Sunday, June 17, 2012

Girl receives vein transplant with her own stem cells

For the first time in medical history, a patient has received a blood vessel transplant made from her own stem cells. After the surgery, the girl, only 10 years of age, recovered successfully and appears to be functioning pretty well with the artificially constructed portal vein, which transports blood coming from the intestines to the liver. The method, developed by the University of Gothenburg, is a prime example of how stem cells can be used to regenerate malfunctioning or dead tissues. Previous studies already showed that it is possible to create such artificial blood vessels.

The patient
A 10-year-old girl from Sweden suffering from frequent blockage in the circulatory system was chosen as the first ever person to receive a stem-cell based engineered blood vessel. The girl had a dysfunctional portal vein, which is needed to get blood from the intestines, carrying nutrients derived from food, to the liver where it is processed and detoxified. Because of the blockage, the normal cycle of nutrient distribution was disturbed, leading to a lack of growth and vitality.

The procedure
It was clear that the girl needed a new portal vein in order to get rid of the frequent obstructions, though such procedures are not that easy. Because of the immune system, one cannot simply give a patient someone else's blood vessels, as this would result in rejection. The Swedish scientists took an 9-cm vein from a deceased donor and used that as a scaffold for their own artificial construction. In order to create their desired blood vessel, primitive blood cells were harvested from the bone marrow, which is the 'birth place' for cells that roam the circulatory system.

As said, the blood vessel obtained from the donor was used as a scaffold: by completely stripping the vessel from cells, the researchers were left with a protein 'skeleton', that could consequently be filled up by the patient's own cells. After reconstructing the vein, the 9-cm tube was regenerated into an actual blood vessel, and deemed fit for transplantation. Surgeons then replaced the malfunctioning portal vein with the artificially constructed version.
Portal vein
The portal vein, that carries blood from the intestines to the liver, is one of the most interesting and peculiar blood vessels of the body. Normally, arteries carry oxygen and nutrients to tissues, and veins transport the 'used' blood back to the heart, where it can be pumped back into the body, after visiting the lungs for oxygen take-up. Because the portal vein transports nutrient-rich blood to liver tissue, it does not function as a true vein, which normally all end up in a big vessel leading back to the heart.
The portal vein, in blue, collects blood coming from the intestines and transports it to the liver.
According to her doctors, the girl experienced a significant improvement in quality of life after transplantation, indicating that the procedure was successful. While donor transplants normally degrade over time due to being recognized by the body's immune system as 'foreign', this will probably not happen with the artificial portal vein. There are several layers of patient-own cells on the outside of the vessel, which will be deemed 'safe' by the immune system. This was also demonstrated by the fact that the girl did not need any immunosuppressive drugs to keep the immune system at bay, which is normally mandatory during transplantation procedures.

The vein transplant is an example of the potential that stem cells carry. Theoretically, it is possible to create all sorts of tissues by using a patient's own stem cells, but despite many attempts, few scientific groups have managed to develop a working transplant. Nevertheless, recent studies have shown some success, and include the production of bones, heart tissue, or the insulin factories that are destroyed in patients with diabetes type I.

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