Transplant: Ginjal Babi ke manusia

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Lab-Engineered Kidney Project
Reaches Early Milestone

 ScienceDaily (June 21, 2012) —
Regenerative medicine researchers at
Wake Forest Baptist Medical Center
have reached an early milestone in a
long-term project that aims to build
replacement kidneys in the lab to help
solve the shortage of donor organs.

 In proof-of-concept research
published online ahead of print in
Annals of Surgery, the team
successfully used pig kidneys to make
"scaffolds" or support structures that
could potentially one day be used to
build new kidneys for human patients.
The idea is to remove all animal cells --
leaving only the organ structure or
"skeleton." A patient's own cells
would then be placed on the scaffold,
making an organ that the patient
theoretically would not reject.
While this is one of the first studies to
assess the possibility of using whole
pig kidneys to engineer replacement
organs, the idea of using organ
structures from pigs to help human
patients is not new. Pig heart valves --
removed of cells -- have been used
for more than three decades to
provide heart valve replacements in
human patients.
"It is important to identify new
sources of transplantable organs
because of the critical shortage of
donor organs," said lead author
Giuseppe Orlando, M.D., an instructor
in surgery and regenerative medicine
at Wake Forest Baptist. "These kidneys
maintain their innate three-
dimensional architecture, as well as
their vascular system, and may
represent the ideal platform for
kidney engineering."
For the research, pig kidneys were
soaked in a detergent to remove all
cells, leaving behind the organ's
"skeleton," including its system of
blood vessels. In addition, the
structure of the nephron -- the
kidney's functional unit -- was
maintained. The scaffolds were
implanted in animals, where they
were re-filled with blood and were
able to maintain normal blood
pressure, proving that the process of
removing cells doesn't affect the
mechanical strength of the vessels.
"There are many challenges to be met
before this system could be used to
engineer replacement kidneys,
including problems with blood clots
forming in the vessels," said Anthony
Atala, M.D., co-author and director of
the Wake Forest Institute for
Regenerative Medicine. "The kidney is
a very complex organ with at least 22
different cell types."
But, the fact that nephron structure is
maintained suggests the potential to
re-populate the kidney with cells,
according to the scientists. They
speculate that new cells introduced
into the scaffold would recognize their
natural niche through physical or
chemical signals of the scaffold.
While the project is in its infancy, the
idea represents a potential solution to
the extreme shortage of donor
kidneys. According to the authors, the
probability in the U.S. of receiving a
kidney transplant within five years of
being added to the waiting list is less
than 35 percent. As of late August
2011, nearly 90,000 patients in the
U.S. were waiting for kidney
transplants.
The science of regenerative medicine
has already had success engineering
skin, cartilage, bladders, urine tubes,
trachea and blood vessels in the lab
that were successfully implanted in
patients. These structures were able to
receive oxygen and nutrients from
nearby vascularized tissues until they
developed their own blood vessel
supply.
However, the "holy grail" of
regenerative medicine is to engineer
more complex organs such as the
kidney, liver, heart and pancreas.
These organs are very dense with cells
and must have their own oxygen
supply to survive. This need for a
scaffold with a full vasculature is why
scientists are exploring the possibility
of removing cells from donor organs
and replacing them with a patient's
own cells.
Scientists have already used scaffolds
from rodents or pigs to engineer
heart, liver, lung and intestinal
scaffolds. When re-populated with
organ-specific cells, these "organoids"
were able to produce some of the
functions of native organs in the lab.
The goal of the current study is to
produce kidney scaffolds from the pig
because of similarities to humans in
terms of organ structure and size.
The research was supported by the
Telemedicine & Advanced Technology
Research Center.
Co-researchers were Sayed-Hadi
Mirmalek-Sani, David C. Sullivan,
Emma Moran, Tamer AbouShwareb,
Alan Farney, Samy Iskandar, Robert J.
Stratta, Anthony Atala, James J. Yoo,
and Shay Soker, Wake Forest Baptist;
Kathryn J. Wood, University of Oxford,
and Paolo De Coppi, Great Ormond
Street Children Hospital-University
College of London.

http://www.sciencedaily.com/releases/2012/06/120621130720.htm