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Researchers reveal why Kidneys from Older
Donors do not last as long as those from
Younger Individuals
Newswise — Kidneys from older donors often
do not survive long after transplantation
because of certain structural dysfunctions
that can occur as the kidney ages, according
to a study appearing in the January 2009
issue of the Journal of the American Society
Nephrology (JASN).
The findings indicate that the number of
functioning glomeruli—the filtering units of
the kidney—drops significantly with age,
leading to a self-perpetuating injury in the
rest of the kidney.
Thousands of individuals are on the waiting
list for kidney transplants in the United
States, and the average waiting time is more
than three years. One response to the donor
deficit has been to increase the number of
transplants from older deceased donors.
However, these kidneys exhibit a striking
reduction in the 5-year graft survival rate.
“We need to understand the process of renal
senescence better in order to better select
older donor organs that are likely to
function well after transplantation,” said
Jane C.Tan, MD, of the Stanford University
Medical Center in Stanford, California.
To understand the aging-related changes in
the kidney that account for the shortened
survival of older organs, Dr. Tan and her
colleagues analyzed the structures of
kidneys from 20 aging (>55 years) and 23
youthful (<40 years) deceased donors.
They also looked specifically at the
glomeruli of a subset of 13 aging and 12
youthful deceased donors that were taken
prior to transplantation.
The investigators found a 32% depression of
the glomerular filtration rate, a measure of
the kidneys’ ability to filter and remove
waste products, in the aging vs youthful
groups. In addition, the number of
functioning glomeruli was profoundly
depressed in older kidneys compared with
younger kidneys.
The authors proposed that this could lead to
a “remnant kidney” phenomenon, whereby a
self-perpetuating injury to the remaining
kidney tissue occurs, ultimately
contributing to shortened survival of the
transplanted organ.
Information from this study might be useful
for selecting kidneys from older donors when
younger organs are not available.
Kidneys with a greater number functioning
glomeruli would clearly be better suited for
transplantation than those with fewer
glomeruli.
This study was supported by NIH grants
R01DK064697 and General Clinical Research
Center grant M01-RR-00070, and by a grant
from the John M. and Abby Sobrato
Foundation.
The article, entitled “Glomerular Function,
Structure and Number in Aging Deceased Donor
Kidney Transplants,” will appear online at
http://jasn.asnjournals.org/ on
Wednesday, September 24, 2008, and in the
January 2009 print issue of JASN.
ASN is a not-for-profit organization of
11,000 physicians and scientists dedicated
to the study of nephrology and committed to
providing a forum for the promulgation of
information regarding the latest research
and clinical findings on kidney diseases.
ASN publishes JASN, the Clinical Journal of
the American Society of Nephrology (CJASN),
and the Nephrology Self-Assessment Program (NephSAP).
In January 2009, the Society will launch ASN
Kidney News, a newsmagazine for
nephrologists, scientists, allied health
professionals, and staff.
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