Lab-grown kidney successfully transplanted into rats

For the first time, complete lab-grown kidneys have been successfully transplanted into rats, filtering and discharging urine as a normal kidney would. Researchers from the Massachusetts General Hospital and Harvard Medical School, took a rat kidney, stripped out its functional cells using a solution of detergent, and left behind a white extracellular matrix, the collagen scaffold that gives the organ its three-dimensional structure. This included scaffolds for blood vessels as well as the key filtering structures of the kidney, and the system for collecting the urine and transporting this to the bladder. The scaffolds were then ‘reseeded’ with new cells and grown in the laboratory, resulting in the generation of a functioning kidney. When they found that the engineered kidney worked, they then transplanted it into a rat and connected it to the rat’s blood system and found that the lab-grown kidney could filter blood, reabsorb important nutrients and salts, and generate urine. The results did show some differences between normal kidneys and lab-grown kidneys. These differences suggested that the kidney structure were immature and not functioning exactly as an adult kidney would. However the researchers concluded that they had achieved three important milestones. First, the generation of three dimensional natural kidney scaffolds which contained no cells. Second, the ‘reseeding’ of these scaffolds with viable kidney tissue using new cells is possible. Lastly, the generation of urine from these bioengineered kidneys both in the lab and in a living rat.

The team is now attempting the same procedure using human kidneys, and also pig kidneys, which could be used to make scaffolds if there was a scarcity of human donors. The team has already successfully repopulated pig kidneys with human cells, but further studies are vital to guarantee that the pig components of the organ do not cause rejection when transplanted into humans. This method would  reduce the need for immune system suppression with drugs, in contrast to when a donor kidney is used, because the kidney will be built with the patient’s own cells. There is no cure for kidney failure. The only available treatments are dialysis or receiving a transplant, which just buy a patient more time but come with considerable limitations on quality of life. And with nearly 1 million patients in the US living with end-stage renal disease (ESRD), with over 100,000 new diagnoses every year, this procedure could address the limited availability of donor kidneys.

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http://www.nature.com/nm/journal/vaop/ncurrent/full/nm.3154.html