CONCEPTXenotransplantation isthe transplantation ofcells, tissues or organsfrom one species toanother, particularlytransplants from animalsto humans.It was formulated toovercome the shortageof donor organs.
TYPES OF XENOTRANSPLANTATION SOLID ORGAN XENOTRA NSPLANT CELLULAR HUMAN/A /TISSUE NIMAL TYPES XENOTRA HYBRID NSPLANT EXTERNAL THERAPIES
CHOOSING THE DONOR SPECIESTYPE BETWEEN EXAMPLECONCORDANT Closely related/si Baboon Human milar speciesDISCORDANT Distantly related/ Pig Human dissimilar species
OVERCOMING HYPERACUTE REJECTION•alter the organ source through using genetically engineeredpigs (e.g., pigs that will lack the α-Gal epitope and/or will havean artificially added gene[s] for human complement-regulatoryproteins (such as decay-accelerating factor)• alter the recipient by depleting naturally occurringantibodies directed against α-Gal (NXAs) prior to xenograftreceipt. Either approach to overcoming HAR may alsofacilitate the potential for the human recipient to be infectedby endogenous retroviruses from the pig xenotransplantationproduct.
2.Acute vascular xenograft rejection,ACXR
OVERCOMING ACUTE VASCULAR REJECTION•Administering a synthetic thrombin inhibitor to modulatethrombogenesis•Depletion of anti-galactose antibodies (XNAs) bytechniques such as immunoadsorption, to preventendothelial cell activation•Inhibiting activation of macrophages (stimulated byCD4+ T cells) and NK cells (stimulated by the release ofIl-2). Thus, the role of MHC molecules and T cellresponses in activation would have to be reassessed foreach species combo.
3.Cellular xenograft rejection,
A proposed strategy to avoid cellular rejection is to induce donornon-responsiveness using hematopoietic chimerism. Donor stemcells are introduced into the bone marrow of the recipient, wherethey coexist with the recipient’s stem cells. The bone marrow stemcells give rise to cells of all hematopoietic lineages, through theprocess of hematopoiesis. Lymphoid progenitor cells are created bythis process and move to the thymus where negative selectioneliminates T cells found to be reactive to self. The existence ofdonor stem cells in the recipient’s bone marrow causes donorreactive T cells to be considered self and undergo apoptosis.
4.Chronic xenograft rejection,
One concern raised about xenotransplantation is the risk of inadvertent transmission ofinfectious agents into xenotransplant recipients and subsequent secondary transmission of infections to the wider human population. This risk is an important obstacle to the use of this technology. The potential for secondary transmission of infections makes the risk of xenozoonoses a global issue. XENOZOONOTIC DISEASE RISK AND PREVENTION ISSUES
"O Adam! shall I lead thee to the Tree of Eternity and to a kingshipthat never decays?" (20:120). Satanalso said "I will mislead them, and I will create in them false desires; I will order them to have (in abundance) the animals ears cut (from the origin), and I will order them to change Allahs creation" (4:119).