New cocktail encourages stem cell diversification

A team of international scientists have discovered a chemical cocktail that enables stem cells to regrow any type of tissue.

The study highlights how totipotent and omnipotent stem cells can be derived from both human and mouse embryos. Modelling early development processes and diseases affecting embryo implantation are two techniques that could be improved as a result of this discovery.

Professor Carlos Izpisua Bemonte, from the Salk Institute and co-author of the paper published in Cell, said: “During embryonic development, both the fertilised egg and its initial cells are considered totipotent, as they can give rise to all embryonic and extra-embryonic lineages. However, the capture of stem cells with such developmental potential in vitro has been a major challenge in stem cell biology. This is the first study reporting the derivation of a stable stem cell type that shows totipotent-like bi-developmental potential towards both embryonic and extra-embryonic lineages.”

Before the cocktail was created, the scientists screened chemical compounds that support pluripotency, discovering a combination of four chemicals and a growth factor was most effective. The cocktail stabilised immature human pluripotent cells, enabling a greater possibility of creating chimeric cells in developing murine embryos.

With the same cocktail was applied to murine cells, the team found that the new stem cells could not only produce embryonic tissue, but also form extra-embryonic cells, which then became the placenta or amniotic sac. These new stem cells could give rise to an entire adult mouse, which the researchers have said is unprecedented and have called extended pluripotent stem (EPS) cells.

Jun Wu, a senior scientist at Salk and first author of the paper, said: “The discovery of EPS cells provides a potential opportunity for developing a universal method to establish stem cells that have extended developmental potency in mammals. Importantly, the superior interspecies chimeric competency of EPS cells makes them especially valuable for studying development, evolution and human organ generation using a host animal species."

The researchers’ next step will be to test if these EPS cells could be used in transgenic animal models and creating replacement product organs. EPS cells could work in tandem with research published at the beginning of the year in Cell, on interspecies chimeras.  The team reported their success in growing a rat pancreas, heart and eyes in a developing mouse. Human cells and tissues were also grown in early-stage pig and cattle embryo, showing that an animal host could one day maybe grow organs for transplantation.