Xenografts or xenotransplantations are methods of organ or tissue transplant involving the use of donors that belong to a different species from that of the recipient. The medical term is derived from the Greek work “xenos” which roughly translates to “foreign”.

The technique is generally utilized as a rather controversial alternative to allotransplantation – which is the transfer of cells, tissues, or organs from two beings that are of the same species. Although it may be resorted to in some cases – especially in surgical cases that require immediate replacement for failing organs – xenografts are still a major issue in the medical field as they are very often deemed as unethical procedures that do not even guarantee complete success and fail-safe organ function. Some significant matters taken into consideration for xenografts includes the concern about the fact that tissue degeneration in animals undergoes a faster aging process than in humans, and, in addition, success rates of xenotransplantations are also frequently questioned.

Despite the various barriers that stand to the success and progression of the performance of xenografts, the technique has still remained in use due to the lack of sufficient human donors. Genetic alteration of cells and tissue acquired from animal donors has further strengthened the method of xenotransplantations since donated components may now be modified in order to decrease the chances of rejection by the human recipient’s immune system.

Animal tissue and organs most commonly and effectively used in xenografts are those obtained from chimpanzees, baboons, or pigs. The most notable forms of xenografts is the transfer of porcine heart valves to replace damaged and deficient human heart valves. Despite several success stories however, rejection still occurs and xenozoonosis, the transmission of infectious pathogens from the donor to the recipient, still exists as a potential complication.