While it may not be possible to grow functional human kidneys in a lab just yet, scientists at Italy’s Mario Negri Institute for Pharmacological Research have definitely come a step closer. In a paper published last week, they reported that they have created kidney-like “organoids,” that perform the same functions as kidneys when implanted in rats.

In previous studies, researchers have used suspensions of embryonic kidney cells to grow tissues similar in form to immature kidneys. These tissues couldn’t perform functions such as blood filtration, however, as they lacked the blood vessels necessary to do so.

In the current study, led by Dr. Christodoulos Xinaris, the researchers once again grew tissue from rat kidney cell suspensions. This time, however, the resulting renal organoids were subsequently soaked in vascular endothelial growth factor (VEGF), which promotes the growth of blood vessels.

The organoids were then implanted below the rats’ existing kidneys, with the animals subsequently receiving VEGF injections for a period of three weeks. It was found that the organoids continued to mature after implantation, and were performing functions such as blood filtration and molecule reabsorption.

One of the renal organoids, implanted in a lab rat host (Image: Dr. Christodoulos Xinaris)

“The ability to build functional renal tissue starting from suspensions of single cells represents a considerable step toward the practical goal of engineering renal tissues suitable for transplantation and offers the methodological basis for a number of investigative and therapeutic applications,” said Dr. Xinaris.

The paper on the research was published in the Journal of the American Society of Nephrology.

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