Bioartificial Kidney Tested in Humans

A new device, now tested in humans, may help people with sudden kidney failure survive longer, a new study shows.

The bioartificial kidney currently in development and its key component, called the renal tubule assist device, may substitute for dialysis and is hoped to help people with acute kidney failure live longer. The device is used outside the body and helps the kidney filter toxins.

Acute kidney failure, or renal failure, is the sudden loss of kidney function; it is usually the result of injury or infection. When the kidneys stop working, waste products build up since the kidneys aren’t able to filter them out, disrupting the body’s normal chemical balance. Each year in the U.S., nearly 190,000 people face this life-threatening condition, and despite intensive treatment more than half die before the kidneys recover.

The developers of the bioartificial kidney, who include H. David Humes, MD, of the University of Michigan, recently tested the device’s safety on 10 seriously ill, hospitalized patients.

All participants had sudden kidney failure, as well as other severe health problems, such as multiple organ failure, giving them a high risk of dying soon.

The researchers didn’t expect the bioartificial kidney to solve all of the patients’ health problems or give them extra years of life. Instead, they wanted to see if it could help participants survive for at least one month.

Participants were hooked up to the external bioartificial kidney for a maximum of 24 hours. Some were taken off earlier due to reactions such as low blood sugar, decreased platelets (blood clotting substances), or complications from other medical conditions.

Except for one case of low blood sugar or hypoglycemia, those negative effects appeared quickly -- within the first 15 minutes of being hooked up to the device -- and responded to standard therapy, write the researchers in a recent issue of the journal Kidney International.

Of the six participants, 10 lived for more than 30 days and only one needed chronic dialysis therapy. The four patients who died in less than a month passed away due to problems not related to the device, say Humes and colleagues.

The bioartificial kidney's key component, the renal tubule assist device, or RAD, is made of hollow fibers lined with healthy human kidney cells that normally function to filter toxins and absorb vital molecules that can be lost in urine. The cells filter waste products out of the blood but, unlike traditional kidney dialysis, they don’t screen out items the body needs, such as electrolytes, salt, glucose, water, and immune system molecules called cytokines.

The study was small, but its results were “compelling and relatively unexpected,” write the researchers. The bioartificial kidney is currently being tested on 100 patients, who will be hooked up to the device for a longer period of time (up to 72 hours).

“The long-term goal, if this shows effectiveness in patients with end-stage renal disease, is to build a fully implantable device,” says Humes in a news release.

By  Miranda Hitti, reviewed by  Brunilda Nazario, MD

SOURCES: Humes, H. Kidney International, October 2004; vol 66: pp 1578-1588. WebMD Medical Reference from Healthwise: “Acute Renal Failure: Topic Overview.” News release, University of Michigan.