The team of Teppei GOTO found that mouse stem cells efficiently differentiated inside rat blastocysts, forming the basic structures of a kidney. After being implanted into pseudo-pregnant rats, the complemented blastocysts matured into normal fetuses. Remarkably, more than two thirds of the resulting rat neonates contained a pair of kidneys derived from the mouse stem cells. Further screening showed that all of the kidneys were structurally intact, and at least half could potentially produce urine.

NIPS news release, February 6, 2019