The pigs, all 14 of them, are doing fine. Considering they’d been retrofitted with bone grown in a laboratory, that came as a pleasant surprise.

“The pigs woke up, and a half-hour later they were eating,” said Gordana Vunjak-Novakovic, a professor of biomedical engineering at Columbia University. “We thought they would be in pain. But no, they’re doing great.”

Dr. Vunjak-Novakovic and her colleagues have managed to create living bone from stem cells. First, they made a CT scan to create a 3-D image of each pig’s jaw. From cow bone, they sculpted a “scaffold” — a three-dimensional copy of the pig bone.

They put the scaffold in a nutrient solution along with stem cells extracted from the pigs. The cells attached to the scaffold, forming a new bone identical to the original. Then the researchers implanted the new bone in each pig. They reported their results in Science Translational Medicine.