Lab-grown kidneys that function when transplanted into an animal

photo credit: The transplanted kidneys were able to pass urine, a major problem in earlier studies. hywards/Shutterstock
photo credit: The transplanted kidneys were able to pass urine, a major problem in earlier studies. hywards/Shutterstock

All over the world, there is an increase in the number of patients who have an end-stage renal disease calling for a need of renal replacement therapy, and many patients lie on their death bed due to the shortage of donor organs. Scientists from the Jikei University School of Medicine in Tokyo have taken this issue a step ahead and for the first time have been successful in generating functional kidneys from human stem cell which could provide hope for patients in the future.

In the impressive new research, scientists have been able to transplant lab-grown kidneys into animals that could then pass urine. The new study focuses on growing them de novo, or from the beginning. The novelty of this study led by Dr. Takashi Yokoo, was to understand the pitfall in the conventional generation of a lab-grown kidney from ES cells, which was its inability to transfer the processed urine into the natural ureter, making the kidney blow up due to pressure.

To get around this problem, the researchers effectively grew extra plumbing and another bladder in host animals. Yokoo and his team used “Stepwise Peristaltic Ureter” (SWPU), the term they coined wherein, the constructed new kidneys were connected to a special drainage tube and a bladder to store the urine until it is ready to be fed to the actual bladder of the recipients. They were then able to demonstrate that, when transplanted into rats and pigs and connected to the animals’ existing bladder, the system functioned effectively. The urine was created in the new kidney, passed into the new bladder, and then into the original bladder.

The next step is that the researchers want to take human stem cells and inject them into pig embryos that have been genetically modified not to grow kidneys, and then transplant the newly grown kidneys back – before they’ve fully grown – into humans. This should mean that the blood vessels that permeate the kidney will also be human, and won’t be rejected. Though this sounds exciting, this research is likely to take years to develop.

Chris Mason, an expert in the field of stem cell research and regenerative medicine, from the University College London remarked, “This is an interesting step forward. The science looks strong and they have good data in animals. But that’s not to say this will work in humans. We are still years off that. It’s very much mechanistic. It moves us closer to understanding how the plumbing might work. At least with kidneys, we can dialyse patients for a while so there would be time to grow kidneys if that becomes possible”.

This study was published in PNAS.

Source: BBC News, IFLS