Building a kidney with stem cells is not enough -- it has to function as well. Scientists move closer to that goal.
In the United States alone, 100,000 people are in need of a kidney transplant. But because of a shortage of kidneys from donors, only 17,000 transplants are performed every year. Twelve people requiring a new kidney die each day.
In light of this shortage, researchers place much hope into developing kidneys artificially. Stem cells, with the potential to develop into any human tissue, may one day be used to generate engineered organs, changing organ transplantation as we know it.
The first step, creating precursors of kidney cells from stem cells, was accomplished several years ago. Then, several groups succeeded in growing "mini kidneys." One group used induced pluripotent stem cells (PSCs) and growth factors to create progenitors with clear characteristics of renal cells. The scientists then cultured these cells with kidney cells from mice; the mice cells allowed the stem cells to form three-dimensional structures of the kidney.
However, building an organ, impressive as it is, does not mean that it is going to be functional. One of the defining features of a kidney -- its ability to excrete -- needed to be addressed. Attempts to connect such a kidney to a bladder via an artificial tube have not been successful.
One group grew their own "kidney buds" and found that hydronephrosis, the swelling of the kidney when urine builds up, developed. Thanks to a technique the researchers call a "stepwise peristaltic ureter" system, they generated a channel in transplanted embryonic pig kidneys, allowing urine to pass through. Construction of this pathway allowed the kidneys to continue to grow.
We at HemaCare are fascinated with all the promise that stem cells hold. For your own research needs, we offer bone marrow, cord blood, and mobilized peripheral blood stem cells, as well as mesenchymal stem cells.
1. Xia, Y. et al. Directed differentiation of human pluripotent cells to ureteric bud kidney progenitor-like cells. Nat Chem Biol 15, 1507-1515. (2013)
2. Yokote, S. et al. Urine excretion strategy for stem cell-generated embryonic kidneys. PNAS USA Early Edition.