According to the National Kidney Foundation, around 96,645 patients in the US are awaiting kidney transplants as a result of kidney failure. However, less than 17,000 kidney transplantations are carried out each year due to a shortage of donors. But a new option could soon be available - in the form of pig kidneys.
Researchers from the University of Florida are investigating the use of a pig kidney as a "scaffold" on which to build a human kidney by injecting it with human stem cells.
The investigators say the stem cells will "take over" the pig kidney, meaning it could be transplanted into humans.
They note that if the procedure proves successful, patients on kidney transplant lists could have their wait for a kidney reduced from years to months, meaning thousands of lives could be saved every year.
How human kidneys can be built using pig kidneys
The researchers say the first step of the process is to take skin cells from a patient suffering from kidney failure. These skin cells are then turned back to stem cells by adding certain chemicals and using specific growth techniques.
The pig kidney is then cleansed of all its cells through a process called decellularization. The investigators note that this process is crucial, and in order to avoid harming the organ structure or clearing away the chemical signals that cause differentiation of cells, it must be approached with care.
After this process, the pig kidney is almost translucent and becomes a "scaffold" in which human cells can grow.
Dr. Edward Ross, a nephrologist and professor of medicine at University of Florida Health, explains:
"The idea was to use a natural architecture, something we could never craft synthetically. The idea is if you put the human stem cells in, they will start to differentiate and remodel the scaffold."
The road so far
Researchers are investigating the use of pig kidneys as 'scaffolds' to grow human kidneys for transplantation.
Dr. Ross says that the research team are currently in the process of "seeding" the human skin cells and incubating them for growth.
He explains that in order for the skin cells to turn into structures, such as blood vessels, they need to be arranged in the correct region of the pig kidney scaffold. At present, the kidneys are connected to devices made up of pumps and vacuums that are helping to push these cells to the correct region.
"There are certain chemicals in the scaffold that tell them what to become, so different parts of the scaffold have different signals. If stem cells land in a particular spot, they will know how to develop," says Dr. Ross.
After this, Dr. Ross says the cells can communicate with each other, and the human cells can begin to reproduce and "claim" the blood vessels of the pig kidney.
Method could reduce need for anti-rejection drugs
The investigators are waiting to see how the pig kidneys develop, but they say they carried out a similar process using rat organs last year, which proved successful.
The researchers note that if this project is successful, not only could the method combat the shortage of kidney donors, it could also limit the need for anti-rejection drugs that can lead to serious side effects, as the kidney contains the patient's own cells.
But they point out that there is a long road ahead, and financial support is needed to help this area of research progress.
"Our next step is to overcome the barriers to get the cells to grow long enough and to differentiate," says Dr. Ross.
Medical News Today recently reported on a study detailing the creation of mini-kidneys grown from human stem cells, which scientists say could help provide better treatment and knowledge of chronic kidney disease (CKD).