Transplanted tissue could offer a solution to kidney donor shortage. Instead of searching for a kidney donor, a new study suggests, one might be able to grow a new kidney. A team headed by Prof. Yair Reisner of the Weizmann Institute of Science in Rehovot, Israel, one of the world's top-ranking multidisciplinary research institutions, has induced human stem cell tissue to grow into functional kidneys, and have accomplished the same with porcine stem cell tissue. Published in Nature Medicine, the method could lead to a promising solution to the severe shortage of kidney donors.



The findings suggest that human or porcine fetal tissue might take on the shape and function of a healthy kidney if transplanted into humans as well. Pig tissue, as opposed to pig organs, is not expected to cause hyperacute rejection (common in cross-species transplants), as has been demonstrated by recent transplants of insulin-producing cell clusters taken from porcine fetal tissue that did not induce such rejection. The scientists hope that porcine stem cells might thus provide a ubiquitous source for those in need of a kidney.



According to the US National Kidney Foundation and the United Network for Organ Sharing, more than 50,000 people in the United States alone are on the waiting list for kidney transplants and more than 2,000 died this year waiting for a match. The wait can last years. And after a kidney is transplanted patients run the risk of transplant rejection.



Reisner and Ph.D. student Benny Dekel of the Weizmann Institute's Immunology Department, with Prof. Justen Passwell, the head of the pediatric department at the Sheba Medical Center, transplanted human and porcine 'kidney precursor cells' (stem cells that are destined to become kidney cells) into mice. Both human and porcine tissues grew into perfect kidneys, the size of the mice's kidneys. The miniature human and pig kidneys were functional, producing urine. In addition, blood supply within the kidney was provided by host blood vessels as opposed to donor blood vessels, greatly lowering the risk of rejection.



The procedure is now in the pre-clinical study stage. If all goes well, a treatment may ensue within a few years.