A 10-year-old girl has had a major blood vessel in her body replaced with one grown with her own stem cells, Swedish doctors report. A vein was taken from a dead man, stripped of its own cells and then bathed in stem cells from the girl, according to a study published in the Lancet. There was a striking improvement in her quality of life. Last year, scientists created a synthetic windpipe and then coated it with a patient's stem cells.