Rat kidneys grown in mice offer new hope for transplant patients

The breakthrough provides a new way of helping to reduce growing organ donor shortages, say scientists.

Researchers in Japan generated rat-derived kidneys in mice using a technique known as interspecies blastocyst complementation.

They say transplantation remains the most effective treatment for end-stage kidney disease.

But a severe shortage of donor organs continues to limit access for millions of patients worldwide.

With demand for kidney transplants expected to reach 5 million patients by 2030 and only a fraction of that need currently being met, scientists are exploring innovative approaches to generate transplantable organs.

For the new study, published in the journal Stem Cell Reports, the Japanese team created mouse embryos genetically unable to form kidneys, leaving a developmental niche that could be filled by injected embryonic stem cells.

Dr. Shunsuke Yuri, of the National Center for Geriatrics and Gerontology in Obu City, said: "When rat embryonic stem cells were introduced into these embryos, they contributed extensively to kidney formation, particularly to nephron progenitor cells and ureteric bud lineages, resulting in the generation of a rat cell-derived kidney.

"Although the interspecies embryos did not survive to birth, preventing assessment of kidney function, the study demonstrates the potential of using one species to generate organs from another."

Dr. Ayako Isotani, of the Nara Institute of Science and Technology, added: " The findings represent an important step toward future efforts to grow transplantable human organs in larger animals, such as pigs, with the long-term goal of helping address the global shortage of donor kidneys."