INTERESTING FACTS ABOUT TRANSPLANTATION

Organ transplantation is now a highly successful procedure and it is considered routine surgical practice for treating many chronic diseases. Over the past 50 years, surgeons have made great strides in kidney, liver, heart or lung transplantation. At least 21 different organs including hearts, livers and kidneys, and tissues including corneas and bone marrow can now be successfully transplanted into patients. Organ recipients can expect to live for years or even decades after receiving a transplanted organ. Despite the progress made over the years, all too often there are no suitable organs available to meet the increasing demand.

TRANSPLANT REJECTION

The body’s immune system is very complex and fights to protect the body from all infections. To ensure successful transplantation, doctors must counteract the immune system’s combative efforts. The immune system’s central function is to distinguish between invading or foreign matter and matter that is a normal part of the body. The immune system attacks foreign matter but leaves normal matter alone. The immune system attacks transplanted tissues because it has no way of distinguishing transplanted tissues from harmful foreign matter.

Because of this rejection, the recipient must take drugs to suppress the immune response. Early anti-rejection drugs such as azathioprine and prednisone would suppress the entire immune system, leaving the recipient vulnerable to infections, certain cancers and toxic side effects. The development of cyclosporine was a major breakthrough in immune suppression. A natural product derived from a soil fungus, cyclosporine suppresses only the part of the immune system that is rejecting the organ and has a less severe impact on other parts.

KIDNEY TRANSPLANTS

Essential (genetic) hypertension (especially in the black population), diabetes (especially in the Caucasian and Asian population), glomerulonephritis and pyelonephritis (inflammation of the kidneys) and inherited diseases (e.g. polycystic kidneys) are the diseases that lead to the need for kidney transplantation.

When these diseases cause kidney failure, patients must undergo regular treatment with either an artificial kidney (haemodialysis) or with continuous peritoneal dialysis. In haemodialysis, the blood is circulated through a machine to remove waste materials, toxins and excess fluids from the bloodstream. The patient is hooked up to the machine three times a week for four hours each time. Dialysis efficiently replaces the filtration, waste and toxin removal, water balance and chemical stability that healthy kidneys normally regulate.

But the kidneys’ synthetic functions — hormone and other chemical production — cannot be substituted. Dialysis patients are prescribed medications that adequately mimic these functions. Dialysis patients can remain well for many years but they never feel as well, nor are rehabilitated CHECK: IS THERE ANOTHER WORD FOR REHABILITATED, OR IS THIS A MEDICAL TERM? as well as kidney transplant recipients. Kidney transplantation is a highly successful — and preferred — procedure.

People have two kidneys but the body needs only one to function. With one kidney sufficient for normal life, this means that you can be a healthy living donor, donating one kidney and retaining the other for normal kidney function. In South Africa, about 20% of transplanted kidneys come from living donors. We aim to double this to 40%. About 80% of transplanted kidneys come from deceased donors.

One year after transplantation, around 90% of the transplanted kidneys are still functioning well. After five years, over 60% are still healthy and do not need dialysis. Some kidney transplant patients have survived for more than 30 years.

LIVER TRANSPLANTS

Cirrhosis, some types of chronic hepatitis, acute liver failure, or inflammation of the bile ducts that lead into the liver (primary sclerosing cholangitis) are the most common diseases that require liver transplantation. For people with severe liver disease, transplantation can sometimes be the only available effective treatment. The liver is the only internal organ that can regenerate itself. After one year, around 80% of transplanted livers are working well. This falls to 60-65% after five years.

HEART AND HEART / LUNG TRANSPLANTS

Heart transplants are perhaps the most dramatic of all organ transplants. Without a functioning heart, a patient cannot survive more than a few minutes.

Christiaan Barnard performed the first human heart transplant on 3 December 1967. Louis Washkansky, a 55-year-old grocer, received the heart of a 25-year-old woman, but died 18 days later. Philip Blaiberg received the second transplant on 2 January 1968 and lived for 563 days after the operation. With the development of powerful anti-rejection drugs, heart transplant surgery became a standard procedure.

Coronary heart failure is the most common cause of heart failure. Heart failure is the final stage in almost any type of heart disease. Also known as congestive heart failure, this is when the heart muscle weakens and cannot pump enough blood to the body.

In response to this blood shortfall, the kidneys conserve water as a means to increase blood volume and the heart is stimulated to pump harder. Excess fluid eventually seeps through the walls of tiny blood vessels and into the tissues. In turn, fluid collects in the lungs. When this happens, patients find it difficult to breathe and must sleep propped up on pillows at night to ease their breathing. Fluid may also build up in the ankles, legs or abdomen.

In the later stages of heart failure, any type of physical activity becomes almost impossible. Heart failure can sometimes be reversed and can often be effectively treated for long periods with a combination of drugs. Heart transplantation is a last resort in the treatment of heart failure.

Heart transplantation is an effective option. Most patients can resume a normal life about six months after surgery. After a year, 85% of heart transplants are still working well. Almost 70% are still working well after five years. But because the supply of donor hearts is limited, many people who could potentially benefit from heart transplantation are not placed on the waiting list.

LUNG TRANSPLANTS

Cystic fibrosis causes severe, irreparable lung damage and patients are increasingly turning to lung transplantation surgery.

In nearly 20% of all cases, the first symptom of cystic fibrosis is intestinal blockage in newborns. In other babies, the first evidence is bulky stool, poor weight gain, flabby muscle tone, or slow growth. These are all products of low levels of digestive enzymes in the intestines. About half of all children with cystic fibrosis first see the doctor for coughing, wheezing, or respiratory tract infections. Teenagers with cystic fibrosis may grow slowly and enter puberty later than their peers.

Cystic fibrosis often causes impaired reproductive function, dehydration from extreme salt loss and frequent lung infections. These infections destroy lung tissue and ultimately lead to the death of cystic fibrosis patients.

Although some patients have complications with transplantation surgery, nearly 80% of cystic fibrosis patients are given an entirely new lease on life when they have lung or combination heart-and-lung transplants.

CORNEA TRANSPLANTS

Eye banks retrieve tissues used in eye surgery to restore or improve sight.
Most eye banks focus on retrieving corneas, the clear front window of the eye.

About the size and
shape of a coin, the cornea transmits light to the interior of the eye,
allowing us to see clearly. Corneal injury, disease or hereditary conditions
can cause clouding, distortion and scarring that may result in complete loss of
sight.

Corneal blindness
is one of the few forms of blindness that can be cured. In a delicate
procedure, the surgeon removes the damaged cornea and replaces it with a donor’s
cornea. Cornea transplants are very successful. If the cornea is placed on the
eye so that blood vessels do not come into contact with it, the cornea
transplant success rate is more than 90%. Without blood vessels, the body
cannot send immune cells to attack the cornea.

SKIN

A burn is caused when heat, chemicals, electricity, or radiation destroy skin tissue.
If 30% or more of the body’s surface is burnt, the burn can become life
threatening. Such extensive burns disrupt the skin’s ability to fight
infection, prevent fluid loss, and regulate body temperature.

Deep burns are
often treated with skin grafts. In this procedure, healthy skin is removed from
another area on the body and transferred to the burned area to cover the wound.
Depending on the size of the burned area, the grafted skin will grow in its new
location and eventually fuse with the healthy skin at the edges of the burn.

If burns cover a
large portion of a patient’s body and there is not enough healthy skin for a
graft, patients may receive skin tissue from skin donors. These temporary skin
grafts help prevent fluid loss and infection while the patient’s own skin heals.
The patient’s immune system eventually rejects and destroys this foreign tissue.

Skin was the first
tissue transplanted. Researchers used skin transplants in the late 1950s and
early 1960s to understand how the immune system responds to transplants.

BONE MARROW

Bone marrow is the living tissue found in the centre of many large bones in the body. Special cells on the bone marrow, called stem cells, are the source of red and white blood cells. Red blood cells are the primary component of blood, and white blood cells are the workhorses of the immune system. When stem cells in bone marrow produce faulty blood cells blood diseases such as leukaemia and sickle cell anaemia can arise.

In some cases, these diseases can be treated by destroying all of the patient’s bone marrow and replacing it with healthy bone marrow from a donor.

In breast or other cancer treatment, intensive radiation or chemotherapy kills the patient’s bone marrow. The bone marrow is then replaced with a transplant.

Donor and recipient stem cells must match more closely in bone marrow transplants than in other organ transplants. If the match is inadequate, the recipient’s body may reject the bone marrow. The white blood cells generated by the donor marrow can also attack the recipient’s body. This phenomenon is known as graft-versus-host disease.

Stem cells could previously only be transplanted from the donor’s bone marrow in a bone marrow transplantation procedure. Recent medical advances now make it possible to recover stem cells from circulating blood. This makes the transplant procedure much simpler and less risky for the donor. A live donor simply donates blood and the necessary cells and components are removed.

BONE

Bone is used in reconstructing the facial features of accident victims. Bone grafts are also used to replace cancerous growths in a patient’s arms or legs. Previously the limb would have to be amputated.

ARTIFICIAL ORGANS AND TISSUES

One way to get around the shortage of donors is to use wholly or partially artificial organs made of plastic, metal, and other synthetic materials. A kidney dialysis machine, for example, is an artificial organ, even if it is too large to implant in the body. The first permanent artificial heart was transplanted in 1982, but the patient survived only for 112 days. Artificial hearts are not widely used today because of the risk of infection and bleeding and concerns about their reliability. In addition, the synthetic materials used to fashion artificial hearts can cause blood clots to form in the heart. These blood clots may travel to a vessel in the neck or head, resulting in a stroke. Instead, emphasis has shifted to the use of left-ventricular assist devices (LVADs), which are implanted beside a patients heart to help it pump blood. LVADs keep patients alive until a donor heart is available. Many artificial devices work to restore the operation of malfunctioning organs without replacing the whole organ. Examples include artificial heart valves and pacemakers to help the heart function properly, and cochlear implants to restore hearing.

XENOTRANSPLANTS

The shortage of donors has led some surgeons to consider using animals as donors. Chimpanzee kidneys were successfully transplanted in 1963, with one recipient living for nine months after the surgery. Although the kidneys were not rejected, they proved too small to keep the recipient alive. Efforts to transplant chimpanzee and baboon hearts into humans in the 1960s and 1970s also failed because the hearts were too small. The first successful baboon organ transplant occurred in 1984, when a baboon's heart was transplanted into a two-week-old premature baby whose heart was congenitally malformed. The baby survived for 20 days before her body rejected the organ. Because of problems with the small size of chimpanzee and baboon organs, doctors are now turning to other species as potential organ donors.

One animal receiving a lot of attention from the medical community is the pig. Pigs have organs that are the right size for human use, they have large litters, and they mature quickly so there is a ready supply of donating animals. Human bodies do not reject some pig tissues, such as heart valves. Surgeons in the United States transplant about 60,000 pig heart valves into humans annually. However, other transplanted pig organs undergo a phenomenon called hyperacute rejection. The recipient's immune system recognizes that the blood vessels in the transplanted organ are foreign and shuts off blood flow to the new organ within hours or even minutes, causing the transplanted organ to blacken and die. Recently, scientists have used genetic engineering techniques to breed pigs whose blood vessels contain the marker antigens found in human blood vessels. Livers from these pigs have been successfully connected to the bloodstream of several patients to clear toxic wastes while the patients' own livers recovered. Fetal pig brain cells have also been used to treat Parkinson disease, and research is underway on using other organs from these pigs.

One of the big drawbacks of xenotransplants is the fear that unknown, possibly deadly viruses could be transferred from animals to humans. Once the animal viruses get into humans, they might spread to other humans. In 1997, scientists showed that pig viruses could infect humans with unpredictable results. The unresolved questions surrounding xenotransplantation mean that future research must be done cautiously.

OTHER TRANSPLANT PROCEDURES

Heart valve transplants are available. Pancreas transplants can be done but the treatment is not available in South Africa. American doctors have started doing small intestine transplants, although this is still an experimental procedure and so reliable survival data is not available. With further research, it may soon be possible to transplant other parts of the body.

ARTIFICIAL ORGANS AND TISSUES
With a shortage of organ donors, it is possible to use wholly or partially artificial organs made of plastic, metal, and other synthetic materials. One example is a kidney dialysis machine, though it is too large to implant in the body.

The first permanent artificial heart was transplanted in 1982, but the patient survived only for 112 days. Artificial hearts are not widely used today because of the risk of infection and bleeding. There are also concerns about their reliability. Artificial hearts are created from synthetic materials which can cause blood clots in the heart. If these blood clots travel to a vessel in the neck or head, the patient could have a stroke. The emphasis has instead shifted to the use of left-ventricular assist devices (LVADs), implanted beside a patient’s heart to help it pump blood. LVADs keep patients alive until a donor heart is available.

Many artificial devices work to restore the operation of malfunctioning organs without replacing the whole organ. Some examples are artificial heart valves and pacemakers that help the heart function properly, and cochlear implants that help restore hearing.

XENOTRANSPLANTS
The organ donor shortage has led some surgeons to consider using animals as donors.

In 1963, one recipient lived for nine months after receiving chimpanzee kidneys. The kidneys were not rejected but they were too small to keep the recipient alive. In the 1960s and 1970s, there were efforts to transplant chimpanzee and baboon hearts into humans. The hearts were too small so the operations failed.

In 1984, for the first time, a baboon's heart was transplanted into a two-week-old premature baby whose heart was congenitally malformed. The baby survived for 20 days before her body rejected the organ. Doctors are now turning to other species as potential organ donors because chimpanzee and baboon organs are too small.

The pig in particular is receiving a lot of attention from the medical community. Pig organs are the right size for human use. They have large litters and they mature quickly, which creates a ready supply of donating animals. Human bodies do not reject some pig tissues such as heart valves.

Every year, surgeons in the United States transplant about 60,000 pig heart valves into humans. Other transplanted pig organs undergo a phenomenon called hyperacute rejection. This when the recipient's immune system recognizes foreign blood vessels in the transplanted organ. The recipient’s blood flow to the new organ shuts off within hours or even minutes, causing the transplanted organ to blacken and die.

Scientists have recently used genetic engineering techniques to breed pigs whose blood vessels contain marker antigens found in human blood vessels. It has been possible to successfully connect these pig livers to a patient’s bloodstream to clear toxic wastes while the patient awaits the recovery of their own livers.

Fetal pig brain cells have also been used to treat Parkinson disease.

The medical profession is doing further research on using other organs from these pigs.

With xenotransplants there is fear that unknown, possibly deadly viruses could be transferred from animals to humans. Once animal viruses get into humans, they might spread to other humans. In 1997, scientists showed that pig viruses could infect humans with unpredictable results. The unresolved questions surrounding xenotransplantation mean that future research must be done cautiously.