Functioning artificial kidney on the way

Using nanotechnology, researchers have taken the first step toward developing a fully functioning artificial kidney for patients with end-stage renal disease, possibly eliminating the need for dialysis or kidney transplantation. The device is small - about the size of a paperback book - and therefore portable or implantable.

In the journal Hemodialysis International, Dr. Allen R. Nissenson, from the University of California at Los Angeles, and colleagues note that the equipment consists of two membranes operating in series within one cartridge. The membranes mimic filter structures found in a real kidney.

As Nissenson told, "a connection to the bloodstream is necessary, which allows blood to flow into the device. In the device, it is filtered and processed by the membranes, with waste and water being discharged into a bag - the external bladder - to be discarded, and important substances like salt, calcium, and nutrients returned to the body." In its final form, the device would operate continuously, imitating natural kidneys. No dialysis solution is used.

Using computer modeling, the researchers found that the device, operating 12 hours per day, 7 days per week, actually provides a greater filtering rate than conventional dialysis given three times a week.

End-stage renal disease is a condition in which the kidneys are no longer able to function normally. Usually this means that they are functioning at less than 10 percent of their normal capacity. When this occurs, dialysis or kidney transplant is needed.

In the United States, more than a third of people with end-stage renal disease have diabetes, and diabetic nephropathy (renal disease due to diabetes) is the leading cause of end-stage renal disease. Up to 40 percent of all people with type 1 (insulin-dependent or juvenile) diabetes eventually develop end-stage renal disease. Kidney disease also can develop in people with type 2 (non-insulin-dependent or adult-onset) diabetes. With either type, poor control of blood sugar increases the risk of end-stage renal disease.

Nissenson emphasized that work on the artificial kidney is "now just past the conceptual phase. We have done extensive computer modeling to predict how the device should work, and we have begun to construct the necessary membranes."

"Future work," he added, "involves producing a complete membrane, incorporating it into the device, and testing the function on animals, before human trials can begin. This next phase of work is expected to take 2 to 4 years, with clinical work possibly starting by 2010" he said.

SOURCE: Hemodialysis International, September 2005.