Human stem cells that are capable of becoming any other kind of cell in the body have previously only been acquired and cultivated with difficulty. A team of European scientists including researchers from the University of Bath has now developed a method to detect such pluripotent cells in a cell culture and preserve them in the laboratory.
"With our guidelines it should be possible for researchers all over the world to obtain these coveted stem cells and, possibly, to develop pioneering treatments with them," says the senior author of the study, Zsuzsanna Izsvák at the Max Delbrück Center for Molecular Medicine (MDC) in the Helmholtz Association, Berlin, Germany.
Her team has been working with Professor Laurence Hurst, Director of the University of Bath's Milner Centre for Evolution in the Department of Biology & Biochemistry and with colleagues from the Paul Ehrlich Institute in Langen, Germany and published the procedure in the scientific journal Nature Protocols.
Scientists hope in the future to use pluripotent stem cells, from which it is theoretically possible to cultivate every type of tissue, to cure a variety of diseases.
Professor Hurst explained: "Most stem cells are primed to some extent to become a certain type of cell. If you use the analogy of a train network, these cells are like one of the main London stations. Trains from Paddington can go to Cardiff or Exeter, but not to Norwich. In the same way, these cells can develop into a fixed number of different cell types.
"However naïve-like pluripotent stem cells are like a central terminus; they are present earlier in the embryo's development and so we think their fates can go in any direction and become any type of cell."
In contrast to, for example, those of mice, human stem cells removed from embryos in the laboratory quickly lose their original state: "Naive stem cells usually make up less than five percent of a cell culture," explains Izsvák.
She and her colleagues have therefore devised a trick to isolate such cells and keep them pluripotent for longer.
The researchers had already presented their methodological principles in late 2014 in the scientific journal Nature. At that time, they had located a sequence named HERVH, which is active in the genetic material of naive stem cells.
Using a reporter gene, which they had linked to a fluorescent protein, the researchers were able to maintain HERVH in an active state and simultaneously detect the cells that had retained pluripotency.
Izsvák notes that this method is suitable not only for embryonic stem cells, but also for induced pluripotent stem cells. These iPS cells are considered an ethically neutral alternative to embryonic cells, because they are artificially rejuvenated mature cells taken from adults.