I'm not a supporter of NASA, or any facet of big government for that matter. NASA is waste incarnate like all government agencies, while philanthropy and the free market seem to be doing a much more efficient job of turning low cost space travel into reality. That said, this Wired article on current NASA ventures into medical research is interesting:
"We plan to use adult stem cells derived from the astronauts' blood and to put that in a zero-G-microgravity-simulating bioreactor," said McGuckin. "Using the right cocktail of stimuli, we can instruct the cells to grow into not only blood, but also the liver or part of the muscles, for example, to regenerate the damaged tissue. The long-term goal would be (to be) able to take those bioreactors on a space flight to regenerate tissue for the astronauts."
Growing body parts on demand has been the Holy Grail of tissue engineering experts all around the world. The main challenge so far has been growing tissue in three dimensions. Because of gravity's effects, cells grown in a flat dish have a sheet-like appearance, behave like individual cells and fail to form the associations that lead to the growth of tissues or organs.
I can't say that the rigors of space travel had occurred to me as a likely near term pressure for funding of regenerative medicine - as opposed to, say, more than 100,000 deaths each and every day and the hundreds of millions who currently suffer the crippling effects of degenerative conditions.
As I note at the Longevity Meme, we're making progress in three-dimensional tissue engineering using biodegradable scaffolds here at the bottom of the gravity well - microgravity experiments are no doubt helpful, but by no means essential.