Tardigrade aka Water Bears have been able to survive in open space for 10 days, that's no air, extremely low pressure, and Radiation levels 4000 times that which would effect a human negatively. They also seem to be able to reconstruct and repair the DNA that get's damaged by said radiation. Some of the Water Bears that were exposed to space for 10 days were able to reproduce when they got back to earth. The other interesting thing is that when they run out of fuel to live (Oxygen, or more specifically, oxygenated water) their bodies go into a stasis that can sustain them for an extremely long time. When they are placed back into oxygenated water, they come out of stasis completely unharmed. This is how they survice space.
If we could adapt the genetic reconstructive behaviours of the Water Bears to medicine, we could increase our life spans exponentially, http://en.wikipedia.org/wiki/Resveratrol
There’s also resveratrol which might be adapted to lengthen life, clean and repair cells and prevent disease, provided we can make it work on humans.