UCSF researchers today unveiled a prototype model of the first implantable artificial kidney,

US scientists prepare first artificial implantable kidney
Updated at: 1445 PST, Thursday, September 09, 2010


WASHINGTON: UCSF researchers today unveiled a prototype model of the first implantable artificial kidney, in a development that one day could eliminate the need for dialysis.

The device, which would include thousands of microscopic filters as well as a bioreactor to mimic the metabolic and water-balancing roles of a real kidney, is being developed in a collaborative effort by engineers, biologists and physicians nationwide, led by Shuvo Roy, PhD, in the UCSF Department of Bioengineering and Therapeutic Sciences.

The treatment has been proven to work for the sickest patients using a room-sized external model developed by a team member in Michigan. Roy’s goal is to apply silicon fabrication technology, along with specially engineered compartments for live kidney cells, to shrink that large-scale technology into a device the size of a coffee cup. The device would then be implanted in the body without the need for immune suppressant medications, allowing the patient to live a more normal life.

“This device is designed to deliver most of the health benefits of a kidney transplant, while addressing the limited number of kidney donors each year,” said Roy, an associate professor in the UCSF School of Pharmacy who specializes in developing micro-electromechanical systems (MEMS) technology for biomedical applications. “This could dramatically reduce the burden of renal failure for millions of people worldwide, while also reducing one of the largest costs in U.S. healthcare.”

The team has established the feasibility of an implantable model in animal models and plans to be ready for clinical trials in five to seven years.

End-stage renal disease, or chronic kidney failure, affects more than 500,000 people per year in the United States alone, and currently is only fully treated with a kidney transplant. That number has been rising between 5-7 percent per year, Roy said, in part because of the kidney damage associated with diabetes and hypertension.

Yet transplants are difficult to obtain: a mere 17,000 donated kidneys were available for transplant last year, while the number of patients on the transplant waiting list currently exceeds 85,000, according to the Organ Procurement ant Transplant Network.

Roughly 350,000 patients are reliant on kidney dialysis, Roy explained, which comes at a tremendous cost. The Medicare system alone spends $25 billion on treatments for kidney failure – more than 6 percent of the total budget – while the disease affects only 1 percent of Medicare recipients, he said. That cost includes almost $75,000 per patient each year for dialysis, according to the U.S. Renal Data System.

Nearly 400,000 people in the United States--and as many as two million worldwide--rely on dialysis machines to filter toxins from their blood because of chronic kidney failure.

Patients must be tethered to machines at least three times a week for three to five hours at a stretch. Even then, a dialysis machine is only about 13 percent as effective as a functional kidney, and the five-year survival rate of patients on dialysis is just 33 to 35 percent.

To restore health, patients need a kidney transplant, and there just aren't enough donor organs to go around. In August, there were 85,000 patients on the U.S. waiting list for a kidney, while only 17,000 kidney transplants took place last year.

A collaborative, multidisciplinary group of labs is working to create the first implantable artificial kidney. The prototype, revealed last week, is compact, no larger than a soup can. It not only filters toxins out of the bloodstream but also uses human kidney cells to perform other vital functions, such as regulating blood pressure and producing vitamin D.

"Dialysis is not only time-consuming, but it's also debilitating. Many patients don't feel good, because it's not doing all the functions of a normal, healthy kidney," says bioengineer Shuvo Roy, whose lab at the University of California, San Francisco produced the new device and is already testing it in animals. "The kidney doesn't just filter toxins. It also has metabolic functions and hormonal functions, and dialysis doesn't capture these abilities."

Making an artificial kidney small enough to fit inside the body is, however, a big challenge. A healthy kidney filters 90 liters of water each day. Current dialysis machines are the size of a small refrigerator, and require substantial pressure to pump enough water through the machine's porous membranes to allow contaminants to be filtered out of the blood.