A Swedish team has successfully carried out womb transplants in sheep, leading to pregnancy. So far the researchers have worked on perfecting the technique of reconnecting the blood vessels and have removed and replaced the uterus in individual animals - known as autologous transplantation. The team removed and replaced the uterus from fourteen ewes and four are now pregnant. The lambs will be delivered by caesarean section later this month. However, complications with the transplant led to the death of seven of the animals. The work was presented at the International Symposium on Uterine Transplantation in Goteburg, Sweden last week, New Scientist magazine reports.
The womb has complicated connections to the blood supply and to the vagina, which must be successfully re-established for a transplant to work. If the transplant is followed by a pregnancy, this puts even greater strain on these new connections. A human womb transplant was attempted in Saudi Arabia in 2000 using a live donor - it was rejected after three months. Professor Mats Brannstrom, leader of the Swedish team, and his colleagues have previously reported successful pregnancies in mice following uterus transplants. The new research shows that the technique can be adapted to large mammals. The team now plans to begin work on transplanting between different animals.
One of the biggest problems for clinical use of womb transplanting technology is the possibility of rejection during a pregnancy, since there are potential problems with the drugs routinely used to suppress the immune system following organ transplants. However, recent research has shown that certain drugs used following kidney transplants do not hurt the developing baby during pregnancy.
A spokesperson from the Royal College of Obstetrics and Gynaecology praised the work saying, 'They are going the right way about it, instead of racing off to do the work in humans'. Talking to reporters Professor Brannstrom explained how his team removed the uterus from the sheep and 'kept it for a couple of hours outside the body'. They then reconnected the blood supply and connection to the vagina. 'After four to six weeks the sheep went back to the farm and then they have been put with rams and they have been mating and four of the five are pregnant. I think this is successful, because what it proves is that you can put the uterus back with a different blood supply and you can do that in large animal species. I think this is one small step forward to human uterus transplantation'.