The body's organs and tissues can be formed abnormally at birth, or can be damaged as a result of accidental injury, infections or disease. When vital organs, such as the liver, kidneys, lungs, pancreas or heart are severely damaged, they may need to be replaced for a person to survive. Replacing some damaged tissues may allow a person to return to a normal life -- a cornea to renew sight or a bone or tendon to restore the ability to walk or move without pain. This link will soon take you to a series of pages detailing the transplantable organs and tissues, along with information about what diseases or injuries cause their failure. For now, it just reloads this page!
Organs can be donated by two types of donors: deceased and living. Tissue, with exception of bone marrow, can only be donated by deceased donors. The transplant process described in this section deals mainly with organs donated by deceased donors. Some patients may choose to have a loved one or friend evaluated to be a living donor.
Once a doctor determines the need for an organ transplant, the patient is referred to a transplant center -- a hospital that performs transplants -- for evaluation. If certain criteria are met, the patient is accepted into the program at that center. The patient's blood and tissue types are determined. Medical and social evaluations to determine the ability for the patient to accept a transplant. Once the evaluation is completed, the patient is listed into a pool of patients waiting for that type of organ.
To find a transplant center, please refer to the national list of transplant centers, or, search in a specific area.
On average, every 13 minutes another name is added to the pool of those in need of organ transplants; 17 people that are listed die every day waiting for a suitable organ.
In 2002, about 25,000 people received an organ transplant. Yet at the end of that year nearly 80,000 people in the US alone were still waiting for a suitable organ. By mid-2004, the number of people had grown to over 86,000. By the beginning of 2006, that number had exceeded 91,000. Every year the gap between those waiting and the number of organs available is tremendous. Clearly, the question to be answered is: Who decides which person gets an organ?
In an attempt to create a fair, equitable system of organ distribution, Congress enacted the National Organ Transplant Act (NOTA) in 1984. NOTA created the Organ Procurement and Transplantation Network (OPTN), which includes all transplant centers, organ procurement organizations (OPOs), tissue-typing laboratories, many scientific organizations interested in transplantation, and representatives of the general public. OPTN activities are overseen by the federal government and carried out by the United Network of Organ Sharing (UNOS) under a contract with the U.S. Department of Health and Human Services. UNOS maintains the OPTN national list of people waiting for organ transplants. Each person accepted into a transplant program is registered with the OPTN. Computers link transplant centers with each of the 59 regional OPOs across the United States and Puerto Rico. Each OPO serves the hospitals within its region and is responsible for the identification, evaluation, maintenance, recovery and transport of organs for transplant.
The OPTN network is accessible 24 hours a day, 7 days a week. When an OPO identifies a donor organ that has become available, the OPO accesses the UNOS computer system called UNet to generate a list of individuals that are potential recipients ranked according to the OPTN policies on organ allocation. These policies are developed by committees of transplant professionals and are open to public address and comment before they are enacted.
So, how does this computer decide whose name appears first on the waiting list? When a person's name is added to the national waiting list, their medical profile is entered and stored in the OPTN database. The person is not placed on a "ranked" list at that time. Rather, the person's name is added to the pool of names of other people waiting for that type of transplant. When a donor organ becomes available, the computer system matches each individual in the pool against the donor's characteristics. Using medical and scientific criteria, the computer then generates a list of individuals ranked in order of which potential recipient has the best match. This process ensures that ALL individuals in the pool are compared to that particular donor before being ranked in the order of who makes the best match. The following criteria are used to determine the best possible match:
After receiving the printout of potential recipients, the OPO coordinator contacts the transplant team physician responsible for the first candidate on the list. The transplant physician reviews the donor information and decides whether this potential recipient and the donor organ are suitable for one another. The physician must also consider whether the potential recipient is available, healthy enough to undergo major surgery, and willing to undergo the transplant immediately. Laboratory testing may be required to determine the patient's condition, not limited to chemistry panels, a chest x-ray, EKG and tissue crossmatching. As soon as these steps have been taken, surgery is scheduled and the transplant occurs.
More information on policies, public forums, and on the OPTN Scientific Database can be obtained at the United Network for Organ Sharing and the Organ Procurement and Transplantation Network websites.
Each person has thousands of genes. The expression of those genes is what makes each of us a unique individual. Some of these genes are visible, displayed in features like hair and eye color. However, many are not so obvious, but rather are expressed within our bodies in blood and tissue proteins. Some of these proteins, called antigens, determine the patient's "tissue type". It is this uniqueness that makes matching donors with recipients so complex. It's not "just" about their blood type!
If you place an organ with a different tissue type into a recipient's body, the recipient's immune system goes on the offensive. Non-self antigens on the surface of the transplanted organ stimulate the production of T cells and of a proteins called antibodies. The T cells and antibodies attack the organ and attempt to kill it's cells. This process is called rejection, and may eventually destroy the organ completely.
In matching a kidney donor and recipient, transplant professionals identify six antigens in each donor and recipient. These six antigens have been called the major histocompatibility complex. "Histo" refers to tissue, and compatibility refers to how closely the donor is matched with the recipient.
Ideal compatibility for a kidney transplant is a six-antigen match between donor and recipient. A six-antigen match occurs 25 percent of the time between siblings with the same parents. It also occurs from time-to-time in the general population. Other than the perfectm atch of identical twins, the six-antigen match is the best single tissie match that can occur between any donor and recipient in terms of testing done today. Because long-term survival after kidney transplantation depends on the quality of the match, the most successful long-term outcomes are between individuals with the best matches.
However, recent medical advances have made finding an ideal match between a kidney donor and recipient less crucial. Immunosuppressive drugs -- medications that can subdue the body's response to a transplanted organ -- have been improved greatly in the last few years. For now, although the best match is still desirable, it is not absolutely necessary.
One last hurdle in matching a kidney donor and recipient must be cleared with a test called crossmatching. Crossmatching involves mixing cells from a potential donor with serum from the recipient. A positive crossmatch is a bad thing. It means that there are already antibodies in the recipient's blood ready to attack the donor organ. (This can happen as a result of previous transplants, blood transfusions or pregnancies.) In the presence of these antibodies, immunosuppressive drugs would not adequately prevent the attack of the new organ. With few exceptions, a positive crossmatch makes a successful transplant between a particular donor/recipient pair impossible.
The donated organ is often surgically removed from the deceased donor at the same time as the recipient is prepared for surgery to reduce the time that the donated organ has to survive outside the body. Since the recipient is often at a different hospital than the donor, a member of the recipient's transplant team may have to travel to the donor's location to remove, evaluate and transport the donated organ. After surgery, the recipient undergoes a period of recovery -- sometimes only a few weeks. However, if the recipient's immune system rejects the donated organ, the recovery period could be much longer.
Rejection is the human body's reaction to a transplanted organ that it views as a foreign invader, much as it would a virus or bacteria. Our body treats a donor organ as if it were invading the body and shouldn't be there. The immune system springs into action the same way it does when the invader is a harmful organism. The immune system first distinguishes "self" from "non-self" by comparing proteins (antigens) on the surface of the "invader" with the body's own antigens. Once a "non-self" invader is detected, cells called lymphocytes attack the "invader" antigens while other lymphocytes produce proteins called antibodies. The antibodies attack and help destroy the invader. Once rejection is underway, things begin to go wrong inside the body of the recipient. The transplanted organ's function is impaired, and a variety of illness symptoms develop.
No two people -- except identical twins -- have identical antigens. Therefore, organ transplantation will almost always cause an immune response and result in an attempt to reject the new organ. Kidneys seem to be more sensitive to rejection than other organs, so tissue typing is done to ensure that the transplanted organ is as similar as possible to the tissues of the recipient. No match (other than an identical twin) is perfect, so the possibility of organ rejection remains.
The way to prevent or resuce rejection (other than finding a rare perfect match) is to use immunosuppressive drugs -- medicines that subdue the body's response to invaders.
If the transplant is successful, the recipient may return to a normal and active life, but must have regular check-ups and continue to take medicine for the rest of his or her life. While transplantation is not a "cure" for all patients, when successful, it provides an increase in the quantity and/or quality of life.
