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 transplantation is an effective therapy for end-stage organ failure and is widely practised around the world. According to WHO, kidney transplants are carried out in 91 countries. Around 66 000 kidney transplants, 21 000 liver transplants and 6000 heart transplants were performed globally in 2005.