Baboons have lived with pig hearts for almost two years
Despite the rapid development of cellular and tissue engineering in recent years, one of the tasks of which is to create artificial organs for transplantation, experts do not discount the possibility of using animal organs for these purposes. Organ transplantation of another type – xenotransplantation – continues to be a very attractive prospect due to the theoretically unlimited amount of donor material and the possibility of obtaining organs of any size. However, the use of this technology is associated with safety issues and problems with the rejection of foreign organs.
Researchers at the National Institute of Heart, Lung and Blood Diseases of the USA, working under the leadership of Muhammad Mohiuddin, managed to achieve an unprecedented long period of functioning of the pig heart in the baboon's body, amounting to almost 600 days. Until now, such transplants have been functioning in the donor's body for no more than 6 months, so the results obtained by the authors can be called a breakthrough.
The piglets used as donors had three modifications in their genome. The first modification consisted in removing the gene encoding the 1,3-galactosultransferase protein. This enzyme synthesizes a carbohydrate localized on the surface of pig cells, which is recognized by the immune cells of other animals. The absence of this gene makes pig organs invisible to the immune system.
The second intervention was the addition of the hCD46 gene, the protein product of which prevents rejection of the pig organ by the immune system of baboons and, theoretically, humans. Another gene embedded in the genome of donor pigs, known as THBD, provides the synthesis of human thrombomodulin, which prevents blood clotting. The authors believe that this modification is the most important.
Another important component of the approach developed by the authors was the addition of antibodies blocking the CD40 immune cell receptor to the immunosuppressant drug administered to the recipient monkeys.
The purpose of the experiments was to study the issues of transplant rejection, so donor organs were implanted into the abdominal cavity of baboons, whose blood supply was still provided by the work of their own hearts.
The authors believe that the complex of genetic modifications and the immunosuppression protocol developed by them will be effective in the transplantation of other organs, although in some cases additional genetic manipulations may be necessary. Additional manipulations will certainly be required when transferring the technique to clinical practice, but the basic principles will remain the same.
The results of the work are presented at the annual congress of the American Association for Thoracic Surgery, American Association for Thoracic Surgery, held April 25-30 in Toronto, Canada.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of New Scientist:
Baboons with pig hearts pave way for human transplants.
12.005.2014