OTT LAB, CENTER FOR REGENERATIVE MEDICINE, MASSACHUSETTS GENERAL HOSPITALResearchers at Massachusetts General Hospital in Boston have made functioning rat kidneys in the lab and transplanted them into the rodents, where the bioengineered organs filtered blood and produced urine, according a report out this week (April 14) in Nature Medicine. The work is an important step toward the long-term goal of creating replacement kidneys for humans, who currently have to wait for donor kidneys.

“The real value of this study is that it’s the kidney [rather than the heart or other organs] and it’s a proof of concept, and the clinical need is so great,” Stephen Badylak of the University of Pittsburgh told The New York Times.

A team led by organ-regeneration specialist Harald Ott made the replacement kidneys by first stripping...