- Grafting a kidney from a compatible donor to restore kidney functions in a recipient suffering from kidney failure is called kidney transplantation. It is also known as renal transplantation.
- The first kidney transplantation was performed between identical twins in 1954 by Dr. Charles Hufnagel, a Washington surgeon.
Eligibility: Any person with terminal renal failure must have a renal transplantation to survive and live longer. However, people who are at risk of suffering from another life-threatening disease are not eligible for a kidney transplantation.
Donors: A living donor’s kidney can be used for transplant. A donor may be an identical twin, a sibling, or a close relative. If the living donors are not available, kidney(s) from cadavers (cadaver is a dead body) may be used. In fact, over half of the kidney transplants across the world are from cadavers. Various types of kidney transplants based on the donors are:
- A kidney transplant from an identical twin is called isogenic graft or isograft. It is always successful.
- A renal transplant from a sibling or a close relative or a cadaver is termed as allogenic graft or homograft. Allografts are usually successful with the use of an immunosuppressant.
- Immunosuppressants are drugs that prevent graft rejection by body’s immune response and might have to taken for life by the recipient. It has been found that many renal transplant recipients have their kidney grafts functional for over 20 years.
- Previously, renal transplantation was limited to or successful in patients under 55 years of age. However, with the development of better techniques these days, kidney grafting has been done in selected patients even in their 70s.
Overall steps in a kidney transplantation procedure are:
1. Pretransplant Preparation: It includes the process of hemodialysis to ensure a relatively normal metabolic state, and provision of functional, infection-free lower urinary tract.
2. Donor selection and kidney preservation:
- A kidney donor should be free of hypertension, diabetes, and malignancy.
- A living donor is also carefully evaluated for emotional stability, normal bilateral renal function, free from other systemic diseases and histocompatibility.
- Cadaveric kidney is obtained from a dead person who was previously healthy, who sustained brain death but maintained stable cardiovascular and renal functions.
- Following brain death, kidneys are removed as early as possible, flushed with special cooling solutions, such as mannitol, and stored in iced solution or may be cryopreserved.
- Such preserved kidneys should be transplanted within 48 hours for them to usually function well.
3. Recipient-donor matching: Recipient and donor are tested for 3 factors:
- Blood group: Recipient’s blood group should be compatible with donor’s blood group.
- Human leukocyte antigen (HLA): It is a genetic marker located on the surface of leukocytes. A person inherits a set of 3 antigens from mother and 3 from the father. A higher number of matching antigens means they are more compatible and hence increases the chances of kidney grafts working and lasting for a long time.
- Antibodies: Small samples of recipient’s and donor’s blood are mixed in a tube and if no reaction occurs, the patient will be able to accept the kidney.
4. Transplant procedure:
- Transplantation is done under general anesthesia.
- Operation take around 3-4 hours. A cut is made in the lower abdomen.
- Donor’s kidney is transplanted retroperitoneally in the iliac fossa.
- Artery and vein of the new kidney are connected to the iliac artery and vein of the recipient.
- Ureter of the new kidney is connected to the urinary bladder of the recipient.
- Often, the new kidney starts producing urine as soon as blood flows through it, but sometimes it may take a few weeks before it starts working.
- A week’s stay in the hospital is necessary to recover from surgery, and longer if there are complications.
- The new kidney takes over the work of two failed kidneys. Unless they are causing infection or high blood pressure, the old kidneys are left in place without being removed.
5. Immunosuppression:
- Immunosuppression means to suppress the immune response of the recipient to graft rejection.
- Prophylactic immunosuppressive therapy is started just before or at the time of renal transplantation.
- An ideal immunosuppressant makes the recipient’s immune system weaker against any foreign tissue but maintains immunity against infection and cancer.
- The drug, named Cyclosporin, is one such immunosuppressant. Use of antiserum to human lymphocytes is equally useful. It destroys T-cell mediated immune responses, but spares humoral antibody responses.
References:
- Nova’s Anatomy and Physiology
- Atlas of Human Anatomy. Seventh edition. Philadelphia, PA, Elsevier, 2019.