Stem cell breakthrough paves way for scientists to grow synthetic kidneys

LOS ANGELES, Calif. — Kidneys are among the most common organs which doctors transplant into patients every year. While modern medicine makes these procedures fairly routine today, people in need of a new kidney still face long delays as hospitals look for compatible donors. Now, a new study is giving thousands of people hope that scientists will one day be able to grow them a new organ. Researchers at the Keck School of Medicine of USC have created a potential building block for creating a synthetic kidney.

Stem cell scientists have successfully generated the basic kidney structures, called organoids. These “mini-kidneys” are similar to the collecting duct system which maintains the body’s fluid and pH balance. Normally, the kidneys do this by concentrating and transporting urine.

“Our progress in creating new types of kidney organoids provides powerful tools for not only understanding development and disease, but also finding new treatments and regenerative approaches for patients,” says corresponding author and assistant professor of medicine Zhongwei Li in a university release.

Kidney ‘ancestor’ cells play a key role

Researchers started their experiments with a collection of ureteric bud progenitor cells (UPCs). These precursor cells play a vital role in the early development of kidneys in animals and humans.

Using both mouse and human UPCs, scientists developed a “cocktail of molecules” which encourages these cells to turn into organoids that resemble uretic buds. During normal development, these branching tubes eventually form the collecting duct system. The team also created a success cocktail which triggers this same process using human stem cells.

The biological success didn’t stop there. Scientists developed another molecular cocktail which drove the newly formed ureteric bud organoids to grow into more mature and complex kidney structures.

How will this lead to making new kidneys?

Study authors combined mouse ureteric bud organoids with additional mouse cells, the progenitor cells of nephrons. These nephrons act as the filtering agents of the kidneys. When researchers inserted a portion of the lab-grown ureteric buds into the nephron cells, the pair grew into a complex network of tubes — just like a normal kidney filtering system.

“Our engineered mouse kidney established a connection between nephron and collecting duct—an essential milestone towards building a functional organ in the future,” Li explains.

Along with this breakthrough, researchers also found they could genetically engineer these organoids to cause diseases. So why would anyone want to do that? Study authors say doing so would help create better models for doctors trying to understand kidney problems in patients. Building kidneys with diseases in them may create a new testing ground for future medical treatments.

According to the American Kidney Fund, nearly 100,000 people are currently on waiting lists for a kidney transplant. The average wait time for a kidney transplant is over three years.

The study appears in the journal Nature Communications.

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