At the annual conference of the European Society of Human Genetics, Professor Hiromitsu Nakauchi, director of the center for stem cell biology and regenerative medicine at the University of Tokyo in Japan, led the new stem cell research breakthrough. Professor Nakauchi called the new technique as blastocyst complementation.

The technique included injecting stem cells from rats into the embryos or blastocysts of mice that could not grow their own organs. Results have shown that the mice were indeed able to grow rat organ.

Professor Nakauchi 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." Furthermore, he said they hoped to further test the technique by growing other organs and were also seeking permission to utilize human stem cells.

He said: "For ethical reasons we cannot make an organ deficient human embryo and use it for blastocyst complementation.

"So to make use of this system to generate human organs, we must use this technique using blastocysts of livestock animals such as pigs instead."

"Blastocyst complementation across species had never been tested before, but we have now shown that it can work."

The researchers, apparently, already managed to produce pigs that were able to generate human blood by injecting blood stem cells from humans into pig fetuses.

Stem cells are said to be biological cells found in all multi-cellular organisms, divide through mitosis or cell division and differentiate into diverse specialized cell types. This self-renewing capability to produce more stem cells could provide the abundant supply or organs for transplant with possible minimized risk for transplant rejection.