New stem cells go back further
This image shows how human naive iPS derived cells (yellow/green cells) integrate in different tissues of developing host mouse embryo (red cells). One of the obstacles to employing human embryonic stem cells for medical use lies in their very promise: They are born to rapidly differentiate into other cell types. Until now, scientists have not been able to efficiently keep embryonic stem cells in their pristine stem state. The alternative that has been proposed to embryonic stem cells – reprogrammed adult cells called induced pluripotent stem cells (iPS cells) – have similar limitations. Though these can differentiate into many different cell types, they retain signs of "priming," – commitment to specific cell lineages. A team at the Weizmann Institute of Science has now taken a large step toward removing that obstacle: They have created iPS cells that are completely "reset" to the earliest possible state and maintained them in that...