· Transplantation is defined as the removal of tissue or organ from one part of the body and transplanting it to another part of the body of the same person or another person of the same species or another individual of different species.
· This process is usually applied to replace the injured or diseased tissues or organs with natural and artificial ones.
· An organ or tissue thus transplanted is known as transplant or graft.
· The person or a source from whom the organ or tissue is taken is called the donor and the person to whom it is transplanted is called the recipient.
· Hamberger was the first person to successfully carry out kidney transplantation in 1953 AD.
· Christian Bernard performed the first successful heart transplantation in 1967 AD. (Cape Town, South Africa)

Types of Transplantation

· On the basis of the relationship of donor and recipient, transplantation is classified into the following four types.
(i) Autograft
· When the donor and recipient are the same people, it is called autograft.
· For example, skin transplantation from trunk to arm of the same individual, a skin graft used for severe skin burns.
· No rejection problem.

(ii) Isograft
· It is a graft between genetically identical individuals of the same species such as identical twins.
· No rejection problem.

(iii) Allograft
· When the donor and recipient are genetically different members of the same species, it is called allograft.
· For example, transplantation from Mr Smith to Mr Jones.

(iv) Xenograft or Heterograft
· It is the transplantation between the animals of the different species.
· For example, transfer of skin of rabbit or monkey or pig to man.
· In allograft and heterograft, the chance of skin rejection is much more by the recipient because of the high immunogenicity of the skin.
· For this, skin removed is subjected to some special treatments to specific proteins and then cryopreserved for emergency use.
· Nowadays, we can culture skin to produce sheets of skin for transplantation.
· Some defective or non-functional organs require replacement to survive and grow normally.
· Transplantation of an organ can provide hope and life to an individual when everything fails.
· It is the last resort as the life expectancy of the individual is short.

A. Tissue Transplantation

· It involves the process of removing part of the tissue from one site and placing it in another site.
· It may be in the same person or from one person to another.
· Some examples are:
(i) Skin transplantation
· In severe burn of the skin or losing a significant skin in road accidents, skin from one site can be removed and planted to another side to correct the defect.

(ii) Bone marrow transplantation
· In leukaemia and aplastic anaemia (lack of functioning of the bone marrow), transplantation of bone marrow from a normal individual can be life-saving.

(iii) Blood donation
· In serve bleeding or severe anaemia, blood donation can be life-saving.

B. Organ Transplantation

· In organ transplantation, the whole organ removed from an individual is transplanted to the other.
· Successfully transplanted organs are cornea, heart, lungs, kidneys, liver, pancreas, intestine etc.

· Some examples of organ transplantation are:

(i) Corneal transplant (Keratoplasty)
· A dead person's cornea is removed within 24 hours after death and transplanted to a blind person to give him a renewed vision.
· People give permission to remove their cornea after death for transplantation.
· It is the most successful and the most widespread transplantation.
· It is highly successful because of the absence of blood vessels in the cornea, an easy surgical procedure to remove the cornea and easy to preserve and survive without immunosuppressive therapy.

(ii) Renal transplant
· In case of damage to the kidney, the kidney from another individual is transplanted.
· In kidney transplantation, a cut is given in the lower abdomen of the patient and the donor's kidney is transplanted in the iliac fossa. The artery and vein of the new kidney are connected to the iliac artery and vein. The ureter of the new kidney is connected to the urinary bladder of the patient.
· The transplanted kidney works over the function of two kidneys. Old and diseased kidneys are left in the same places unless they cause infection or high blood pressure.
· World’s first kidney transplant was made by Dr Charles Hufnagel (1957 AD), in Washington, USA, between two identical twins.

Benefits of Organ Transplantation

· Successfully transplanted organs are cornea, heart, lungs, kidneys, liver, pancreas, intestine etc.
· Organ transplantation is a useful procedure to replace injured or hopelessly diseased organs with healthy donor organs.
· It is applied in those cases where the survival of animals is in danger. It is an important field of medical science.
· It has offered hope and survival of life to many patients.
· By organ transplantation, many defective and non-functional organs have been replaced by healthy ones.
· It restores the function of the diseased and damaged organs.
· Skin transplantation is done for burn cases and accidents.
· Millions of blind people are provided with renewed vision by corneal transplantation. It is highly successful.
· Kidney transplantation is done for those whose kidneys are fully damaged or if kidney failure cannot be treated with drugs and dialysis. It is the only hope and life of kidney patients.
· In case of leukaemia and aplastic anaemia, bone marrow from another healthy person is transplanted to save the life.

Rejection of Transplanted Organs

· The main problem of organ transplantation is that the recipient body recognizes the transplanted organs as foreign bodies or antigens.
· So, the recipient body produces antibodies against a grafted organ, consequently, a foreign graft may be rejected by the recipient's immune system.
· It is called rejection.

Ways to Prevent Rejection:
a. By using immunosuppressive drugs: Drugs like Azathioprine, Imuran and Cyclosporine are used to suppress the immune system of the patient. These drugs are very expensive and make the body vulnerable to infections.

b. The organ to be transplanted must be taken from their family members. In the case of kidney transplantation, if it is taken from a sibling or identical twins, chances of acceptance are more.

c. Immune system can be suppressed by radiation.

d. Tissue typing: Genes responsible for the graft rejection are histocompatibility genes or H genes of Human Lymphocyte Antigen (HLA). The success of transplantation depends on the matching of the HLA that occur on all cells of the body. The test carried out to match the HLA antigens of the donor and recipient is called tissue typing. The survival rate of the transplanted organs is more when HLA types are matched.

e. Use of Monoclonal antibodies: Monoclonal antibodies recognize and destroy only the killer T cells that are responsible for rejection. But the rest of the immune system would run continuously.
· Tissue and organ banks have been established in various parts of the world.
· Donor cards: Many people carry donor cards with them at all times, as they are happy to donate their organs when they are close to ending their lives.

Organ to be removed Should be Removed Within
Cornea Up to 24 hours after death
Skin Up to 4 hours after death
Bone Up to 24 hours after death

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