Faculty voice: Amy Ralston: Lessons from the Mouse Embryo

  • Mar 18, 2016
  • Faculty & Staff, Research, Biochemistry

Amy Ralston

MSU College of Natural Science Assistant Professor Amy Ralston and her research team have identified the earliest possible source of stem cells in the mouse embryo.

When most animals begin life, cells immediately begin accepting assignments to become a head, a tail or a vital organ. However, the cells of mammalian embryos get to make a different first choice — to become the protective placenta or to commit to forming the baby. These events happen during the first four or five days of human pregnancy.

We have identified the earliest possible source of stem cells in the embryo. Pluripotent stem cells can either be produced when scientists reprogram mature adult cells, or created by embryos during the crucial four-day window of a mammalian pregnancy.

Embryos make pluripotent stem cells with 100 percent efficiency. The process of reprogramming cells, manipulating our own cells to become stem cells, is merely 1 percent efficient. Embryos have it figured out, and we need to learn how they’re doing it.

Our research team first discovered that in mouse embryos, the gene Sox2 appears to be acting ahead of other genes traditionally identified as playing crucial roles in stem cell formation. Now, we’re trying to decipher why Sox2 is taking the lead role.

We know Sox2 is the first indicator that a cell is pluripotent. In fact, Sox2 may be the pre-pluripotent gene. We show that Sox2 is detectable in just one or two cells of the embryo earlier than previously thought, and earlier than other known stem cell genes.

The second discovery is that Sox2 has broader influence than initially thought. The gene appears to help coordinate the cells that make the fetus and the other cells that establish the pregnancy and nurture the fetus. Future research will focus on studying exactly why Sox2 is playing this role.

What we’ve learned from the embryo is how to improve efficiency, a process that could someday lead to generating stem cells for clinical purposes with a much higher success rate.