Research team successfully clones human kidney in rats

Researchers have succeeded in cloning a human kidney by cultivating human stem cells extracted from adult bone marrow into rat embryos.

According to the research team, the development could lead to expanding regenerative medicine to treat disorders in anatomically complicated organs, including kidneys and lungs.

A report of the team's study will be published in the online edition of U.S. publication Proceedings of the National Academy of Sciences early next month.

The team was headed by Takashi Yokoo of the Department of Internal Medicine and Gene Therapy at Tokyo's Jikei University School of Medicine.

He said the team removed rat embryos from the uterus, implanted human stem cells -- treated with neutrophic factor genes to help the organ develop -- into the area in the embryos where the kidneys were being generated and cultured the embryos in vitro.

Two days after the stem cell implantation, the researchers extracted the kidney area from the embryos. After six days of incubation, they discovered the development of nephrons, or an excretory unit of the kidney.

The team confirmed the genes were developed from human bone marrow stem cells. They then transplanted the kidney into the stomach of another rat and watched it grew to about 150 mg in two weeks.

The team successfully treated a mouse suffering Fabry's disease, a genetic kidney defect.