(CN) – Facing a global shortage of organ donors for patients in need of new kidneys, researchers in Japan announced Tuesday they’re closing in on perfecting lab-grown kidneys that could one day be used in humans.
More than 95,000 people are on the waiting list for a kidney donation in the United States, and the demand far outpaces supply.
Researchers at the National Institute for Physiological Sciences in Japan have worked for years to fill the supply gap by developing a method for growing healthy organs outside the human body.
Such a breakthrough would benefit patients with end-stage renal disease, which requires a full kidney transplant in order for patients to live.
Kidneys provide the critical function of filtering waste and fluids from blood and then passing them out of the body through urine. Patients with end-stage renal disease have lost kidney function, which causes dangerous levels of fluid and electrolytes to build up in the body.
In a study published in Nature Communications, researchers at the Institute said they may soon be able to generate kidneys for human transplantation using a method in which they grew mouse kidneys inside rats with just a few transplanted mouse stem cells.
The process, called blastocyst complementation, injects stem cells from a donor into a cluster of cells formed several days after egg fertilization of animals who are missing specific organs.
The stem cells then transform into the entire missing organ in the host animal while retaining the characteristics of the donor.
Teppei Goto, lead author of the study, said the method was used previously to generate rat pancreases in mutant mice lacking the organ.
"We therefore decided to investigate whether the method could be used to generate functional kidneys, which would have much greater application in regenerative medicine owing to the high donor demand," Goto said.
Researchers were initially unsuccessful, finding that rat stem cells did not transform into the two main types of cells needed for kidney formation. But the method was successful when the process was reversed.
Blastocysts that researchers injected into pregnant rats matured into normal fetuses, the study found, and more than 2/3 of the infant rats contained a pair of kidneys derived from the mouse stem cells.
Further tests showed that all of the kidneys were structurally intact, and at least half could potentially produce urine.
Study author Masumi Hirabayashi said the findings confirm that blastocyst complementation is a viable method for generating kidneys for humans.
"In the future, this approach could be used to generate human stem cell-derived organs in livestock, potentially extending the lifespan and improving the quality of life of millions of people worldwide," Hirabayashi said.