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Organ Transplantation: Notes on Various Types of Organ Transplantation!
Transplantation involves the removal of damaged/injured tissues or organs from the body of a person and their substitution by similar tissues/organs from a donor.
The world’s first successful organ transplant was kidney transplantation which was undertaken by David Hume and Joseph Kelly at the Peter Brigham Hospital in Boston in 1954.
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The first kidney transplant in India was performed on Dec. 1, 1971 at the Christian Medical College, Vellore (Tamil Nadu).
Organs which are transplanted:
Transplants of organs that are now feasible include bone marrow, lungs, heart, liver, cornea and also kidneys as written above.
Types of organ transplantation:
Organ transplantation is of four types.
1. Auto-graft:
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It is grafting of one’s own tissue to another part of the body, e.g., skin graft. It is most successful transplantation.
2. Iso-graft:
It is transplantation from a twin brother or sister i.e., donor and recipient are genetically identical.
3. Allograft:
It is the transplantation between individuals of same species, but with different genetic background.
4. Xeno-graft:
It is transplantation between animals of different species. Tissue matching, blood group matching are essential before undertaking any graft/ transplant. Transplantation may result in the rejection of transplanted organs. The immune system recognizes the protein in the transplanted tissue or organs as foreign and initiates cellular immunity. To suppress the immune response during transplantation, histocompatibility antigen and immunosuppresants play an important role.
(i) Histocompatibility is the property of having the same or mostly the same alleles of a set of genes called the major histocompatibility complex. The major histocompatibility complex (MHC) is a set of molecules displayed on cell surfaces that are responsible for lymphocyte recognition and antigen presentation. It is encoded by several genes located on human chromosome 6. Major histocompatibility complex (MHC) is also referred as the HLA (or Human Leucocyte Antigen) System in humans.
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(ii) Immunosuppressive drugs or immunosuppressant’s are drugs that are used to prevent rejection. A kidney transplant from an identical twin is always successful. If kidney is transplanted from other person except twin is also successful with the use of an immunosuppressant. The drug, named cyclosporine is a good immunosuppressant. Cyclosporine A is produced by Trichoderna polysporum. It destroys T-cell mediated immune responses, while spares humoral antibody responses. This drug prevents rejection of kidney, heart and liver transplants.
