Recent advancements in engineering mean that the first preclinical trials for an artificial kidney could happen soon.
Like all those whose kidneys have failed, Scott Burton’s life revolves around dialysis. For nearly two decades, Burton has been hooked up (or, since 2020, has hooked himself up at home) to a dialysis machine that performs the job his kidneys normally would. The process is arduous, time-consuming, and expensive. Except for a brief window before his body rejected a kidney transplant, Burton has depended on machines to take the place of his kidneys since he was 12-years-old. His whole life, the 39-year-old says, revolves around dialysis.
“Whenever I try to plan anything, I also have to plan my dialysis,” says Burton says, who works as a freelance videographer and editor. “It’s a full-time job in itself.”
Many of those on dialysis are in line for a kidney transplant that would allow them to trade thrice-weekly dialysis and strict dietary limits for a lifetime of immunosuppressants. Burton’s previous transplant means that his body will likely reject another donated kidney unless it matches perfectly—something he’s not counting on. It’s why he’s enthusiastic about the development of artificial kidneys, small wearable or implantable devices that would do the job of a healthy kidney while giving users like Burton more flexibility for traveling, working, and more.
Still, the devices aren’t ready for testing in humans—yet. But recent advancements in engineering mean that the first preclinical trials for an artificial kidney could happen soon, according to Jonathan Himmelfarb, a nephrologist at the University of Washington.
“It would liberate people with kidney failure,” Himmelfarb says.
An engineering marvel
Compared to the heart or the brain, the kidney doesn’t get as much respect from the medical profession, but its job is far more complex. “It does hundreds of different things,” says UCLA’s Ira Kurtz.
Kurtz would know. He’s worked as a nephrologist for 37 years, devoting his career to helping those with kidney disease. While his colleagues in cardiology and endocrinology have seen major advances in the development of artificial hearts and insulin pumps, little has changed for patients on hemodialysis. The machines remain bulky and require large volumes of a liquid called dialysate to remove toxins from a patient’s blood, along with gallons of purified water. A kidney transplant is the next best thing to someone’s own, functioning organ, but with over 600,000 Americans on dialysis and only about 100,000 kidney transplants each year, most of those in kidney failure are stuck on dialysis.
Part of the lack of progress in artificial kidney design is the sheer complexity of the kidney’s job. Each of the 45 different cell types in the kidney do something different.
Part of the lack of progress in artificial kidney design is the sheer complexity of the kidney’s job. To build an artificial heart, Kurtz says, you basically need to engineer a pump. An artificial pancreas needs to balance blood sugar levels with insulin secretion. While neither of these tasks is simple, they are fairly straightforward. The kidney, on the other hand, does more than get rid of waste products like urea and other toxins. Each of the 45 different cell types in the kidney do something different, helping to regulate electrolytes like sodium, potassium, and phosphorous; maintaining blood pressure and water balance; guiding the body’s hormonal and inflammatory responses; and aiding in the formation of red blood cells.
There's been little progress for patients during Ira Kurtz's 37 years as a nephrologist. Artificial kidneys would change that.
UCLA
Dialysis primarily filters waste, and does so well enough to keep someone alive, but it isn’t a true artificial kidney because it doesn’t perform the kidney’s other jobs, according to Kurtz, such as sensing levels of toxins, wastes, and electrolytes in the blood. Due to the size and water requirements of existing dialysis machines, the equipment isn’t portable. Physicians write a prescription for a certain duration of dialysis and assess how well it’s working with semi-regular blood tests. The process of dialysis itself, however, is conducted blind. Doctors can’t tell how much dialysis a patient needs based on kidney values at the time of treatment, says Meera Harhay, a nephrologist at Drexel University in Philadelphia.
But it’s the impact of dialysis on their day-to-day lives that creates the most problems for patients. Only one-quarter of those on dialysis are able to remain employed (compared to 85% of similar-aged adults), and many report a low quality of life. Having more flexibility in life would make a major different to her patients, Harhay says.
“Almost half their week is taken up by the burden of their treatment. It really eats away at their freedom and their ability to do things that add value to their life,” she says.
Art imitates life
The challenge for artificial kidney designers was how to compress the kidney’s natural functions into a portable, wearable, or implantable device that wouldn’t need constant access to gallons of purified and sterilized water. The other universal challenge they faced was ensuring that any part of the artificial kidney that would come in contact with blood was kept germ-free to prevent infection.
As part of the 2021 KidneyX Prize, a partnership between the U.S. Department of Health and Human Services and the American Society of Nephrology, inventors were challenged to create prototypes for artificial kidneys. Himmelfarb’s team at the University of Washington’s Center for Dialysis Innovation won the prize by focusing on miniaturizing existing technologies to create a portable dialysis machine. The backpack sized AKTIV device (Ambulatory Kidney to Increase Vitality) will recycle dialysate in a closed loop system that removes urea from blood and uses light-based chemical reactions to convert the urea to nitrogen and carbon dioxide, which allows the dialysate to be recirculated.
Himmelfarb says that the AKTIV can be used when at home, work, or traveling, which will give users more flexibility and freedom. “If you had a 30-pound device that you could put in the overhead bins when traveling, you could go visit your grandkids,” he says.
Kurtz’s team at UCLA partnered with the U.S. Kidney Research Corporation and Arkansas University to develop a dialysate-free desktop device (about the size of a small printer) as the first phase of a progression that will he hopes will lead to something small and implantable. Part of the reason for the artificial kidney’s size, Kurtz says, is the number of functions his team are cramming into it. Not only will it filter urea from blood, but it will also use electricity to help regulate electrolyte levels in a process called electrodeionization. Kurtz emphasizes that these additional functions are what makes his design a true artificial kidney instead of just a small dialysis machine.
One version of an artificial kidney.
UCLA
“It doesn't have just a static function. It has a bank of sensors that measure chemicals in the blood and feeds that information back to the device,” Kurtz says.
Other startups are getting in on the game. Nephria Bio, a spinout from the South Korean-based EOFlow, is working to develop a wearable dialysis device, akin to an insulin pump, that uses miniature cartridges with nanomaterial filters to clean blood (Harhay is a scientific advisor to Nephria). Ian Welsford, Nephria’s co-founder and CTO, says that the device’s design means that it can also be used to treat acute kidney injuries in resource-limited settings. These potentials have garnered interest and investment in artificial kidneys from the U.S. Department of Defense.
For his part, Burton is most interested in an implantable device, as that would give him the most freedom. Even having a regular outpatient procedure to change batteries or filters would be a minor inconvenience to him.
“Being plugged into a machine, that’s not mimicking life,” he says.
This article was first published by Leaps.org on May 5, 2022.
A biotech in Cambridge, Mass., is targeting a rare disease called cystinosis with gene therapy. It's been effective for five patients in a clinical trial that's still underway.
Recently, AVROBIO compiled positive clinical data from this first and only gene therapy trial for the disease. The data show the potential of the therapy to genetically modify the patients’ own hematopoietic stem cells—a certain type of cell that’s capable of developing into all different types of blood cells—to express the functional protein they are deficient in. It stabilizes or reduces the impact of cystinosis on multiple tissues with a single dose.
Medical researchers have found that more than 80 different mutations to a gene called CTNS are responsible for causing cystinosis. The most common mutation results in a deficiency of the protein cystinosin. That protein functions as a transporter that regulates a lot metabolic processes in the cells.
“One of the first things we see in patients clinically is an accumulation of a particular amino acid called cystine, which grows toxic cystine crystals in the cells that cause serious complications,” explains Essra Rihda, chief medical officer for AVROBIO. “That happens in the cells across the tissues and organs of the body, so the disease affects many parts of the body.”
Jordan Janz, 23, meets Stephanie Cherqui, the principal investigator of his gene therapy trial, before the trial started in 2019.
Jordan Janz
According to Rihda, although cystinosis can occur in kids and adults, the most severe form of the disease affects infants and makes up about 95 percent of overall cases. Children typically appear healthy at birth, but around six to 18 months, they start to present for medical attention with failure to thrive.
Additionally, infants with cystinosis often urinate frequently, a sign of polyuria, and they are thirsty all the time, since the disease usually starts in the kidneys. Many develop chronic kidney disease that ultimately progresses to the point where the kidney no longer supports the body’s needs. At that stage, dialysis is required and then a transplant. From there the disease spreads to many other organs, including the eyes, muscles, heart, nervous system, etc.
“The gene for cystinosis is expressed in every single tissue we have, and the accumulation of this toxic buildup alters all of the organs of the patient, so little by little all of the organs start to fail,” says Stephanie Cherqui, principal investigator of Cherqui Lab, which is part of UC San Diego’s Department of Pediatrics.
Since the 1950s, a drug called cysteamine showed some therapeutic effect on cystinosis. It was approved by the FDA in 1994 to prevent damage that may be caused by the buildup of cystine crystals in organs. Prior to FDA approval, Cherqui says, children were dying of the disease before they were ten-years-old or after a kidney transplant. By taking oral cysteamine, they can live from 20 to 50 years longer. But it’s a challenging drug because it has to be taken every 6 or 12 hours, and there are serious gastric side effects such as nausea and diarrhea.
“With all of the complications they develop, the typical patient takes 40 to 60 pills a day around the clock,” Cherqui says. “They literally have a suitcase of medications they have to carry everywhere, and all of those medications don’t stop the progression of the disease, and they still die from it.”
Cherqui has been a proponent of gene therapy to treat children’s disorders since studying cystinosis while earning her doctorate in 2002. Today, her lab focuses on developing stem cell and gene therapy strategies for degenerative, hereditary disorders such as cystinosis that affect multiple systems of the body. “Because cystinosis expresses in every tissue in the body, I decided to use the blood-forming stem cells that we have in our bone marrow,” she explains. “These cells can migrate to anywhere in the body where the person has an injury from the disease.”
AVROBIO’s hematopoietic stem cell gene therapy approach collects stem cells from the patient’s bone marrow. They then genetically modify the stem cells to give the patient a copy of the healthy CTNS gene, which the person either doesn’t have or it’s defective.
The patient first undergoes apheresis, a medical procedure in which their blood is passed through an apparatus that separates out the diseased stem cells, and a process called conditioning is used to help eliminate the damaged cells so they can be replaced by the infusion of the patient’s genetically modified stem cells. Once they become engrafted into the patient’s bone marrow, they reproduce into a lot of daughter cells, and all of those daughter cells contain the CTNS gene. Those cells are able to express the healthy, functional, active protein throughout the body to correct the metabolic problem caused by cystinosis.
“What we’re seeing in the adult patients who have been dosed to date is the consistent and sustained engraftment of our genetically modified cells, 17 to 27 months post-gene therapy, so that’s very encouraging and positive,” says Rihda, the chief medical officer at AVROBIO.
When Janz was 11-years-old, his mother got him enrolled in the trial of a new form of cysteamine that would only need to be taken every 12 hours instead of every six. Two years later, she made sure he was the first person on the list for Cherqui’s current stem cell gene therapy trial.
AVROBIO researchers have also confirmed stabilization or improvement in motor coordination and visual perception in the trial participants, suggesting a potential impact on the neuropathology of the disease. Data from five dosed patients show strong safety and tolerability as well as reduced accumulation of cystine crystals in cells across multiple tissues in the first three patients. None of the five patients need to take oral cysteamine.
Janz’s mother, Barb Kulyk, whom he credits with always making him take his medications and keeping him hydrated, had been following Cherqui’s research since his early childhood. When Janz was 11-years-old, she got him enrolled in the trial of a new form of cysteamine that would only need to be taken every 12 hours instead of every six. When he was 17, the FDA approved that drug. Two years later, his mother made sure he was the first person on the list for Cherqui’s current stem cell gene therapy trial. He received his new stem cells on October 7th, 2019, went home in January 2020, and returned to working full time in February.
Jordan Janz, pictured here with his girlfriend, has a new lease on life, plus a new hair color.
Jordan Janz
He notes that his energy level is significantly better, and his mother has noticed much improvement in him and his daily functioning: He rarely vomits or gets nauseous in the morning, and he has more color in his face as well as his hair. Although he could finish his participation at any time, he recently decided to continue in the clinical trial.
Before the trial, Janz was taking 56 pills daily. He is completely off all of those medications and only takes pills to keep his kidneys working. Because of the damage caused by cystinosis over the course of his life, he’s down to about 20 percent kidney function and will eventually need a transplant.
“Some day, though, thanks to Dr. Cherqui’s team and AVROBIO’s work, when I get a new kidney, cystinosis won’t destroy it,” he concludes.
