器官移植: Organ transplant
Organ transplantation is the moving of an organ from one body to another, or from a donor site 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 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, while musculoskeleletal transplants outnumber them by more than tenfold.
Organ donors may be living, or brain dead. Blood 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.
In the United States of America, tissue transplants are regulated by the U.S. Alcohol and Drug Administration (FDA) which sets strict regulations on the safety of the transplants, primarily aimed at the prevention of the spread of communicable disease. Regulations include criteria for donor screening and testing as well as strict regulations on the processing and distribution of tissue grafts. Organ transplants are not regulated by the FDA.
Transplantation medicine is one of the most challenging and complex areas of modern medicine. Some of the key areas for medical management are the problems of transplant rejection, during which the body has an immune response to the transplanted organ, possibly leading to transplant failure and the need to immediately remove the organ from the recipient. When possible, transplant rejection can be reduced through serotyping to determine the most appropriate donor-recipient match and through the use of immunosuppressant drugs.
In most countries there is a shortage of suitable organs for transplantation. Countries often have formal systems in place to manage the process of determining who is an organ donor and in what order organ recipients receive available organs.
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