Artificial kidneys

The Dawn of the Artificial Kidney

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Artificial kidneys may sound like something from a science fiction movie, but these ground-breaking new treatments are currently being designed and tested across the globe.

These scientific advances offer patients with kidney failure the hope of more prompt or less burdensome treatments in the future, but can they become a reality?

Today, patients with kidney failure have two main options: a kidney transplant or dialysis. Either treatment can replace some lost kidney function and prolong life, but each comes with drawbacks. People opting for a transplant may face long waiting times due to donor organ shortages and need lifelong immunosuppression treatment.

On the flipside, those receiving dialysis can begin treatment more promptly, but often feel tied down by the demands of regular dialysis sessions and dietary restrictions.

Meet the innovative dialysis and transplant technologies being developed for the future:

The wearable artificial kidney

These coffee-cup sized devices would potentially allow a patient to receive blood-filtering dialysis (haemodialysis) during the day or night. This would mean more frequent or continuous removal of wastes and fluids, and improved quality of life. The devices are lightweight and will rely on long-lasting batteries, advances in miniaturisation, new filtering materials and highly permeable membranes.

One of the best-known artificial kidneys is the Wearable Artificial Kidney (WAK), being developed at the University of Washington. It weighs about 5 kg and is worn on the waist like a toolkit belt, with a catheter connecting it to the bloodstream. It’s the only device so far tested in humans.

Patients taking part in trials in Italy and the Royal Free Hospital, London, wore the WAK for up to 8 hours. The next clinical trials will take place in the USA. The US body that approves new drugs and devices (the FDA) sees such potential in the WAK that they selected it for a ‘fast track’ innovation programme, meaning the developers can get expert advice on trial design and commercialisation.

The Dutch Kidney Foundation has also invested in the development of a portable artificial kidney called the Neokidney. This is a small haemodialysis device for nighttime use. It’s much smaller and more portable than current home haemodialysis machines.

There are important technical and safety issues to solve before wearable artificial kidneys become a reality. We don’t expect them to be available for many years. Moreover, before use in the UK, regulatory approval and appropriate professional and patient training and monitoring needs to be in place.

The bioartifical or ‘cyborg’ implantable kidney

This small, surgically implanted device consists of a highly permeable filtration unit and human kidney cells. Because the device contains live cells, it can theoretically not only filter the blood, but also perform other important functions of a real kidney, such as releasing hormones to control blood pressure.

The best-known bioartificial kidney is being developed by The Kidney Project, at the University of California, San Francisco:

The team is currently raising money to finish preclinical studies and build prototypes. Safety trials could start in 2018, followed by human trials of the prototype as early as 2020. Technical challenges include being able to keep the device working long-term.

Laboratory-grown living kidneys

Several researchers around the world are attempting to grow a complete human kidney using kidney cells from embryos, stem cells from adults or cloned tissue.

A team from Manchester University is the first in the world to have grown the parts of the kidney that filter blood (nephrons) in a laboratory dish using human stem cells
(www.manchester.ac.uk/discover/news/scientists-create-functioning-kidney-tissue). Stem cells are early cells that usually lie dormant in the body, but that can develop into many different cell types when needed. The laboratory-grown nephrons were then implanted into a mouse and were able to filter the animal’s blood and produce urine, similarly to how a normal kidney works.

With healthy kidneys having an estimated 1 million nephrons each, the process would need scaling up to grow whole organs ready for transplantation. The beauty of using a patient’s own stem cells is that this could help to avoid their body rejecting the laboratory-grown kidney (which can happen with today’s kidney transplants).

This research is in the early days and a lot more work is needed, but the ability to grow nephrons in the lab is an exciting development.

Tags: Research blogs, dialysis, transplant

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