Four young women born with abnormal or missing vaginas were implanted with lab-grown versions made from their own cells, the latest astonishing success in creating replacement organs that have so far included tracheas, bladders and urethras.
The breakthrough was reported yesterday in the medical journal The Lancet, alongside news that surgeons in Switzerland had carried out the first operations to repair cancer-ravaged noses using supplementary tissue grown from the patient's own cartilage cells.
However, the fact that sets of female sexual organs had been grown in a laboratory and successfully transplanted perhaps better demonstrates the potential of regenerative medicine.
Follow-up tests show the new vaginas are indistinguishable from the women's own tissue and have grown in size as the young women, who got the implants as teenagers, matured.
All four of the women are now sexually active and report normal vaginal function. Two of the four, who were born with a working uterus but no vagina, now menstruate normally.
It is not yet clear whether these women can bear children, but the fact that they are menstruating suggests their ovaries are working, so it may be possible, said Dr Anthony Atala, director of Wake Forest Baptist Medical Centre's Institute for Regenerative Medicine in the US state of North Carolina. In prior studies, Atala's team used the approach to make replacement bladders and urethras in young boys.
Atala said the pilot study conducted with colleagues in Mexico was the first to show that vaginal organs custom-built in the lab using patients' own cells could be successfully used in humans.
All four of the women in the study were born with Mayer-Rokitansky-Küster-Hauser syndrome, a rare genetic condition in which the vagina and uterus are underdeveloped or absent. Conventional treatment generally involves the use of grafts made from intestinal tissue or from skin.
Girls in the study ranged in age from 13 to 18 at the time of the operations, performed between June 2005 and October 2008.
The researchers started off by collecting a small amount of cells from genital tissue and grew two types of cells in the lab: muscle cells and epithelial cells, a type of cell that lines body cavities. About four weeks later, the team started applying layers of the cells onto a scaffold made of collagen, which the body can absorb. They shaped the organ to fit the patient and placed it in an incubator.
A week later, the team created a cavity in the body and surgically attached the vaginal implants to existing reproductive organs. Once implanted, nerves and blood vessels formed to feed the new organ, and new cells eventually replaced the scaffolding.
"By the six-month time point, you couldn't tell the difference between engineered organ and the normal organ," Atala said.
The team continued to monitor the young women, taking tissue biopsies, MRI scans and internal exams, for up to eight years from the initial implants.
All of these tests showed the engineered vaginas "were similar in make-up and function to native tissue," said Atlantida-Raya Rivera, director of the HIMFG Tissue Engineering Laboratory at the Metropolitan Autonomous University in Mexico City, where the surgeries were performed.
Additional reporting by Agence France-Presse