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Miniature kidney grown in a dish

Mini kidney Australian researchers have grown a rudimentary kidney in the laboratory from human stem cells, an advance they say could lead to better ways of treating renal disease and testing drug safety.

Professor Melissa Little, from the University of Queensland's Institute for Molecular Bioscience, and colleagues, were able to guide embryonic stem cells to produce the cell types needed to 'self-organise' into a miniature kidney in a dish.

"It's much smaller than an adult kidney. It's essentially a little developing kidney," says Little.

The key to achieving this outcome was providing the cells with perfectly-calibrated combinations of molecules called growth factors.

By bathing the stem cells in particular concentrations of growth factors at particular times, they were able to guide them to grow and differentiate in a process that mimicked normal development.

"We had to walk the cells through all the steps they normally would take during development," says Little. "We used what normally happens in development to tell us what to add."

The researchers were initially aiming to coax the stem cells to produce just one type of kidney cell. But they were surprised to find that they had managed to form two key cell types, both of which are required to assemble a kidney. The research is published in the journal Nature Cell Biology.

"We went in thinking we would be able to make a single stem cell type, but we looked down the microscope and realised we were getting both types," says Little.

The upshot of this success was that the cells in the dish organised themselves to create the complex structures that exist within the kidney.

The results went further than those achieved recently by US researchers, published in the same journal, says Little.

"What we've made is a much more complex set of cells. That's a huge advance in terms of what has been possible to date."

Mini kidney

Little says the kidney her group produced is similar to the kidney of a 5-week-old embryo.

In the short term, their results could prove very useful for testing whether new drugs are toxic to kidneys, the researchers say.

"We are already in discussions with commercial partners about developing it for this purpose," says Little.

Looking further ahead, this week's results could also lead to improved treatments for patients with kidney disease.

"One in three Australians is at risk of developing chronic kidney disease and the only therapies currently available are kidney transplant and dialysis," says Little.

"Only one in four patients will receive a donated organ, and dialysis is an ongoing and restrictive treatment regime. We need to improve outcomes for patients with this debilitating condition."

In all likelihood, using this technology to produce kidneys for transplantation would be decades away, but the researchers say their early results are very promising.

"The fact that such stem cell populations can undergo self-organisation in the laboratory bodes well for the future of tissue bioengineering to replace damaged and diseased organs and tissues."