The gravity dilemma

That promise is tempered by a frustrating earthly problem: The planet's gravity makes it tough to grow the vast quantities of cells necessary for future therapies that may require more than a billion per patient.

“With current technology right now, even if the FDA instantly approved any of these therapies, we don't have the capacity to manufacture” what's needed, Millman said.

The issue? In large bioreactors, the cells need to be stirred vigorously or they clump or fall to the bottom of the tank, Millman said. The stress can cause most cells to die.

“In zero G, there's no force on the cells, so they can just grow in a different way,” Svendsen said.

The Cedars-Sinai team has sent up what are called induced pluripotent stem cells. Many scientists consider them the perfect starting materials for all sorts of personalized, cell-based treatments. They carry a patient's own DNA, and their versatility makes them similar to embryonic stem cells, only they are reprogrammed from adults' skin or blood cells.

For their experiment, which is being funded by NASA, a shoebox-sized container holds bags filled with spheres of cells and all of the pumps and solutions needed to keep them alive for four weeks. The cargo will also include neural stem cells originating from Svendsen. The scientists used stem cells derived from their own white blood cells because it was easy for them to give consent.

They will run the experiment remotely with a box of cells on Earth for comparison. They'll get the space experiment back in five weeks or so, when it returns in the same SpaceX capsule.

The work is designed to pave the way for more NASA-funded research. If they are able to figure out how to make billions of cells in orbit, Svendsen said, “the impact could be huge.”