 Organ
Transplants
We have come a long way since the first kidney transplant was performed
almost 60 years ago. Doctors now have the expertise to replace many parts of
our bodies with success, saving thousands of lives every year.
Transplantation began at the turn of the century, shortly after blood
groups were identified and the first successful blood transfusions between
unrelated individuals had been made. Sadly, the first transplants were
fraught with failure because they used organs from donors who were unrelated
to the recipients.
The key to the success of later transplants was the introduction of drugs
such as cyclosporin which suppress the immune system and help to prevent
rejection.
NEW DISCOVERIES
In addition, tissue typing was
developed for some transplants. Just as people's blood groups can vary, it
was discovered that their tissue does too. Kidneys and bone marrow grafts
are tissue typed to match recipients when they come from unrelated donors. A
donor's tissue type is established by screening their white blood cells, or
lymphocytes. Experience has shown that this substantially improves the
success rate of transplants in these cases. Other organs are matched to
recipients by size and blood group.
And most recently, newer, more effective drugs derived from fungal
extracts, such as cyclosporin, have made new organ transplants like the
small bowel possible.
Kidneys are the most commonly transplanted organs with around 1,700
transplants performed every year in the UK. But hearts, lungs and livers are
being transplanted in ever increasing numbers.
SUCCESS RATES
Nowadays, 75 per cent of heart
transplant patients have a working graft one year after their operation and,
for kidney transplant patients, that figure rises to 85 per cent. More than
80 per cent of liver transplant patients ahve a working graft after one year
and more than 60 per cent of heart and lung transplant patients.
The first heart transplant was carried out in Capetown, South Africa in
1967 by world-famous surgeon Dr Christiaan Barnard. And in 1987, the
so-called 'domino' heart-long transplant was first carried out in the UK by
transplant surgeon Sir Magdi Yacoub at Harefield Hospital. This is where a
patient with unhealthy lungs gets a new heart and lungs from the same donor,
and in turn their own heart is donated to another patient. this has proved
more successful than simply replacing a diseased lung.
MAKING HISTORY
In 1990, a heart and lung
transplant patient made history by racing against the recipient of his own
donated heart at the British Transplant Games which were held at London's
Crystal Palace.
The domino operation is now helping victims of the genetic condition,
cystic fibrosis. Sufferers develop enlarged hearts because the disease
interferes with blood flow from the lungs to the brain.
In the domino operation, the new heart and lungs are transplanted to
replace one of the sufferer's sick longs. The enlarged heart must be
replaced because it would be too powerful for the new lungs. The heart is
still healthy, however, even though it's enlarged, so it can be donated to
someone who needs a bigger heart.
Liver transplants were first performed in the UK in 1968. Following early
disappointments, the development of new drugs and surgery means that more
than 500 liver transplants are now performed every year and approximately 70
of them are on children.
NEW SIGHT
Corneal grafts are used to
restore and improve the sight of approximately 2,000 patients every year in
the UK. the cornea -- the transparent 'window' over the front of the eye --
can cause blindness if it is damaged or diseased. Corneas are now stored in
'eye banks' ready for use. Over 90 per cent of these grafts are functioning
successfully a year after they were transplanted.
A wide range of other tissues can be 'recycled' within our bodies or
donated to other patients. These include bone marrow, saving the lives of
those with leukaemia, aplastic anaemia and other diseases; skin, which
provides burns victims with a live dressing; bone to prevent people with
bone cancer from having limbs amputated; plus cartilage, hair (with skin),
veins and arteries.
The main danger following transplantation is organ rejection, either by
the recipient of the organ or by the donated organ itself. To reduce this
risk, cyclosporin and other drugs that suppress the body's immune responses
are given. The downside of immunosuppressive therapy is that it makes the
body more susceptible to infections.
Those who undergo an organ transplant operation will need to take
immunosuppressant drugs indefinitely, and this also puts them at increased
risk of developing certain types of cancer.
SAVING MANY LIVES
Able to provide two kidneys, two
lungs, a heart, liver, pancreas and two corneas, one person has the
potential to save seven lives and restore the sight of two people. This
number may soon increase to nine if small bowel transplants become more
successful.
Though organs are normally taken
from dead people, bone marrow, a slice of liver and a kidney can be taken
from live donors. A kidney from a live donor is best taken from a blood
relation as this tissue is inherited from the parents. Although there is
only a slight risk to a kidney donor's health, he may actually take longer
to recover than the patient.
The condition of the organs taken
from a dead donor is more important than how old the donor is. Kidneys and
corneas from people who die at the age of 70 or over can still be used and
the heart, lungs and liver of donors up to about 50 can be transplanted.
Most organs from dead donors, apart from corneas, are taken from patients
who have died in intensive care. This is because, despite the fact they are
'brain-stem dead', which means there is no activity in the brain, the body
needs to be kept ventilated to prevent the organs from deteriorating.
MEDICAL ETHICS
There are very strict ethical guidelines laid down by the medical profession
to determine whether a brain death has occurred. These involve two sets of
tests for brain activity which legally must be carried out by different
specialists, whose work is totally separate from the transplant surgery
team, between one and 12 hours apart. The first set of results indicating
brain death must be confirmed by the second.
Getting donated organs to patients quickly is vital, especially for heart
and lung transplants which must be transplanted within four to five hours of
death. A liver can wait up to 18 hours and a kidney up to 36 hours. Organs
are placed in plastic bags, packed with ice and transported in chilled boxes
kept at between 0-4°C. Corneas can be preserved for up to a month in special
nutrient-rich fluid.
NEW SKIN GRAFTS
A new technique allowing modified skin to be grown in the laboratory from a
square centimetre of donor skin and stored under liquid nitrogen has opened
the possibility for skin banks to provide emergency skin grafts for serious
burns patients.
This is a breakthrough because normal donor skin is rejected by the
recipient and can only be used as a temporary dressing. The modified skin
contains no hair follicles, sweat glands or blood vessels and seems to be
tolerated without the use of drugs.
FUTURE HOPES
A possibility in years to come is brain tissue transplants. to treat
Parkinson's disease, where the brain fails to produce enough of the
chemical, dopamine, to control muscle action. Scientists are hoping that the
transplanted brain tissue could produce enough of the chemical to cure the
disorder.
Eventually, limb, hand, feet and face transplants may be possible for those
who have been severely disfigured in accidents. The donor parts would
outperform even the most sophisticated artificial spare parts.
DONOR SHORTAGE
There are almost 5,000 patients awaiting donor organs in the UK and Ireland
and the situation is getting worse. Kidney patients are lucky in that they
can usually be kept going with regular life-saving dialysis. For others,
like heart and liver patients, time is running out and, tragically, many die
because a donor cannot be found in time.
In a bid to meet the demand, doctors are now working towards xenografting --
using animal organs as spare parts. Pig heart valves have been used
successfully in heart surgery for several years. Experts in the field
predict that animal organ transplants will be introduced within the next
decade.
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