Organ transplantation is the moving of an organ from one body to another or from a donor site to another location
on the patient’s own body, for the purpose of replacing the recipient’s damaged or absent organ. The emerging field
of regenerative medicine is allowing scientists and engineers to create organs to be re-grown from the patient’s own
cells (stem cells, or cells extracted from the failing organs). Organs and/or tissues that are transplanted within the
same person’s body are called autografts. Transplants that are recently performed between two subjects of the same species
are called allografts. Allografts can either be from a living or cadaveric source.
Organs that can be transplanted are the heart, kidneys, liver, lungs, pancreas, intestine, and thymus. Tissues include
bones, tendons (both referred to as musculoskeletal grafts), cornea, skin, heart valves, and veins. Worldwide, the kidneys
are the most commonly transplanted organs, followed closely by the liver and then the heart. The cornea and musculoskeletal
grafts are the most commonly transplanted tissues; these outnumber organ transplants by more than tenfold.
Organ donors may be living, or brain dead. Tissue may be recovered from donors who are cardiac dead – up to 24 hours past
the cessation of heartbeat. Unlike organs, most tissues (with the exception of corneas) can be preserved and stored for up
to five years, meaning they can be “banked”. Transplantation raises a number of bioethical issues, including the definition
of death, when and how consent should be given for an organ to be transplanted and payment for organs for transplantation.
Other ethical issues include transplantation tourism and more broadly the socio-economic context in which organ harvesting
or transplantation may occur. A particular problem is organ trafficking. Some organs, such as the brain, cannot yet be
transplanted in humans.