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![OVERCOMING HYPERACUTE REJECTION
•alter the organ source through using genetically engineered
pigs (e.g., pigs that will lack the α-Gal epitope and/or will have
an artificially added gene[s] for human complement-regulatory
proteins (such as decay-accelerating factor)
• alter the recipient by depleting naturally occurring
antibodies directed against α-Gal (NXAs) prior to xenograft
receipt. Either approach to overcoming HAR may also
facilitate the potential for the human recipient to be infected
by endogenous retroviruses from the pig xenotransplantation
product.](https://image.slidesharecdn.com/xenotransplantation-130202201601-phpapp02/75/Xenotransplantation-9-2048.jpg)
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Xenotransplantation
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- 2. CONCEPT Xenotransplantation is the transplantationof cells, tissues or organs from one species to another, particularly transplants from animals to humans. It was formulated to overcome the shortage of donor organs.
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- 5. TYPES OF XENOTRANSPLANTATION SOLID ORGAN XENOTRA NSPLANT CELLULAR HUMAN/A /TISSUE NIMAL TYPES XENOTRA HYBRID NSPLANT EXTERNAL THERAPIES
- 6. CHOOSING THE DONORSPECIES TYPE BETWEEN EXAMPLE CONCORDANT Closely related/si Baboon Human milar species DISCORDANT Distantly related/ Pig Human dissimilar species
- 7. TRANSPLANTATION REJECTION;IMMUNOLOGICAL BARRIERS 1.Hyperacute xenograft rejection,HXR 2.Cellular xenograft rejection, 3.Acute vascular xenograft rejection,ACXR 4.Chronic xenograft rejection,
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- 9. OVERCOMING HYPERACUTE REJECTION •alterthe organ source through using genetically engineered pigs (e.g., pigs that will lack the α-Gal epitope and/or will have an artificially added gene[s] for human complement-regulatory proteins (such as decay-accelerating factor) • alter the recipient by depleting naturally occurring antibodies directed against α-Gal (NXAs) prior to xenograft receipt. Either approach to overcoming HAR may also facilitate the potential for the human recipient to be infected by endogenous retroviruses from the pig xenotransplantation product.
- 10. 2.Acute vascular xenograftrejection,ACXR
- 11. OVERCOMING ACUTE VASCULARREJECTION •Administering a synthetic thrombin inhibitor to modulate thrombogenesis •Depletion of anti-galactose antibodies (XNAs) by techniques such as immunoadsorption, to prevent endothelial cell activation •Inhibiting activation of macrophages (stimulated by CD4+ T cells) and NK cells (stimulated by the release of Il-2). Thus, the role of MHC molecules and T cell responses in activation would have to be reassessed for each species combo.
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- 13. A proposed strategyto avoid cellular rejection is to induce donor non-responsiveness using hematopoietic chimerism. Donor stem cells are introduced into the bone marrow of the recipient, where they coexist with the recipient’s stem cells. The bone marrow stem cells give rise to cells of all hematopoietic lineages, through the process of hematopoiesis. Lymphoid progenitor cells are created by this process and move to the thymus where negative selection eliminates T cells found to be reactive to self. The existence of donor stem cells in the recipient’s bone marrow causes donor reactive T cells to be considered self and undergo apoptosis.
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- 15. One concern raisedabout xenotransplantation is the risk of inadvertent transmission of infectious 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
- 16. "O Adam! shallI lead thee to the Tree of Eternity and to a kingship that never decays?" (20:120). Satan also 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 Allah's creation" (4:119).
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