Scientists in Australia have grown kidney tissue from stem cells, a crucial step toward creating fully functional, laboratory-made organs.

In this breakthrough study, a team of researchers from Murdoch Children’s Research Institute turned stem cells from human skin into multiple cell types found in kidneys. The newly developed tissue, which is similar to the kidney of a human embryo, contained collecting ducts and blood-filtering units called nephrons, according to the researchers.

The researchers, which detailed their findings in the journal Nature, clarified that the tissue is not a viable organ and cannot be transplanted yet into sick patients. However, they said that the “organoid” may be useful for other purposes such as replacing animals in drug toxicity tests.

According to the team, a series of experiments was conducted to perfect the chemical signals that the stem cells need to receive to form early stage collecting ducts and nephrons. The scientists said that the cells clumped together into primitive kidneys over nearly three weeks in culture. “They spontaneously formed complex kidney organoids,” the researchers said in the journal.

In 2013, the team marked a major medical advancement when they grew the world’s first mini-kidney in a dish. However, their earlier work only had two key cell types, while the recent one is already complex and more like a real kidney.

It has long been the medical field’s objective to create human organs from cells, considering the critical shortage of donor organs to replace those damaged by accident or disease. The process is complicated and challenging, especially in organs composed of a multitude of different cell types such as the kidney, which has more than 20.

In an accompanying article in the same journal, University of Edinburgh anatomy expert Jamie Davies writes that the work represents an important step toward building stem-cell-derived kidneys. “There is a long way to go until clinically useful transplantable kidneys can be engineered,” he says.

According to Davies, however, the organoids may already fulfill a completely different medical need, which is testing the safety of new drugs for humans. He said that the cell types that are most vulnerable to damage by drugs are present in the organoids.

Stem cells are primitive cells. As they develop, they grow into the various specialised cells that make up the different organs, such as the brain, heart and kidney. There have been previous studies that attempted to grow organoid stomachs, livers, retinas and brain and heart tissue from stem cells.

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