The term cytokine is derived from a combination of two Greek words - cyto meaning cell and kinos meaning movement. Cytokines are cell signalling molecules that aid cell to cell communication in immune responses and stimulate the movement of cells towards sites of inflammation, infection and trauma.
Organs that have been successfully transplanted include the heart, kidneys, liver, lungs, pancreas, intestine, and thymus. Some organs, like the brain, cannot be transplanted. Tissues include bones, tendons (both referred to as musculoskeletal grafts), corneae, skin, heart valves, nerves and veins.
Organ procurement is a surgical procedure that removes organs or tissues for reuse, typically for organ transplantation. It is heavily regulated by United Network for Organ Sharing to prevent unethical allocation of organs. There are over 110,000 patients on the national waiting list for organ transplantation and in 2016, only about 33,000 organ transplants were performed. Due to the lack of organ availability, about 20 patients die each day on the waiting list for organs. Organ transplantation and allocation is mired in ethical debate because of this limited availability of organs for transplant. In the United States in 2016, there were 19,057 kidney transplants, 7,841 liver transplants, 3,191 heart transplants, and 2,327 lung transplants performed.