Bacteria Could Help Failing Kidneys
Microbes groomed to breakdown toxic waste
between dialysis sessions.
Around 250,000 people in the US need dialysis
each year.
A spoonful of microbes or a capsule of enzymes
could soon lengthen the time between kidney patients'
dialysis sessions, researchers told last week's
annual meeting of the American Society for Artificial
Internal Organs, in Washington DC.
Diabetes and chronic high blood pressure can stress
the kidneys and cause toxic substances like urea,
creatinine and uric acid to accumulate in the
blood and diffuse into the gut. To filter these
out, around 250,000 people in United States alone
undergo dialysis treatment each year.
Biotechnologist Jill O'Loughlin and her colleagues
at Brown University in Providence, Rhode Island,
have come up with one possible alternative: a
trio of enzymes in tiny capsules, about half a
millimetre in diameter. They isolated the enzymes
- urease, uricase and creatininase - from the
jack bean plant and two types of bacteria.
"We're trying to design a therapy that would
supplement dialysis by reducing the metabolites
between treatments," says O'Loughlin. In
a solution that mimics a patient's stomach contents,
the capsules broke down all the uric acid, 97
per cent of the urea and 70 per cent of the creatinine
within 24 hours. Preliminary experiments in rats
are underway.
Microbiologist Beena Patel of Kibow Biotech Inc.
in Philadelphia, Pennsylvania, and her colleagues
are developing a different dialysis adjunct, based
on the power of soil bacteria to destroy urea.
They put the bacterium Bacillus pasteurii to the
test in a human gut simulator that mimics the
flora and acid environment of the digestive system,
from stomach to descending colon.
In less than 24 hours, B. pasteurii broke down
around 60 per cent of the urea in the system,
without harming the natural bacterial mix. Initial
studies in rats and pigs, where the bacteria are
mixed into the feed, also look promising, says
clinical study coordinator Pari Ranganathan.
"Dialysis is so expensive," Ranganathan
says. "We are targeting people who need it
and can't afford it." But there are big hurdles
ahead - the bacteria or enzymes must remain in
the human gut long enough to do their work, and
their by-products must be harmless.
American Society for Artificial Internal Organs
- International Society for Artificial Organs
Joint Conference,Washington, June 24, 2003
References: O'Loughlin, J. A., Bruder, J. M. &
Lysaght, M. J. Degradation of uremic toxins with
free and encapsulated enzymes. ASAIO Journal,
49, 208, (2003). Patel, B. G., Ranganathan, N.
& Friedman, E. A. Artificial Swallowable Kidney
Formulation. ASAIO Journal, 49, 201, (2003).
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