Shuvo Roy, PhD, a translational bioengineer and professor of bioengineering at the University of California, San Francisco, along with William Fissell, MD, of Vanderbilt University Medical Center in Nashville, Tennessee, are leading The Kidney Project, an effort to develop an implantable bioartificial kidney. So far, investigators have successfully tested prototypes implanted into healthy pigs. In an interview with Renal & Urology News, Dr Roy describes various aspects of the innovative technology.
At what stage of development is the artificial kidney?
Dr Roy: We are in the preclinical development stage. We have created functional small-scale prototypes and shown that they operate as intended in healthy pigs. Next, we need to create larger devices with enough capacity to treat humans and test them in pigs with compromised kidney function.
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What are the principal components of the device and how do they work?
Dr Roy: The bioartificial kidney consists of 2 primary components that work together to get rid of wastes. First, the blood-filtering “hemofilter” component processes incoming blood to create a watery ultrafiltrate that contains dissolved toxins as well as sugars and salts. Second, a “bioreactor” containing cultured 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 is directed to the bladder for excretion.
How big will it be?
Dr Roy: The first versions of the device will be about the size of a coffee mug, and we expect to shrink the package size as our manufacturing techniques evolve.
How were you able to develop a device that can perform the functions of today’s dialysis machines yet be a fraction of the size?
Dr Roy: We are using technology borrowed from the semiconductor electronics industry to precisely pattern silicon wafers into filtration membranes that mimic the function of the native kidneys. Traditional dialysis machines use filters whose polymer membranes have a wide variation in pore size, meaning that they are inefficient in filtering the blood. Our membrane pores are precisely engineered to retain larger molecules (like albumin) and let waste products (like urea and creatinine) pass. This level of precision allows for a much higher hydraulic permeability than the traditional membranes, enabling a much more efficient device. This means that the device can be small enough for implantation and can filter the blood under the body’s blood pressure alone, without blood pumps or batteries.
Where will the device be implanted?
Dr Roy: The device will be implanted in the abdomen so that it can be connected to the nearby iliac artery, vein, and bladder, similar to a kidney transplant. This location also allows for easy surgical access, should the device ever need to be repaired or replaced.
Will patients still be required to take immunosuppressive medication?
Dr Roy: No! This is one of the big advantages of the artificial kidney. The precise size of our membranes’ pores makes it so that small molecules can pass through the device, but larger molecules and immune cells cannot pass through. This means that the kidney cells in the bioreactor remain isolated from the patient’s immune system, and the body won’t recognize and reject the device.
When do you foresee a clinical trial?
Dr Roy: This is a function of resources. We can be ready to start a clinical trial in 3 to 4 years if we have the $10 million we need to complete the device scale-up and the FDA-required testing. Since we don’t know how quickly we’ll be able to raise this funding, it’s difficult to predict when a trial will start. We are actively fundraising and hope to secure these funds as soon as possible.
Editor’s note: Dr Roy said people interested in donating to the project can visit bit.ly//Givetokidney.
