Working with stem cells comes at a price. When isolated, 99 percent of stem cells die, making it prohibitively difficult to manipulate their genes or expand their numbers for clinical use.
By tinkering with the medium in which cells are grown, researchers at the Salk Institute for Biological Studies created a type of stem cell with a survival rate of 30 to 40 percent, vs. 1 percent. The cells are far easier to culture, and their genetic defects are more readily repaired.
The human version of the cells, called region-selective pluripotent stem cells, or rsPSCs, can also grow inside a mouse, something other human stem cells can’t do, says Jun Wu, a research associate involved in the work, published in May in Nature.
“It offers the first proof of concept that it’s possible to incorporate human cells efficiently into another species,” Wu says. This suggests someday it may be possible to grow a human organ, such as a pancreas, inside a pig and then transplant it into a diabetic patient.