A coffee cup-sized implant that mimics the functions of the human kidney could be a life-saving option for patients with chronic kidney disease

A coffee cup-sized implant that mimics the functions of the human kidney could be a life-saving option for patients with chronic kidney disease.

The implant is expected to begin trials later this year and if successful, it could be available within a few years, saving patients from dialysis or needing a transplant —there are currently 30,000 people in the UK having dialysis, and 5,000 on the waiting list for a donor kidney.

Around one in eight Britons will develop chronic kidney disease in their lifetime, with half of all over-75s suffering it to some degree. It is often caused by poorly controlled diabetes or high blood pressure.

Healthy kidneys remove toxins from the blood, control the body’s fluid balance and make hormones which help control blood pressure, red blood cell production and keep bones healthy.

Kidney failure is where the organ’s ability to do these things falls below 15 per cent of its normal capacity, causing toxins to build up in the blood and water to gather in the lungs — with potentially fatal consequences.

The most effective treatment is a transplant, but demand for organs far outstrips supply.

The only other option is dialysis, where a machine takes over the function of diseased kidneys to clean the blood of waste, salts and excess fluid — without dialysis, these could build up to fatal levels.

Dialysis can be inconvenient as people usually go to hospital for treatment, typically three sessions a week, for three to four hours at a time. Dialysis is also associated with fatigue and depression, can remove too many nutrients from the blood and only works while patients are connected to the machine.

The idea with the artificial kidney is that it continuously filters blood inside the body and avoids these problems — researchers at the University of California, San Francisco, have developed it over the past 20 years.

The implant is essentially two components — filters to separate the various substances in the blood, and a ‘bioreactor’ which transfers these either to the blood, or to the bladder for removal from the body. These are encased in a hard-wearing box coated in a film made from materials safe for use inside the body. It is connected with tubes to nearby veins and to the bladder.

The artificial kidney first passes blood through layered silicon filters to remove waste and then through the ‘bioreactor’ made of lab-grown live kidney cells which reabsorb vital salts, sugars and water into the blood, in a similar way to a real kidney.

Cleaned blood is returned to the circulation through a vein the implant is connected to, while waste material drains into the bladder via a tube.

Researchers believe they will start testing parts of the device on humans within months, after trials in pigs showed success in overcoming a problem with blood clots. Blood has a natural tendency to clot, which caused problems in earlier prototypes of the device.

Around one in eight Britons will develop chronic kidney disease in their lifetime, with half of all over-75s suffering it to some degree. It is often caused by poorly controlled diabetes or high blood pressure

Clots not only stop the implant working but could prove fatal if they travel to the brain, heart or lungs — so it was vital the U.S. scientists overcame this issue before taking it further.

They have developed two mechanisms for stopping the problem by changing the way blood flows through the device, and its coating is thought to prevent clots, too.

Once it is ready for humans, the artificial kidney would be implanted in a similar way to kidney transplant surgery, under general anaesthetic. Professor Shuvo Roy, a bioengineer who is leading the project, told Good Health: ‘We are wrapping up the preclinical studies and awaiting approval from our ethics board on the first safety study in patients. [We are] hopefully starting the first trial to test safety in 2018.’

The first trials will check if materials in the device are safe for humans and whether components can filter human blood effectively. Within two years, trials of the implanted device should begin with a small number of patients.

If successful and the device is approved, it could be available in Britain within just a few years.

The researchers will present an update on the research at the UK Annual Dialysis Conference in Manchester in September.

Sandip Mitra, a consultant nephrologist at Manchester University NHS Foundation Trust, said the project was ‘an exciting advance’. ‘A treatment option that could overcome some of the limitations of dialysis and organ transplantation would be a significant step change . . . and will have a significant impact on patients’ lives,’ he said.

But Jamie Davies, professor of experimental anatomy at the University of Edinburgh and a researcher with Kidney Research UK, warned the technology was far from ready.

‘A practical device is still likely to be a long way in the future, and it is important that kidney patients still do all they can to protect the kidney function they have. It is also very important that donors still come forward,’ he said.