Scientists at Massachusetts General Hospital have built a functional engineered rat kidney, washed clean of its former cells and re-seeded with fresh ones, and transplanted it into a live rat. The engineered kidney can produce urine and expel it through a ureter, and it didn't produce any blood clots.
The fact that it actually worked -- it produced urine -- is a major breakthrough for tissue engineering, which faces probably its greatest challenge with the all-important kidney. The team also washed out a human and a pig kidney, although those weren't transplanted.
Bioengineered Rat Kidney
Current Music: Metric -- Nothing But Time ♬