A three-dimensional (3D) clinostat is a device for generating multidirectional G force, resulting in an environment with an average of 10(3) G. Here we report that human mesenchymal stem cells (hMSCs) cultured in a 3D-clinostat (group CL) showed marked proliferation (13-fold in a week) compared with cells cultured under normal conditions of 1 G (group C) (4-fold in a week). Flow cytometry revealed a 6-fold increase in the number of hMSCs double-positive for CD44/CD29 or CD90/CD29 in group CL after 7 days in culture, compared with group C. Telomere length remained the same in cells from both groups during culturing. Group C cells showed increasing expression levels of type II collagen and aggrecan over the culture period, whereas group CL cells showed a decrease to undetectable levels. Pellets of hMSCs from each group were explanted into cartilagedefective mice. The transplants from group CL formed hyaline cartilage after 7 days, whereas the transplants from group C formed only noncartilage tissue containing a small number of cells. These results show that hMSCs cultured in a 3D-clinostat possess the strong proliferative characteristic of stem cells and retain their ability to differentiate into hyaline cartilage after transplantation. On the contrary, cells cultured in a 1-G environment do not maintain these features. Simulated microgravity may thus provide an environment to successfully expand stem cell populations in vitro without culture supplements that can adversely affect stem cell-derived transplantations. This method has significant potential for regenerative medicine and developmental biology.
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http://sfxhosted.exlibrisgroup.com/mayo?sid=OVID:embase&id=pmid:&id=doi:10.1089%2Fscd.2006.15.921&issn=1547-3287&isbn=&volume=15&issue=6&spage=921&pages=921-929&date=2006&title=Stem+Cells+and+Development&atitle=Microgravity+potentiates+stem+cell+proliferation+while+sustaining+the+capability+of+differentiation&aulast=Yuge&pid=%3Cauthor%3EYuge+L.%3C%2Fauthor%3E&%3CAN%3E2007051139%3C%2FAN%3E