A Japanese team said Tuesday it is planning a clinical study to temporarily transplant a pig's kidney into an unborn child with severe kidney disease, in what would be the first case of a domestic animal-to-human transplant.

The team, which includes the Jikei University School of Medicine, is seeking to apply for approval with a state-designated committee as early as this year after going through an ethical review at the facility where the transplant would carried out, it said.

To address any ethical issues, the group, which also includes the National Center for Child Health and Development, plans to hold an open lecture to obtain understanding from the public before the application, it said.

File photo taken in July 2010 shows the National Center for Child Health and Development in Tokyo. (Kyodo)

Under the plan, an unborn child diagnosed with potter sequence, a disease in which the sufferer cannot produce enough urine, will be transplanted with a 2-millimeter kidney taken from a fetal pig 30 days after fertilization, the team said.

The disease causes the fetus to become compressed as the amount of amniotic fluid is reduced during pregnancy, resulting in lung damage, developmental disorders and limb deformities.

In the operation, a pig's kidney is injected by a hypodermic shot under the skin of the unborn baby's back around four weeks before the due date, enabling the fetus to produce urine, the team said.

After the baby is born, urine produced by the transplanted pig's kidney will be released via a tube inserted into the baby's back.

The pig's kidney will be removed several weeks later if the baby grows to a weight where he or she becomes able to undergo dialysis treatment, the team said.

While the operation would be the first to be carried out in Japan, pig-to-human transplants have been conducted in the United States.

A team at New York University said it transplanted a genetically modified pig's kidney into a human body in 2021, while the University of Maryland said last year its team performed the second pig's heart transplant on a patient deemed ineligible for a traditional heart transplant.

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