With nearly 100,000 patients awaiting a kidney transplant and fewer than one-fifth likely to undergo the procedure each year, a promising hybrid device that works from the inside to provide renal functions beyond dialysis 24 hours a day, seven days a week, has the potential to change a lot of lives, not to mention substantially lower Medicare costs.
Shuvo Roy, PhD, associate professor in the Department of Bioengineering and Therapeutic Sciences at the University of California–San Francisco School of Pharmacy and technical director of The Kidney Project (http://pharmacy.ucsf.edu/kidney-project/; Facebook.com/ArtificialKidney) updates Renal & Urology News on his group’s work.
How did you begin to develop the artificial kidney?
Dr. Roy: In the early 2000’s, we proved that the science worked. We took off-the-shelf, bulky, large, technology that we hooked up in a circuit to mimic how our kidneys work, and my colleague at the University of Michigan, Dr. David Humes, applied this to about 60 intensive care unit (ICU) patients who were suffering from acute renal failure. About half of them survived beyond six months—longer than they would have lasted on dialysis.
That clinical trial gave us a lot of confidence that this concept of a filter plus a bioreactor actually does provide a therapeutic benefit. But then the question became, “How do we take this concept from the large-scale technologies of the ICU and apply it to people who go to the dialysis center three times a week?”
And what was the answer?
Dr. Roy: The medical director on our team, William Fissell, MD, who is a nephrologist [with an engineering degree from Massachusetts Institute of Technology—Eds.], said we’d have to shrink the technology into something smaller that could be implanted; that could allow patients the freedom of mobility and the ability to eat and drink normally; and that could operate continuously, 24/7, to provide the benefit of toxin removal as well as the biological functions of the kidney that dialysis does not provide, such as help regulate blood pressure, help produce vitamins, and help with the acid levels of the blood.
How does the function of the artificial kidney differ from dialysis?
Dr. Roy: The five-year survival rate for dialysis hovers around 35%, but for kidney transplantation, it is well beyond 80%. The reason for that is dialysis simply does not provide the biological functions of a healthy kidney.
Our device mimics the native kidney, with a filter serving as the glomerulus. The filter is followed by a tubule—the bioreactor—which is lined with cells, to provide the full functions of a kidney. In typical dialysis you just do the filtration part; you don’t mimic the cell part at all.
Our device will be connected to the blood vessels, as a kidney transplant would be. One very exciting aspect is the membrane technology we have developed for the hemofilter: It’s so efficient that it will allow for filtration without the need for an electrical power supply, connections to the outside, or a battery. So just based on the blood pressure, we will be able to get therapy that’s sufficient to keep the patient alive 24/7.
What is the status of the artificial kidney now?
Dr. Roy: Over the last 10 years, we have been on a journey to miniaturize the components of our device to the size of a small to-go coffee cup using silicon nanotechnology. We enclosed the cells of the bioreactor in a container with tiny windows that allow for interaction between the body and cells but prevent the body’s immune system from getting to these cells.
We showed this to work on the bench, in small animals, in sheep, and in pigs with much success; it is all working in principle. The next step, which is what we are starting now, is to integrate the filter and the bioreactor into a single compact unit and do the animal testing that will let us validate this for subsequent human study.
I think we will be ready to test in humans by 2017, if not before. We are collaborating closely with the FDA as part of the agency’s Innovation Pathways 2.0 program to design this research.