XENOTRANSPLANTATION

CONCEPT

Xenotransplantation is the transplantation of 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.

HISTORY

STATISTIC

S

TYPES

SOLID ORGAN XENOTRANSPLA

NT

CELLULAR

/TISSUE XENOTRANSPLA

NT

EXTERNAL

THERAPIES

HUMAN/

ANIMAL HYBRID

TYPES OF XENOTRANSPLANTATION

CHOOSING THE DONOR SPECIES

TYPE BETWEEN EXAMPLE

CONCORDANT Closely related/similar species

Baboon Human

DISCORDANT Distantly related/ dissimilar species

Pig Human

TRANSPLANTATION REJECTION;IMMUNOLOGICAL

BARRIERS

2.Cellular xenograft rejection,

1.Hyperacute xenograft rejection,HXR

3.Acute vascular xenograft rejection,ACXR

4.Chronic xenograft rejection,

1.Hyperacute xenograft rejection,HXR

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.

2.Acute vascular xenograft rejection,ACXR

OVERCOMING ACUTE VASCULAR REJECTION

•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.

3.Cellular xenograft rejection,

OVERCOMING CELLULAR REJECTION

A proposed strategy to 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.

4.Chronic xenograft rejection,

XENOZOONOTIC DISEASE RISK AND PREVENTION ISSUES

One concern raised about 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.

ISLAM’S PERSPECTIVE ABOUT XENOTRANSPLANTATION

"O Adam! shall I 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).

THANK YOU !