As if astronauts didn't already have enough health-related concerns to be worried about, a new study shows that microgravity environments speed up biological aging and the onset of cardiovascular disease by affecting blood vessel cells.
Simply put, humans are not built for space. Even after short bursts of exposure to microgravity, astronauts suffer muscle atrophy, bone density loss, immune response impairments, and cardiovascular deconditioning. We know that microgravity screws up organisms at the cellular level, inhibiting gene expression (including cell signalling, response to stress, and changes in temperature). Exposure to microgravity also damages our eyes and brain, including a condition similar to idiopathic intracranial hypertension (the swelling of the brain).

But wait, there's more! A new study published in the Journal of Federation of American Societies for Experimental Biology shows that microgravity also induces endothelial dysfunction — the accelerated aging of endothelial cells which line the inner surfaces of blood vessels.
A research team from the Institute of Molecular Science and Technologies in Milan determined this by analyzing experiments conducted on the International Space Station. They compared space-flown endothelial cells to cells cultured under normal gravity. They looked for differences in gene expression and in the profile of secreted proteins. The researchers discovered that the space-flown cells differentially expressed more than 1,000 genes and secreted high amounts of pro-inflammatory cytokines which induced significant oxidative stress — a key factor in human aging.
Yet more evidence that space is hazardous to humans — and that we seriously need to get going on creating artificial gravity environments. Or the genetic/cybernetic redesign of humans for space.