A breakthrough in organ transplant surgery promises end the agonies of patients and donors
WITH worldwide shortage of human
ns for transplantation, xenotransrnt surgery is a welcome change. The
Ift,Apinsfer of animal organs into humans
prevent organ donors from being
rived of an organ, and the right
unt of money. If unlimited organs
available, about 100,000 transplant
cries would be conducted in the us
estimates Daniel Salomon, transet immunologist at the Scripps
arch Institute in La Jolla, forriia, (The Economist, Vol 337, No,937).
In the last couple of years, several
0-human and two baboon-to
an transplants have taken place. A
kaboon bone marrow transplant operaDan would be conducted on an AIDS
ti nt in San Francisco this year. A
gz,esh biotech firm has bred pigs for the
sole purpose of organ and tissue translants (Down To Earth, Vol 4, No 12).
This would open up new vistas and
50ing hope to millions waiting for an
10 But for virologists like Jonathan
Uan at the Southwest Foundation for
OPT edical Research, xenotransplantanon is a medical nightmare. What if anirifections carried into the human
proliferate under suitable condition What if they are transmitted into
:humans and spark a pandemic?
Organ transplant surgery requires
Cression of the immune system, so
the organ is not rejected by the
Prpient's immune system. Thus, the
une response is controlled by
Utaming a strict drug regimen. This
@kes the organ recipients susceptible
U.;,-.ous health problems for the rest
their lives.
Virulence and 'new' disease are
related. No one knows which
I;nism is likely to be harmful. For
ple, the Macaque herpes is fatal for
bbut not to macaques. The post effects of the organism on the
rMans can be known by outward
toms only. The AIDS virus was
ro'wn till it reached the developed
d and research showed that Hiv was
r= from monkeys into humans.
While the natural hosts have been
unaffected, the virus has created a pandemic.
There are also endogenous
retroviruses present in all animals
which are passed on passively
from generation to generation
through the host's DNA. Can they
wreak havoc on contact with a forbody? While animal
breeding eign
can remove all known pathogens,
eliminating endogenous retroviruses
requires further research in genetics.
The proponents of xenotransplant
think the risks are few as they are concentrating on organs from baboons and
pigs. While pigs are fast-breeding and
can be bred into pathogen-free colonies
easily, baboons are closely related to
humans, but are slow breeding animals.
Baboon bone marrow could help
destroy or control the AIDS virus, say
transplant immunologists. The monkeys' immune system possibly has HIV
fighting agents. Besides, baboon tissues
are to be used as a stop-gap arrangement which can be replaced by human
tissues later, but even then, infectious
agents from the animal organ could be
transmitted to the human body.
Pigs offer a safer option. Humans
have consumed pigs through the ages
New for old and both share some common diseases
like influenza. As they breed fast, they
could be bred free of all diseases found
in pigs. But, as they are not closely related to humans, the human immune system has to be adapted to make it accept
their organs.
The proponents feel minimising
risks through known animal diseases
and keeping a close post-operative
watch on organ recipients, with their
consent, would help. But this would not
prevent a disease from passing on
unknowingly to fellow human beings,
argue the opponents. Till the problems
are ironed out, the solution lies with
authorities who can issue regulations. If
laws dealing with taking organs from
the newly dead could be implemented
easily, then there is still hope for many.
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