Scientists at Kyushu University said Monday they have succeeded in producing mice with immune systems close to those of humans, a development that is expected to contribute to research in medical treatment for a variety of diseases.

Mine Harada, a professor at the school's medical department who heads the team, said the discovery will enable researchers to conduct experiments in an environment similar to the human body, like a "living test tube."

"We have now succeeded in making (the mice's immune systems) 70 percent to 80 percent like humans, and we want to improve that further," Harada said. "We also want to work on enhancing the longevity of the mice so they can be used for research on cancer, which usually takes time to develop into illness."

In their experiments, the scientists first created genetically modified mice whose original immune systems as mice did not function. Human hematopoietic stem cells were then implanted into their veins within 48 hours after they were born.

The hematopoietic stem cells settled in the bone marrow, and the main cells of the immune system developed into humanlike ones, according to Harada.

The group also succeeded in having the mice develop human leukemia, Harada said.

They hope this will enable researchers to decode various illnesses and use the mice to "reconstruct" the illnesses of individual patients in order to find the appropriate treatment, including the most effective cancer drug.