Imagine the following scenario. A few years from now, those who can afford it will contract cloning labs to grow clones to supply duplicate organs or replace body parts. Clones will be genetically matched to clients so they can be used in transplants without being attacked by the client’s immune system. To side-step the ethical argument of what is considered human, the client’s clones will be grown as headless embryos, without a brain or a central nervous system. Destined never to leave the lab, these cloned embryos will develop all the necessary body parts, including a heart, a circulatory system, lungs, and a digestive system. For those without deep pockets, the cloning labs will offer economy clones featuring one or more specific organs. Using embryo cloning techniques developed in Britain in the late 1990s, the cloning labs will grow these headless clones to match each stage of a child’s or adult’s development, so that organs will be available throughout the client’s life.
Bitte loggen Sie sich ein, um Zugang zu diesem Inhalt zu erhalten
According to the US Food and Drug Administration (FDA),
xenotransplantation refers to any procedure that involves the transplantation, implantation, or infusion into a human recipient of either (1) live cells, tissues, or organs from a nonhuman animal source or (2) human body fluids, cells, tissues, or organs that have had contact with live nonhuman animal cells, tissues, or organs. By this definition, nonliving biological products from nonhuman animals, such as porcine heart valves, are not xenotransplantation products. Depending on the relationship between donor and recipient species, the xenotransplant can be
concordant or
discordant. Concordant species are closely related species, for example mouse and rat. In contrast, discordant species are not closely related, as in the case of pig and human. A concordant recipient takes many days to reject an organ, whereas a discordant recipient may reject the organ within a few minutes or hours.
Transmissible spongiform encephalopathies are a family of fatal diseases of humans and animals that cause irreversible brain damage. The diseases are believed to be caused by
prions (specific proteins), which can jump the species barrier from, for example, cattle to humans. Transmissible spongiform encephalopathies have exhibited transmission to new hosts through transplanted grafts and across species lines. That patients manifesting signs of a possible xenosis after transplantation would have to be quarantined is not inconceivable.
