Kidney failure affects 700,000 Americans and two million people worldwide. Treatment is severely limited by a scarcity of donor organs and the burden and expense of recurring dialysis.

Now William Fissell, MD, and colleagues have taken a major step forward in bioengineering an implantable universal donor kidney that can clean the bloodstream without the need for electrical power, pumps or dialysis.

The "bioreactor" contains functional renal tubular epithelial cells that are powered by chemical energy and which selectively reabsorb salt, water, glucose and amino acids while blocking reabsorption of uremic toxins and concentrating wastes in the urine.

Through pharmacological manipulations—inhibiting transforming growth factor-beta (TGF-beta) and adding metformin, a key enzyme activator—the researchers were able to increase salt and water transport by primary renal tubular cells grown on easily manufactured cell culture materials.

The finding, reported in the journal Tissue Engineering, is "a breakthrough step making achieving an implantable artificial kidney device possible," the researchers concluded.

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