Researchers at the University of California, San Francisco (UCSF), are developing an implantable artificial kidney that can closely replicate the functions of real kidneys.
If they are successful, the scientists’ work could help eliminate the need for dialysis.
Kidney transplants for patients with end-stage renal disease (ESRD) have a high rate of success.
About 93 percent of transplanted kidneys are still working after a year and 83 percent are functioning after three years.
Patients commonly wait five to 10 years for a suitable organ to become available.
Average life expectancy for dialysis patients is five to 10 years, although some have lived for decades.
However, dialysis — which filters out some (but not all) toxins from the bloodstream that would normally be eliminated by the kidneys — must be performed on a daily basis if done at home via peritoneal dialysis.
It requires three visits to a clinic weekly if performed via hemodialysis.
“The implantable bioartificial kidney is an alternative to dialysis and other externally wearable devices that would tether patients or limit their mobility,” Shuvo Roy, a professor in the UCSF Department of Bioengineering and Therapeutic Sciences and co-inventor of the device, told Healthline. “A live kidney transplant from a matching donor is still considered one of the best treatment options for ESRD, but unfortunately, there is shortage of organ donors that prevents transplants from being available to the vast majority of ESRD patients. Unlike transplants, our device will not require that patients be on immunosuppressive drugs to prevent rejection.”
Human trials of the device are about to begin.
Roy said the bioartificial kidney could eventually be used by the vast majority of the people now on dialysis and the kidney transplant list.
“This is a long-term solution, and any case where a kidney transplant is needed, our device will be a viable option,” said Roy.
How the device works
Roy leads The Kidney Project, a national research initiative centered on development and testing of a surgically implanted, freestanding bioartificial kidney that performs "the vast majority of the filtration, balancing, and other biological functions of the natural kidney.”
Powered by the body’s own blood pressure, the device does not require the external tubes or tethers associated with wearable artificial kidneys, such as that invented by Victor Gura of Cedars-Sinai Medical Center in Los Angeles. That device was tested on seven dialysis patients at the University of Washington Medical Center in Seattle in 2015.
The two-part implanted artificial kidney incorporates recent developments in silicon nanotechnology, which makes it possible to mass-produce reliable, robust, and compact filtering membranes.
The technology also has novel molecular coatings that protect the silicon membranes and make them blood-compatible.
“A hemofilter module processes incoming blood to create a watery ultrafiltrate that contains dissolved toxins as well as sugars and salts,” explained Roy. “Second, a bioreactor of kidney cells processes the ultrafiltrate and sends the sugars and salts back into the blood. In the process, water is also reabsorbed back into the body, concentrating the ultrafiltrate into ‘urine,’ which will be directed to the bladder for excretion.”
Patients with the implant may still be required to take hormonal supplements, however, as they currently do on dialysis, said Roy.
Development of alternatives to current treatments for kidney disease is “very important, since the outcomes of premature mortality and poor quality of life are common for the dialysis population, particularly for in-center hemodialysis,” Dr. Joseph Vassalotti, chief medical officer for the National Kidney Foundation, told Healthline.
The steps ahead
The Kidney Project is raising money to complete preclinical studies of the device modules and to build full-scale prototypes for the first round of human studies.
Initial clinical trials on the individual modules are expected to begin early next year.
Testing of a working prototype of the bioartificial kidney is slated for 2020.
“The long-term challenges center around keeping the device operating trouble-free after implantation beyond a few months,” said Roy. “Some problems won’t become clear until we do clinical trials.”
In addition to $6 million in government grants, the Kidney Project has received substantial donations from individuals in furtherance of its work to create an implantable artificial kidney.
“Their support is a testament to the acute need for a revolution in ESRD treatment, and the donations we have received are invaluable in allowing our research to progress,” said Roy.
In the future, scientists may be able to grow artificial kidneys.
In 2013, researchers, led by Melissa Little of the University of Queensland's Institute for Molecular Bioscience, were able to grow a primitive kidney from human stem cells.
In 2016, researchers from the Salk Institute in California reported that they were able to grow nephron progenitor cells, which can differentiate into kidney tissue, in the lab.
Such research continues, but the ability to grow replacement organs remains a more distant dream than an implantable artificial kidney.