and whole body systems, yet the root causes are not understood or known. In order to gain insight, it is important to study the fundamental functional unit of tissues and organs, which is the cell. By studying a single cell type in culture instead of whole tissues or organs, the scientist will be able to clearly investigate the root molecular and cellular biological effects of the space flight environment on the cell and eliminate potential complicating factors due to different cell types that may make up a specific tissue type or organ. The bleomycin study will examine the induction of, as well as cellular responses to, DNA double strand breaks (DSB) in the microgravity environment. Living organisms in space are constantly exposed to space radiation and other environmental toxins. Differences in the capability to repair or misrepair DNA damages between the microG and 1G conditions will impact the accuracy of the risk assessment of astronauts, and the accuracy in predicting the mutation rate in microorganisms.
The data from this study will provide deeper insight into how gene expression regulates cellular adaptation to the space flight environment. Specifically, it will provide further understanding of the roles microRNA (miRNA) play in gene expression regulation that will be of benefit to both space flight exploration and Earth scientific research.
The identification of the role of miRNA in gene regulation will help to elucidate the fundamental process that are affect by or regulate adaptation to the space flight environment. Since this experiment compares space flight samples with ground samples, differences between the the specimens will elucidate unknown functions of miRNA and identification of cellular/biochemical pathways that are regulated by miRNAs. Also, since the experiment uses normal human fibroblast in their non-dividing condition, it will provide new information on how normal cellular function and adaptation are affected by the space environment. Collectively, the data may be used for Earth-based fundamental and biomedical research to examine if the changes observed in space flight are seen in disease states of tissues and organs. Furthermore, the data may point out important targets for further study in ground-based and space-based research. Ultimately, the data may be applied to understanding tissue and organ structural maintenance and disease.
1) Determine miRNA expression profiles in confluent AG1522 human fibroblast cells in space and on the ground with PCR array.
2) Determine gene expression profiles in confluent AG1522 human fibroblast cells in space and on the ground with Illumina gene array.
3) Determine changes in miRNA and gene expression profiles in and pathways affected by the microgravity environment using statistical and bioinformatics methodologies. Determine correlation between miRNA and RNA expression patterns.
4) Measure the number of DSB in the cultures used for the Bleomycin study plus 1-3 above.
Human tissues and organs are made of non-dividing but functional cells. According to Earth-based experiments, non-dividing cells’ genetic expression and micro-RNA profiles change in response to simulated microgravity. Micro-7 is the first space experiment to directly investigate how microgravity affects the gene expression and physical shape of fibroblasts, which are common tissue cells. Fibroblasts are critical for wound healing and tissue structure, so understanding how they function in space could provide crucial insight for future space missions.
Understanding the differences between cells’ genetic expression on the ground and in microgravity can provide new insights into genetic regulation and signaling pathways. Micro-7 aims to explain the role of micro-RNA, a type of molecule involved in how genetic information is processed in a cell. Micro-RNA might be important in regulating how cells respond to the space environment, and data from Micro-7 could be compared with ground-based data to provide insight into miRNA’s role in gene regulation. Understanding fundamental molecular processes in cells could provide new pathways for disease treatment, including potential new pharmaceutical products.
Operational Requirements and Protocols
The crew will inject a preservative or fixative into the biochamber at specific time points. After the specimens are processed, the biochambers will be transferred to either +4 oC or -80 oC stowage. If the CGBA will be powered for return, the +4 oC stowed specimens may be returned to the CGBA for return, otherwise the specimens will be transferred to a +4 oC cold stowage bag. The cryo (if needed) specimens will be transferred to either GLACIER or a cryo-cold stowage bag for return.^ back to top
Decadal Survey Recommendations
Information Pending^ back to top
Among space radiation and other environmental factors, microgravity is undoubtedly the most significant stress experienced by living organisms during spaceflight and has been shown to influence gene expression (the making of useful products in the body to maintain life) patterns and protein levels in lab-grown cells. Early space studies with human fibroblasts (connective tissue) have identified genes whose expression levels were modified as a result of spaceflight, but it was not known whether non-dividing cultured cells respond to the absence of gravity as well. In an experiment conducted onboard the International Space Station (ISS), growth inhibited human fibroblast cells were grown in space for 3 and 14 days, respectively, to investigate changes in gene and microRNA, or “miRNA,” which are non-coding RNAs that play key roles in the regulation of gene expression in cells. Results of the experiment showed that on day 3, both the flown and ground cells were still growing slowly and the genetic changes seen with these cells were not space induced but related to cell growth. On day 14, when the cells had mostly stopped dividing and were in a resting state, the gene and miRNA expression profile of the flight sample was indistinguishable from that of the ground sample. Analysis of cytoskeletal (filaments and tubules within the cell) changes showed no difference between the flown and ground samples. Although the cells seem to multiply faster in space than they did on the ground, data suggest that in true non dividing human fibroblast cells in culture, microgravity has little effect on their gene and miRNA. This finding may provide a partial explanation for the different responses to microgravity between cells in the body and cells in culture since cells in living organisms in the true microgravity environment still experience mechanical forces from varying blood pressures that cells in culture do not experience.^ back to top
Zhang Y, Lu T, Wong M, Wang X, Stodieck LS, Karouia F, Story M, Wu H. Transient gene and microRNA expression profile changes of confluent human fibroblast cells in spaceflight. FASEB: Federation of American Societies for Experimental Biology Journal. 2016 February 25; epub: fj.201500121. DOI: 10.1096/fj.201500121. PMID: 26917741.
Ground Based Results Publications
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NASA Image: ISS039E015593 - NASA astronaut Rick Mastracchio processes a Micro-7 BioCell Habitat with use of a Fixation Kit.
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NASA Image: ISS039E015644 - NASA astronaut Rick Mastracchio processes a Micro-7 BioCell Habitat with use of a Fixation Kit.
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NASA Image: ISS039E018752 - NASA astronaut Rick Mastracchio processes a Micro-7 BioCell Habitat with use of a Fixation Kit.
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