A model of the implantable bioartificial kidney shows the
two-stage system
End-stage renal disease, or chronic kidney failure, affects
more than 500,000 people per year in the U.S. alone, and
currently is only fully treated with a kidney transplant. That
number has been rising between five to seven percent per year
and with just 17,000 donated kidneys available for transplant
last year the waiting list currently exceeds 85,000, according
to the Organ Procurement and Transplant Network. Those who can’t
secure a kidney for transplant are left reliant on kidney
dialysis. An expensive and time consuming process that typically
requires three sessions per week, for three to five hours per
session, in which blood is pumped through an external circuit
for filtration. In a development that could one day eliminate
the need for dialysis, researchers have unveiled a prototype
model of the first implantable artificial kidney.
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
University of
California, San Francisco (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.
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.
“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.”
Aside from the toll taken on human patients resulting from
the exhausting schedule, dialysis only replaces 13 percent of
kidney function. As a result, only 35 percent of patients
survive for more than five years.
The implantable device aims to eradicate that problem with a
two-stage system that uses a hemofilter to remove toxins from
the blood, while applying recent advances in tissue engineering
to grow renal tubule cells to provide other biological functions
of a healthy kidney. The process relies on the body’s blood
pressure to perform filtration without needing pumps or an
electrical power supply.
Roy’s team is collaborating with 10 other teams of
researchers on the project, including the Cleveland Clinic where
Roy initially developed the idea, Case Western Reserve
University, University of Michigan, Ohio State University, and
Penn State University.
The first phase of the project, which has already been
completed, focused on developing the technologies required to
reduce the device to a size that could fit into the body and
testing the individual components in animal models. In the
second and current phase, the team is working on scaling up the
device for humans. The team now has the components and a visual
model and is pursuing federal and private support to bring the
project to clinical use.
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