Researchers from the Murdoch Childrens Research Institute (MCRI) and biotech company Organovo have used cutting-edge technology to bioprint miniature human kidneys in the lab, paving the way for new treatments for kidney failure and possibly lab-grown transplants. Their study has been published in the journal Nature Materials.

Like squeezing toothpaste out of a tube, extrusion-based 3D bioprinting uses a bioink made from a stem cell paste, squeezed out through a computer-guided pipette to create artificial living tissue in a dish. According to MCRI Professor Melissa Little, a world leader in modelling the human kidney, this new bioprinting method is faster and more reliable than previous methods, allowing the whole process to be scaled up. 3D bioprinting could now create about 200 mini kidneys in 10 minutes without compromising quality.

From larger than a grain of rice to the size of a fingernail, bioprinted mini kidneys fully resemble a regular-sized kidney, including the tiny tubes and blood vessels that form the organs filtering structures called nephrons. Prof Little said the mini organs will be used to screen drugs to find new treatments for kidney disease or to test if a new drug was likely to injure the kidney.

Drug-induced injury to the kidney is a major side effect and difficult to predict using animal studies; bioprinting human kidneys are a practical approach to testing for toxicity before use, she said.

In the study, researchers tested the toxicity of aminoglycosides a class of antibiotics that commonly damage the kidney. Prof Little said, We found increased death of particular types of cells in the kidneys treated with aminoglycosides.

By generating stem cells from a patient with a genetic kidney disease, and then growing mini kidneys from them, also paves the way for tailoring treatment plans specific to each patient, which could be extended to a range of kidney diseases.

Prof Little said the study also showed that 3D bioprinting of stem cells can produce large enough sheets of kidney tissue needed for transplants. She noted, 3D bioprinting can generate larger amounts of kidney tissue but with precise manipulation of biophysical properties, including cell number and conformation, improving the outcome.

Prof Little said prior to this study the possibility of using mini kidneys to generate transplantable tissue was too far away to contemplate, but that may no longer be the case.

The pathway to renal replacement therapy using stem cell-derived kidney tissue will need a massive increase in the number of nephron structures present in the tissue to be transplanted, she said.

By using extrusion bioprinting, we improved the final nephron count, which will ultimately determine whether we can transplant these tissues into people.

Image credit: stock.adobe.com/au/bluebay2014

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Mini kidneys bioprinted in the lab - Lab + Life Scientist