Reconstructing the life history of a single cell

Researchers have developed new methods to trace the life history of individual cells back to their origins in the fertilised egg.

By looking at the copy of the human genome present in healthy cells, they were able to build a picture of each cell's development from the early embryo on its journey to become part of an adult organ.

During the life of an individual, all cells in the body develop mutations, known as somatic mutations, which are not inherited from parents or passed on to offspring. These somatic mutations carry a coded record of the lifetime experiences of each cell.

By looking at the numbers and types of mutations in a cell's DNA, researchers were able to assess whether the cell had divided a few times or many times and detect the imprints, known as signatures, of the processes of DNA damage and repair that the cells had been exposed to during the life of the individual. Furthermore, comparing each cell's mutations with those of other cells in the body enabled scientists to map out a detailed tree of development from the fertilised egg.

"With this novel approach, we can peer back into an organism's development," says Dr Sam Behjati, first author from the Wellcome Trust Sanger Institute. "If we can better understand how normal, healthy cells mutate as they divide over a person's lifetime, we will gain a fundamental insight into what can be considered normal and how this differs from what we see in cancer cells."