For the first time doctors have successfully transplanted a vein grown with a patient's own stem cells, another example of scientists producing human body parts in the lab.

The patient was a 10-year-old girl in Sweden who was suffering from a severe vein blockage to her liver. Using stem cells from the girl's bone marrow, scientists grew millions of cells to cover the vein, a process that took about two weeks. The new blood vessel was then transplanted into the patient.

Because the procedure used her own cells, the girl did not have to take any drugs to stop her immune system from attacking the new vein, as is usually the case in transplants involving donor tissue.

"This is the future for tissue engineering, where we can make tailor-made organs for patients," said Suchitra Sumitran-Holgersson of the University of Gothenburg, one of the study's authors.