London: Human organs could soon be grown inside pigs for use in transplant operations, as scientists claim to have made a stem cell breakthrough, allowing them to create genetically altered animals that have organs belonging to another species.

The technique, developed by a team at the University of Tokyo in Japan, involves injecting stem cells of an animal into the embryos of another animal that had been genetically altered so they could not produce their own organs.

The researchers said the technique could allow pigs to grow human organs from patient's stem cells for use as transplants, according to reports.

By using a patient's own stem cells it could help to reduce the risk of the transplanted organ being rejected while also providing a plentiful supply of donor organs, they said.

Professor Hiromitsu Nakauchi, who led the research, said: "Our ultimate goal is to generate human organs from induced pluripotent stem cells.

"The technique, called blastocyst complementation, provides us with a novel approach for organ supply. We have successfully tried it between mice and rats. We are now rather
confident in generating functional human organs using this approach."

Professor Nakauchi, who presented the study at the annual conference of the European Society of Human Genetics, used a type of adult stem cell known as induced pluripotent
stem cells, which can be taken from a sample of tissue such as the skin and encouraged to grow into any type of cell found in the body.