Muscle cells live for approximately 15 years. However, most of the tissues within the human body regenerate, and all the dead cells are replaced at some point during the lifespan of the body.
An accurate life span of a cell can be measured by applying the techniques of carbon-14 dating to the body's DNA. The research carried out by Dr. Jonas Frisen, a professor in stem cell research at the Karolinska Institute in Stockholm, showed that the majority of cells in the body are less than 10 years old, and he states he can measure their ages to an accuracy of two years. Skin cells are replaced roughly every two weeks, and adult liver cells have a life span of between 300 and 500 days.