What if an artificial kidney could work continuously inside the body and do more than simply filter the blood? By combining advanced technology with living kidney cells, researchers in the Netherlands are working towards just that. The ultimate goal is an implantable bioartificial kidney — and the building blocks for it are being developed today.
For people with kidney failure, dialysis is lifesaving. But it is also demanding. Treatment often takes several hours at a time, several times a week, and current dialysis replaces only part of what healthy kidneys normally do.
That is why the Dutch Kidney Foundation and its partners are looking beyond today’s dialysis. Together, we are working towards a bioartificial, or biohybrid, kidney: a device that combines artificial filters with living kidney cells and could eventually function continuously inside the body.
The recently launched BioHybrid Kidney Crossing Borders (XB) research programme brings that vision a step closer. Led by UMC Utrecht, it brings together researchers from UMC Utrecht, Utrecht University, the University of Twente and imec, alongside the Dutch Kidney Foundation, RegMed XB and several medtech companies. [1]
More than a smaller dialysis machine
A healthy kidney does much more than remove waste products from the blood. After filtering the blood, the kidneys recover water, salts and other useful substances that the body needs. Kidney cells also actively transport substances in and out of the filtered fluid.
A conventional dialysis machine mainly focuses on filtering the blood. A bioartificial kidney aims to reproduce more of these natural kidney functions.
That is where living kidney cells become important.
Karin Gerritsen, internist-nephrologist at UMC Utrecht, is one of the researchers working towards new forms of kidney replacement therapy. She also discussed the development of the bioartificial kidney together with Dutch Kidney Foundation innovation programme manager Jasper Boomker in the BNR Beter podcast. [2]
As Gerritsen explains:
“A bioartificial kidney also contains living kidney cells. They can help recover water and useful substances from the filtrate.” [1]*
Those cells could also help remove waste products more effectively, bringing treatment closer to what a healthy kidney does.
The ambition, in other words, is not simply to make dialysis smaller. It is to make kidney replacement work more like a real kidney.
Building it step by step
Dr Jeroen Vollenbroek of UMC Utrecht leads the BioHybrid Kidney XB research project. His team’s ideal end point is an artificial kidney that can be placed inside the body of someone with kidney failure and continuously take over important kidney functions. [3]
But a device this complex cannot be developed in one leap. Instead, the researchers are deliberately working through a series of intermediate steps.
As Vollenbroek puts it:
“By developing intermediate solutions in different steps, we can help patients sooner.” [3]*
That principle is central to the programme. Researchers are not only aiming for an implantable kidney in the distant future. They are also developing technologies that could potentially improve treatment along the way.
Step 1: a small filter for the blood
The first goal is a hemofilter: a small device that filters the blood.
Researchers are developing smart materials with a special surface that can remain in contact with blood for long periods without causing unwanted clotting.
In the future, such a filter might be implanted in the body while remaining connected to a dialysis system outside the body. Because blood could flow directly through the implanted filter, it might reduce the need to repeatedly access the bloodstream with dialysis needles.
Even before a complete bioartificial kidney exists, one of its building blocks could therefore potentially make dialysis less burdensome.
Step 2: adding living kidney cells
Filtering is only one part of what the kidneys do.
After blood is filtered, kidney tubules recover water and regulate salts and other substances. Without this process, the body would lose large amounts of valuable fluid and substances.
Reproducing these functions is considerably more complex than simply filtering blood. Vollenbroek and his colleagues therefore want to develop an artificial kidney tubule, combining specially designed materials with living kidney cells. [3]
The material needs to perform several tasks at once. Kidney cells need to attach to it, stay healthy and function correctly, while the material itself should not cause harmful reactions in the body.
If the researchers succeed, the cells could perform some of the transport functions that kidney cells normally carry out inside our kidneys.
This combination of biology and engineering is what makes the kidney bioartificial.
Step 3: bringing the functions together
The next step is to combine the artificial filter and living-cell component into a complete biohybrid kidney.
The first complete system is expected to operate outside the body. It would combine blood filtration with some of the transport functions performed by living kidney cells.
This external system could already be valuable in two ways. It might become an improvement to dialysis in its own right, while at the same time demonstrating that the different components of a bioartificial kidney can work together. [3]
Only after those technologies have been shown to work safely and reliably can researchers move further towards a device that functions inside the body.
Helping patients before the final destination
This step-by-step strategy is important because patients should not necessarily have to wait for the final implantable kidney before the research begins to make a difference.
Intermediate technologies could already improve treatment.
A better blood filter might make dialysis safer or less burdensome. A device containing kidney cells could reproduce more kidney functions than conventional dialysis. And an external bioartificial kidney could potentially become a treatment before a fully implantable version is possible.
The hope is that these advances could eventually mean less dependence on dialysis centres, more energy and greater freedom in everyday life for people with kidney failure.
Each intermediate result also teaches researchers something new about what an implantable artificial kidney will ultimately need.
From scientific discovery to treatment
Developing the science is only one part of the challenge.
A technology that works in a laboratory must eventually be produced safely, reliably and at sufficient scale before it can become a treatment for patients.
That is why cooperation between researchers and companies is an essential part of BioHybrid Kidney XB.
The Dutch Kidney Foundation is taking an active role in connecting those worlds. We support research, but also help bring together scientists, companies, clinicians and patients so that promising discoveries have a better chance of progressing towards clinical use.
For Jasper Boomker, Programme Manager Research & Innovation at the Dutch Kidney Foundation, that broader role is crucial:
“Funding research remains important. But we must also ensure that new knowledge can make the step towards the patient.” [4]*
Researchers may know how kidney cells behave and what functions a bioartificial kidney needs to reproduce. Companies, meanwhile, can provide expertise in materials, engineering, manufacturing, medical-device development and scaling up production.
Bringing those capabilities together can help turn promising laboratory findings into technologies that can actually be used.
New partnerships to accelerate progress
To encourage this cooperation, the Dutch Kidney Foundation organised a matchmaking initiative connecting researchers with companies that could contribute missing expertise.
It has already led to new research consortia.
For example, researchers at Utrecht University have demonstrated that kidney cells can grow on special membranes while retaining important functions. Moving from a laboratory experiment towards a treatment, however, requires much more: methods for producing the technology at scale, reliable logistics and manufacturing processes, and ways of integrating it safely into a medical device. [4]
Health~Holland is supporting this public-private collaboration with €2.1 million, alongside support from the Dutch Kidney Foundation. [1,4]
It is this combination of kidney biology, advanced materials, microtechnology, engineering and industrial expertise that could make a bioartificial kidney possible.
The long-term vision: continuous kidney replacement inside the body
Ultimately, the ambition goes much further than improving existing dialysis.
Researchers envision a small bioartificial kidney that could be implanted in the body and function continuously, day and night.
Continuous treatment could more closely resemble the way our natural kidneys work than treatment in separate dialysis sessions. Instead of alternating between dialysis and periods in which fluid and waste products build up again, kidney functions could potentially be supported continuously.
For patients, that could mean far less dependence on fixed dialysis schedules and more freedom to work, study, travel and take part in everyday life.
It is a compelling vision — but there is still a long way to go.
Researchers need to show that filters can function safely for long periods, that living kidney cells remain healthy and functional, that blood does not clot around the device, that its materials are accepted by the body and that all the different components can operate together reliably.
There is therefore no responsible date yet for when a fully implantable bioartificial kidney might become available to patients.
As Gerritsen also emphasises, many scientific and technological breakthroughs are still needed. At the same time, every advance brings the field a little closer to that longer-term goal. [1]
A route towards the kidney treatment of the future
What is emerging from the research is not a single leap from today’s dialysis machine to tomorrow’s implant.
It is a route.
It runs from better and smaller filters, to materials that can safely remain in contact with blood, to artificial kidney tubules containing living kidney cells. From there, researchers aim to combine those technologies into an external biohybrid kidney and, ultimately, a device that could function inside the body.
Karin Gerritsen’s work shows why living cells could allow kidney replacement therapy to do more of what healthy kidneys naturally do. Jeroen Vollenbroek and his team are developing the technological building blocks step by step. And Jasper Boomker and the Dutch Kidney Foundation are helping create the partnerships needed to move those innovations from research towards patients.
That combination of science, technology and collaboration is at the heart of BioHybrid Kidney XB.
For the Dutch Kidney Foundation, the bigger picture is clear: improving life for people with kidney disease today, while investing in the breakthroughs that could fundamentally change kidney care tomorrow.
Sources
[1] Dutch Kidney Foundation — Uniek programma dat moet leiden tot een biokunstnier gestart in UMC Utrecht
[2] BNR Beter — Nederlandse onderzoekers werken aan implanteerbare kunstnier: ‘van gekweekte niercellen’, interview with Karin Gerritsen (UMC Utrecht) and Jasper Boomker (Dutch Kidney Foundation)
[3] Dutch Kidney Foundation — Stap voor stap richting een implanteerbare kunstnier, interview with Dr Jeroen Vollenbroek (UMC Utrecht)
[4] Dutch Kidney Foundation — Samenwerking brengt biokunstnier dichterbij
*Quotes have been translated from Dutch into English for this article.