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A mini-kidney organoid of 1 mm diameter grown from a patient’s stem cells. Photo: Freedman and Bonventre labsFor the first time, scientists have used stem cells to grow kidney organoids in petri dishes. They say the mini-kidneys offer a ways to develop and test drugs for kidney disease.

The pluripotent stem cells used are human cells that can develop into any type of organ in the body. When treated with a chemical cocktail, they mature into structures that resemble miniature kidneys. These organoids contain tubules, filtering cells, and blood vessel cells. They transport chemicals and respond to toxic injury in ways that are similar to kidney tubules in people.

The findings are published in the journal Nature Communications.

“A major unanswered question was whether we could re-create human kidney disease in a lab petri dish using this technology,” says Benjamin Freedman, who led the studies at Brigham and Women’s Hospital in Boston and is now an assistant professor of medicine in the nephrology division at the University of Washington. “Answering this question was important for understanding the potential of mini-kidneys for clinical kidney regeneration and drug discovery.”

To re-create human disease, researchers used the gene-editing technique called CRISPR. They engineered mini-kidneys with genetic changes linked to two common kidney diseases: polycystic kidney disease and glomerulonephritis.

The organoids developed characteristics of these diseases. Those with mutations in polycystic kidney disease genes formed balloon-like, fluid-filled sacks, called cysts, from kidney tubules. The organoids with mutations in podocalyxin, a gene linked to glomerulonephritis, lost connections between filtering cells.

“Mutation of a single gene results in changes kidney structures associated with human disease, thereby allowing better understand of the disease and serving as models to develop therapeutic agents to treat these diseases,” says Joseph Bonventre, senior author and chief of the renal division at Brigham and Women’s Hospital.

“These genetically engineered mini-kidneys,” Freedman says, “have taught us that human disease boils down to simple components that can be re-created in a petri dish. This provides us with faster, better ways to perform ‘clinical trials in a dish’ to test drugs and therapies that might work in humans.”

Genetically matched kidney organoids without disease-linked mutations showed no signs of either disease, Freedman says.

“CRISPR can be used to correct gene mutations,” explained Freedman. “Our findings suggest that gene correction using CRISPR may be a promising therapeutic strategy.”

In the United States, costs for kidney disease are about 40 billion dollars per year. Kidney disease affects approximately 700 million people worldwide. Twelve million patients have polycystic kidney disease and two million have complete kidney failure. Dialysis and kidney transplantation, the only options for patients in kidney failure, can cause harmful side effects and poor quality-of-life.

“As a result of this new technology, we can now grow, on demand, new kidney tissue that is 100 percent immunocompatible with an individual’s own body," says Freedman. “We have shown that these tissues can mimic both healthy and diseased kidneys, and that the organoids can survive in mice after being transplanted. The next question is whether the organoids can perform the functions of kidneys after transplantation.”

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