Add kidneys to the list of organs -- including hearts, eyeballs, and penises -- which researchers hope to soon be able to replace with bioengineered or synthetic alternatives.

H. David Humes, MD and his team at the University of Michigan Department of Internal Medicine have created an artificial kidney, using a mix of living cells and synthetic biocompatible materials.  The only problem is that it's the size of a small room.

Dr. Humes is working with Shuvo Roy, PhD, a member of the the UCSF Department of Bioengineering and Therapeutic Sciences, to use silicon fabrication techniques to shrink the device to an implantable size.  Such a device could save the lives of hundreds, if not thousands of victims of kidney failure whose long wait for organ donors often proves fatal.

One section of the artificial kidney consists of micro filters, that selectively expel metabolic wastes from the blood stream.  A secondary part consists BioCartridge of renal tubule cells that further mimic the metabolic and water balance functionality of a biological kidney.

Professor Roy, who teaches at the UCSF School of Pharmacy which specializes in developing micro-electromechanical systems (MEMS) technology for biomedical applications, says the project's ambitious objective is to shrink the massive device to the size of a coffee cup.

The team hopes to be able to implant the device without the need for anti-rejection therapies by making it as biocompatible as possible.  For anyone who's taking biomedical engineering course-work on a graduate level or done biomedical research, it's instantly apparent that this is an ambitious, but perhaps impossible objective in the short term, given the body's propensity to encase or otherwise adversely respond to even relatively biocompatible artificial materials.

Still, Professor Roy is hopeful, stating, "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.  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."

Chronic kidney failure, also known as end-stage renal disease, affects approximately 500,000 Americans a year.  The disease tends to be directly caused diabetes and hypertension and given Americans' growing girth (which increases ones propensity to these diseases) it is perhaps unsurprising that the number of afflicted is rising 5 to 7 percent annually.

According to the Organ Procurement and Transplant Network, over 85,000 people are on an organ waiting list, but only 17,000 kidneys were donated last year.  An organ replacement is the only cure for kidney failure.

Currently 6 percent of Medicare funding, or roughly $25B USD, goes to treating renal failure.  The government contributes roughly $75,000 a year to fund dialysis treatments for each of some of the 350,000 individuals suffering from the disease.

Dialysis is an unpleasant experience, to say the least.  It require three 3 to 5 hour sessions a week and is exhausting to patients.  And it only replaces 13 percent of kidney function.  However, it's patients' only hope of survival at this point.

Only 35 percent of patients survive more than 5 years on dialysis.

Besides U of M and UCSF, 9 other teams of researchers are collaborating on the project, including teams from the Cleveland Clinic where Roy initially proposed the project, Case Western Reserve University, Ohio State University, and Penn State University.

Animal testing (implantation) of fabrication-shrunk models is already complete.  Now the challenge is to scale up those successes to a human-size device, which encompasses the functionality of the room-sized construct.

One underlying problem is that the diseases that cause kidney failure -- hypertension, diabetes, etc. -- tend to tax replacement organs and will likely stress the replacement implant as well.  Thus without fundamental lifestyle changes (diabetes management via insulin therapy, losing weight) the likely pricey implant may only prove a temporary fix.