Bone Cell Mechanosensitivity in Weightlessness (FLOW)
Research Area: Cellular Biology
Expedition(s): 8 and 9
Principal Investigator(s): ● Jenneke Klein Nulend, ACTA-Free University Amsterdam,
Amsterdam, Netherlands
● Rommel G. Bacabac, ACTA-Free University Amsterdam,
Amsterdam, Netherlands
● Jack van Loon, ACTA-Free University Amsterdam, Amsterdam,
Netherlands
RESEARCH OBJECTIVES
The Bone Cell Mechanosensitivity in Weightlessness (FLOW) investigation tests whether near-
weightlessness decreases the sensitivity of chicken osteocytes for mechanical stress through a
decrease in early signaling molecules that are involved in the mechanical loading-induced
osteogenic response (formation of bone). Osteocytes, the bone mechanosensitive cells, will be
compared with osteoblasts (the bone forming cells) and periosteal fibroblasts (cells found
around or near bones, from which connective tissue develops).
RESULTS
Due to unforeseen hardware complications, results from in-flight cultures are considered lost.
Ground control experiments showed an accumulative increase of nitric oxide in medium for
osteocytes (as well as for osteoblasts and periosteal fibroblasts). Data from the online-nitric
oxide sensor showed that the nitric oxide produced in medium by osteocytes increased sharply
after pulse shear stress stimulations. COX-2 mRNA expression revealed high levels in
osteoblasts compared to the other cell types tested. In conclusion, preparations for the FLOW
experiment and preliminary ground results indicate that the FLOW setup is viable for a future
flight opportunity.
PUBLICATION(S)
Bacabac RG, van Loon JJ, Blieck-Hogervorst JM, et al. Microgravity and bone cell
mechanosensitivity: FLOW experiment during the DELTA mission. Microgravity Science and
Technology. September 2007;19(5-6):133-137. doi: 10.1007/BF02919468.
This investigation is complete and all results are published.