produzieren menschliche Nieren
Rehovot, Israel (December 22, 2002) -- In vielen entwickelten
Ländern erweist es sich als schwierig, den Bedarf an Spendernieren
zu befriedigen. Jetzt ist es Prof. Yair Reisner am Weizmann Institute
of Science, Rehovot, Israel, gelungen, eine Alternative zu entwickeln.
gelang dem Team um Prof. Reisner menschliche und Schweine-Stammzellen
in Mäuse zu implantieren. Aus diesen Stammzellen wuchsen menschliche
Nieren bzw. Schweinenieren, die die Größe von Mäusenieren haben.
Diese Nieren werden von den Mäusen nicht abgestoßen. Sie sind
funktionsfähig und produzieren Urin. Nach Meinung der Forscher
ist es denkbar, dass diese Nieren innerhalb von 2 Jahren bei der
Therapie von Nierenversagen eingesetzt werden können.
Kidneys Created In Mice: Transplanted Tissue Could Offer A Solution
To Kidney Donor Shortage
Rehovot, Israel (December 22, 2002) -- Instead of searching for
a kidney donor, a new study suggests, one might be able to grow
a new kidney. A team headed by Prof. Yair Reisner of the Weizmann
Institute of Science has induced human stem cell tissue to grow
into functional kidneys, and have accomplished the same with porcine
stem cell tissue. Published in Nature Medicine, the method could
lead to a promising solution to the severe shortage of kidney
findings suggest that human or porcine fetal tissue might take
on the shape and function of a healthy kidney if transplanted
into humans as well. Pig tissue, as opposed to pig organs, is
not expected to cause hyperacute rejection (common in cross-species
transplants), as has been demonstrated by recent transplants of
insulin-producing cell clusters taken from porcine fetal tissue
that did not induce such rejection. The scientists hope that porcine
stem cells might thus provide a ubiquitous source for those in
need of a kidney.
to the U.S. National Kidney Foundation and the United Network
for Organ Sharing, more than 50,000 people in the United States
alone are on the waiting list for kidney transplants and more
than 2,000 died this year waiting for a match. The wait can last
years. And after a kidney is transplanted patients run the risk
of transplant rejection.
and Ph.D. student Benny Dekel of the Weizmann Institute's Immunology
Department, with Prof. Justen Passwell, the head of the pediatric
department at the Sheba Medical Center, transplanted human and
porcine "kidney precursor cells" (stem cells that are
destined to become kidney cells) into mice. Both human and porcine
tissues grew into perfect kidneys, the size of the mice's kidneys.
The miniature human and pig kidneys were functional, producing
urine. In addition, blood supply within the kidney was provided
by host blood vessels as opposed to donor blood vessels, greatly
lowering the risk of rejection.
scientists pinpointed the ideal time during embryonic development
in which the stem cells have the best chance to form well-functioning
kidneys with minimal risk for immune rejection. Their findings
suggest that 7-8 week (human) and 4 week (porcine) tissue offers
an optimal window of opportunity for transplantation. If taken
at earlier time points the tissues will develop disorganized tissue
that would include non-kidney structures such as bone, cartilage,
and muscle. If taken at later time points the risk for immune
rejection is substantial.
this optimal time range the tissue doesn't contain certain cells
that the body recognizes as foreign (antigen-presenting cells),
the scientists found. These cells, which originate in the blood
system, reach a developing kidney only after ten weeks.
growing the human and porcine kidney tissue in mice, the scientists
checked how human lymphocytes (fighter cells in the immune system)
might react to it. They injected human lymphocytes into immunodeficient
mice (that have no immune system and thus do not interfere with
the immune response). The findings were encouraging: as long as
the kidney precursors were transplanted within the right time
range, the lymphocytes did not attack the new pig or human kidneys
– despite the fact that lymphocytes and kidney precursors originated
from different donors. Immune rejection was also tested in normal
mice and was shown to be reduced compared to that induced by precursors
from later time points.
procedure is now in the pre-clinical study stage. If all goes
well, a treatment may ensue within a few years.
Reisner is the incumbent of the Henry H. Drake Professorial Chair
in Immunology. His research is supported by Richard M. Beleson,
San Francisco, CA, Renee Companez, Australia, Concern Foundation,
Ligue Nationale Francaise Contre Le Cancer, M.D. Moross Institute
for Cancer Research, Gabrielle Rich Leukemia Research Foundation,
Rowland Schaefer, Pembroke Pines, FL, Union Bank of Switzerland-Optimus
Weizmann Institute of Science, in Rehovot, Israel, is one of the
world's foremost centers of scientific research and graduate study.
Its 2,500 scientists, students, technicians, and engineers pursue
basic research in the quest for knowledge and the enhancement
of humanity. New ways of fighting disease and hunger, protecting
the environment, and harnessing alternative sources of energy
are high priorities at Weizmann.
This story has been adapted from a news release issued for journalists
and other members of the public. If you wish to quote any part
of this story, please credit Weizmann Institute as the
original source. You may also wish to include the following link
in any citation:
Informationen (Originalquelle mit Passwortabfrage für Medizin-Experten)