Financial Daily from THE HINDU group of publications
Wednesday, Dec 25, 2002
Human kidneys grown in mice
PUNE, Dec. 24
SCIENTISTS of the Weizmann Institute of Science in Israel say they have successfully grown the world's first functioning human kidneys in a breakthrough that holds potential benefits for thousands of people.
According to the scientists, headed by Prof Yair Reisner, they have transformed cells taken from embryonic tissue into new, functioning organs. The kidneys grow blood vessels and produce urine just like normal organs.
As of now, the scientists have grown the `spare-part' kidneys only in laboratory mice. However, they predict that their research will revolutionise transplant medicine in that patients, instead of waiting for donors, will be able to grow their replacement organs.
This breakthrough revolves around stem cells, the body's mother cells which have the potential to develop into any type of tissue or organ. The richest source of the cells is embryonic tissue.
The scientists took stem cells from areas of both human and pig embryos they believed would be rich in precursor kidney cells - those likely to form kidney tissue - and implanted them into the mice. They found that the cells grew to form perfect human or pig kidneys. The fully functional kidneys grow new blood vessels, thereby reducing significantly the chances of rejection. The results suggest that human or pig foetal tissue would take on the shape and function of a healthy kidney if transplanted into humans. Further, they indicate that the use of pig foetal tissue, as against pig organs, will not trigger the kind of rejection seen in cross-species transplants.
The scientists have expressed the hope that, amid controversy over the use of human foetuses, pig stem cells might provide an ethically acceptable source.
According to Prof Reisner, kidney transplantation has replaced an area of major medical advances over the last 30 years - but the availability of tissues has remained a major obstacle. "This can potentially be overcome by the use of cells derived from early embryos and foetal tissue."
He believes that `spare-part' organs for human patients will be available in a few years. Stem cells would be used to grow a new organ, probably in the abdomen. Once it is fully grown, surgeons will be able to use it to replace an old, failing kidney.
The Israeli scientists have identified the time during embryonic development in which the stem cells have the best chance to form functioning kidneys. Their experiments with human immune cells have also indicated that the correct timing of the process can stop the body rejecting the new organ.
Patients receiving `spare-part' organs grown in this way might not even need immuno-suppressants. The breakthrough is of considerable significance to India, which has come to be known as a "warehouse for kidneys" or a "great organ bazaar", and has become one of the largest centers for kidney transplants in the world, offering low costs and almost immediate availability.
In a country where one person out of every three lives in poverty, a huge transplant industry has grown after drugs were developed in the seventies to control the body's rejection of foreign objects. Renal transplants became common in India about 13 years ago when the anti-rejection drug cyclosporine became available locally.
The use of powerful immuno-suppressant drugs and new surgical techniques have combined to indirectly boost the kidney transplant activities. The dramatic success rates of operations, India's lack of medical regulations and an environment of lax medical ethics have also contributed to the growth of kidney transplants.
The result, in the words of an observer, has been "a marriage of unequals, wedding wealthy but desperate people dependent on dialysis machines to those in India grounded down by the hopelessness of poverty".
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