Genetically Engineered Pigs to Save Lives

Xenotransplantation (inter-species transplantation) could solve the organ shortage problem. Pigs are suitable animals for this due their large litter sizes, their fast growth rate and because they can be reared in conditions which are pathogen free. They can be genetically modified to produce organs which the human body is less likely to reject on transplantation and although pig valves and skin has been used in human transplants, entire organs have not yet been used as immune system attack is much more aggressive when organs are transplanted between species, rather than within species.

Hyperacute rejection was avoided by genetically modifying some pigs to lack the gene alpha-1, 3-galactosyferase, which adds sugar molecules to its cells, as monkey and human immune systems aggressively reject this. Another hurdle, cell mediated rejection, where transplanted organs are rejected 1-2 weeks after transplantation due to attack by specific T lymphocytes, however immunosuppressive drugs can quieten this immune system response. Delayed xenograph reaction occurs within 3-5 days of the transplant, where platelet coagulation in the donor organ’s blood capillaries occurs due to activation of inflammatory responses. Through addition of human compliment modulating proteins, this can be suppressed. The use of pig organs in humans would gain significant health and economic benefits as the demand for organs may match the supply and money spent on caring for organ failure patients would be reduced. However, a concern is that pig organs could be carriers of unknown viruses along with ethical objections to using humanised animals as organ farms.