A group of researchers from the University of Washington have successfully established a new line of naive embryonic stem cells. These stem cells represent the earliest developmental state yet for established cells, and retained the ability to give rise to the largest range of cells so far. In fact, these cells can develop into any cell type within the body in a process called pluripotency. 

Stem cells are cells that can differentiate (change) into other types of specialized cell. There are two main types; embryonic, which are derived from early embryos, and adult, which can be found in numerous different tissues. Stem cells have been the focus of much research in the recent years because of their inherent ability to be able to change into particular types of cells, a property which can be induced in the lab. This means that they have various therapeutic potentials, including regenerative medicine. Stem cells are already widely used in medicine today, for example in bone marrow transplantation. Despite their potential, there is concern in stem cell therapy that the cells may become cancerous if they do not stop dividing. 

Naive embryonic stem cell lines have been developed before by a different technique to that in this study. This was by creating transgenic cells via the insertion of certain genes, which induced the cells to become naive. While these cells are useful in laboratory research, unfortunately they cannot be transplanted into humans. 

In this study, published in PNAS, a group of researchers led by Dr. Carol Ware were able to successfully establish this cell line through the use of a technique called "reverse toggling". This involved taking stem cells that were further developed, and incubating them in a cocktail of factors which caused them to revert back to their naive state. These cells, called Elf1 cells, were then maintained in a specially developed tissue culture medium. They then used this medium to investigate whether they could create a stable naive cell line directly from naive cells harvested from donated embryos; and they succeeded, representing a major advance in the field. It is hoped that in the future these cell lines may be used for growing tissues and organs for transplantation.