The data suggest that alterations in cell metabolism, immune cell function, cell division, and cell attachment have occurred in space. Scientists have reported that after nine days in space, human immune cells failed to differentiate into mature effector cells. The results of investigations into how the stress of space flight can alter normal metabolic activities and important aspects of immune cell function may indicate the body's inability to produce mature and fully differentiated cells in space. This may lead to health problems on long-term spaceflights, including impaired healing abilities and increased risk of infection. Studies on rat bone cells revealed a significant number of floating, dead bone forming cells.
Bone cells die if they are unsuccessful in attaching themselves to something.
This finding could be significant since many biological processes, both in single cells and in multi-celled organisms, depend on cell attachment and the recognition processes. The finding suggests that gravity clues may be required to show the cells where to attach themselves. Furthermore, studies of rat bone cells also revealed that healthy cells showed no signs of producing minerals. It may be that bone cells do not need to produce minerals to support themselves in a microgravity environment. Similar studies of mouse bone cells developed in space and of those developed on the ground revealed similar changes in attachment properties in microgravity.