A major step towards transplantable lab-grown organs

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For the first time in medical history, biologists have transplanted a functional lab-grown kidney into a live animal.

Ever since scientists started dabbling with stem cells — those super-adaptable “pluripotent” cells that can transform into virtually any other kind of cell — there’s been hope that we’ll eventually figure out how to grow fully functional replacement organs in the lab. And indeed, regenerative medicine has shown much promise over the years, including successful experiments in which tiny mouse hearts and other organs have been grown.


But building an approximation of an organ with stem cells is one thing — actually getting it to work properly in anticipation of transplantation is quite another. Now, researchers working at Massachusetts General Hospital in Boston may have overcome this major hurdle.

A team led by Harald Ott took a pre-existing rat’s kidney and stripped it of all its cells by washing it with a special detergent-like mixture. Once the native cells were stripped away, the biologists were left with a kidney scaffold that they used to create a bioengineered graft of the real thing.


To create this graft, they introduced stem cells and fostered their re-growth. Specifically, the team re-seeded the kidney scaffolds with epithelial and endothelial cells, and used a pressure gradient to ensure that the right cells were growing in the right places (a process that was key to the experiment).

Eventually, after five days in an incubating chamber, the tissue became functional, resulting in grafts that could produce rudimentary urine — urine that did not function as well as natural ones, but was an acceptably close approximation for the purposes of the experiment (the scientists admitted that this is something they’re going to have to work on, a limitation that was likely the result of the immaturity of the kidney cells used).


But once they were satisfied that the lab-grown kidneys were working, then then transplanted them into live rats where they continued to function and produce the rudimentary urine.

The experiment resulted in the first functional lab-grown transplanted organ — a breakthrough that could eventually result in similar transplants in humans. And in fact, during the experiment, the researchers also worked with human and pig kidneys (though not for transplantation).


Read the entire study at Nature Medicine: “Regeneration and experimental orthotopic transplantation of a bioengineered kidney”.

Images: Shutterstock/Jeff Cameron Collingwood; Ott Lab, Center for Regenerative Medicine, Massachusetts General Hospital.